C3 Engine Squeak

[Pat K.]

I have a '69 L36 with a rebuilt motor. The motor has about 1,500 miles on it. This past weekend I drove the car approximately 90 miles continuously on the Turnpike at speeds of 70-80 mph.

When I pulled the car into my driveway there was a squeak coming from the top right side of the motor towards the back. The squeak was continuous at approximately 1 second intervals. I turned the car off, let it cool down, then took it out for another spin, and once the car warmed up the squeak returned. There's no squeak when the engine is cold. There's no degradation in performance with the squeak.

I brought the car to a friend who is a mechanic and he said it sounded like a rocker arm. He recommended changing the oil and add a ½ quart of GM EOS. After the oil change I started the car, warmed it up and the squeak is gone. I've taken it out for several spins since the oil change and the squeak has not returned.

Most of the rocker arms are original. I plan on pulling the valve cover and inspecting the rocker arms.

Does this sound like a rocker arm problem or something else?

[Michael H.]

Re: C3 Engine Squeak

Pat,

Years ago, this was a very common problem. In the late 60's and early 70's, it was so common on new cars that GM issued a bulletin to dealers about it and their recommended first time fix was to add one small bottle of positraction additive to the engine oil, then advise the customer to put several hundred miles on the car. If the squeak returned, the next step was to replace the affected rocker arm/ball assembly. The problem mostly affected the 230 CI 6 cylinder engine but did also show up on all V8 engines.

Give the EOS a try and see what happens. It may permanently solve the problem.

Michael

[Pat K.]

Re: C3 Engine Squeak

Michael,

It's comforting to hear it's not a major problem.

Since the squeak has not returned I've been debating whether I should even pull the valve cover. Would it be good procedure to have a look at the rocker arms in that area?

Also, should I add the EOS on the next oil change?

Thanks,

Pat

[Michael H.]

Re: C3 Engine Squeak

Pat,

I would probably drive the car as is and see what happens as there is a good chance that the problem will never return. Even if it does return, you really haven't lost anything other than a can of EOS.

All of the warranty rocker arms that were submitted to engineering showed no gauling or metal loss so there should be no danger to your engine even if the problem returns.

I would try just oil at the next change. It shouldn't be necessary to add anything else.

[Pat K.]

Thanks! *NM*

[Marc R.]

Re: Thanks!

What is EOS?

[Tony H.]

Re: Thanks!

Engine Oil Supplement

[Pat K.]

Re: Thanks!

http://www.gmgoodwrench.com/PartsAccessories/EngineProducts.html

[Donald M.]

Re: Thanks!

Engine Oil Supplement. It is sold by GM as a very viscous additive to oil or to use to coat new metal parts during assembly (cam lobes, lifters, etc.). Basically, it thickens the oil so it will be less prone to run-off when the engine is shut off.It is also available in the aftermarket as STP. Been on the market for years.

[Michael H.]

Re: Thanks!

EOS is a GM marketed engine oil supplement. Been available at all GM dealers for decades.

[Marc R.]

Re: C3 Engine Squeak

Ahhh....certainly familar with STP; didn't know EOS. My '69 350/350 with 11.1 doesn't use or loose oil....runs super, burns rubber in all 4 and won 1st place in a local show last weekend. Life's good.

[John H.]

Re: C3 Engine Squeak

Did see a fair number of burned rocker balls, however, usually from the exhaust side; standard fix was to put the ball from the adjacent intake rocker on the exhaust (already worn-in) and put the new ball on the intake rocker, which runs at lower temperature. The aftermarket cured it with grooved rocker balls.

[Michael H.]

Re: C3 Engine Squeak

Yes, I remember that recommendation from engineering for the SCCA Camaro in 68-69. At that time, the rules stated that production rocker arms had to be used instead of aftermarket rollers and a fair amount of exhaust arms were burning. Was about that same time that the new "polished pallet" arm was released for service. Most of the problem was due to the excessive valve spring presure that the 142 HD service spring produced.

[Mike McKown]

Re: C3 Engine Squeak

I think there was a TSB on this. John's right. put the noisy ball on an intake and get a new one for the squeaker. I did this once on a '57 Chevy 283 I rebuilt. I didn't buy a new ball, just swapped the ball to another rocker and the noise went away and stayed away.