February 28, 2024, 06:46 AM
421philtIntake gaskets leaking
Recently had my cylinder heads rebuilt (Dart Pro 1 bbc) also surfaced .006. Now have a small antifreeze leak around intake gaskets. Should intake be cut too? Engine builder didn't think so...
February 28, 2024, 07:53 AM
TOP38I can't see .006" making any real difference but it's easy to check once you get it off and cleaned.
Check the end rail clearances with the intake on the motor. If it doesn't hit either the front or rear rail with no gasket you should be good there. If it hits then its possible the intake is really being support by the block on not the heads which won't let the intake crush/seal on the intake gaskets.
To check the sides of the intake: Lay the intake back on the motor, as long as the ends don't bottom out on the block, on the front and rear corners where the intake is resting on the heads, see if the intake meets the end evenly from the bottom to the top, if there is a gap at either end measure it with feeler gauges. If it's out enough here then you would also be sucking in oil from the lifter valley or leaking air in at the tops of the ports. this is usually not an issue unless the heads have been angle milled.
February 28, 2024, 09:11 AM
vetmanHavent used endrail gaskets for years just because of this issue-clean use a good silicon sealer on end rails allow to dry before firing engine
February 29, 2024, 07:56 AM
FootbrakeJimquote:
Originally posted by TOP38:
I can't see .006" making any real difference but it's easy to check once you get it off and cleaned.
Check the end rail clearances with the intake on the motor. If it doesn't hit either the front or rear rail with no gasket you should be good there. If it hits then its possible the intake is really being support by the block on not the heads which won't let the intake crush/seal on the intake gaskets.
To check the sides of the intake: Lay the intake back on the motor, as long as the ends don't bottom out on the block, on the front and rear corners where the intake is resting on the heads, see if the intake meets the end evenly from the bottom to the top, if there is a gap at either end measure it with feeler gauges. If it's out enough here then you would also be sucking in oil from the lifter valley or leaking air in at the tops of the ports. this is usually not an issue unless the heads have been angle milled.
^^^ This. And especially if you have a block and/or heads that were previously owned by someone else. Remember that either decking a block, or milling heads, moves the heads closer together. which can cause the intake to sit up higher than normal, and can also cause leaks. Evidence of this is if you have a large gap at the end rails. I bought some used heads years ago that were fresh from the machine shop. They had been milled so much that I could not bolt on the intake manifold, the holes in the heads were misaligned that badly. I even opened up all the bolt holes in the manifold with a burr, and still wound up having to get the intake flanges machined. Dave (I Make HP on here) was a machinist and posted a great formula years ago, on how to measure and calculate the amount of material to cut and the proper angle to correctly restore the intake to head mating surfaces.
February 29, 2024, 02:32 PM
Big StevePermatex Ultra Grey is your friend
March 04, 2024, 12:00 PM
421philtA friend told me to try a .030 intake gasket and so far no leaks. Thanks all !
March 05, 2024, 11:41 AM
FootbrakeJimquote:
Originally posted by 421philt:
A friend told me to try a .030 intake gasket and so far no leaks. Thanks all !
Glad to hear you got it fixed. I also recommend the Fel-Pro intake gaskets with the raised blue rubber bead around the ports and water holes, they are very forgiving of less than perfect mating surfaces...
quote:
Originally posted by Big Steve:
Permatex Ultra Grey is your friend
Lol. Steve, I used that stuff just one time on an intake. Made the mistake of smearing a thin layer around all openings between heads and intake. Never will again. Definitely sealed it up. Darned near impossible to remove! A huge pry bar couldn't budge it. I even attached my engine hoist to the manifold, and that shyt literally lifted an all steel BBC and was about to lift the front end of a door car off the ground!
I ended up taking some long thin box-cutter blades and cutting through the Ultra-Gray at the end gaps and along both sides of the intake gaskets. Some tough sealer, no doubt. But you better pray you never need to take it apart.