My son just bought this car and the previous owner said it would run fine
until it got hot and then it wouldn't accelerate and would idle poorly. Any
ideas ? I have relays, fuel pumps and the like on the short list. Bummer is
this is a european car and I don't expect to be able to find lots of parts
out there, any leads on those?
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Could be fuel evaporation - the formulation of petrol when it was built
didn't allow evaporation as easily as these days. So check all routing of
pipes etc and for any missing shields, and that under bonnet airflow is
*Honk if you love peace and quiet*
Dave Plowman email@example.com London SW
Here in Omaha, there's a few 3.5L m30 motors show up a month. My '86 535i
has the same motor as the 635. I have plenty of fuses, relays, and some
other ignition/injection parts, including a working set of 6 injectors for
that motor. If you can't find something cheap, let me know. I also have a
compilation CD of a few DIY repairs that reference that body or mechanicals
and the engine. Two junk yards here have a small selection of main fuel
pumps (pretty sturdy). The in-tank pump my be your problem. If it doesn't
work, the main pump may be overheating and beginning to fail. I replaced my
in-tank pump with one for a '76 Vega and it can pump hard enough to be the
main pump! $38 at Advance Auto Parts and it is also used to power the 350
Chevy motor so it should handle the 42-45 pounds the m30 needs (even though
it's only a helper pump). I have found that you can run the 535/635 without
the in-tank pump, but with a filtered suction tube, and be OK as long as
it's driven peacefully. I did for a year. These cars have lots of cross-over
parts internally so they are easy to find.
Bill in Omaha (major snow melting!)
A car this old could have enough miles on it to have worn out the
distributor bushings. This causes the timing to become very erratic, the
engine misses and stumbles, especially at high rpms, which causes it to be
unable to accelerate. It happened to my '84 318i at somewhere around 300k
miles. Just one more possibility for your list.
The 635 is Motronic so it won't have a separate distributor drive shaft,
it's bolted to the end of the camshaft. But a new rotor arm is worth the
money as it's probably ancient! I'd also check the distributor cap for
wear and pitting. You'll get replacements from www.bavauto.com.
Does the temperature gauge show the car to be overheating?
Who needs a life when you've got Unix? :-)
Email: firstname.lastname@example.org, John G.Burns B.Eng, Bonny Scotland
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