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1,6,7,8 - Series and Mini Cooper General Chat related to models that do not fit into particular categories above. Please try to put your discussion in more appropriate sections. This section does cover the 1 Series, MINI Cooper and 8-Series vehicles: BMW 830i, BMW 840Ci, BMW 850i, BMW 850Ci, BMW 850CSi, M8, Alpina B12, BMW CS Concept and others.

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Old 10-08-2009, 03:45 AM   #1 (permalink)
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88 730i

I'm about to buy a 1988 730i and was wondering what i should look out for...

it's an automatic so i'm already assuming the tranny is messed up and i read something about corroded cylinder walls.

anything else i should be aware of?

thanks,

sully
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Old 10-08-2009, 07:28 AM   #2 (permalink)
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The Tranny should be fine read below, also the cylinder walls should be fine, The Nikasil problem read next post.


BMW E32 THE 10 MOST COMMON PROBLEMS

But dont let this put you off!!!

The E32 is an excellent car, but even the flagship of the BMW range has a few weak spots. Most of the problems exist in all models in the range, some only for the V8 models.

The following list is in order of highest to lowest chance of problems



1. The Dreaded Shimmy

Both the E32 and the E38 7-Series can suffer from the dreaded 'shimmy'. This is wheel-wobble that usually first shows itself under braking, for instance, when coming off a motorway intersection and braking from high speed. The wobble can be felt through the steering-wheel but it usually disappears as the car speed reduces.

Sometimes this is all you ever get, but more usually you will start to get wobble as the car is accelerated through 50 - 60MPH. The more you drive the car the worse it will get. The wobble is quite often accompanied by tram lining and a general feeling of imprecision from the steering in general.

The shimmies are often an indication of general wear in the steering system and suspension, the BMW E32 has a great deal of weight over the front wheels, especially when braking. It also seems to have a resonant frequency that occurs between 50 and 60 MPH, if there is any weakness it is at this speed where the problems will occur.


2. Cooling system

This is another problem that the E32 shares with the E38. There are two areas of the cooling system that are particularly weak:

Radiator. The E32 radiators have a plastic body, they break around the Top Hose connection. The Top Hose fitted to the radiator with the aid of a Jubilee-clip. The usual problem is that the plastic pipe that the hose is connected to cracks under the Jubilee-clip and this causes a small weep around the hose that is difficult to trace. The usual evidence is white marks down the side of the radiator. The only repair is the replacement of the radiator.

Viscous Fan. The Viscous Fan is mounted on the water pump shaft and is driven by the main belt from the crankshaft pulley. The assembly consists of a temperature-dependant viscous-clutch driven from the pump shaft that drives a large plastic fan. When the clutch is cold the fan idles and can be stopped with a rolled-up newspaper (the usual test), once the clutch is hot the fan is driven with a much greater torque and produces a great deal of air-flow. The usual problem is that the clutch fails and the fan cannot produce enough air-flow. The fault will show itself when the car is stationary when it will rapidly overheat. The temperature-rise is usually halted by the the auxiliary fan (A/C fan) which will operate independently to the A/C system when required. Once the car is moving the temperature starts to drop. A more unusual problem is that the clutch seizes, this is first noticed by large whooshing noises when the car is revved-up. Replace the viscous coupling immediately if this happens as the fan will disintegrate and this can cause all sorts of damage including big holes in the bonnet! Replacement of the Viscous Fan is pretty simple and is covered here (E38 shown E32 similar)



3. Air Conditioning.

The A/C system tends to slowly leak gas, fortunately re-gassing gets things going again successfully.


4. PCV Valve Failure.

The V8 E32's suffer from PCV valve failure when they reach a certain age. The PCV valve consists of a diaphragm fitted to a housing that is fitted to the rear of the inlet manifold and when this is damaged it can cause erratic idling and excess smoke. Often mistaken for Nikasil problems in the early models, the repair is pretty straight-forward but does require a bit of patience especially when trying to get the Torx bolts out of the bellows assembly.

5. Trans Prog Error.

If there is one fault that makes you sweat, this is it! You get the message of doom on the OBC and the gearbox locks itself in 3rd on the 4-speed boxes or 4th on the 5-speed boxes. You immediately realise that the cost of a replacement box is more than the car is worth and aim the car at something that will produce a terminal insurance claim. However, don't panic, in 9 cases out of 10 the problem is easy to fix. Here is the most likely candidates:

Battery Voltage Too Low. The E32 hates having a low battery voltage and one of the first things that gives up is the gearbox. Although the EGS (control unit) keeps running, the 12V solenoids in the gearbox don't, the EGS sees this as a failure of the valve-body and gives up. Low battery voltage is often due to short trips, failing battery or a faulty alternator. Disconnect the battery, replace if needed or give it an overnight charge and have another go, hopefully the problem will not return.

S.E.M Switch. This is the Sports, Economy, Manual switch next to the shifter (marked SE* on the V8's). Although it is a simple momentary switch it can intermittently make contact when in the rest position, or select 'S' and 'M' at the same time. This causes an error in the EGS. The switch can be removed and cleaned or (for emergency use) you can replace it with the sunroof switch!

Shifter Selector Switch. The selector switch is a multi-pole, multi-throw unit and produces a switch pattern (akin to binary) to the EGS. Problems occur when the contacts get dirty and the one of the switch elements fails to make contact. The switch pattern sent to the EGS is incorrect and the EGS flags a Trans Prog Error. The shifter selector switch can be removed and cleaned with contact cleaner quite successfully.

Low ATF Level-Filter Blocked. Pretty obvious one this, however, the box usually starts slipping when cornering first. Still, when all else has failed it is worth replacing the filter and getting the oil changed.



6. Rocker-Cover Leaks.

A small oil leak isn't too much of a problem unless the oil fills up the spark-plug holes! Unfortunately this is exactly what happens on the V8 models. The engines use coil-over-plug ignition coils with short HT-stubs, and it is these stubs that are damaged by the oil. Once the HT-stubs are damaged the engine will start to misfire. The repair is covered here.


7. Noisy Tappets.

There are two different problems here. The M60-engined cars get noisy tappets that come and go, this is not a problem and is covered here.

The M30-engined cars get noisy tappets due to cam wear due to a lack of lubrication. The lack of lubrication is due to the loosening of hollow bolts known as 'Banjo Bolts'. These bolts direct oil from the upper oil gallery to the cam spray bar. The problem is that the bolts cannot be tightened too much as they will be damaged due to the hollow construction and they eventually come loose and this starves the front lobes of oil. The bolts should be locked with thread-lock but even this gives up, especially when the bolts are 'checked for tightness'. Banjo Bolts can be purchased with wire-holes so the bolts can be wired in position, this is the preferred method as it is impossible to remove all traces of the oil from the gallery which is required to use thread-lock. Unfortunately, once the tappets get noisy the cam is a gonner, the wise money is on replacing the Banjo Bolts with the wired types before this becomes a problem.



8. Blower Final Stage (Sword) Failure.

Another classic problem that causes much angst. The 'Sword' is used to control the speed of the ventilation system blower fan. Rather than just having a couple of ballast resistors as was seen in lesser models, the E32 has a continuously-adjustable speed control. This is achieved with a number of Field-Effect-Transistors (FET's) mounted on a metal heatsink that vaguely resembles a sword. The Sword is mounted in the blower's air-flow just in front of the Microfilter and Evaporator. When the FET's fail they usually fail short-circuit which means that the fan runs continuously at full-speed. If the solder-joints fail the fan fails to run unless the fan-speed is set to full, this is because a relay is used across the FET's at full-speed.

Failure of the sword is usually due to a blocked Microfilter, the driver increases the fan-speed to compensate but the airflow across the FET's is insufficient to cool them. They get hot enough to melt the solder connections which eventually leads to 'dry' joints, quite often the FET's give up altogether. The FET's can be replaced with a little soldering skill.



9. Lighting Problems-False OBC Messages.

There are a number of faults covered here all lumped under one heading but all concerning the external lighting. The E32 lighting system changed quite considerably across the model years and some faults are confined to certain years:

False 'Bulb Failure' Messages. If you have a single warning message (usually brake light or rear side-light warning) and the bulb is definitely working the most likely cause is corrosion on the bulb-contacts. Clean the contacts with fine emery-cloth and squirt some contact-cleaner on the contacts....that usually cures the fault.

If you get multiple warnings on the later V8 models, side lights, rear lights, brake lights etc. then the fault is usually due to the headlight-aim motors. These get electrically noisy and the noise confuses the Check-Control-Module (CCM). The simple repair is to get the headlights aimed correctly and then remove the connector to the motors.

Intermittent Rear/Brake lights. If you have rear lights that are intermittent the most likely cause is the famous 'Mustard Relay' which was present on early models. The picture below shows where it isn't on the later models as the Mustard Relay was replaced by electronics in the LKM (Lamp Control Model). The relay can be taken apart and re-soldered.

Intermittent Headlights. On the early models this fault is again due to fatigued solder-joints but this time on the LKM. The early LKM's had relay's soldered to the main PCB and the weight of these relay's eventually fatigue the solder joints. The LKM can be taken apart and the solder joints remade.



10. External Temperature -37F.

Another trivial fault but still annoying, this is due to either the probe (shown below at the top LHS of the RHS fog light cavity), or the connection into the loom which is found behind the cavity.

Good luck with you purchase.
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Last edited by marti5; 10-08-2009 at 07:40 AM.
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Old 10-08-2009, 07:41 AM   #3 (permalink)
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History

Nikasil is a manufacturing process that was used by BMW to turn the relatively soft aluminium cylinder bores into a bearing surface. This process involved impregnating the bores with a Nickel-Silicone compound which chemically bonds with the Aluminium bore surface. The resultant bore has exceptional wear-resistance, much superior to the standard Iron liner.
Unfortunately, the high Sulphur content of some fuels (not necessarily the cheapest) which broke-down the chemical bond resulting in a bore that was essentially machined aluminium. Where this problem occurred the piston rings would rapidly wear away the cylinder bore to a point where compression was lost. Once compression was lost the engine would fail to tick-over smoothly and power-output would reduce. Most noticeably, the car would become very difficult to start as the lack of compression at cranking speeds would not produce combustion. The cure (as is so often quoted) is to replace the short block, there is no chance of reconditioning the bores. The usual advice was to look out for V8's that rocked at tick-over or that smoked when started.

Today

The above is all pretty standard stuff, and all pretty out-of-date. In 2008 the Nikasil issue is 15 years old. The Nikasil problem has really been and gone. The fuel available in the UK is low in Sulphur and any V8 that was affected (and there were very few genuine cases) are either sporting replacement engines or being recycled. Once the Nikasil-impregnated bores were compromised they very rapidly deteriorated to a point where they were un-driveable and un-saleable.

One interesting point is the test for bore-wear is the 'leak-down test' which measures the amount of air that leaks past the piston-rings at a given air-volume. The equipment consists of a reservoir of compressed air at a pre-defined pressure that is passed through an aperture of a given cross-section, this gives a metered amount of air. This air supply is connected to one cylinder at a time who's piston is set to the bottom of the power-stroke. The measured pressure at the cylinder is compared to the primary air-pressure before that aperture and expressed as a percentage with greater than 14% difference being a fail. What is important about this is that a flooded M60 will fail the test whether has bore wear or not! Anyone who has tried to start a flooded M60 will notice just how fast they turn-over, this is because the oil that is normally between the piston-rings and the bore has been washed away by the over-rich fuel. I wonder how many M60's have been scrapped just because they were flooded.

However, the 'Nikasil problem' is brilliant news to buyers of V8's as it makes them less desirable and hence, cheaper. I have never heard of a genuine case of bore-wear on the M60 due to Nikasil and I've been driving 7-Series cars for a long time, including an E32 V8 730i! The lumpy V8's have all turned out to be caused by the usual 'oil down the sparkplug holes' or PCV valve failure, both of which are easy to repair (we have full instructions here). My own '93 V8 730i was sold as a 'Nikasil' case and demanded a low buying price, just like every other V8 E32 I have known, the fault was a punctured PCV valve!

There are some E32's with worn-bores, but that is true for any car with 15-year-old bores, you are just as likely to see worn bores on an M30 or M70 as you are on an M60. In 2008 the 'Nikasil Problem' is over and done!

Go and bag yourself a bargain V8
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Old 10-08-2009, 09:04 AM   #4 (permalink)
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thanks for all the help man, that was great stuff.

yeah, hopefully he'll reply to my email, and i'll be able to pick it up...
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