Rough idle on S38 M5 3.8 - buying advice -

[Speedy]

I can buy an M5 3.8 '93 60.000 miles. (not from BMW dealer). I testdrived it and the car was fast.
However, I have never driven or heard an M5 before and I am worried about the engine in the car on offer:
1. idle was rough (around 900 rpm)like hot cams were fitted, but I was told engine was completely standard.
2. gear shifted smooth, but when shifting gear(both warm and cold; even when not pulling hard) the engine made loud combustion noises. it sounded like combustion took place in the exhaust. One 75mm exhaust pipe was fitted with two silencers. No catalyst was fitted, but lambda was fitted.
3. distribution cover right side was really greasy from oil, no real leakage but a few oil drops were hanging on the underside of the engine.
4. seller said the 3.8 engine can be recognized by the missing distributor at the front of the engine; instead on this place there's mechanism for variable valve timing.

The seller told me this is normal on an M5 3.8 engine with this mileage. Is he right ??

I am worried about the cylinder head/camshafts in particular. Car did not smoke white or oily fumes. Oil filler cap was clean.


I hope you will share your experiences with me.
Thanks in advance

[John Robinson]

Hi Speedy,

Firstly, I should point out that I dont know vary much about the 3.8, just the 3.6, but they are very similar.

1) it is completely normal for these cars to have a lumpy idle. They do indeed have hot cams.

2) That exhast sounds non standard to me, it should be a twin system, about 50mm each. This is probably what is causing the combustion noises you describe

4) To my knowledge, the 3.8 does not have variable valve timing.

Regards

John

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Visit the ///M5 Springboard, at http://www.netspace.net.au/~jrobbo/M5

[Chris]

Leave it where it is and go for a stock car with a service book.

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///Chris