Hello fellows,

I have an '86 760 turbo that has a lot of mechanical noise in the engine. It's been my experience that this is not uncommon in early B230FTs, esp ones that may have been less than perfectly cared for. (this is the case with mine)

The biggest noise appears to me to be rod bearing noise, and/or perhaps piston slap. The valve train also makes a lot of noise (which I'm told is indicative of oil getting to the valve train?).

Anyway, it makes a lot of noise. It runs great, it just sounds like hell. Pretty much everyone that's 'met' the car has asked me if it's a diesel or not.

Anyway, I've recently completed a bunch of little things I've wanted to get done for some time which I thought were negatively affecting my fuel mileage.

For example:
- All vacuum hoses have been replaced, with the exception of the turbo's wastegate actuator, which appears to be in very good health.
- new O2 sensor (old one died)
- there was a small exhaust leak, pre-O2 sensor, which I suspected was leaking fresh air into exhaust stream, or letting exhaust out of the stream
- fixed a broken wire in the injectors (I chased this for a few months before finding it)
- new wires & rotor button ~20k kms ago (timed then as well)
- new AMM-turbo and turbo output hoses
- brakes (needed to do pads on all four wheels for safety inspection, replaced one front and one rear caliper) so rolling resistance should be down
- finally tracked down a small fuel leak in tank return line
- good fuel injector cleaner (Sea Foam)
- maybe some other little things I can't remember

As I checked off each item on my list I expected my fuel mileage to improve but it just doesn't seem to be improving. So now I'm looking at other things.

I was wondering if it's possible that my knock sensor is being fooled by all the mechanical noise in the engine (which sounds to my non-piezo non-computerized ears a little like engine knock) as pre-ignition knock and retarding the timing completely?

I also considered the possibility that my AMM isn't reading right?

Any ideas at all would help a lot. I'm planning on doing a fairly large road trip in the next few weeks (~3000kms) and I'd love to get back to getting 500km on a tank (right now I'm getting about 400km/tank)(60L tank so that's about 55L fuel)


-Joel
--
1986 760 (B230FT) 420k+