What intake manifold sealant to use?

[pb3]

I am about to fit my new EFI intake manifold and am unsure of the best sealant to use.

High temp silicon is the favourite but I have heard it needs to be 02 sensor safe, otherwise any uncured silicon coats the 02 sensor and knackers it pretty quickly. Also where should it be used, ie just around the coolant ports or around all ports? I did notice that I had a small amount of oil weeping from the V into some intakes when I took the original off and this had no additional sealing other than the gasket.

[tuxman]

Hi Phil did a lot of reserch on this as i had a air leak on my inlet manifold on my first engine , spoke to one of the engine builders at D.B.E. they build all the engines for audi dtm he recommended a spray called ,hylomar gasket dressing spray i got mine from demon tweeks you spray a thin coat on to each side of the gasket before fitting seemed to work very well . Simon

[Boosted LS1]

I had an air leak on a manifold so fixed it with an anerobic sealant. It's more expensive but used by a lot of car manufacturers.

Boosted.

[davefiddes]

I used some Loctite silicone that I got from Halfords. In the small print on the back it says that its "sensor safe" which is the magic phrase you're looking for. The stuff seems to work OK and my engine ran just fine after fitting with no leaks. Takes quite a while to cure fully.

Had a look to see if I could find the Loctite number but I've put it somewhere safe... It's not their high-temp copper impregnated stuff that Halfords also sell.

[CanAm Dave]

I use Permatex sensor-safe high temp rtv silicone. Real Steel sell it 01895-440505.
Regards Dave

[jschwartz]

Apply rtv silicone sealer to the water ports only, and along the front and rear edge of block. Discard the rubber or cork seal for the front and rear of block/manifold and use only the bead of silicone sealant.
O2 safe doesn't matter as it won't come in contact with O2 here.
Jeff S

[pb3]

Jeff, how realiable is the sealing around each intake port. I know in theory it should be perfect but when I took the old manifold off it looked like oil could have been making its way into three or more of the eight ports. This is why I was asking what is best to use. The gaskets I have have a silicone 'ring' on each port but so did the last one so I am guessing slightly more sealing is required. Your thoughts would be appreciated, thanks.

[jschwartz]

If oil's getting through the intake gasket at the bottom, the heads and or intake needs to be machined again. Some engine builders angle mill the head to gain more compression, which requires to machine the intake to match. Sometimes parts get mixed up. If you don't want to machine, try the silone beaded gaskets you have and monitor oil consumtion. If you're smoking out the exhaust, and using a liter of oil per 600 miles you'll for sure need to machine to correct it.
Jeff S

[john3000]

I have seen a Loctite 5920 copper silicon sealant used to seal the inside baffle and casing.

I was wondering if normal high temperature RTV Silicon would do the job.

Thanks