View Full Version : Intake Manifold Leaks
ColoradoZ28 Oct 27th, 99, 07:15 PM I've got a 69 302DZ with aluminum intake manifold. There are 12 allen head bolts, six to a side. It appears I have a small amount of oil and coolant coming up from a few of these bolts. What is the best way to seal up these leaks? I was going to pull the bolts and add some silicon sealer. Do I need to pull the entire manifold? What is the torque spec for the intake manifold bolts?
elcamino72 Oct 27th, 99, 07:27 PM The best way to fix your probelm is to pull the manifold off and replace the gaskets. I have been told that you can't use Fel-Pro's Perma Torque Intake Manifold gaskets w/ Aluminum manifolds. There is an order in which to torque the bolts. I'm currently at college and don't have any of my manuals w/ me. Somebody could definatly be able to post them for you.
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Bryan Shook
Burgettstown, Pa
Favorite Quote - Some people have shrinks. Some people have their garage.
www.geocities.com/motorcity/speedway/6673 (http://www.geocities.com/motorcity/speedway/6673)
GregGold Oct 29th, 99, 10:35 AM You may also consider cellophane tape to seal the bolts.
Kevin Oct 29th, 99, 02:26 PM You don't need to pull the intake just replace one bolt at a time - starting with the ones closest to the carb and working your way to the ends. I wrapped mine with teflon tape to keep the oil from seeping up the threads. Torque spec is 25 lbs/ft.
elcamino72 Oct 29th, 99, 07:23 PM If he has the leaks, he might as well replace the intake gaskets. I'm getting my Overhaul manual on Sat. I'll post the torque sequence and specs then.
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Bryan Shook
Burgettstown, Pa
Favorite Quote - Some people have shrinks. Some people have their garage.
www.geocities.com/motorcity/speedway/6673 (http://www.geocities.com/motorcity/speedway/6673)
ColoradoZ28 Oct 29th, 99, 08:45 PM Thanks for the replies. First I'm going to seal the bolts using teflon tape one bolt at a time as suggested by Kevin. If that does not work then I will pull the intake and install new gaskets appropriate for aluminum as suggested by Bryan. I'll check for Bryan's upcoming reply for future reference.
Dave Birdwell Oct 30th, 99, 02:57 PM Get rid of the allen head bolts, too. Get the right bolts from one of the parts suppliers.
Torque, as mentioned, is 25 lbs-ft.
The sequence is to start with the four in the middle by the carb, and then work your way out towards the end, tightening the four closest to the previous middle four, then the very last four. Go back and retorque them in order again once you go through. The middle four will loosen after you tighten the outside eight.
elcamino72 Oct 30th, 99, 03:14 PM Dave is right, maybe this will help.
12 11 4 1 5 6
Front of car
10 9 3 2 7 8
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Bryan Shook
Burgettstown, Pa
Favorite Quote - Some people have shrinks. Some people have their garage.
www.geocities.com/motorcity/speedway/6673 (http://www.geocities.com/motorcity/speedway/6673)
ColoradoZ28 Nov 11th, 99, 08:38 PM I just picked up a set of intake bolts from a local reseller, who in turn got them from the Classic catalog. The catalog states the washers are incorporated into the head; ie. no separate washer. Is this correct? Additionally I found that half of the allen head bolts currently on the intake were almost finger lose. How often do these bolts need to be retorqued? Will the correct bolts make a difference and stay tightened? The bolts I got are listed as K0079 in the Classic Industries Camaro catalog.
Thanks, Mark
Joe Harrison Nov 13th, 99, 08:14 AM With an aluminum intake you might want to check the torque after a few weeks of starting and stopping. As the intake heats up and cools the bolts will loosen a little. Small block are famous for intake leaks like yours and leaking into the ports. If you replace the gaskets use avaition form-a-gasket around the intake ports on the heads and intake and a very thin amount of silicone around the water jaket ports on the front and rear. Do not apply any of these sealers to the gaskets. When you have you intake off you will see some of the intake bolts go all the way through the head and these are the bolts that oil seaps up through the treads. If you use the aviation form-a-gasket on the threads of these bolts you will stop the leaks. Aviation form-a-gasket is not to be confused with indian head sealer. Indian head drys hard, aviation form-a-gasket dries but stays pliable, I use it on head bolts also. If your bolts were finger tight I would replace the gaskets. I would bet they will or are leaking into the intake ports. When this happens you start using oil and get deposit build up on you intake valve, if you have ever seen this it looks like a big blob of carbon. As the carbon builds up the valve stem stays hot and you take a chance of hanging a valve in the guide. I could go on but I think you get the idea. It is not always bad guides that cuase this build up most of the time it is leaking intakes, you can tell if the intake was or is leaking when you pull it off and oil is present in the intake port runner. As we all know only air and gas go's through there, not oil.
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