valve cover sealing

[tom.mcinerney]

My truck came with a leak in driver's side valve cover. Just fired up after replacing heads, etc, and now leaks at same place, between studs supporting injector pipes. I tested 'crankcase depression' with manometer [immediately suspected excessive blowby], but that seems fine, two inches at 2500rpm, no load.
So, any tips on the installation? I used Permatex 'Ultrablue' because i've found it seems a good sealer. I think the problem was 1.) the Helm manual advised not to tighten so much that all rtv squeezed out. 2.)Then have to attach fuel pipe brackets to valve cover studs.
The stamped covers are SOOO wimpy; and i'm accustomed to thicker stuff with stiffeners, and a gasket....

[Uncle Wally]

Tom,

When I popped mine off to replace the gaskets, it seamed that the repair shop that did it last used copius amounts of black rtv to seal them up. One leaked, the other didn't. I'm not entirely convinved that's the best way to do business as there was no gasket at all. It seamed to work on one side though.

Waldo

[britannic]

I tried the cork gasket that came with the upper timing kit and it worked for the first 6000 miles, then the cork bust in two at a couple of spots and it started leaking.

Prior to that the military had used black RTV which proved leak free over 200K. The valve cover has to be completely flat without warpage etc.

[catmandoo]

the trick is to apply a good bead on the valve cover and just set it on the head and run the bolts in and as they say do not tighten just snug and let it set.for 24 hours then attach the brackets.if you look at most gm cars from the late 80's up they have little dimples next to the bolt holes,this is to keep you from pushing the sealer out when you tighten the **** out of em.i actually like the late 80's up 350's that have the rubber in the little channel. flop it on the head tighten 3 bolts tight and your done.

[Dieselboy]

GM manual calls for 20 ft-lb of torque on these bolts. That split the cork gaskets on mine, so another set was installed with copious amounts of black RTV and a just enough force where the silicone started to ooze. Works well so far.

International 7.3 IDIs have a similar problem since their valve covers are made of thin piece of stamped steel - just like ours! The trick that was employed from the 6.9 to 7.3 generation change was the use of a set of tabs (about 1/8" thick) that each bolt threaded through; it helped distribute the clamping force across the seal about an inch of either side of the hole.

That's a pretty neat trick for not a lot of ca$h. :cool:

EDIT: spelling

[ 03-30-2004, 06:32 AM: Message edited by: Dieselboy ]

[Brandon]

Get the GRAY silicone from GM. It is alot stiffer than what is sold at the parts stores. It is what was used at the factory. Use denatured alcohol to clean the area with first and make sure there is no oil at all around the area.