88 m6 help

[Grantste]

Hey all, im new here. I was passed down an 88 m6 that was sitting for 3 years or so and has pretty bad rat damage in the engine bay. Any thought on fixing the harness thats in it? Or just sell the car. Car has some rust spots as well but overall would be a fun car to just be a driver.

[jbd5015]

Good news is that most of the harness is for the ECU, pretty easy to check continuity for those from the ECU above the glove box.

The harness isnt over complicated, just time consuming to repair correctly to look factory, which is worth it for the M cars.

Next concern is the fuel tank, they are steel in these cars. If the tank was anything but completely full, there is likely to be rust.

You owe it to the car to get a baseline on the situation, which should really take an afternoon or two if you are mechanically inclined.

[BimmerFlyer]

An M car with world bumpers, there are not many of those made !! The most desirable one of all (after the Euro ones) You might want to evaluate its overall condition, besides the rust and rats, and see if fixing it up might be worth it? Post some pictures of it, we can help you decide…..couple of minor rust spots are not uncommon, but can also be a sign of a lot more issues… these cars do have a tendency to rust…and it gets expensive real fast to fix that….. M cars, like all BMW’s have a tendency to not take to well to neglected maintenance items either, might take a bit of coin to get up to speed…..electrical system on these cars is pretty simple by todays standards, fixing harness should be no big deal for anyone handy with a multi meter and a soldering iron, just takes time…. where is the car located?
Pete

[Grantste]

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heres a few photos when i first got it and cleaned it up a bit. Thanks for the replies! Will get some more photos tomorrow of the harness and rust spots. Car is in Arizona now.

[RSheiman]

You never mentioned if it functions, what works and what does not. BTW, my 88 M6 is in good to excellent condition and Hagerty just advised I should increase my coverage to $58,500 so that should help you decide.

[DesktopDave]

Count me as one of the envious ones, nice score on that car! Given that it's a project car, rescued from neglect, likely to be back on the road, you really made my day. Don't get freaked out about the costs of rare Motorsport parts. The rear mount battery setup, trunk trim, some variants of fuel tanks are among major differences I've seen, but it's all bolt-on stuff and can be replaced with lesser parts if it's too far gone. I'd recommend saving any parts that get condemned, keep them with the car to preserve its value. Many of the M-Sport parts can easily be substituted from base model E24s, other BMWs, or even other related makes like Volvo or MB without hurting the value of the car.

The rodent damage is bad news, since the M6 wiring harness & ECU (DME) are pretty hard to come by and pretty specific to the S38B35 motor. BMW even changed the harness & DME during the years of M6 production. I think the Euro & North American models even differ between each other. The good news is that it's relatively easy to repair by splicing wires from other BMW harnesses. Good sources are the more common M30B32 & B34 from mid-80s E23/E24/E28. Late model E24 with the M30B35 are even more similar, and the early E34 535i & E32 735i can be a great source of spares.

BMW built the E24 in small numbers over a very long production run, they're almost like a custom-built car. You'll run into a lot of incompatible parts given the really late build date of your car. The ///M6 gearbox & diff are more or less specific to that particular car and the S38 stuff is all hard to come by. You should have a Getrag 280 and a large case LSD. The block is related to the M30, looks nearly identical, but it's most definitely not the same. All are worth considerable money but finding the right buyer can be a challenge.

I hope you can keep the car original, but if you have a burned valve or some other major big-money problem, I'd suspect you could get your money back out of it.

[e24mpwr]

The block is related to the M30, looks nearly identical, but it's most definitely not the same.

My understanding is the block is a lot closer to the M90

[DesktopDave]

My understanding is the block is a lot closer to the M90

That's my understanding too, but I've only seen a few and never had them side-by-side to compare. The M30 block casting was pretty limited as far as a larger bore was concerned. The M88, M90 & S38 blocks were cast with a bit more metal in the cylinder cores to compensate. They looked to be siamesed cylinders to me; BMW machined extra steam holes on the block deck between the bores to help with cooling. The S38 blocks I've seen also have slight differences in the external block casting, like the oil return port above the coolant drain plug.