Intake manifold-5.8 EFI-HELP!!!!
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From: Colville, Washington
Intake manifold-5.8 EFI-HELP!!!!
1989 F250 4x4 with 5.8EFI(SD)-how do you get the lower intake to seal up well??? I have had constant problems with both vacuum and coolant leaks. I have torqued in sequence every time(about 5 trips thru each time installed) and was only able to get it sealed once! I had to rebuild the engine and now, with less than 2000 miles I have an intake leak of coolant and vacuum.
I am looking for any suggestions of technique, gaskets, tips, tricks, etc. to help me out.
TIA!!
I am looking for any suggestions of technique, gaskets, tips, tricks, etc. to help me out.TIA!!
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how do you install intake gaskets? do u use the end seals or use rtv silicone instead of end seals?
before i install both intake/head gasket i use a little gasket sealer around the coolant passages and rtv sealer around the exhaust passages before installing gaskets, then i throw away the end seals and use black rtv silicone to seal both ends of manifold(make sure u build up sufficient rtv to both ends. i use 2 intake bolts (with the heads cut off) as a guide before installing the intake.
before i install both intake/head gasket i use a little gasket sealer around the coolant passages and rtv sealer around the exhaust passages before installing gaskets, then i throw away the end seals and use black rtv silicone to seal both ends of manifold(make sure u build up sufficient rtv to both ends. i use 2 intake bolts (with the heads cut off) as a guide before installing the intake.
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From: Ottawa, Ontario
Clean the block thoroughly and glue the end seals in place with contact cement. Now apply RTV to the other intake gaskets and the top of the end gaskets and install the lower intake, this should seal up really well and completely prevent blown out end seals.
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From: Colville, Washington
Thanks for the tips, I have been using RTV in place of the end seals, they do not appear to be an issue. The leaks have been at the bottom of the intake ports(sucking oil into intake and vacuum leak) and at the rear water port that leaks coolant.
What brand gaskets have you had success with? Are you using standard replacements or performance sets??
What brand gaskets have you had success with? Are you using standard replacements or performance sets??
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Joined: Dec 2007
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I've never had this happen with FelPros. Can you get your hands on some blue dye to see if the intake is warped or bowed? You put blue dye on the heads then set the intake on sans gaskets to see if you have parallel surfaces. The blue dye should transfer evenly, if not get another intake and try again.
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I have been wondering if I have a warpage issue, I will try to dye check the mating surface and get back.
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From: Jackson
A lesser known issue is that when you mill the heads you change the contact area of the intake mating surface. If the heads have been milled .020 or greater, the intake needs to be milled to compensate. .020 = .010 off each side and .0141 from the manifold bottom. .030 = .015 off each side and .0212 from the manifold bottom. Taken from 'How to rebuild your small block Ford' p78-79.
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From: Colville, Washington
Well,I die checked the intake/head mating surface and........there is a considerable portion of the mating surface that does not touch!! As a matter of fact, only about 15% of one side makes contact and about 25% of the other side! It looks like I'll send it to a machine shop to see if they can mill it or be looking for a replacement manifold.
Thanks for the tips and suggestions, guys.
Thanks for the tips and suggestions, guys.
) to make a trip there to see what they have.
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