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09-15-2009, 09:58 PM
| | Apprentice | | Join Date: Jun 2003 Location: Illinois
Posts: 59
| |  Aluminum Valve Cover Leak
Yes, I finally dumped the old leaky, warped plastic valve cover for a shiny new aluminum one. You guessed it, it leaks.
I used Red High temperature RTV silicone along with a cork gasket. I applied the silicon between the block and the gasket and between the valve cover and the gasket. You know, made a sandwich.
When I took the valve cover off, I noticed the silicone didn't stick to the aluminum valve cover. It's probably because I didn't clean it off before assembly.
I searched the forum and it seems. some folks recommend not using the silicone and gasket while others recommend using gobs of it.
So please share your opinion?
Should I use the silicone?
Should I use something else.
Also, it seems to be leaking in the same place as the plastic one. Could there be an imperfection in the head surface?
Thanks
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09-15-2009, 11:26 PM
| | Old Hand | | Join Date: Mar 2003 Location: Fairbanks, Alaska
Posts: 643
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I have done it both ways with good results. What make is your new cover and how does it attach (using the 2 stock studs or bolts along the edges)?
All my experience with aluminum covers has been with the stock 4.0 type. The first one I put on a 258 after taping the head for bolts along the edge. I did not use an gasket just some RTV it worked good. The second is the cover on my 4.0, it leaked and I reinstalled with a cork gasket with a small amount of silicon between the cork and the cover the bottom I left dry, it does not leak.
Aftermarket covers may not work as mine did.
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Wilhelm
I will start using Metric only when the duodecimal system is adopted!!
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09-15-2009, 11:29 PM
|  | Can't Get Enough | | Join Date: Dec 2006 Location: S. CA
Posts: 1,333
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Yep.....fun things.......
Well...this is how I have always solved the problem....
Remove the valve cover and clean it well....especially the gasket surface...
I don't use a gasket....
Get a tube of 3M RTV....I prefer the black....
Run a bead around the mating surface of the valve cover....about 1/4" high....high enough so that it is above the outside lip....
Real important part here....let it sit for about 45 min to an hour.....you want the surface to not stick to your finger when you touch it but you want it to still be flexible....
Now place it on the head.......
REAL REAL important part.....only lightly snug down the bolts/nuts....and let it sit over night.....
Next morning....tighten it up.....
If it leaks after that....something else is wrong.
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84 CJ7, SOA, 5.7LTBI, 4L60E, 32"x11.5 (35's on order), 4.10 gears, F/Det, R/ARB, Full Roll Cage,
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09-15-2009, 11:59 PM
|  | Official Curmudgeon | | Join Date: Nov 2001 Location: Kansas
Posts: 4,340
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Quote:
Originally Posted by bandhmo2  I did not use an gasket just some RTV it worked good. | I did that with a Clifford and had 2 spots where the rocker arms touched the inside of the valve cover. One of them was on an intake valve and caused a backfire through the carb. Quote:
Originally Posted by oldmangump Also, it seems to be leaking in the same place as the plastic one. Could there be an imperfection in the head surface? | If it’s at the back, it leaks there because that’s the low spot. An imperfection small enough not to see shouldn’t make a difference, the silicone will fill it. If you want to feel better about it, clean the sealing surface on the head and coat it with ink using a magic marker then lightly run a large file across the surface. Any low spot will show up with the ink not removed.
And, do what he said. Quote:
Originally Posted by JeepDawg Now place it on the head.......
REAL REAL important part.....only lightly snug down the bolts/nuts....and let it sit over night.....
Next morning....tighten it up.....
If it leaks after that....something else is wrong. | DO NOT OVER TIGHTEN!
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Last edited by CJ7Taz; 09-16-2009 at 12:14 AM.
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09-16-2009, 12:16 AM
|  | Keyboard Implanted | | Join Date: Jan 2000 Location: Bay Area, California
Posts: 2,420
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If it is a 4wd cover, this is what I found:
1. You need a gasket, RTV will work great as an addition, if it is set up good. To get the clearance, you need a gasket.
2. Make sure your motor mounts are good because of #3:
3. It is a PITA to get to the bolt next to the firewall. When your mounts are bad it is darn near impossible! Use some blue threadlocker on it once you get it torqued correctly, it just loves to loosen and leak, especially on to the clutch.
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Scott
1985 CJ7 T.H.O.R
"He brought me up out of the pit of destruction, out of the miry clay, And He set my feet upon a rock making my footsteps firm."
-Psalm 40:2
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09-19-2009, 09:54 PM
| | Apprentice | | Join Date: Jun 2003 Location: Illinois
Posts: 59
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Thanks for the suggestions!
I've included a picture that may help answer some of your questions.
I did get the valve cover from 4WDH. It is not leaking from the back. Although; I agree that getting to that rear screw is a bear. (Access improved, somewhat, with the fiberglass body.)
It's funny I'm having so much trouble with this because there realy isn't much pressure involved but it's leaking like a little pig.
Thanks again for your help.
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09-21-2009, 02:41 PM
|  | Addict | | Join Date: Jun 2003 Location: Valdosta, Georgia
Posts: 400
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Something I did on my 460 covers was identical to JeepDawg's suggestion with this added tidbit. Before the final tightening of the covers I took them off and wiped the newly made gasket with a thin coat of grease. They sealed just the same but made for an easy removal later.
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09-21-2009, 07:34 PM
| | Veteran | | Join Date: Mar 2000 Location: So. Jersey
Posts: 997
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09-21-2009, 09:58 PM
|  | I Might Just Know What I'm Talking About | | Join Date: Sep 1999 Location: Owensboro, KY
Posts: 1,666
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As said before clean the surfaces well.
Apply one bead, two can cause a bubble even around the bolt holes.
Tighten evenly and not too much.
Let it dry over night and tigthen a wee bit more.
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09-28-2009, 12:40 AM
|  | Newbie | | Join Date: Mar 2009 Location: Carolina
Posts: 18
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Didn't see it mentioned here, so I'll go ahead & say it.
The torquing sequence I used was similar to the head bolt pattern.
Start near the center & spiral your way out to the ends.
Repeat up to five times & only go to the recommended torque. (can't remember the number, off the top of my head due to oldtimer's disease)
You may hear it make ticking noises while cooling for a few days after doing this.
Mine is still leak free.
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