The generic faults are well documented on this forum & the E34 M5 FAQS.The Gorilla said:Hi,
Since posting a few days ago, re- putting a 3.8 into a 3.6 car, a nice condition 3.8 6 Speed car has come up for sale near to where I live.
What are the things to look for, I've owned the 3.6 since new, 1990, and its been very reliable, except the normal wear and tear items.
On the 3.8 car what should I look for other than -
Wiring loom under rear seat
The car has done just over 95,000 miles has been well looked after and has a comprehensive service history, with main dealers up to 85,000 miles.
Any well known tell, tells, or known traits for the 3.8 6 Speed would be more than welcome.
Hertfordshire1 had quite a few birthdays come at once on his car but looks like a lot was down to the car being incorrectly stored sometime in the past.
Air con working on these cars is a must. It really can be a wallet emptying task sorting it.
The oil leaks around the sump & front cover are popular as will be numerous pipes starting to soften & collapse.
At this mileage its a good idea to have the car on a lift so all the suspension & hydraulic pipes plus accumilators are visible.
Recommending a 3.8 to an owner of a 3.6 is such a swings & roundabouts affair. Each has its merits which for me revolve around the cost & frequency of failure of EDC damper units on the later car, wheras a 3.6 is a doddle here.
It does sound to me like you have a very nice long term owned 3.6
Raymond Woertmann & Ivan Dias, a couple of our Forum Moderators still run 3.6 versions. If the 3.8 was such a leap forward why did these long term owners not move to a 3.8 ?
I have a 3.8 but it has sorely tried my patience in the last yr. Absolutely thousands have been spent.
You really could buy into some serious grief despite the service history which ive found can mean nothing.
Good luck with your final decision.