Valve cover gaskets and all that!


New Member
May 26, 2001
Take out 4 screws and replace the gasket and screws. Yer right!

What about a 78 motor that has not been apart for 23 years?

Here are some of my experiences:

First spray all of the nuts and bolts you can find with lub. 3 days before the "operation". Then go ahead and break off 2 of the turbo to downpipe bolts. Wind up grinding off 1 of the plenum bracket nuts on the manifold with a Dremal tool, no stud damage.

Remove the carb., marking all of the pipes with tape and black marker. By the time all the wrenching and cleaning was finished most of these tapes had disappeared or were illegible. Make sure you have a good vac. diagram availaible before you start this whole process.

Remove the turbo and plenum in one piece. THANKS Rich for this usefull tip. It is a struggle to get it out through all the wires and pipes but it works OK. Leave the turbo mounting bracket attached to the turbo.

On removing the turbo and plenum I was greeted with about a 1/4 " of black gunge and the local chipmunks winter storage area.

After a lot of scaping and brushing with kerosine , and trying to avoid filling all of the openings with crap, I finally discovered the valve cover were painted blue!

I managed to remove the passenger side valve cover without removing the down pipe. A bonus.

I now understand Freddies comment about these things leaking when they are not running. The cover is thin gauge, and was distorted due to all my futile wrenching over the years in an effort to keep the oil in. The head gasket surface is about 3/16" wide and rough cast.

After straigtening out the covers I decided to use a combination cork/nitride gasket as it was softer and more pliable than the standard cork. I thought it might have a better chance at sealing.

I assembled it dry and tightened lightly. THANKS Freddie for this tip. I did not have a nut driver that would fit over the long prongs on the bolts, so I just use a long socket and extention without the rachet.

The 2 broken bolts in the turbo were drilled out and Helicoiled. Being tight of wallet I did not want to sport out on a 10 mm Helicoil kit, so I used a 3/8 UNC which was at hand. Although the 3/8 UNC is slightly smaller than a 10mm / 1.5 this was not a problem.

My EGR valve has not been working for years so I installed a new one. I can not figure out why the EGR manifold between the exhust and EGR was clean, but the between the EGR and plenum was totaly blocked. Filled completly with black carbon like concrete. The plenum itself was totaly clean. Any explainations?

Although the PCV looked in good shape I replaced it any way.

Having removed the EGR manifold from the block resulted in a problem realigning it with the plenum on replacement. It took 3 dry runs at this before a satisfactory alignment was achieved. Do this without any gaskets. Avoid removing the EGR manifold from the block if possible.

The original gaskets on the EGR and manifold were metal reinforced. I could not get any of these gaskets. The new EGR was supplied with a "paper" gasket which I used. I manufactured the EGR gaskets from Victor Reinz gasket material # JV 125.

The gasket between the turbo and manifold was about 3/16" thick, of unknown material, and had metal bushes around the 3 mounting bolts. For this I laminated 6 thicknesses of the JV 125 material, and glued them together with a light coating of contact cement with the bushes installed.

I found the best way to get this back together was to position the turbo/plenum assembly in place, and then slide the gaskets into place. Don't forget that tubo drain hose. Little devil.

The 78 does not use gaskets on the exhust/turbo connections, but a spherical "taper" to allow for alignment. I noticed on taking it apart that there was exhust cement used here. On reassembly I also used cement very sparingly as I did not want this guck going through the turbo.

I replaced a few miles of crispy vacuum lines. The EGR/EFE temperature switch has a moulded plug with the lines permantly attached. I thought I would discard this and leave the EFE disconected [ permently open ] ,and connect the EGR straight to the carb. EGR port. BIG MISTAKE!!!! On starting the car it took 3 attempts to get it out of the garage and then it drove down the road like a camel with the hump. The moral of this story is don't feed EGR into a cold engine. I think Buick does it at 180 F.

On a re-exam of the plug I found that there was sufficient good pipe at the plug to re-attach new lines. When I did this and re-plumbed the EFE/EGR per Buick everthing was AOK.

I also disconnected the plenum heating pipes. No bad results from this so far.

So far no gaskets have been sucked in or blown out, and there appears to be no valve cover oil leaks. Dispite all the tribulations I am very happy with the outcome.

Don't let all this Fluff discourage you from doing this job ,just allow a looooong weekend.

THANKS again for all your help and support in this project.

Here's something I'd like to share with you guys. Back in July while I was reading an engine rebuilding book I picked up on this sealant that most better rebuilders use. 3M's Super Weatherstrip Adhesive. Part #051135-08001. (And it's cheap too! Try it!)

I've tried red RTV, black, Permatex and they all have their uses. But this sealant does everything and has a 'kick ass' seal. (try removing it and you'll see what I mean). So far since I've used it not one seal has opened. I've used it on the oil pan with cork gaskets, thermostat cover, valve cover gaskets, water pump and timing chain cover gaskets and nothing beats it. It's excellant for the transmission pan gasket too. After spreading, it remains tacky so gaskets won't slip like when using red RTV. This yellow goop is sure to gain your trust once you've put it thru the test of the average street mechanic. You'll never go back to the others once you've tried it....:D