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Discussion Starter · #1 ·
we just built a sb chevy 355ci. it has aluminum weiand intake and aluminum heads. the heads are holly made by broadix. my problem is it is leaking oil at the back of the intake. it is blowing bubbles of oil " i kid you not". i didn't think there should be that much pressure in the lifter valley. i was told to do away with the front and back gaskets on intake and just use silicone. any suggestions about back pressure. have moroso valve covers with breathers.
 

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There is also a oil galley back there that uses a screw in oil pressure sending unit or straight lined to a oil pressure gauge. You may want to check it as sometimes if a dab of sealant isn't used on the threads it'll leak. However if your sure the intake is leaking then in other cases I've seen them leak in the rear if the silicon wasn't done properly even with valve cover breathers. If your not running a PCV, if vacuum allows then try one and see if it solves the issue. If not you'll have to remove the intake, clean it real good as well as the heads and china walls and redo the job. If you have to do so then make sure you lay rags in the lifter valley to prevent any trash from falling down into the engine and stuff paper towels in the intake runners to prevent the same.
 

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Discussion Starter · #3 ·
thanks

Thanks, i am going to redo the intake and just use silicone. i can't use pcv valve so i am just going to try to put another breather on each side. it just blew my mind to see bubbles coming out from the back of the intake. i cked the fitting for the oil line and didn't see any oil coming from there. thanks again, guess i need to get back to work.
 

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Hopefully I'm catching you in time don't use fel pro intake gaskets.
Go to your local parts store and use the Mr. Gasket cheapy's hanging on the shelf. Some Fel Pro gaskets are not for use with aluminum intakes and in the time it would take to tell you which numbers to ask for I recommend just using the mr. gasket jobs.
 

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I had this problem once and what I Did was take some lacquer thinner and wipe the block front and back where the intake sets as well as the intake ends,also wipe the the heads. This will remove any oil and make the silicone stick.
 

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Discussion Starter · #7 ·
Thanx

Thanks guys for all the good info. I sprayed the block and intake and heads with brake clean then wiped down with thinner. i am a mopar guy and never had this kind of problem. i just didn't have the bucks to build a good mopar so small block chevy it is. you can bet that next time i will just wait and save enough to build another mopar.
 

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I put the intake gasket on and coat the bottom with a transfer dye. Then I torque it down. Once correct torque is completed I loosen it up and remove it. The dye will show you where there was contact and if no dye then you have to apply a thicker coating of the coating you choose to use. I also anneal all of my head gaskets and that seems to help with their life too. But not all head gaskets are intended for that kind of heat. I also do my valve covers applying the dye to the bottom of the gasket. It has worked for me for years.
Normbc9
 
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