What would ejecting a valve shim sound like...

[Runningjon]

...and how much of an effect would it have on drivability?

Fairly simple question, I hope... I am curious because I am trying to track down an obnoxiously loud clicking/tapping coming from my 93MTX
Thanks for your input.
Jon

 

[SLOSHO89]

Is your low oil presure light on?

 

[Mike Kopstain]

Jon, it's a once off thing. You'll hear a clang or the sound of the shim being shot out once, and from there on you'll hear the sound of the cam lobe grinding itself down on the shim bucket.

Has your car ever had the valve adjustment done? It is very likely that the sound can just a very out of spec valve. If that's the case, you may or may not be able to re-use the cam. If the shim is ejected or chewed up, it will be very evident when taking the valve covers off.

 

[Runningjon]

Thanks for the replies, unfortunately you didn't say what I wanted you to say:

It got it's first valve adjustment at about 155k (it's got 174,485.8 miles now). And the oil light only flickers right before it dies (less than 500RPM)

Here is the whole story:
My original post

Since then I have had the lower end apart and found that one of my Connecting Rods actually had no bearings, everything was still intact, just minus 1 set of bearings oh_my , the other 5 sets of (original) rod bearing's were completely hosed, not a single part of any bearing was shiny, they were all completely worn out. I figured $40 for new bearings and endcaps as a last ditch effort to see if it would fix the problem was worth it, at least I might get a few thousand miles before it needed a total rebuild/motor swap. Did I mention that there was no visible damage to the Crankshaft? .

With a new set of bearings and new endcaps It fired up on the first crank and made the exact same noise as before, only it sounded like it ran better and no longer turned on the oil pressure light. I haven't driven or even run it for more than about 3 seconds since I had it towed home on Christmas.
I was just sitting here thinking about it, and thought, "hey maybe I'm incredibly lucky and the noise is actually a missing shim?" thumbs_u

<small>[ February 04, 2003, 07:27 PM: Message edited by: Runningjon ]</small>

 

[Mike Kopstain]

What do you mean "no bearings"? Some one removed the bearings on that connecting rod? How did you check the tolerances? If that motor was driven for any amount of time with a set of bearings missing I would suggest that your crank is screwed. That is bad times.

 

[Runningjon]

I guess "no bearings" is a little misleading...

I found about 20 pieces of bearing in the bottom of my oil pan, and the oil was really shiny when I drained it out.

The best way to describe what I think happened was that I was driving and the one connecting rod started to get bigger and bigger gaps between the bearings, and eventually the upper and lower bearings exploded, and scattered everywhere.

Funny thing is, there were no visible scratches on the rod, end cap or crankshaft. I could still see the oil marks and the "tabs" for both upper and lower bearings.
It's currently all covered up in my driveway, waiting for this summer when it will get a serious rebuild or new motor. I was just hoping someone would come up with a "miracle cure" so that I can have my SHO back. I'm getting very tired of driving my Dad's 1991 Volvo Stationwagon. I have to use all of it's whopping 107 horsepower just to sustain 65mph on the freeway.
Thanks again,
Jon

 

[SLOSHO89]

I asked about the oil presure light because I was going to suggest maybe the rod bearings were bad.

Did you put in new main bearings as well? If the rod bearings were bad I'd imagine the main bearings can't be much better.

You could pull the intake and valve covers to see if there are any missing/damaged shims.

When I bought my SHO it was missing a rod bearing as well, and it made a horribly loud sound and you had to keep your foot on the gas to keep it running.

Efren

 

[SLOSHO89]

Originally posted by Runningjon:
...and how much of an effect would it have on drivability?

Fairly simple question, I hope... I am curious because I am trying to track down an obnoxiously loud clicking/tapping coming from my 93MTX
QUOTE]

Ohh....I could answer some of these questions

It wouldn't effect driveability very much. Some one on the board (Heather/Casca) was missing a shim. The car still drove fine etc... I never heard it in person though.

How loud is it? Does the sound make you cringe? Or you just know something isn't quite right?

Efren

 

[Mark in PDX]

You know, I had an annoying 'knocking' or rattling sound coming from my top end.. I finally got tired of techs telling me it was a rock in my exhaust and pulled the exhaust system off and fired the car up.. Noise gone.. But wait.. My cat is still rattling.. duh.. Bad catalytic converter.. It was starting to disintegrate- It had a bad fuel mixture issue for a couple months before i got it and a month afterwards.. killed the cats.
Get a rubber mallet and bang on the cat, if it rattles, your cats are bad -
Mark
89 Red
89 Black
89 Black
89 Red 'Parts'

 

[billh]

Runningjon:
...and how much of an effect would it have on drivability?

Fairly simple question, I hope... I am curious because I am trying to track down an obnoxiously loud clicking/tapping coming from my 93MTX
Thanks for your input.
Jon

I could be wrong. (At least that's what my wife keeps telling me) but I would think that given the thickness of the shim, if one were to come out, that valve would not open. Given that these engines have extra valves, the cylinder would still produce power, depending on if it was an intake, and futher a primary or secondary intake, or an exhaust valve, you might not notice a driveability problem. I can't imagaine would it would take to actually toss a shim, though.