Are you referring to the harmonic balancer? How did it slip back? I thought it would be keyed or have a stop to prevent it from going back into engine too much?

 

Yes, the harmonic balancer. On my '91 4.9L, the balancer is composed of two parts of metal separated by rubber between them. The rubber had gotten old and dry and the outer part slipped back a little hitting the cover.

 

OK, so for the life of me I can't pinpoint the noise I am having. I really wanted the satisfaction of finding and repairing the problem myself, butsince I was unable to locate the problem, I will now have to resort to using trained professionals


So, I took it to a local very reputable mom/pop repair shop. It is used by many in my town. They have been in business for over 20 years. They have been recommended on several occasions.


Mechanic/owner used a stethoscope and prodded all over (AC, PS pump, smog pump, belt tensioner, water pump, timing chain cover, etc. He got under truck and prodded all over underneath as well. He placed the stethoscope end very close to harmonic balancer (while engine was running) and believes sound is coming from there.


He believes it is the harmonic balancer. It doesn't appear to be hitting the timing marker nor does it appear to be hitting anything else (at least from his 10 min inspection). I asked why would it make like a bearing or metal slapping noise. He couldn't explain it but simply said he strongly suspects the HB.


So, I will take it to him and see what happens. I am planning a 650 mile RT to AZ in the next two weeks and don't want any surprises on the road (at least the ones I suspect can be a problem).


Thoughts on how a HB can make a bearing/tapping noise if it is not hitting anything?


Also, if he changes HB and it is not the problem, am I out the cost of the total repair bill? At the dealer/stealer, one only pays when the problem is repaired.

 

Chain slap from inside the timing case?

It's a '92 so at least you don't have that crappy plastic cam gear wearing out.
I'm not sure how many miles it would take to wear the roller chain of an EFI engine to that point, or if it's ever been changed.

You might want to check for slop.

 

with 60K miles I wouldn't think chain slop woud occur. Like I said mechanic thinks it is the harmonic balancer. Will know later today when he works on it!!!

 

That's a question to take up with the repair shop not a forum. We don't make the policies of the repair shop. A clear discussion of expectations seems in order so that each party knows what to expect of the other.

 

I'm just trying to think of what could be knocking in that area.
You've already said the balancer is not hitting.
There are NO moving parts.
Steel, bonded to rubber, to a steel outer ring....

 

OK....results are in......


The serpentine belt pulleys were lose!!! Apparently, I did not tighten them the last time I removed them.


I feel so angry with myself for missing this


I thought I paid great attention to detail....at least most of the time I guess.


Anyway, he found the issue as he was diagnosing by removing each belt separately. He noticed something off with the pulley and when he touched the bolts (no belts on it) one was finger lose and the three others were lose, but not finger lose. he tightened them down, installed belts, fired it up and no noise!!


So, back in action and preparing for a run to AZ and pulling a boat of 5er back!

 

Don't beat yourself up. Show me somebody that's done a bunch of work on their vehicles and claims to have never made a dumb mistake, and I'll show you a liar. Your mistake was frustrating, but at least it was benign. Nothing went boom.

 

Glad you got it figured out. On the bright side at least it was an easy fix!