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E30 BMW Buying Guide Translated from German

May 15, 2010
By

If you’re in the market for an BMW E30 (1983-1991 well technically to 1994 but let’s not get all technical :)) you should probably have a look at this buyers guide. Got this write up from http://www.e30forum.de/diyfaq/kaufberatung/kaufberatung.htm unfortunately it is in German… fortunately i have done my best to translate it to English! Enjoy! I have added and changed quite a few things that I felt were necessary, but more or less kept the main points and guidelines the same. If you dont want to bring this whole big writeup with you when viewing a car i highly recommend just printing off the pictures with boxes around the problem area’s so to remind you of the places to look.

Here we would like to present a comprehensive buying guide for the E30.

Whether you haven’t bought an E30 yet, or perhaps already have and would just like to have a look over the weak points; you’re in the right place! Most of the stuff in brackets is me talking not the creator of this write up.

First we will define all the models that were under the E30 chassis code. Then I will continue with fundamental technical weaknesses of the E30. From there we continue onto the typical E30 Rust points (let it be known that rtsauto believes that rust is the cancer and devil of cars) and also other general vulnerabilities. Forth we will cover the engines that were available to E30 Models (minus s14 and aplina/hartge engine). To the best of our knowledge we here have produced the most comprehensive E30 buying guide.

Legend:

1 - The vehicles
2 - technical vulnerabilities
3 – Body and rust points
4 - E30 motors and their Vulnerabilities

1 – The Vehicles

Here is a brief overview of the models under the E30 chassis code (minus Z1 and alpina/hartge models).

316: (now rare) carbureted and is fairly thirsty so it doesn’t necessarily get the best gas mileage, and comparatively to other e30’s has poor performance.

316i: Has an M40B16 engine (1.6L) that produces about the same amount of power as the M10B18 (1.8L)

318i: In Europe 1982-1987 318i – 1.8 L M10B18 I4, 105 PS (77 kW; 104 hp) 1987-1994 318i – 1.8 L M40B18 I4, 115 PS (85 kW; 113 hp)

In North America it was only offered for one year 1984-1985 318i – 1.8 L M10B18 I4, 101 hp (75 kW) and again in 1990-1991 (as assumed from http://bmwfans.info/parts/catalog/E30/4-doors/USA/318i-M42/LHD/M/) sold only in north america as a 318i with a m42b18, contrary to the m40 the Europe version had.

318is: Offered for one year in north America and Three years in Europe it had the M42B18 (1.8L) which produced a nice 134hp and was a “sport” model. Meaning it had sport seats an optional limited slip diff, and sport suspension. So it’s a nice little handling car.

320i: Super quite, introduction to the 6 cylinders of the E30 Chassis but it burns to much gas for its power (like a 318i) some may say it burns even more than a 325i.

323i: Usually doesn’t have a catalytic converter (I personally don’t think it’s a problem), but otherwise its super

325i: Smooth operation, barely more expensive than 318is/320i to maintain but a much better car. It might be described as the all around best bang for the buck model, it can be used to take your grandma shopping and then later in the day be a nice car on the Nurburgring.

325is: 2 door, limited slip, sport seats, sports suspension came standard. All of which were options for the 325i.

325e: m20b27 2.7 liter economy version of the m20 engine (the 325i had m20b25 a 2.5 liter engine) don’t be fooled though even though it has a higher displacement it produces significantly less horse power and only a little bit more torque. The 325i is what you want. However a m20b27 block and a m20b25 head can be mated to make a stroker that has a nice amount of horse power and torque.

M3: a pure driving machine, anything but reasonable / economical, the m3 has a s14 4 cylinder some would call “race” engine that loves to live up in the high revs (someone told me that in the manual it advises you to go onto the highway and rev it high after a certain amount of time of city driving, but this could just be a myth). Personally unless you have a lot of money I would stay away from this car. The rebuild cost on a s14 is astronomical and parts are but impossible to find used and even sometimes new.

324d: Should be an alternative to the 324td because they both use about the same amount of diesel, however produces less horsepower.

324td: a typical diesel in the late 80s, adequate performance and low consumption. These have a forged (instead of cast) crankshaft that is perfect for a turbo build in a gasoline m20.

2 - Technical vulnerabilities

Here are the typically identified E30 Vulnerabilities.
All displayed weak points apply equally to Sedan, Convertible Touring and
Baur TC’s ..

The following are all of the known technical weaknesses of the engine, drive train, steering and suspension on the BMW E30.
We will explain briefly what is known about this vulnerable area, and the cost and urgency of repair.
Rear shock mounts:

The rear shock mounts connects the shock absorber to the body. When driving over pavement edges if a noise is heard from the rear than that is probably the problem. Defects should be immediately corrected here, as in extreme cases; the shock separates from the body (I have seen it happen because of rust also). Cost is dependent on how extensive the problem is, but usually 20-50EUR.

Subframe bushings:

The rear sub frame bushings connects the subframe with the rear portion of the body. Only visual inspection is needed. If the bushing is exessivly worn it should be fixed as soon as possible because it has a negative effect on handling (I have also seen a case where it tore right off and the subframe fell of the body and started dragging. Some special tools are necessary. An experienced or willing Do it yourselfer can do this however special tools may need to be bought or rented. Both Bushings cost about 50EUR. Labor shouldn’t be more then at a honest auto shop 150EUR.

Parking Brake:

The normal brake intervals shouldn’t create any problems with the regular brakes. However, more attention should be given to the parking brake (hand brake), at least for cars with rear disc brakes. In some cases the hand brake is loose or doesn’t engage fully. To determine the condition of the brake apply the emergency brake very slowly when driving. If you find its loose then a tightening should be able to fix the problem. If not the cost of new brake pads for the brakes are approximately 30 EUR.

Differential:

The rear axle differential (differential gear) gives power to the rear wheels at a certain ratio (more acceleration or more top speed) and can be ether open (one wheel peel in the winter) or limited slip that makes both rear tires spin simultaneously. There are 2 different things that can cause “Singing” in a differential. First, it can be due to the rubber mounts that connect it to the axle or the drive shaft connector, Second it can be do to and increased wear in the differential.
Old oil may be responsible for the noise also try replacing it with good fresh oil. Sometimes the gasket on the differential leaks so check it and tighten it or replace the gasket if it is leaking! With too little oil it will break. If it is “broken”, depending on the extent it will cost 30 to 150-EUR. Worst case scenario a used diff can be had used for roughly 200-300 dollars. If you’re replacing the diff this would be a good time to upgrade to a limited slip if you have an open diff!

Guibo/flex disk on the driveshaft:

The Guibo and the center bearing dampers vibrations from the driveshaft.
If there is a defect in the guibo, then usually impacts in the driveshaft become noticeable .If the center bearing is damaged, it can be a cause to “singing” sound. The sound maybe be coming from the differential so check both. The parts cost approximately 50, – EUR.
A repair is feasible for the do it yourselfer, however, don’t forget you will have to take off the exhaust and driveshaft: so plan accordingly!

Transmission:

The transmission of the E30 is prone to leaks especially at the oil gasket of the gear output shaft.
The new gasket is about 10 EUR however plan accordingly because you will have to take off the exhaust and driveshaft also.

Circuit / shift linkage:

For vehicles with mileage from about 150,000km, the shifter becomes “sloppy” and has a lot of play. Parts shouldn’t cost more then 100 depending on what your replacing (can be as minimal as a cir-clip/washer, but if you’re going to do it I recommend replacing all wear parts and making it good as new.)

Central Lock:

The central locking should be tested at every lock/unlock location including the two front doors and trunk. It is common to have the front doors not work but the trunk to work.
If there is a defect, then the cause could be a defective control motor, oxidized cable connections on the control unit. Used parts should be cheap to get, however it is a common problem so depending on what is broken try getting new parts if possible.

Control arm / tie rod ends:

The wishbone, or more precisely the outer ball joint of the control arm, is worn in uniform routine. A typical BMW weakness. It is a relatively easy and cheap repair, but is the development arm of the advance. The ball joint can be replaced (except for in the aluminum m3 control arms). However it might just be better to replace the whole control arm which comes with the balljoint for roughly 100-200 dollars. Or if the balljoint on the tie rod is worn a replacement shouldn’t be more than 100 dollars.

Steering rack:

There are often leaks for the vehicles with power steering. Best case scenario it is only a loose hose connection, and power steering becomes resealed again. However a full rebuild is usually in need. (Cost: about 300,-EUR). You can usually do it yourself seals are about 50,-EUR.

Fan clutch/Fan:

The fan of the E30 is not driven constantly, rather mechanically by
viscosity clutch which engages and disengages. The advantage is that the fan only works when it’s necessary. Thus less power is robbed from the engine. However, there is one drawback, the coupling is a commonly a breaking point. A new one is roughly 100 while used it can be had for 20. When in storage the fan should be left standing because if you lay it down the oil could leak out and make it useless.
It can easily be don’t by Do it yourselfers, 32 mm wrench is needed (WARNING: Reverse threaded).

Front Shock mounts:

The Front shock mounts connect the shock to the body. At high mileage and even with lowered vehicles the mount is worn. It can usually be defined as making a sound when going over a bump/imperfection in the road. Replaceable for 120 ,-EUR, don’t forget spring tensioners and air tools!.

Cylinder head / valve train/ timing belt

The six-cylinder (M20, 320i, 323i, 325i, 325e) the headgasket or head is prone to failure a very easy way to identify if this has happened is to check if there is coolant in the oil (take the oil cap off it you see milky looking stuff on the cap then run and run fast…. Or get a damn good deal on the car because you’re going to need a new engine/rebuild).

Do not forget to change the timing belt water pump and tensioner at least every 60,000 miles (100,000 km). If it fails say goodbye to your engine.

In the first four-cylinder models is the old M10, M40 and the newer modern M42 engine to distinguish between.
The newer M40 engine is very prone to broken-cams. It can be avoided with good maintenance.

For more information refer to “E30 motors and their Vulnerabilities

3 – Body and rust points

This section focuses on the “weakness” areas of the E30 body.
First and foremost, we will demonstrate the usual areas for rust, but also the technical weaknesses of the body are shown here.

We start with probably the most common type, the sedan/coupe, in addition to the convertible and Touring.

The baur top cabriolet takes a privileged position.
When speaking purely about the body it is technically very similar to the 2 door coupe, the baur is covered at the end of this subsection.

Each framed body in the pictures shows a vulnerability.

The Cabriolet has the following weaknesses in addition to the sedan/coupe:

The Touring has the following weaknesses in addition to the sedan/coupe:

Generally speaking, edges rust almost always on older vehicles. Consequently, there will be no extra mention of such areas. When inspecting the car all edges should be searched;all door edge, hood edges and trunk.

Rust and its control is a very large topic. I here at rtsauto I believe the correct way to avoid rust is to rustbullet or POR-15 as much of the car as possible; that includes but not limited to, under the carpets, the trunk, the under body, under trim (not over paint), etc. and virtually any area you can get your hands on that will not affect the exterior look of the car. The rest (ie painted portions) should be cleaned and waxed, and if you’re going to drive it in the winter por15 and/or rust bullet even more, and then get it rust proofed by a place that doesn’t drill holes.

Sunroof

Unfortunately the e30 is prone to rust on and around the sunroof. It should be looked over closely at the seams (sunroof open) for rust that may already be present. A repair is extremely expensive. These repairs are extremely complex in such areas. Consider if the car is worth dumping an extra few thousand dollars into. Rust repair and paint isn’t cheap for the good places, never trust macco!

Front valance:

Later years had galvanized Front valances but not all, stone chips are inevitable especially if your car is lowered. With a really low car the paint may be scuffed off which will induce rust to form quicker.
A replacement is still relatively easy to find, usually relatively Inexpensive. A swap is just time consuming but can be done fairly easily.

Side mirrors:

The side mirrors are a real weakness. Without external influence, it rusts here more quickly. However in my experience (rtsauto) I find that they are aluminum and oxidize instead of rust which makes the paint fall off and pitting to occur, sanding/painting should take care of the problem, or you should be able to get a pair for relatively cheap used.

Taillights:

The headlight seals lose their elasticity over time, water flooding in from rain/washing is the result. The water accumulates mostly on the left and right in the side tanks of the trunk (battery area on the right, and on the left the area where the factory jack goes),in the spare wheel well, and under the carpet where the battery wiring goes into the cabin on the right. Thanks to carpets water usually stays for longer then it should which thus accelerates rust. There is also sometimes rust around the taillights, catch it as soon as possible the bigger it gets the more it costs to fix. The seals cost a few Euros and can be changed by almost anyone.

Rear license plate area:

Look around where the 2 lights are that illuminate the license plate in the back. Then open the trunk and look under the plastic at the edge of the trunk, then check under the trunk seals. All these places are VERY common places for rust. Repairing isn’t cheap! Be careful when lifting the trunk seal as it may be old and brittle, it may break apart instead of lift up in one piece.

Exhaust cut-out:

Usually associated with 1988+ E30’s because of updated bumpers; If the e30 has rust it has it around the Exhaust cut out because of the sharp edge after cutting. Repairing is complex if it’s serious, if its minor a patch should do.

Right side of rear valance/tow hooking area:

Usually associated with 1988+ E30’s because of updated bumpers; If the e30 has rust it has it around the right side area of the valance where the tow hooking area is. The U shaped holder seems to be the culprit for inducing rust around this area.

Fenders on the front:

The fenders are major areas for rust because it usually is struck by rocks flying off the tires and a haven for water to get trapped after it flies off the tire (I recommend OEM mudflapps). It usually isn’t worth repairing try finding an OEM set… aftermarket has a shitty fitment. Then make sure to wax it specifically at the bottom right (bottom right of the driver’s fender, bottom left of the passenger fender) where it connects to the body/meets the door because that is the most common place for rust.

Window frame (windshield):

Here, too, seems to be Factory weakness. Usually rusts from the inside (probably the water drains/seals). A very common area is one the left and right A pillars; fix it ASAP and remember because its probably rusting from the inside out its probably a hell of a lot worse than it looks. The windshield should be removed in case of rust repair to make sure you are getting all of it.

Rear side windows Convertible:

If during a test drive the rear window rattles or whistles then you need to adjust/change the washers so there is no play. Almost anyone can do this. Refer to: Setting Cabrio washers.

Top electric drive:

A common fault is not the motor rather the gears, but even then the gears aren’t week, what causes it to break is the lack of care given to a cleaning and lubing the rods which puts more and more tension on the gear until it can’t handle it no more. Motor-gear replacement is about 350 EUR.

Rear seat:

The rust preventive under the back seat doesn’t seem to be covered often. However it is often that around the plate underneath rust seems to form. At rtsauto as I stated before the best solution is to por15 or rust bullet the living hell out of such areas.

Rear wheel well:

In Touring and Convertible rear wheel arches are often places to look for rust. Severity ranges from surface rust to all out swiss cheese. Repairs take extensive welding skills and thus cost a lot to fix + the cost of paint.

Strut Brace Convertible:

Unlike the sedan and Touring, a convertible is structurally weaker because it lacks the top portion of its body. I highly recommend getting a strut brace for the engine bay. It makes your car more ridged by keeping the struts from .

Tailgate of the Touring:

The tailgate of the Touring is certainly no masterpiece of BMW. Adjust valves, replace the dried out seal to keep water out and you should be fine.

Make sure the tailgate drainage is clean of dirt and junk.

Tailgate hinge Touring:

The washer fluid tubes may very well need to be replaced at this age you will need about 3 meters worth. And check the hinges themselves for rust.

Rear window wiper

Problem one is that it doesn’t go back and forth properly which is the fault of the motor/gears. Second is where it rests it should rest horizontally not vertically the later should be able to fixed with a new switch the first needs a new motor/gears.

The Baur-Topcabriolet
The “exotic”

In the years 1983-1991 Baur provided an BMW E30 called the “Baur-Topcabriolet”.
They were offered at BMW dealerships as a conversion for 3500 Euro to the 2 door.
Essentially it is a more ridged convertible.

The Baur is based on a normal two-door model.

First of all one: you should absolutely make sure that all the Baur-parts are in good condition, as these parts are very rare and are now almost worth as much as gold.
This is especially true for the somewhat unstable adjustment mechanism for the elevating roof ( picture 1, picture 2 ) and for the GRP and foam, consisting of the hard-top ( Fig. 3 ) and the closures of the top ( Figure 4 ). Here hooks break from the manufactured zinc die a lot.
These three positions are particularly vulnerable and therefore are rare.

Otherwise make sure the trim on the outside of the B-pillar is not missing and the rear side windows are intact, and both are the real deal; because normal sedan windows almost look identical to the real deal.
( Fig. 5 ).

Make sure the roof mechanism itself is solid and has no problems ( Fig. 6 ) .

Changing the hardtop is practically impossible due to the way it separates.

Inside, the rear side panels should be intact
( Figure 7 )

The actual conversion in the body area is nearly indestructible, because the places that were converted were galvanized.( Fig. 1 , Figure 8 ).

Generally, even when buying a Baur: the car with less rust is the best option. Remember it is always cheaper to fix a shitty engine/mechanics then it is to fix rust.

And lastly it is a better car to be in during an accident over a cabrio!

4 - E30 motors and their Vulnerabilities
Here are the E30 engine specific weaknesses.

All shown weaknesses apply equally to Sedan, Convertible and Touring.
Direct links:

1 - M10 engine
2 - M40-Motor
3 - M42 engine
4 - M20 engine

The M10 Engine:

The M10 engine is the oldest of the four-cylinder E30.It was originally in the E21 and was available in the E30 until the introduction of the M40 in a carbureted and fuel injected form. It is the most reliable engine in the family of 4 cylinders and was even used as a basis for Formula 1 cars. Even with its age it still manages to get less than 10 km per 100k (More than 23 miles per gallon). A convertible was never offered with this engine.
The power ranges from a 89hp/140Nm (316 carburetor) to 104hp/145Nm (318i without CAT).

Fan Clutch:

The fan of the E30 is not driven constantly, rather mechanically by
viscosity clutch which engages and disengages. The advantage is that the fan only works when it’s necessary. Thus less power is robbed from the engine. However, there is one drawback, the coupling is a commonly a breaking point. A new one is roughly 100 while used it can be had for 20. When in storage the fan should be left standing because if you lay it down the oil could leak out and make it useless.
It can easily be don’t by Do it yourselfers, 32 mm wrench is needed (WARNING: Reverse threaded).

Water pump:

If the water pump fails then it will stop circulating coolant and you will realize a fairly quick rise of the coolant gauge needle. Don’t let your car over heat! Replacing can be done by a do it yourselfer, a lot time for draining the coolant and refilling it. Parts should be around $50.

Timing Chain:

Unlike the M40, M42 and M20 the M10 has a timing chain instead of a timing belt. Basically it allows for A LOT of miles without changing, it’s a chain, its metal you don’t need to change it like rubber that dries out (ie timing belt) replacing is time consuming and costly. Periodically check the tensioner.

Camshaft:

A potential fault of all these engines, usually caused by neglected maintenance; The M10 however is the least destructible of all of the engines mentioned. Its one tough motor!

Rocker:

Just like the M20 engine the M10 also has rocker arms if one breaks say goodbye to your cylinder.

Distributor cap and rotor:

The distributor cap and rotor are wear items and should be replaced after a while for roughly $80. It can be done by almost anyone.

Piston bearings:

Although the piston bearings are not a typical weak point, it should still be mentioned.
In general, all piston bearings in engines are wear parts (also the bearings of the crankshaft).
This is, however, in most cases within compliance think about replacing them after about 200,000 km
illustration (in German, I’ll try in the future to convert this to English also) using the M20 engine: connecting rod service.

The M40 engine

The M40 engine is the smallest in the E30 family. It was produced from 9 / 87 (318i) or 9 / 88 (316i) was used until the end of production (1994 Touring). As usual as all four-cylinder engines, the M40 is a revvy engine, even with its small size it creates an admirable amount of power; 101hp/142Nm in the 316i and 118hp in the 318i.

Piston bearings:

Although the piston bearings are not a typical weak point, it should still be mentioned.
In general, all piston bearings in engines are wear parts (also the bearings of the crankshaft).
This is, however, in most cases within compliance think about replacing them after about 200,000 km
illustration (in German, I’ll try in the future to convert this to English also) using the M20 engine: connecting rod service.

Rockers arm / Valves train:

Being hydraulic unlike the m10 and m20 the valves train adjusts itself and is practically maintenance free. It is normal for it to make a clacking noise during warm up and should be mistaken for being broken: However, if after warm up the clacking continues then the hydraulic system has most likely failed. Any repairs here are recommended to be performed by a shop.

Camshaft:

The camshaft is very vulnerable in the M40. If the motor is not regularly serviced (oil and filter change) if not done then the oil film will become virtually nonexistent. What happens: metal rubbing on metal, the camshaft has increased wear, (technical term: Worn camshaft). Power loss is the result. An exchange of the camshaft is needed which is very expensive. (Original 280 EUR, 500 EUR optimized camshaft (www.motorrevision.de). Also revving a cold engine has an identical effect, so don’t do it!
If you have faith in yourself then you can do it, if not have a shop do it.
Guidelines: camshaft

Injectors:

Usually not a problem but if they clog then you will fell a power loss especially under load. Its recommended you just get them refurbished rather than the significantly more expensive route of getting them new.

Distributor cap and rotor:

Wear item and can oxidize. Rough running engine and misfiring can be products of a bad distributor cap and rotor. An easy job to replace.

Thermostat:

If your temp gauge is acting funny (to high or to low) or is not warming up after a long time then consider changing the thermostat as it controls the opening of a coolant valve at a certain temperature.

Water pump:

If the water pump fails then it will stop circulating coolant and you will realize a fairly quick rise of the coolant gauge needle. Don’t let your car over heat! Replacing can be done by a do it yourselfer, a lot time for draining the coolant and refilling it. Parts should be around $50.

The M42 Engine

The M42 engine is the most modern of all the E30 engines. The M42 was in the 318is (135hp/172Nm 1988-1991,  1990-1991 in the 318is and 318i in North America). This is the only 4 valve per cylinder designed engine in the range of e30 engines except for the s14 in the m3. There has never been a convertible with this engine; A very revvy engine that has a sporty feel.
Piston bearings:

Although the piston bearings are not a typical weak point, it should still be mentioned.
In general, all piston bearings in engines are wear parts (also the bearings of the crankshaft).
This is, however, in most cases within compliance think about replacing them after about 200,000 km
illustration (in German, I’ll try in the future to convert this to English also) using the M20 engine: connecting rod service.

Valve train:

Being hydraulic unlike the m10 and m20 the valves train adjusts itself and is practically maintenance free. It is normal for it to make a clacking noise during warm up and should be mistaken for being broken: However, if after warm up the clacking continues then the hydraulic system has most likely failed. Any repairs here are recommended to be performed by a shop.

Duplex timing chain:

Compared to the M40 engines the IS has a timing chain where most engines have a timing belt.
This has advantage because unlike the belt it doesn’t tear. However if its not oiled then you will have problems. Make sure the chain tensioner is in good condition because repairs are very expensive. Minimal rattle is fine under 3000rpm but if it persists higher in the rev range then the solution may get very expensive.

Thermostat:

If your temp gauge is acting funny (to high or to low) or is not warming up after a long time then consider changing the thermostat as it controls the opening of a coolant valve at a certain temperature.

Water pump:

If the water pump fails then it will stop circulating coolant and you will realize a fairly quick rise of the coolant gauge needle. Don’t let your car over heat! Replacing can be done by a do it yourselfer, a lot time for draining the coolant and refilling it. Parts should be around $50.

The M20 Engine

Der M20-Motor.

The M20 engine is the six-cylinder engine of the E30. The M20 was produced throughout the production of the E30 (1982-1994, from 1982 to 1986 without standard CAT’s). It is refined, powerful and reliable. It makes 128hp/164Nm (320i from 1985),149hp/205Nm (323i from 1983) to 168hp/222Nm (325i 1986). The performance of the M20 engine varied over the years of construction, precise details can be found in this list.

Distributor cap and rotor:

Wear item and can oxidize. Rough running engine and misfiring can be products of a bad distributor cap and rotor. An easy job to replace.

Valve train / valve clearance:

If you notice a valve tick adjust the clearance of the valve train. This should be done every 15,000Km but usually people wait a lot longer for some reason. Another possible cause on top of valve tick is smoke out of the exhaust because if the clearance is off the valve will not seal right and thus produce bad combustion and thus smoke out of the exhaust.

Rocker arms:

The rocker arms are the link between the camshaft and valve. The control cams of the camshaft push against the rocker arm, which sit on a shaft. A failure usually means a destroyed cylinder.
An experienced Do it yourselfer can do this job.

Injectors:

Usually not a problem but if they clog then you will fell a power loss especially under load. Its recommended you just get them refurbished rather than the significantly more expensive route of getting them new.

Fuel pressure regulator:

The fuel pressure regulator is not generally prone to defects. However, power loss, and bad throttle response are usually symptoms.

Cylinder head

The head gasket and cylinder head (by virtue of warping/cracking) is prone to failure around the 5th and 6th cylinder area. Check the oil cap for a milky looking substance it may indicate coolant in the oil which means a bad head gasket or warped/cracked head. Also check the coolant reservoir for oil. The engine oil may have moisture in it (creating the milky substance) if it has been sitting for a long time, but in ether case don’t run your car on this milky concoction change the oil and see if the milky substance reoccurs.

Throttle / Idle Control:

With the engine running problems may be stuttering, too little power, hesitates, and a bad or inconsistent idle.

The idle problem is usually a vacuum leak notably check the elbow from the AFM to the intake manifold. It could also be a bad idle control valve, usually a good cleaning will take care of things but it may need complete replacing.

If the engine revs fine in neutral (manual car) or at a stop but hesitates while driving (pushing the pedal down all the way and it barely goes and then decides it wants to go normally by itself again and repeats) then it could very well be you O2 sensor and don’t be fooled it won’t always trigger a check engine code! To determine if this is the problem unplug the o2 sensor and go for a drive this time the check engine light will go on but don’t worry you’re not doing anything bad, what the car is forced to do is run on its default map off the ECU. If it drives fine then the o2 sensor is your problem, so replace it if it continues to persist then start checking other areas like the ECU and AFM.

Piston bearings:

Although the piston bearings are not a typical weak point, it should still be mentioned.
In general, all piston bearings in engines are wear parts (also the bearings of the crankshaft).
This is, however, in most cases within compliance think about replacing them after about 200,000 km
illustration (in German, I’ll try in the future to convert this to English also) using the M20 engine: connecting rod service.

Water pump/timing belt:

The water pump usually fails because the timing belt fails and if the timing belt fails then say goodbye to your engine because it is an interference engine which means valves will contact pistons; and this is never good! It’s not a question of did it cause damage; it’s a question of HOW MUCH damage?

If its just the water pump that fails then you will see your car starting to overheat (coolant temp gauge going past middle), turn it off and let it cool down, don’t let your car over heat!

It is recommended that when changing the timing belt every 60,000 miles (100,000km) you should also replace the water pump and tensioner.

Fan clutch:

The fan of the E30 is not driven constantly, rather mechanically by
viscosity clutch which engages and disengages. The advantage is that the fan only works when it’s necessary. Thus less power is robbed from the engine. However, there is one drawback, the coupling is a commonly a breaking point. A new one is roughly 100 while used it can be had for 20. When in storage the fan should be left standing because if you lay it down the oil could leak out and make it useless.
It can easily be don’t by Do it yourselfers, 32 mm wrench is needed (WARNING: Reverse threaded).

Now that all possible points of failure of the engines have been described, one might think the E30 engines are vulnerable. This is deceptive; when the engine is cold take care of it and maintain it well, a BMW engine is very robust, personally id say if taken care of borderline bulletproof.

10 Responses to E30 BMW Buying Guide Translated from German

  1. Peter on August 1, 2010 at 1:38 pm

    Hi. What a master piece, your translation! Just found you on the Net. Regarding a 1990 325ic with hardtop (ht) problem: 1. inside; entire lining ‘falls’ from/does not stick to ht due to brittle glue.
    2. outside: water enters above the rear window, leak probably along the two
    screwed-on metal strut(s) [=Streben].

    Would appreciate your expertise, perhaps a Website, etc. Thanks a lot. Peter.

  2. PT on August 22, 2010 at 4:02 pm

    My cousin recommended this blog and she was totally right keep up the fantastic work!

  3. zerodtkjoe on October 20, 2010 at 6:20 am

    Thanks for the info

  4. Yudi Riswanto on October 21, 2010 at 2:10 am

    My car is M10 (1987) there is some noise in engine, I think the cam chain (timing chain) that causes that sound. My question is :
    1. whether the timing chain for M10 can be adjusted manualy? If possible how can I do that?
    2. Can you send me the engine picture which showing timing chain side for my refference ?
    3. Can you send me also the picture of transmission section and differential because I want to try chancge clutch by my self.
    Thanks for your help.

    Yudi.

  5. roclafamilia on October 21, 2010 at 8:54 am

    Helpful blog, bookmarked the website with hopes to read more!

  6. mervyn on November 11, 2010 at 6:06 am

    I have owned my ’87 e30 325is coupe from new. All the information posted is so accurate and helpfull. Thanks very much.
    Regards,
    Mervyn

  7. damien rene on December 2, 2010 at 3:16 am

    Hi, i am from mauritius and own an e30. my problem is that the engine has been changed, and i do not know which one it is!!! and i hea some intermittent crackling at times, a metallic one. but each time i get to a shop it stops!! plz can you help? will a picture help? where can i send it? lots of thx. hope to hear from you soon.

  8. admin on December 4, 2010 at 6:57 pm

    Yes a picture would help, send it to me at rytisb2003@yahoo.com and i should be able to tell you what it is, you need to be more specific with the crackling noise to even remotely guess what it is.

  9. [...] E30 M3 Buying Guide/Advice - RS Auto [...]

  10. johand on January 25, 2014 at 3:36 pm

    Great stuff thanks. I am new to this page, trying to
    Findout were to post questions

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