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fivewindowcoupe 06-26-2009 12:17 PM

ZZ383 knocking
I installed a new ZZ383 crate motor in my 40 Willys coupe and have only put on about 100 miles and its started knocking. Not a loud knock, just barely noticable. I've traced the knock to the passenger side either the #6 or#8 cylinder. With a mechanics stethoscope touching the block you can actually feel the tapping. It appears to be at the top of the block at the head. The tapping disappears as you travel down to the oil pan rail. This was not there in the beginning. I broke the engine in as per GM's instructions but I only went to 4000 - 45000 rom instead of the 5000 rpm spec'd by GM. I read somewhere (not sure if it was on this forum) of a similar complaint and the problems/difficulties trying to deal with GM and the warranty. I don't know the outcome of that issue. Can anyopne advise me, first is this tapping going the be a concern and second was that person successful with his warranty ?


cobalt327 06-26-2009 01:54 PM


Originally Posted by fivewindowcoupe
I've traced the knock to the passenger side either the #6 or#8 cylinder. *snip* I broke the engine in as per GM's instructions but I only went to 4000 - 45000 rom instead of the 5000 rpm spec'd by GM.

I would suggest you pull the valve cover and carefully check the valve lash on the suspect valves, and readjust them just as you originally did.

If the tapping diminishes then returns yet again- there's a good chance a cam lobe is going away.

Is there a reason you didn't follow GM's instructions regarding break-in?

SDLuck 06-26-2009 02:32 PM

There was some information on piston slap on some of these engines,try a google search

fivewindowcoupe 06-26-2009 03:44 PM

actually the GM manual states "to about 5000 RPM". So I figured I was close enough. It would be great if all it was was a valve adjustment and I'll check that but wouldn't you here that through the valve cover with the stethescope? It has roller lifters so I doubt it would be a worn cam lobe. It's not loud and it does not seem to be getting worse, loud enough to be annoying.


cobalt327 06-26-2009 06:56 PM

I wasn't thinking- the engine a roller, obviously. :drunk:

Check into the piston slap that SDLuck mentioned earlier. There were occurrences of it, although I hadn't heard of it recently.

zz71s 06-26-2009 09:09 PM

I had a problem with valve train noise with my zz4.
You need to check the rocker studs make sure they are tight.
I also had a problem with GM and there warranty if you installed the engine your self it is parts only, if you used a certified GM mech. maybe you might get the full warranty if your dealership honors the warranty
My local dealership would not honor my warrantyGM wanted me to get the car towed 45 min. away.
Needless to say I have been band from my local dealership they claim I have a little temper.

anyone who is thinking about buying a GM crate engine read the warranty very very closely.

fivewindowcoupe 06-27-2009 07:32 AM

with piston slap, would it not be there right from the beginning? I drove this for about 40 miles then I did the 5000 RPM thing and changed the oil as per GM's manual. It was after this that the knocking occurred. The noise is there all the time and is related to engine RPM (not to vehicle speed). It is there in drive or neutral. I have been driving (and not lightly I might add) this for approx. 50 miles so far after the first oil change and it still has the power and oil pressure is still good. I am very impressed with this motor and the performance level but the knocking is annoying. If the warranty only covers parts (I did install it myself) then I might as well drive it until it explodes since I'm gonna have to pay labour anyway.

zz71s 06-27-2009 09:47 AM

Dont let my story scare you try your dealership.

FmrStrtracer 06-27-2009 12:01 PM

Have you checked your flexplate and torque converter bolts? If one of them is loose it will cause a knocking than seems to come from within the engine. Just a thought

lt1tyrell 03-19-2010 08:29 AM

What ever happened with your engine???

fivewindowcoupe 03-19-2010 05:03 PM

I'll try not to be long winded so here goes. Here in Canada we have to go through the GM dealer where we purchased the engine. I spoke with the service manager and was advised that I would have to bring it in so they could hear the knocking and then tear it down to find the cause. I was not going to leave my car there under any circumstances. I went to an engine builder who came highly reccomended. I brought the car to him and he was able to hear the noise personally. I took the motor out and took it to the engine builder for teardown. I asked him to document everything. The results were thus: there was no sealant on the rocker arm studs so oil was getting past the threads and into the cylinder (the upper cylinders were coated with an oily sooty deposit). The piston to wall clearance was found to be .0025" - .0030" skirt clearance (specs call for .001"). The pistons have a coated skirt and 4 of the 8 pistons showed signs of scuffing (including the #8 piston which is the one I determined to be knocking). This info was sent to the service manager who in turn sent it to the GM rep. Well GM authorized and paid for (fully) to have my motor rebuilt by the engine builder including the $700 dyno fee. I was pleasantly surprised, I thought that I would have a fight on my hands. They did offer to replace it with another crate motor but I told them that I did not want to go through this again and neither would they. The motor is back in my Willys and is running strong (so far).


lt1tyrell 03-19-2010 05:07 PM

Thanks for filling me in, I have a zz4 still sitting in the crate for my car that I purchased in the US. I really hope mine works out for me becuase the warranty would probably be a huge hassle for me now if I have a problem!

fivewindowcoupe 03-19-2010 07:35 PM

I hope you have better luck than I. There wasn't a problem with the parts, they were all top notch. It was a problem with the machine work. Not sure if the machining was done in Mexico however the motor was assembled there. The issue that I was going to have with the dealership that I bought my motor from was that at the end of the year (2009) they were no longer going to be affiliated with GM. It was a GMC, Pontiac dealership that was being dumped by GM. I only had till the end of the year to fix the problem. I was lucky, it wotked out for me. One added note, I have a friend of mine who had bought a ZZ502 that he put in his 70 Nova. He had to take it out and have it re-honed and re-ringed as it was using oil big time. It seems that the honing wasn't done properly and was too coarse for the rings. Another problem with machining.

Good luck


302 Z28 03-19-2010 08:56 PM

I have a friend who has a 70 Chevelle with a 572 crate that trashed a lifter along with the engine. GM warranted the entire engine, gave him a new one and installed it at the local Chevy dealership.

lt1tyrell 03-20-2010 06:02 AM

Wow I thought they would have had better quality control than this! Any other bad experiences with GM crate engines?

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