[V8] drip = rattle = new motor (almost)

[Dave Saad]

I have not been driving the V8 much since I went back to school, and  
since it had a small coolant leak that I did not have time to fix. I  
just drove my truck instead, and let the V8 basically sit for the  
last 6 months. On the occasions I did drive it, it seemed to make  
more and louder noises from the right head each time. Some of you may  
remember that I also just spent a bunch of money replacing the rings  
and doing a full valve job. The noise was finally so bad that people  
I did not know would walk up to me and tell me I had a rod knocking.

The main noise appeared after the motor warmed up (cold it was pretty  
quiet), and fit exactly the description in the manual for a bad "oil  
retention valve".  I pulled the intake to investigate and swapped the  
two valves from side to side to see if one was really bad. (they are  
~ $200 and I am a poor student now so it was worth my time)
No change.

I was pretty convinced now that I had some serious rod bearing  
problem because the heads were rebuilt (but lifters were not  
replaced), the t-belt was new 6 months ago, and all the t-belt  
rollers were about 30K miles old. Recall that I re-used the rod  
bearings for the re-ring job.

I finally decided to tear into it expecting that I was going to have  
to find another motor - which really meant that I would be getting a  
new car as my business manager is getting sick of what she perceives  
as endless problems.  I took all the front covers off and ran the  
motor that way and found that one of the idler bearings was beginning  
to howl a little. Very obvious with an automotive stethoscope, but  
the main clank seemed to be coming from the cylinder wall just behind  
the two idler bearings.  Against my better judgement, I decided to  
try two more new idler bearings and another t-belt. After I ordered  
those parts, I found the main problem.  Coolant from a loose hose  
clamp on the thermostat was leaking down into the t-belt area and  
ended up causing the t-belt adjustor to nearly seize up on its pivot.  
I cleaned up this part and this time I lubed it with graphite.
I put it all back together it is quite as a brand new motor.

Apparently this same pivot point is a big problem in the V6 Audi  
motors too.

I think I have learned a few tricks that will help the next person  
who does a t-belt to prevent the "clank" that so many of us have  
experienced after a t-belt job.

First, make certain that the adjustor pivot operates freely.  I am  
trying graphite lube - maybe some other grease would work OK or maybe  
even assemble dry. I don't recall the manual saying to do anything  
here - so maybe dry is the way to go. Just remember that this spot  
will almost certainly get coolant on it at some point.

Next, when the procedure says to rotate the motor two times and  
recheck the tensioner adjustment, if it moves much at all, this  
indicates a possible binding adjustor.  I used the starter to rotate  
the crank many times and it took three or four tries to get the  
adjustment to stay put. I am pretty sure I had the belt too lose the  
last time I did it - and this somehow causes the clanking noise.  
Using the starter ensures that the belt is centered on all of the  
various pulleys.

On the idler bearings, I discovered that the OEM bearings have an  
orange seal, and have 12 balls in them. The replacements have 11  
balls with a black seal and feel a little looser. I think that these  
somehow can slap if the belt is too loose and the noise telegraphs  
all over the right head. Next time, I may try to get the OEM bearings.

With the t-belt noises all fixed, I still had a really loud lifter.  
My Audi guru told be to put some ATF in the oil - it works like magic.
I figured what the heck and poured a quart of ATF in. Within 10  
minutes the lifter noise was gone and has not come back yet. We will  
see how permanent a fix this is but for now all is well.

Dave