3.1L Lifter problem

[Joseph Upson]

What are the possibilities it's the piston problem GM had with the 3100 & 3400? From the possibilities seemingly ruled out, I think that's a very good possibility.

The clacking noise in my engine changed as it warmed up and with oil changes, it was also audible inside and out of the car and over the years got louder. It could also explain the power loss because the noise suggested it was intense enough to trip the knock sensor although the Fiero doesn't have one. The engine I had was a 2000 and the noise sounded as if it was coming from the top of the engine.

When it was disassembled it appeared all of the pistons had excessive bore clearance.

[19Cutlass94]

Its piston slap. I took apart a '96 3100 and the amount of room that the piston could move was almost an 1/16 inch. As it warms up everything expands and the noise goes away.

[talon2swords]

Update:


Note: I had to sign in as new user, my old ID wouldn't work (?).


Ok, I still have the car. The noise persists, but is kinda quiet. The car drives pretty good still, I just take it to work occasionally ( I have 3 vehicles now anyway).

If I haven't already mentioned, I briefly took it to a mechanic (after I worked on it), and he said it sounded like a valve train noise. I couldn't leave it with him (they always want you to leave it with them) because I didn't have a ride back home.

Anyway, I finally found a youtube video online that sounds like it did BEFORE I put a new set of lifters and LIM in it.

http://www.youtube.com/watch?v=lPYkW25o-XQ&feature=related

It still sounds like this, only much quieter now, and the noise is always there-warm or cold.

Anyhow, sorry for continuous posting, but I like the car and wanted to check all I could one more time before I leave it with a mechanic to diagnose (and I didn't have sound clip before). Thanks again if you have any ideas what this noise is.

[94GPGTP]

does it sound anything like this??

http://youtube.com/watch?v=7Gk7u1HErfw

That is my car now.. after replacing the lifters,pushrods and rocker arms and LIM that noise is still there and car drives the same.. I am putting another engine in it this week so i will be all good.. hopefully...

[talon2swords]

does it sound anything like this??

http://youtube.com/watch?v=7Gk7u1HErfw

That is my car now.. after replacing the lifters,pushrods and rocker arms and LIM that noise is still there and car drives the same.. I am putting another engine in it this week so i will be all good.. hopefully...

Actually yeah it does (the start up portion), but mine is much quieter now than that. And I don't have any hesitation or stalling (anymore). I read somewhere that knocking can trip the knock sensor and lead to hesisitation. I'll have to read up on that.

Power is pretty good for an old engine, but the valve train is a tad loud on heavy acceleration (no knocking-just not as smooth as it used to be).

[TDIXON]

hello my 1996 grandam gt makes the same noise as yours just not as loud and it doesnt lack power either. ive replaced everything as you have including oil pump and drive shaft,chain and guides and noise still there. although it only makes that noise at idle now rpms raise no noise back to idle noise is back. im sorry for intruding on your thread but now i know im not the only one with this problem. im completely confused to what it might be. one mechanic told me possibly oil pump gear drive. but i dont know so good luck with yours and hopefully youll find the prob because im stummped with mine.

[talon2swords]

hello my 1996 grandam gt makes the same noise as yours just not as loud and it doesnt lack power either. ive replaced everything as you have including oil pump and drive shaft,chain and guides and noise still there. although it only makes that noise at idle now rpms raise no noise back to idle noise is back. im sorry for intruding on your thread but now i know im not the only one with this problem. im completely confused to what it might be. one mechanic told me possibly oil pump gear drive. but i dont know so good luck with yours and hopefully youll find the prob because im stummped with mine.

I am confused about it too. I'm no professional mechanic, but it appears someone has already "replaced" everything in the last few posts in this topic, and it still doesn't help (eliminate it).

Thanks for your contributions, I think I'm going to stop wasting money, maybe take it to a couple chevy mechanics for opinions, but unless it is a timing issue or a block/piston problem, I'm clueless right now.

[TDIXON]

no prob im tired of sticking cash into mine so im going to wait for awhile to see if anyone else has this prob. and maybe get lucky that they figure it out and replace something that i havent thought of. then ill fix it to see if it works but until then drive it till it breaks and replace motor.

[talon2swords]

I've been reading up on carbon deposits and how they may can cause knocking in the engine. (My car may have an appointment with "GM topend cleaner" soon.)

When I took the LIM off two of my 3100 cars, I noticed a lot of carbon gunk had accumulated on the top of the valve heads and inside the lower intake in general. Maybe PVC valve has something to do with this.

Like I said earlier, I cleaned a lot of this carbon buildup out best I could with a toothbrush and solvent (intake gum-out spray cleaner). Some of this solvent did drop into the combustion chamber, probably sat for a few days while I worked on it on and off on the upper engine, and may have also dissolved some of the carbon buildup associated with the pistons. That might have helped lesson what was causing the noise--don't know.

Also before I took the intake off, I added the valvemedic stuff to the oil which temporarily got rid of the noise and restored power for a little while. Maybe this had something to do with some of the carbon buildup as well--don't know.

Could be a lot of carbon buildup on top of the pistons too. Maybe it can be cleaned out chemically. The cleaner doesn't cost that much and is worth a try. Read something about taking out the spark plugs and funneling the liquid cleaner into each of the cylinders and let sit for several hours.

Condition is called "Carbon Knock."

Wish I had gone ahead and taken heads off car now and cleaned up everything. Oh well.

[TDIXON]

well if it works let me know and ill try the same.but when i had mine apart it was as clean as a whistle but anything is possible.

[RickCoMatic]

You should have "Probed" the Engine before going-in after the Lifter. You could havve performed a number of tests to determine where the noise was coming from. Have a look at the ends of the Push Rods and see if they are all OK. When you get this car running again ... use a 4-foot section of small diameter wooden dowel to Probe the engine for unusual noise. Place one end on the engine and the other end cover with your thumb and "Listen" to your thumbnail for any unusual noises.

[talon2swords]

You should have "Probed" the Engine before going-in after the Lifter. You could havve performed a number of tests to determine where the noise was coming from. Have a look at the ends of the Push Rods and see if they are all OK. When you get this car running again ... use a 4-foot section of small diameter wooden dowel to Probe the engine for unusual noise. Place one end on the engine and the other end cover with your thumb and "Listen" to your thumbnail for any unusual noises.

I have probed my car's engine in several places with a stethoscope and I am confused about the source, I can't seem to locate it. I hear it "at a distance" at various places with the scope, but the noise is not sufficiently "loud" enough in any one place to isolate it. It's clearly heard outside the vehicle, but trying to probe for it is proving difficult. I guess I will try the underside next.

I'm not an expert, but the pushrods appeared ok. I have thought about going in again and re-examining everything more closely, but since the noise is pretty much the same as before, only less intense, and I also see people here have replaced everything but the kitchen sink in their engines to no avail, I was hoping someone had some alternative ideas about what it could be or if there was a failure [part] trend in these engines with this exact type of noise.

[RickCoMatic]

Now you face a problem of eliminating the source. You should run the engine ... Probe the Block at each Cylinder and take-off the Spark Plug Wire to each Cylinder, in turn. If the Knock goes away while you have the Plug Wire off the Coil to a particular Cylinder ... Your search can be focused on the Piston, Wrist Pin and Big-End Bearings on the Cylinder that ... when disconnected ... caused the knock to quiet down or disappear. If the knock goes away ... right away ... this test is for the Big-Ends. You may have Spun a Bearing Half-shell and the Cylinder not firing causes that Bearing not to knock as severely as it would under power.

A higher pitched "Thunk" being the Big End Bearing or "loose" Cap.
A low sounding "Thump" ... a Main Bearing.

[talon2swords]

Now you face a problem of eliminating the source. You should run the engine ... Probe the Block at each Cylinder and take-off the Spark Plug Wire to each Cylinder, in turn. If the Knock goes away while you have the Plug Wire off the Coil to a particular Cylinder ... Your search can be focused on the Piston, Wrist Pin and Big-End Bearings on the Cylinder that ... when disconnected ... caused the knock to quiet down or disappear. If the knock goes away ... right away ... this test is for the Big-Ends. You may have Spun a Bearing Half-shell and the Cylinder not firing causes that Bearing not to knock as severely as it would under power.

A higher pitched "Thunk" being the Big End Bearing or "loose" Cap.
A low sounding "Thump" ... a Main Bearing.

I read that procedure in my Haynes manual and have already done it. The noise was constant each time a wire was removed (it didn't go away). I think I'm going to repeat the procedure one more time just to make sure, maybe re-check my spark plugs too.

[Hell_raiser]

the rocker arm would be loose