MLiebal

So for a 3.4 engine, with an exhaust valve clearance at .012" (.001" too tight), will it quiet a noisy valve by shimming? There is 2 that are at .016 (.001 too loose). Ticking is very noticable. Have to have radio up very loud to cover over noise lol!

Compression and leak down look good. No flexplate issue nor water pump. All from passenger side, mostly exhaust manifold/head.
Only has 300k miles on a 96 3.4 eninge.
Has anyone had success quieting an engine with shimming?
Should the exhaust be set close to the upper limit.

BTW the intakes were all mid spec, awesome!!

Thanks

brianh699

Looser is better too tight you may burn a valve up. If it's noisy it's loose tightening it up will quiet it down, just don't go too tight or the valve won't be able to dissipate heat through the head because it never fully seats.

MLiebal

Thanks for reply Brian
That is the theory. But I have gap.
a. Is .001 too loose equal noise? Or
b. Is .001 too tight equal noise? Or
c. Noise is coming from other causes?

No doubt less than zero gap will cause the valve to hold open and burn, but I dont think I am anywhere near that.
I have searched and have yet to hear of someone that had specs close to the limits and what results they had on noise with shimming?
I did see where folks were saying set exhaust on loose side, but no comment on noise.
Whew, what to do?

nothingbetter

you could also be hearing your injectors clicking

MLiebal

Thanks, I did disconnect each injector, not them.
I also disconnected each spark plug, so no archy sparky clicking.

rworegon

Yes, proper valve clearances can quiet the 3.4 valve train. Is 0.001 out either way enough to make a difference, I don't know. Maybe Vital22re will chime in as he has done numerous 3.4 swaps and may have the insight.

MLiebal

I did some snooping on TTORA and found some good info:
http://www.ttora.com/forum/showthrea...lve+adjustment

I am now hopefull for some success with shimming my valves.

MLiebal

Oh what the heck, that did nothing to improve the clicking.
I had a pretty go blowby on cold pressure test. And compression was low on that cylinder when cold.
Worn piston??? I'm betting.
Crappy crap!

vital22re

iTrader: (2)

Post up a video with sound. 300k is a lot of miles. And unless they drove it like an old lady... things are beginning to wear. In general practice loose valves do make a little noise. How do the valve covers look? Hows your oil pressure? Does the clicking go away if you rev the motor?

Texas_Ace

Yeah a video would help.

A round of seafoam/MMO would not hurt either. Do a search for the thread I posted on that.

MLiebal

Thanks all
I have taken a gopro vid, but the sound is not so good.
I did take the vehicle to dealer who I know the master tech.
He says it is most likely a rod bearing going, at the crank.
Says it is not too bad yet. It is possible to drop the pan (major pia) and remove the cap from the rod, if the crank is not too bad, put in a smaller diameter bearing in, and be fine.
But if the crank is scored (ie bearing spun) then no go. This is not a daily driver, but I want to get 50k more miles out of it.
Does the front diff have to be taken out fully to get the pan out? Could I just unbolt it and lower? Leaving the half shafts in?
I need to get to the rod end on cylinder 5, which close to the back of the engine.
Thanks

ARB1977

With 300K I wouldn't worry about it. Maybe try a thicker oil.

MLiebal

Thanks ARB, heavier oil did little. I dont want to be pulling dirtbikes or jetskis and blow the motor at higher revs. If the bearing tries to spin and seizes on the crank, it busts the rod and throws it through the block wall. Not pretty!
Seems worth a shot to see if I can tighten the crank end of the rod w a smaller bearing.

MLiebal

Quickie update
So I yanked the front differential, not fun. Dropped the oil pan.
The bottom looked good. I pulled the connecting rod caps off of cylinders 1,3,5 (where the noise came from). The crank pin looks great! Amazing. The journals look almost new. Some shiny spots on the ends of the bearing.
I just dont think I found the noise!
I'll mic and check the crank pins.
What do I do next???
Noise was really noticeable. People look up when I drive by. Noise is there at idle and under load. Let up on the gas and really cant hear it.
Really have truck torn down and still cant determine real cause!
Frustrations gallore!
Help please?

blake.nemitz

no chance its an exhaust leak?

MLiebal

Thanks Blake
I cant believe the toy tech and I missed it, but I will look super close. It would make sense, but I could not see or smell exhaust under the hood. I looked around the manifold and did not see any of the tell-tales.
It has to be something!

Ipaman

I remember I had a old Nissan truck that clicked real bad. It ended up being a timing belt guide I beleieve. Is it possible it's coming from the timing belt ? I'm just throwing out an idea.

rworegon

Could it be the fan bracket bearing or timing belt bearing is bad and the sound is transmitting?

MLiebal

Thanks gang!
I have pulled all belts off.No better
I used the sthethoscope, not from water pump or front bearings, though kind of cool to listen to each. They have their own sounds

I'm ordering replacement rod bearings. The shaft pins are normal.
Who know??