Lets talk about intake gaskets . . . . .

[eric76]

I don't know what all has been going on out there when it comes to intake gaskets but I feel like something is going on somewhere to be causing me and other a lot of problems. My ordeal started in the fall of 2020. I just had a new 350 build done and after letting it sit for several days of temperature swings I noticed that I had coolant on the front coolant port location on top of the intake manifold. I then checked the torque on the intake and it was still good. The engine ran just fine and no signs of vacuum leaks or leaking coolant while running.

I kept having this problem and thought it was install error or something else. Took off intake and thought bad gasket install. I never in the past experienced this problem to where the intake gaskets seal fine during operation and stuff and hold pressure with a coolant pressure tester but yet after sitting for several days the intake gaskets will soak up and wick coolant and eventually sweat it out the top of the gaskets.

After three years and then changing out to milder heads and de tuning my build for more of a daily driver type of a deal and going from one brand of intake gaskets to another I could not get this problem figured out on what is causing it. Used feeler gauges and other ways of checking for warpage etc I finally after doing so much checking of things bought the BHJ intake angle gauge and it works good for the most part but when checking the angle on an intake manifold, the area I have circled and pointed at kind of is a downer as you can't get a reading on the the bottom most part on the angle gauge but it will give you an idea though if there is something of concern. I went through several brand new intakes and different brands and several sets of gaskets and the problems persisted and finally bought the angle gauge so I can check angles right off the bat to rule a lot of things out.

I had this gasket sweating coolant problem show up on two different builds and no matter of what method I used such as RTV or no RTV around the coolant ports and always use RTV on the China walls, it would seal and run just fine but always sweat coolant. In all my years I never saw or experienced anything like this. I have posted on other forums and have found out some other folks have ran into this problem within the last few years. They run there engine and it is fine and dry around the gaskets but let it sit for several days and temeprature swings then it will sweat coolant out the gaskets.

Below is some photos of what I am talking about. Also is the angle gauge I bought. The old Felpro gauge is made slightly better especially on the one part of the BHJ angle gauge where its circled at. The felpro gauge you would be able to use a feeler gauge to check better.

The worst results I got was using the Felpro 1205s3 intake gaskets which are a composite gasket with a .005 steel core inside the gasket. I put the intake and torqued it down. Let it sit dry for a few days. Then filled up with antifreeze and the next day I come out to where the first 1/4 of the front gasket is completly soaked with coolant and sweating out the top of the gaskets. I then drained my coolant and then took the intake back off and the gasket not only soaked up coolant and sweated it out but also sweated the coolant into my intake runners but not the valley on those gaskets.

Got the gauge and used it and everything was good as far as cylinder heads as well as the intake angles went. I finally after exhausting so many thing bought a set of Felpro 90314-2 intake gaskets which are a stock replacement type that are laminated steel core and it has given me the best results but still sweat a bit here and there but nothing like the just composite gaskets and no longer soak up like they did. The heads and intakes all checked out good on both builds. The gauge is worth the money and comes in handy and never thought there was so much that needs to be checked on these things especially with the lack of quality control on intakes and machining the angles etc.

I don't know if Felpro or other manufactures changed something in the gasket materials or perhaps something in just plain old green coolant but ever since the lock downs many folks have seen an increase of unusual issues with intake gaskets and this is on non sbc stuff as well. If you blow up the photos you can see things better. Sorry for long post.

[Tom68]

If you blow up the photos you can see things better. Sorry for long post.

Looks like it's time to throw a can of Wynns radiator stop leak in. Bodgy fix....but if it works you can sleep at night.

[Bill Chase]

How much is the IAG-1 intake jig? Looked at BHJ website and there is no price

[eric76]

It was not cheap and was just over $220 shipped give or take a few. That was last year when I bought it and the price might be different now. They are really nice to deal with and shipped pretty fast.

[Crew Chief]

I've seen some heads where someone took a vary small centre punch and put little dimples around the intake ports....the bottom of the port and top and down the centre wall....I assume trying ti hold the gasket better....

[In-Tech]

Hiya's
The LS3 intake has a similar problem area. I would use a thin smear of Ultra-Grey on the fel-pro paper with no issues.
GM's great wisdom solved this, I didn't know the gasket existed. Now, a thin smear of oil and re-use

LS3_19180613.jpg

[turbo camino]

Where is the water in a LS3 gasket?

[In-Tech]

Hiya's,
No water, sorry about old bad picture.

430_LS.jpg

[turbo camino]

Yep, that's an LS engine for sure. Dry intake. Don't see how it's relevant to Gen 1 SBC intake gaskets leaking water.

[In-Tech]

I think I am getting a little paranoid in my old age It seems lately on a few of the other car forums I frequent that there have been a lot of problems with the Fel Pro performance style gaskets with the blue rtv bead around the ports. Mainly it seems like they are moving out of place at the bottoms of the ports and in between ports. I dont know if it is really an issue or if it is installation error ? I have used those gaskets for years and have not had any issues that I know of.

I am putting together an almost stock 350 Chevy engine with cast iron heads. They have a Performer intake. If you go to Edelbrocks web page and look at the instructions it states "do not use competition style intake gaskets" because of this very issue. On this engine I am seriously thinking about just using the stock Fel Pro blue "hard" intake gaskets. They fit the ports and the intake just fine.

What are your thoughts ?

Yep, that's an LS engine for sure. Dry intake. Don't see how it's relevant to Gen 1 SBC intake gaskets leaking water.

Sorry, it has nothing to do with any Gen. It seemed, and with pics, people were complaining about the intake ports leaking. Maybe I missed a water port discussion. It's a given to put silicone around the water ports amongst a couple other places.

[turbo camino]

The Gen 1 SBC gaskets in question are about like cardboard, with a printed silicone bead around the ports. Soft, squishy, and the hard pre-cured silicone only helps them squirm around when they shouldn't. They are not a metal frame gasket like the LSA, or a formed silicone that fits into a receiver groove like other LS's. Stone-age tech here.