Engine clatter...need hel to daignose, please!

[kingston]

OK, here's the skinny...

I own an `88 325 (SETA engine). The engine had been kinda loud (primarily valve noise) lately. Over the last weekend I replaced the Timing Belt & Tensioner, the water pump performed a valve adjustment.

The car seems to be running about the same as it was before, but it seems like there is a lower (more bass) noise. Increases with engine speed.

I had begun to think I had rod knock. After reading a bunch of threads on r3v and elsewhere, it seemed that I could remove the spark plug wires one at a time. When I got to the cylinder with a bad bearing, the noise should stop. I don't think I messed up the timing belt, as I've driven well over a hundred miles on it since the installation...

Well, what happened when I got to cylinder #4 was that very little changed. Whenever I removed other plugs, the engine would stumble noticably. Not so with #4! I tried swapping plugs from another cylinder, but no change.

The head seems to have a lot of oil in it, but my plugs looked pretty good when I pulled them. No oil fouling.

The sound seems to get quieter as the engine warms up, but I'm not positive about that.

I am actually thinking that I may have an exhaust leak. The heat shield part of the exhaust gaskets is broken completely off on one set of headers, and the other one's about to fal off as well. If the OUTSIDE of the gaskets are that bad, maybe the inside is shot, too...

Possible thoughts: Exhaust leak? Bad injector in cylinder #4, low compression in that cylinder... I'll see if Advance Auto has a Compression leakdown tool I can rent tomorrow. I may also pick up some new o-rings and pintles and try to clean out the injectors.

What else?? And, THANK YOU!

[ForcedFirebird]

Use a piece of hose between your ear and the oil pan like a stethoscope, then again on the top end, then around the suspected exhaust leaks. Should reveal where it's coming from.

[kingston]

Thanks for the response!

I tried using a screwdriver for the same general purpose today (to sense where the vibrations were coming from), and it didn't seem like it was a bottom-end issue, but using a hose makes a LOT more sense!

I've got the exhaust bolts soaking in PB blaster right now. I've got the exhaust gaskets that I'd been saving for when I swapped the 'i' model head on my SETA block, but I think now's the time to use `em! I assume I can't just remove the exhaust nuts and headers - I am assuming that I actually need to remove them from the downpipes as well (with the triangular gaskets) before I can remove them from the head, correct?

And, apologies for my craptastic spelling in the title!

[ForcedFirebird]

No, you can take the exhaust manis off the head just fine. You may have to loosen the hangers underneath to let the front down pipe move since there's not a flex on that one.

[kingston]

Thanks again!!!!