'02 Impala 3.4l 103K: Loud(er) Upper Engine Clicking

'02 Impala 3.4l 103K: Loud(er) Upper Engine Clicking

First noticed the engine clicking last April when the car had about 91k miles on it. At that time - and up until yesterday, I guess, it was only on startup on cold mornings, so I kept an eye on it but didn’t really do anything about it.

Today, the noise is louder and it’s not going away as the engine warms up - it’s staying just as loud. The only thing that changes is the periodicity is slowing down as the engine slows down. It’s definitely coming from the very top of the engine, and I’m guessing it’s piston slap or lifter noise. I just took the car on a relatively short 170 mile roundtrip this weekend and didn’t notice this noise, so I think it just got loud today. I also just changed the oil 1k miles ago, and the dipstick is right up into the cross-hatched area with good color (golden-brown), so that’s not it. I always change the oil every 3k miles, so it’s not from maintenance neglect. I’m guessing that this is related to the manifold intake leak, which I’m sure the car has, but the leak is very small.

The question is: should I pour in some SeaFoam right now? Does that stuff work? Is there a penalty for using this stuff? I’d like to buy a little time so I can decide what I’m going to do next.

Do you have a manuel that tells you when to have your valves adjusted? It sounds like that is what is needed. Im not familiar with your engine. Does it have overhead cams? If it does then it could use shims to adjust the valve or it might be able to adjust them with a lossening of a nut and a turn of a screw. Someone else will have to tell us which one it is.

If it has the lifter, pushrod and rocker arm style then you may have a pushrod get loose enough it could throw it through the valve cover. If this is not corrected.

Either way you need to get it looked at or if your capable to do it yourself get a repair manuel and adjust them yourself.

i would imagine the timing belt is stretching JUST enough to clack, but not crunch (if you get the drift)

after ruling out obvious loose, rattling things, i would go to the timing belt area.


Yes, I have the shop manuals, and no I’m not a mechanic but I have done everything just short of what this job would entail. The camshaft is down in the block. If you remove the upper intake, then the lower intake, the pushrods and rocker arms are exposed with the lifters and camshaft down in the center of the “V” (it’s a V-6 engine). Right now I’m thinking the slow coolant leak (past the intake gaskets) has damaged the lifters, so now the gasket job also includes new lifters (which I don’t think is that big of a deal if you’re already down in there)


It’s a timing chain - not a belt, and since the engine only has 103k original miles on it (I bought it brand new), I’m thinking the chain is good for another 100k. The noise is definitely coming from the top of the engine and it’s almost certainly the lifters/pushrods/rocker arms linkage.

I’ve got info on getting down to and replacing the intake gaskets, but the lifters are an unknown to me. AutoZone sells replacements for $9 a piece. They look like short cylinders. I guess I would need 12 of them (2 per cylinder?). But how are they replaced? Do they just drop in?

What about those lubricants to help me make it to the weekend when I’ll probably start this project (b/c the car still needs to run about 30 miles per day until then). Will Marvel Mystery Oil or Sea Foam or even Transmission fluid help to clean out the engine’s innards before opening it up? A co-worker here just went through a similar problem with his '98 Sierra and he tried MMO and the tranny fluid thing (for two days), but neither made the tapping/clicking noise go away completely. He finally opened it up and changed the bad lifter and gaskets - only to have to open it up again to replace ALL the lifters.

Regarding the intake gasket job.

1.) If I also replace all the lifters, will I have to adjust all the rocker arms? Also, is there a tool to compress the spring on the rocker arm to get the pushrod out w/o touching the rocker arm bolt?

2.) I know I’ll need to plug all the holes into the engine after removing the lower intake to clean out the valley, but how do I get any loose gunk out of there? Do I use a shop vac?

3.) Do I use brake cleaner to clean both the intake seal edges and the valley inside the engine?

4.) What is the “grey engine assembly stuff”? At DTips.com, that ASE Master mechanic did a 3.4 intake and it looked like he used a caulking gun to lay a seriously thick bead of grey something stuff. What is this stuff?

5.) Do I have to worry about TDC? I don’t remember this being part of the procedure in the manuals. I don’t think the distributor (or its replacement - the synchronizer?) is removed.

6.) I’ve got the Felpro gaskets with the metal frames. Bought them about 8 months ago. I’m pretty sure these are OK to use unless someone thinks otherwise.

I think I can do this job, but it’ll be the first time I’ve dug into the center of an engine. My biggest concern is the little things: keeping everything straight so it all goes back in the way it came out, cleaning everything properly and correctly, torqueing everything properly, lubricating everything properly (the lifters will need Cam lube, right?), etc.

I’ve got the shop manuals and have spilled out the procedure into a straightline stepwise list, but a few of the steps seem vague to me. Might have to post back with those questions before starting (Hopefully this weekend).

My daughter once had a Celebrity with a 2.8l engine, which I believe are in the same family of engines. The knocking in her engine was excessive valve lash. Since this engine has hydraulic lifters, any valve lash is too much. They are easy to adjust, remove the valve covers and with the engine running, loosen the nut on the rocker until the clacking starts, then slowly go down 1.5 turns.

This not only got rid of the noise, it restored a lot of the lost power. It went to almost 200k without anymore trouble.

I definitely think this is a stuck lifter. You should get yourself a short piece of garden hose or similar and use it as a stethoscope to try to figure out which valve cover the clicking is coming from-- if it’s the front one, it shouldn’t be a big deal to take it off and free the lifter. If it’s the back one, it can be trickier to do and in that case I might consider using the MMO or Seafoam to knock it loose.

these valves require no periodic adjustment they tighten 14 lb ft + 30 degrees and thats it. this engine does have issues with intake gaskets leaking how long has this been going on? you say very small is that based on what you see leaking on the outside of the engine? it may also be leaking internally and thats not good. does the car act like its missing?

keith you should check your facts please before giving out that kind of information . colt hero you will need a inch lbs torque wrench an angle meter and you should also know that the intake and exhaust push rods are different lenghts if you get them mixed up your looking at new valves which require the removal of the heads you dont want to go there. and you do not have to worry about top dead center. and you are correct once you get the intake off and rocker arms and pushrods out you just need to remove the retainer above the lifters and you can replace the lifters, i will tell you you should take a good look at the cam and make sure it doesnt have any bad spots on it if you have to replace it you will have to remove the engine . and also i have seen these cars with over 200,000 miles and never a timing chain problem not that it cant happen just would be out of the norm.

If you have the “shop manuels” Then they should be able to tell you how to remove and replace the lifters. You said “I’m thinking the slow coolant leak (past the intake gaskets) has damaged the lifters, so now the gasket job also includes new lifters”. Does your oil look milky in color? If not then you must have a very small leak which I don’t think hurt the lifter. But you do need to get this repaired as soon as possible. Don’t want to see the pushrod get lose enough it comes of the rocker arm and go through your valve cover. There is alot of great info here.

If you are capable of removeing and replaceing the intake gaskets then it would be easy to also replace all the lifters at the same time before reassembly of the intake. Just follow the manuel for spec and removal.

"keith you should check your facts please before giving out that kind of information "

You should read my post before you go flaming me. I was referring to the 2.8l engine which is in the same family of engines as the 3.4. What I said does apply to the 2.8 and 3.1l engine, both of which I have some experience. I have not worked on a 3.4 but was led to believe that the only difference was displacement, but it turns out that the rockers were changed as well.

The new rockers have a roller bearing in them and they have a different mounting procedure. I’d recommend that Colt Hero do check the torque on the rockers to see if they are tight enough before going in any further.

was not flaming at you ( whatever flaming is) i did say please and the 3.1 and 3.4 are virtually the same engine with the exception of displacement

No, no missing. Runs fine.