[Miket]

I am going to keep this short, but thought it might be valuable to most on the board...

Last March I bought a ZZ502 for my 71 Chevy Cheyenne. It made squeaking noises from the top end of the motor from day one. I contacted the dealer I bought it from and over the course of last year, jumped through a bunch of hoops to eliminate every possibility but the motor. Finally after realizing it was probably the motor, it was removed and shipped back to the dealer(who has a machine shop, builds race motors and is reputable). Once there, they put it on their dyno and heard for themselves the noise I was complaining about. They disassembled the motor completely but found no real cause of the the noise. During my quest to find the problem on my own, someone in a forum like this said they experienced the same exact problem. Come to find out it was pushrods rubbing on the guideplates due to the poor steel rocker geometry.

Long story short (like I said above), I took the liberty of upgrading the motor abit while it was apart....cam, roller rockers, pushrods, intake and porting....Last week I received the dyno sheet for my ZZ and found it came in at 663HP at 5800 rpm and 620 lb/ft torque at 4800 rpm.

I guess the lesson learned is to have the crate motor dynoed and broke in before shipping...overall I am very happy.

The dealer was Sallee Chevrolet in Oregon.

[302 Z28]

Lucky for you that you had a dealer that was willing to go the distance with you. That is the first time I have heard of such a problem with a 502 crate. They are real popular in my neck of the woods.

Vince

[jtk22ny]

I purchased a ZZ502 Deluxe in 2006 (early motor, #1113) and installed it in my Model "A" Coupe in 2008. Upon initial fire i heard a squeaking noise coming from inside the motor and couldn't identify it initially. Oil pressure was good and temperature under 200 degrees. I pulled the valve cover and found that the rockers had started to gaul as the balls didn't have any reliefs in them. I called GM performance and at first the tech stated there wasn't an issue and that the motor was out of warranty (not a great public relations ploy) but upon further investigation GM had opened up a case #49228 called "GM Squeaker 502". They told me i could purchase the revised rockers & balls but I declined and instead installed a set of roller rockers from Comp Cams and have had no further valve train issues.

I have 1500 miles on the engine and just noticed anti-freeze weeping from between the block & head. GM stated no cases have been opened for this issue but to re-torque head bolts which I did and found 8 of the 4"& 5" bolts at 65lbs and they should be at 75lbs. I ran the valves and will fire it up tonight once i install new collector gaskets. Just wanted to offer up my experience in case others have experienced the same issues without any answers.

[jtk22ny]

Originally Posted by jtk22ny

I purchased a ZZ502 Deluxe in 2006 (early motor, #1113) and installed it in my Model "A" Coupe in 2008. Upon initial fire i heard a squeaking noise coming from inside the motor and couldn't identify it initially. Oil pressure was good and temperature under 200 degrees. I pulled the valve cover and found that the rockers had started to gaul as the balls didn't have any reliefs in them. I called GM performance and at first the tech stated there wasn't an issue and that the motor was out of warranty (not a great public relations ploy) but upon further investigation GM had opened up a case #49228 called "GM Squeaker 502". They told me i could purchase the revised rockers & balls but I declined and instead installed a set of roller rockers from Comp Cams and have had no further valve train issues.

I have 1500 miles on the engine and just noticed anti-freeze weeping from between the block & head. GM stated no cases have been opened for this issue but to re-torque head bolts which I did and found 8 of the 4"& 5" bolts at 65lbs and they should be at 75lbs. I ran the valves and will fire it up tonight once i install new collector gaskets. Just wanted to offer up my experience in case others have experienced the same issues without any answers.

UPDATE 8-26: Fired the engine last night with the Bars Leak pellets (Bars Leak makes the sealant pellets for GM who re-packages them with their part #). Ran the engine for a half hour and drove for 15 minutes as well and as of this morning there is no weeping between the cylinder head and block. I believe the combination of re-torqueing and the pellets resolved this issue.

[Double_v23]

I am sorry to hear that you put pellets into the cooling system of your engine. If I were you I would flush the cooling system as soon as possible. Also, the next time you have a temperature gun handy....warm up the engine, point the laser at the bottom fins of the radiator, work your way up the radiator from side to side, if there is a significant change in temperature at any point then from that point down is how much of your radiator is clogged....Hopefully it has not clogged more than a few rows, usually this requires replacing the radiator core.

Also, I wish luck to whoever does your engine work, you have effectively cemented the heads to the block.

[jtk22ny]

Poor choice of words, I used the Bars Leak organic tablets not the rabbit pellets... Thanks, Jim

[Double_v23]

Regardless of what you call it...it is never a good idea. There are two things that should be used to fix leaks, New Parts and quality machine work. Stop Leak, block sealer, and anything that says Bar's on it are for engines that have 200,000 miles and need to get someone to work for another week or so.

You might as well have dumped a box of Bandaids in the cooling system.

Yes....this wording sounds harsh....but I just can't wrap my mind around someone who spends thousands on an engine and then takes shortcuts that are harmful to the investment that they just made.

It would be like buying a bunch of stock in a company and then spreading rumors that they are being investigated by the government.

[BOBCRMAN@aol.com]

GM is one of Bars Leaks biggest customers..

[Double_v23]

I don't doubt it, they probably started selling it because so many people were buying it. Why spend a little time and effort now, when you can just poor this magic elixir into your engine and all your problems disappear.

I wonder if you dump this stuff into your system if it voids your Manufacturers warranty?

[cobalt327]

Some copper head gasket manufacturers recommend using it.

From HERE:

Post installation: radiator coolant "stop-leak".

Once the engine is back together it sometimes may be necessary to use a coolant "stop-leak". There are many on the market. If you have a favorite use it. I have found that this may prevent an engine "tear-down".

[Double_v23]

If a head gasket manufacturer recommends it then I would be inclined not to use their products.

It all boils down to quality of parts, machine work, and assembly.

"You can do it nice or you can do it twice"

[artsvettes]

Originally Posted by Double_v23

If a head gasket manufacturer recommends it then I would be inclined not to use their products.

It all boils down to quality of parts, machine work, and assembly.

"You can do it nice or you can do it twice"

Two tablets were always dropped in the radiator, before radiator fill at our GM assembly plant

[cobalt327]

Originally Posted by artsvettes

Two tablets were always dropped in the radiator, before radiator fill at our GM assembly plant

I had heard that- from even going back YEARS ago. Until now, I never had a reliable source (other than the product literature) to back it up.

[jtk22ny]

No short cuts were taken.. The fix was the re-torque of the 8-10 4" & 5" headbolts (center cylinders, 3/5, 4/6) that were at 60-65 ft lbs rather then the required 75 ft lbs. The couple organic coolant tabs were just a precaution to help with the sealing of the various metallic surfaces/gaskets in the ZZ502 engine... I appreciate everyones passion & response but the gist of this message was just to alert folks to the "GM 502 Squeaker" rocker arm issue on the early engines and that GM Performance had an open case on file... Again, thanks and enjoy your 502, I am...
Jim

[cobalt327]

Originally Posted by jtk22ny

No short cuts were taken.. The fix was the re-torque of the 8-10 4" & 5" headbolts (center cylinders, 3/5, 4/6) that were at 60-65 ft lbs rather then the required 75 ft lbs. The couple organic coolant tabs were just a precaution to help with the sealing of the various metallic surfaces/gaskets in the ZZ502 engine... I appreciate everyones passion & response but the gist of this message was just to alert folks to the "GM 502 Squeaker" rocker arm issue on the early engines and that GM Performance had an open case on file... Again, thanks and enjoy your 502, I am...
Jim

Do you know if the GM fix involved using grooved rocker balls?

I've always been of the opinion that a solid rocker ball would provide more surface to distribute the load than grooved balls, and if the solid balls and the rockers themselves had the proper heat treat and metallurgical properties, they would do the job better (given adaquate lubrication) than the grooved balls- up to the point where spring pressures were too high.