Is there an intake gasket revision?

[EdH]

I think I read somewhere that there is a revised manifold gasket put out by GM. Anyone have more info on this. This would be for the 5.7l Vortec in a 96 Suburban. If anyone has had their's replaced in the past, how long can the repair be expected to last? It's time to have mine replaced and I don't have the time so it's off to a shop. Mechanic says it's a plastic gasket and he doesn't use a sealer and he's never had one come back. Any thoughts?

[Old Dave]

My son's starting leaking about 3 weeks ago, started out just a few spots and quickly turned into the size of a basketball in just a few days. Him and one of his friends replaced it on a Sat. and took them about 5-6 hrs. He used Felpro gaskets from the auto parts store and used a gasket sealer called "Great Stuff" on the front and back of the intake manifold rather than the tube of black RTV that came with the kit. It's been about 3 weeks and no leaks.

[Thunderbolt]

Fel-pro gaskets and sensor safe RTV. The key is make sure you don't over torque the bolts. I did mine 82,000 miles ago and it is still good to go.

[SpitAndDirt]

Just an opinion, but go to the dealer and get the proper intake gaskets. Felpro makes excellent gaskets too. Look at both before buying, if they are identical, go with the cheaper one. However, I would personally stick with the GM ones in this area. As for the reason why they leak, its usually caused by the Orange Dex Cool. Have your system flushed and Green Antifreeze put back in when you have the gaskets changed. As for the RTV mentioned, I hope it was not used on the gaskets themselves. The RTV should only be used in the front and rear of the intake manifold. And that's if GM doesn't have a rubber insert that takes the place of RTV. Only the GM Parts guys will know.

[Ketch]

Originally Posted by SpitAndDirt

As for the reason why they leak, its usually caused by the Orange Dex Cool. Have your system flushed and Green Antifreeze put back in when you have the gaskets changed.

This is not the reason they leak. There could be a couple of reasons why they start to leak i.e. they leak because the factory is notorious for overtorqueing and squeezing them down to where they fail (mine where pancaked) or the RTV is either poorly applied or just gets old.

Replacing Dexcool with old style antifreeze (Green stuff) has been discussed extensively in these forums. There is no evidence that Dexcool causes problems in and off itself. Like many newer technologies these days, it requires different handling and different maintenance. Too many old school folks would rather blame the new technology than change old habits. Where have I heard that before....? Green may be more forgiving when it comes to not being topped up, or improperly mixed. But it may cause more problems i.e. with sensors and other parts - on down the road a spell.

I have written elsewhere in the Sub and Tahoe forums about the correct procedure for putting in new batch of Dexcool. COMPLETELY flush the system, use distilled water, pre mix your batch exactly 50/50, clean your overflow tank out etc... Search on my name.

As for the gaskets - you certainly do not apply RTV to them ----- EXCEPT where your supposed to. There are fingers in the gaskets designed to mesh with the RTV. I'm not sure if S&D you just were not clear but just be sure that you overlap the RTV sealant into the gasket end fingers so there is not a gap between RTV and gasket - per the instructions that come with the gasket!

The manifold must be completely scraped and cleaned.

The manifold bolts must been torqued exactly. I cant remember without looking it up but it was inch/lbs and not foot/lbs.

The Felpro RTV tube is barely enough so buy a separate tube and use it instead.

[Thunderbolt]

I believe the main reason they leak is partly because of over torquing the bolts and partly due to design. The intake mating surface is at an angle while the intake bolts go straight down. This along with over torquing the bolts actally forces the intake to slide on the gasket and damage it. It was apparent that mine were over torqued just by the damage that was done to the gasket. As far as the RTV goes I personally only use it across the front and back of the intake, But have heard of several people running a small bead around the coolant ports as well. I personally don't reccomend that method because the intake will seal fine with proper torquing.The torque specs straight from a dealers computer are as follows. Lower intake first pass is 27 in lbs, second pass is 106 in lbs and the final pass is 11 ft lbs. The upper intake is 44 in lbs for the first pass and 88 in lbs for the final pass.

[Fireplug]

As a retired GM Master Tech and ASE Master tech
I have replaced many intake gaskets in my years.
The intakes have been leaking LONG before the new antifreeze came out.
Most of the leaks where do to
1. The chevy V8 does not heat up enenly some spots get hotter then other spots and that causes the gaskets and rtv to wear out.
2. Lack of fluid changes oil, antifreeze.
3.Cooling system problems causing the engine to rum hotter then factory specs.
4. You have to different types of metal 1 type for the heads and a 2nd for the intake and the new style is plastic intakes.
As for the gaskets if you do some checking you will find out that Fel-Pro makes the GM factory gaskets.
Fireplug

[markdpro]

Originally Posted by Fireplug

As a retired GM Master Tech and ASE Master tech
I have replaced many intake gaskets in my years.
The intakes have been leaking LONG before the new antifreeze came out.
Most of the leaks where do to
1. The chevy V8 does not heat up enenly some spots get hotter then other spots and that causes the gaskets and rtv to wear out.
2. Lack of fluid changes oil, antifreeze.
3.Cooling system problems causing the engine to rum hotter then factory specs.
4. You have to different types of metal 1 type for the heads and a 2nd for the intake and the new style is plastic intakes.
As for the gaskets if you do some checking you will find out that Fel-Pro makes the GM factory gaskets.
Fireplug

Hello
I had the manifold replaced and now I have the top of the hill rumble and miss in my 5.7 Yukon.

I noticed today that there seems to be a vacant port on my evaporative control valve. Is this some kind of purge or did the tech miss a hose? I can't find a loose hose or another vacant port