Merlin heads, new 502-valve cover oil leak??

SteveDavid · 06-11-2002, 01:28 AM

Friends,

Installed Merlin heads on new 502 engines and used existing 500 EFI valve covers (blue) with the ruber o ring gaskets. Had oil leaks pretty bad on header side of valve covers during dyno runs. Ground off the aluminum tabs on the mating side of the valve cover so the o rings would seat better on the heads and eliminated most leaks, except for a small one on the starter motor side of one of the engines. Have any of you had this problem, and if so what did you to correct the situation?

Thanks for your help!

Steve David

Griff · 06-11-2002, 01:50 AM

You've already ground off the tabs, so I would try some of the steel cored, thicker, flat gaskets.

SteveDavid · 06-11-2002, 02:03 AM

Thanks Griff, was leaning towards that, or RTV silicone. Apparently the landing flange on the Merlin heads are a different thickness then GM heads?

Thanks again,

Steve

Louie · 06-11-2002, 08:55 AM

I believe the Merlins require a MK IV style cover and gasket due to their thin rail.Had the same problem on mine,switched to the old style covers and fixed.

FloridianSon · 06-11-2002, 12:34 PM

Good thread Steve I just made the same switch and would not have known about the problem! Thanks to you to Louie.

aTX427 · 06-11-2002, 12:51 PM

Steve,
This may be too simple, but did you bottom out the nut on the stud before it sealed down on the o-ring? Had the same thing happen once.

John

SteveDavid · 06-12-2002, 03:56 AM

Friends,

Thanks for the responses.

Thus far:

Replaced the std. studs with ss all thread studs to avoid bottoming out. (Thanks John

Measured the landing area/mating surface of the head and valve cover and Louie you're right on target. The O ring just barely mates to the Merlin head.

Of the three engines, only this one valve cover has this one small leak. So rather then changing all 6 valve covers I'm going to try using a small bead of RTV sealant on the head surface. Then reattach the valve cover using light pressure until the RTV dries. After it dries I'll snug it down to full torque load.

Unfortunately it had to be the center engine with this problem. The rear engine valve covers come off pretty easy. The header configuration on the center engine requires removal of the header to get the valve cover off. It's about a three arm process and real creative use of the major dirty word

Thanks again for your help.