Question about vacuum leaks
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
I think no. If you had an intake manifold gasket leak to valley, it would burn oil, by sucking oil vapor into the intake ports under high vacuum conditions. You claim that your engine doesn't burn oil, so...
Safety Car
Joined: Jan 2004
Posts: 3,759
Likes: 8
I don't know of an article. But here's how I do it.
First apply a thin coat of gray RTV to the side of the gasket that contacts the head. Place the gasket on the head where you want it to be. Then carefully place the intake on and start the bolts. I snug all the bolts and then torque to 10 ft-lb stating with the center bolts and working out. Let the RTV cure for 24 hours and remove the intake. Now apply a healthy bead of RTV to the rails and a thin coat on the gasket. Install the intake and torque per the manual. Make sure that you can see RTV squeezed out on the rails.
First apply a thin coat of gray RTV to the side of the gasket that contacts the head. Place the gasket on the head where you want it to be. Then carefully place the intake on and start the bolts. I snug all the bolts and then torque to 10 ft-lb stating with the center bolts and working out. Let the RTV cure for 24 hours and remove the intake. Now apply a healthy bead of RTV to the rails and a thin coat on the gasket. Install the intake and torque per the manual. Make sure that you can see RTV squeezed out on the rails.
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
I do basically the same thing and yes, you can put the silicone under the gasket. As cumbercr said, put the silicone on the 4 corners where the head meets the block and put a light skin on the bottom of the gasket. Then my way is to use 4 - 1 inch 3/8 bolts with flat washers on them, run the bolts down by hand, NO WRENCHES, until they are seated against the gasket, holding it in place. Be sure the gasket is centered over the holes before running the bolts down. I then let everything set for an hour or so and then I put the bead of silicone on the china wall, front & rear, I let that sit for another 15-20 minutes so there is a slight skin on the silicone. I then install the intake & torque it down to specs using the sequence shown in the fsm.
Safety Car
Joined: Jan 2004
Posts: 3,759
Likes: 8
I do basically the same thing and yes, you can put the silicone under the gasket. As cumbercr said, put the silicone on the 4 corners where the head meets the block and put a light skin on the bottom of the gasket. Then my way is to use 4 - 1 inch 3/8 bolts with flat washers on them, run the bolts down by hand, NO WRENCHES, until they are seated against the gasket, holding it in place. Be sure the gasket is centered over the holes before running the bolts down. I then let everything set for an hour or so and then I put the bead of silicone on the china wall, front & rear, I let that sit for another 15-20 minutes so there is a slight skin on the silicone. I then install the intake & torque it down to specs using the sequence shown in the fsm.
I figured that would cause some compromise of the china wall seal at the corner there since the RTV at the china wall isn't being done all at the same time, i.e. china wall and above and below gasket at china wall.
But maybe it wouldn't matter if the bottom corners of the gasket are RTV'd at the china wall without any of it oozing out on the china wall or on top of the gasket. Then after the gasket is set, you could then run a bead of RTV on top of the gasket and along the china wall.
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
Yes, I put the light film of RTV on the gasket and just a little dab at each of the 4 corners, then I set the gasket in place and put in the bolts to hold it in position. Then after about an hour I remove the bolts, apply the rtv bead to the china walls, let it skin over a bit, then VERY carefully set the intake straight down into position, start all of the bolts and tighten down using the proper sequence just until they are snug, then torque them down.
