manifold Sealant
Thread Starter
Advanced
Joined: Dec 2011
Posts: 61
Likes: 0
manifold Sealant
I just bought a fel pro manifold gasket set for my 73 big block. The instructions say to use RTV black on the corners of the valley gasket.
It has been a few years since I put on a manifold. Should I use sealant on the valley gaskets top and bottom surface. Should I use sealant around the coolant passages ???
It has been a few years since I put on a manifold. Should I use sealant on the valley gaskets top and bottom surface. Should I use sealant around the coolant passages ???
Burning Brakes
Joined: Jun 2009
Posts: 840
Likes: 4
From: Syracuse IN
We use RTV Ultra black. Clean all mating surfaces, I prefer acetone. Lay a bead of RTV similar to a welding bead. usually 1/4 to 3/8 width and height. Set the intake down carefully and tighten to specs. Allow to dry for at least a few hrs before starting. Good luck Al
Advanced
Joined: Jan 2013
Posts: 99
Likes: 3
From: Salem Ohio
I am not a fan of RTV and most of the time you can tell a rookie did it. Go to you local GM dealer and buy a tube of GMS, it is the same basic concept. Clean both the intake and the valley with brake parts cleaner on a rag and scub it good. Apply the GMS with a smooth 1/4" bead, it is ok to get a little under/over the intake gasket at the head. Do not use any on th gasket around the water passages. Torque it down and by the time it's together start up and drive. Unlike RTV the GMS will stick to the metal and you will need to scrape it off if you pull it apart again. You can only get this at a dealer, it is a little more money but it doesn't leak. I don't like oil leaks and really only like doing it once.
As for your felpro kit you may have rubber gaskets that will lay on the valley. If you use them, then Yes use the GMS in the corners just not under or over the rubber. I glue the intake gasket with trim adheasive to the head so it doesn't move on assembly.
It has been a little while since I worked as a mechanic at a Chevy garage but the GMS would have been a mistake if they quite making it, it really worked that well.
As for your felpro kit you may have rubber gaskets that will lay on the valley. If you use them, then Yes use the GMS in the corners just not under or over the rubber. I glue the intake gasket with trim adheasive to the head so it doesn't move on assembly.
It has been a little while since I worked as a mechanic at a Chevy garage but the GMS would have been a mistake if they quite making it, it really worked that well.
Last edited by 1969Corvette; Mar 31, 2013 at 11:20 AM.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
If you used the "RTV bead" approach for the valley end-seals, you need to clean surfaces and lay the bead at each end [as described above]. But you DO NOT want to torque the manifold down at that time.
Install all the manifold bolts BY HAND and put no torque on them. Allow to set up overnight; THEN torque those bolts up in 'stages'....1/3 torque for all of them, 2/3 torque for all of them, then 100% of specified torque for them.
This will allow the RTV to be relatively solid when you torque the bolts and provide some compression to that flexible bead. It will be a much more stable seal.
Note: RTV 'Black' sealant is formulated to seal petroleum products, while other RTV products are not so good at that. Make sure you purchase RTV Black for this purpose. Also, you should not use this to coat gaskets. Only use for the 'corner' joints where gasket sections mate, for the end seals on intake manifold, and for junctions of multi-piece oil pan gaskets.
Install all the manifold bolts BY HAND and put no torque on them. Allow to set up overnight; THEN torque those bolts up in 'stages'....1/3 torque for all of them, 2/3 torque for all of them, then 100% of specified torque for them.
This will allow the RTV to be relatively solid when you torque the bolts and provide some compression to that flexible bead. It will be a much more stable seal.
Note: RTV 'Black' sealant is formulated to seal petroleum products, while other RTV products are not so good at that. Make sure you purchase RTV Black for this purpose. Also, you should not use this to coat gaskets. Only use for the 'corner' joints where gasket sections mate, for the end seals on intake manifold, and for junctions of multi-piece oil pan gaskets.
Advanced
Joined: Jan 2013
Posts: 99
Likes: 3
From: Salem Ohio
If you used the "RTV bead" approach for the valley end-seals, you need to clean surfaces and lay the bead at each end [as described above]. But you DO NOT want to torque the manifold down at that time.
Install all the manifold bolts BY HAND and put no torque on them. Allow to set up overnight; THEN torque those bolts up in 'stages'....1/3 torque for all of them, 2/3 torque for all of them, then 100% of specified torque for them.
This will allow the RTV to be relatively solid when you torque the bolts and provide some compression to that flexible bead. It will be a much more stable seal.
Note: RTV 'Black' sealant is formulated to seal petroleum products, while other RTV products are not so good at that. Make sure you purchase RTV Black for this purpose. Also, you should not use this to coat gaskets. Only use for the 'corner' joints where gasket sections mate, for the end seals on intake manifold, and for junctions of multi-piece oil pan gaskets.
Install all the manifold bolts BY HAND and put no torque on them. Allow to set up overnight; THEN torque those bolts up in 'stages'....1/3 torque for all of them, 2/3 torque for all of them, then 100% of specified torque for them.
This will allow the RTV to be relatively solid when you torque the bolts and provide some compression to that flexible bead. It will be a much more stable seal.
Note: RTV 'Black' sealant is formulated to seal petroleum products, while other RTV products are not so good at that. Make sure you purchase RTV Black for this purpose. Also, you should not use this to coat gaskets. Only use for the 'corner' joints where gasket sections mate, for the end seals on intake manifold, and for junctions of multi-piece oil pan gaskets.
What ever the OP uses the most important part is scrubbing the engine and manifold clean with a good fast drying cleaner, brake parts cleaner works and so will a few other chemicals. If you can get GMS
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Drifting
Joined: Nov 2002
Posts: 1,692
Likes: 207
From: Loveland, CO
Right Stuff fan also.
A couple of suggestions. Lay the manifold on the block to see how much of a gap you have on the end walls. This will give you an idea of how much of a bead you will need.
Also, lay the intake gaskets on the engine, with intake manifold laying on top, to see if everthing fits properly. I just went through this issue on my tri-power and was amazed to learn that some gasket printo-seal blue strips were not under the intake aluminum. I went through 3gasket sets before finding one that would work. I had test fit the gaskets to the head port, but didn't notice until everything was sealed and torqued up, that the intake manifold did not cover the printo-seal areas.
Ralph.
A couple of suggestions. Lay the manifold on the block to see how much of a gap you have on the end walls. This will give you an idea of how much of a bead you will need.
Also, lay the intake gaskets on the engine, with intake manifold laying on top, to see if everthing fits properly. I just went through this issue on my tri-power and was amazed to learn that some gasket printo-seal blue strips were not under the intake aluminum. I went through 3gasket sets before finding one that would work. I had test fit the gaskets to the head port, but didn't notice until everything was sealed and torqued up, that the intake manifold did not cover the printo-seal areas.
Ralph.
