87 260e rough running

[sepherial]

Hi, I bought an 87 260e. It had thrown a piston. After some major reworking I had the car back up to purring smoothly. That was until one day I was revving the engine and I heard a loud metallic sound clank. Its been running really rough ever since. I replace the blown OVP and it at least idles now. There was quite a bit of gas in the oil from the blown OVP. I changed it, got a new set of plugs as well. I have 160psi on each cylinder and there is no water or oil leakage. The plugs seem to be getting carbonized pretty quickly, like its not firing just right. It starts up cold really nice at first, but within 30 seconds it starts to sound like its almost starving for gas with no power from the accelerator barely. I heard it might be the camshaft position sensor overheating, but if you have any help for me I would greatly appreciate it. Thanks!

[pawoSD]

Sounds like perhaps a valve was damaged or something when that occurred.

The M103 does not have a camshaft position sensor.....and a sensor can't really overheat.

I am guessing something in the motor is physically damaged.

[sepherial]

Well I thought that too maybe, but I wouldn't have 160psi still if a valve was damaged would I? And I think I meant the Crank Position Sensor, the one directly in the front of the motor that attaches near the head.

[pawoSD]

Originally Posted by sepherial

And I think I meant the Crank Position Sensor, the one directly in the front of the motor that attaches near the head.

All that sensor does is read signal for the tachometer gauge.

The "Crank Position Sensor" that provides RPM signal to the injection computer, is located at the back of the engine right down near where the oil filter is.

It can't really "overheat"....its a Hall effect sensor....it generates small pulses of voltage from magnets on the flywheel. The worst that can happen to it is that it may degrade over time (the sensor itself or the wiring) and not provide an in-spec signal....causing engine stalls.

[sepherial]

Hmm, Im gonna try and check on the sensor then behind the motor before I start talking more motor work. Like I said it seems to start up fine and then eventually starts to sound like its misfiring/stalling. Hopefully I can just replace that sensor.

[Ivanerrol]

Are you loosing oil and or blowing smoke on deceleration?

Gunking up plugs could be a sign of valve seals and or guides. Compression test will not show this. You need a leak down test.

How many K's has this car done. The metallic clang that you heard sounds like a bit of a worry.

[david s poole]

pull the valve cover and check the rocker assemblies.they are well known for pulling threads in the four bolts that hold down each assembly.steel bolts into aluminum threads and your recent work could have been all that was needed to weaken the threads.fairly easy job to helicoil.

[pawoSD]

Originally Posted by david s poole

pull the valve cover and check the rocker assemblies.they are well known for pulling threads in the four bolts that hold down each assembly.steel bolts into aluminum threads and your recent work could have been all that was needed to weaken the threads.fairly easy job to helicoil.

I agree on checking this, especially if the motor is higher miles.....

[sepherial]

Yeah the car had 208k miles when I bought it. I don't seem to be loosing oil, but I am getting some heavy smoke when I press the accelerator. No power and lots of smoke :p I will definately check the rocker assembly. I noticed when pulling the valve cover that the metal plate on the inside of the valve cover had a hole pressed in it, almost like a lifter raised up and hit it real hard, maybe accounting for the loud clank noise I heard initially. Is this something possibly caused by the loose threads? Thanks, a bunch, you all have given me a lot of things I can take a look at.