426 Hemi Valve Cover gasket leak
#1254325
06/20/12 12:07 PM
06/20/12 12:07 PM
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Joined: Jun 2012
Posts: 43
Pacific Grove, CA
black68gtx
OP
member
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OP
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Joined: Jun 2012
Posts: 43
Pacific Grove, CA
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I have had this problem with my 426 hemi leaking oil the past 4 years and finally pulled the motor to change the gaskets.
I've replaced the valve cover gaskets, head gaskets, intake gaskets and oil pan gaskets all replaced.
After putting the hemi back in and drove 100 mile I developed a leak (passenger side).
I noticed that the gasket on the valve cover (bottom front right) at the curved cutout area was buldging out. I know that it wasn't like that before I left. I had already replaced these gasket before putting the engine back in cause I had over tighened them and they really buldged out.
What if anything has anyone done to keep these gaskets in place. I put the gaskets on in stages to stop this from happening.
step 1 RTV'd the gasket to the valve cover (keeping the gasket in place) 24 hours later I RTV'd them to the head.
step 2 lightly tightened the nuts down
step 3 24 hours later tightened them a little more.
does anyone have a cure? and what's with that little cutout area where the buldge is?
Last edited by black68gtx; 06/20/12 12:31 PM.
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Re: 426 Hemi Valve Cover gasket leak
[Re: black68gtx]
#1254326
06/20/12 12:59 PM
06/20/12 12:59 PM
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Joined: May 2005
Posts: 6,446
NJ-USA
HPMike
master
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master
Joined: May 2005
Posts: 6,446
NJ-USA
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Quote:
I have had this problem with my 426 hemi leaking oil the past 4 years and finally pulled the motor to change the gaskets.
I've replaced the valve cover gaskets, head gaskets, intake gaskets and oil pan gaskets all replaced.
After putting the hemi back in and drove 100 mile I developed a leak (passenger side).
I noticed that the gasket on the valve cover (bottom front right) at the curved cutout area was buldging out. I know that it wasn't like that before I left. I had already replaced these gasket before putting the engine back in cause I had over tighened them and they really buldged out.
What if anything has anyone done to keep these gaskets in place. I put the gaskets on in stages to stop this from happening.
step 1 RTV'd the gasket to the valve cover (keeping the gasket in place) 24 hours later I RTV'd them to the head.
step 2 lightly tightened the nuts down
step 3 24 hours later tightened them a little more.
does anyone have a cure? and what's with that little cutout area where the buldge is?
Its actually rare for a hemi to leak from the valve cover. They have sufficient clamping to get a good seal. More often than not its the head/block juncture. The drainbacks at the corners leak and fool many into believing its the valve cover. Check it out...
MB
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Re: 426 Hemi Valve Cover gasket leak
[Re: HPMike]
#1254327
06/20/12 02:40 PM
06/20/12 02:40 PM
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Joined: Jun 2012
Posts: 43
Pacific Grove, CA
black68gtx
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OP
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Joined: Jun 2012
Posts: 43
Pacific Grove, CA
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Yeah that was my thoughts, all the way home.
But after I wiped it down and ran it, I could see the oil coming from the front corner of the crimped area.
Strange as to why the gasket want's to slide out there.
Last edited by black68gtx; 06/20/12 03:11 PM.
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Re: 426 Hemi Valve Cover gasket leak
[Re: black68gtx]
#1254328
06/20/12 05:07 PM
06/20/12 05:07 PM
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Joined: Jan 2005
Posts: 1,527
minnesota
Kirby
pro stock
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pro stock
Joined: Jan 2005
Posts: 1,527
minnesota
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Quote:
Yeah that was my thoughts, all the way home.
But after I wiped it down and ran it, I could see the oil coming from the front corner of the crimped area.
Strange as to why the gasket want's to slide out there.
Gasket squirting out is usually a sign of over tightening. I put some blue reusable (Felpro) I think, gaskets on mine- and they've been great. 
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Re: 426 Hemi Valve Cover gasket leak
[Re: black68gtx]
#1254329
06/20/12 06:55 PM
06/20/12 06:55 PM
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Joined: Mar 2005
Posts: 322
Itasca, Texas
Mad_Scientist
enthusiast
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enthusiast
Joined: Mar 2005
Posts: 322
Itasca, Texas
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Not a Hemi, but same concept. I usually come back after 24 hours and do one more 1/2 turn after it has cured. I haven't had any problems with them leaking since I started doing this. I do this whenever I replace any gasket and use RTV. Be sure you don't over tighten though!  Oh, and I try to use Fel-pro whenever I can.
69 Super Bee 440 5-speed
70 Dart Swinger 340 4-speed
69 Camaro SS 396 4-speed
66 Cutlass Convertilbe
70 Judge Ram Air III 4-speed
68 F-100 SWB
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Re: 426 Hemi Valve Cover gasket leak
[Re: sthemi]
#1254331
06/27/12 06:21 PM
06/27/12 06:21 PM
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Joined: Jun 2012
Posts: 43
Pacific Grove, CA
black68gtx
OP
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OP
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Joined: Jun 2012
Posts: 43
Pacific Grove, CA
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Ok...so I took the valve cover off and sure as heck the cover cut into the gasket right at the crimped area. Here's a picture.
I swear that I didn't over tighten (I thought that I had learned from the first time) it but the picture tells the story.
Last edited by black68gtx; 06/27/12 06:24 PM.
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Re: 426 Hemi Valve Cover gasket leak
[Re: Kirby]
#1254332
06/27/12 06:27 PM
06/27/12 06:27 PM
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Joined: Jul 2005
Posts: 1,954
Blairsden, CA
Triggerfish
top fuel
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top fuel
Joined: Jul 2005
Posts: 1,954
Blairsden, CA
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Quote:
Quote:
Yeah that was my thoughts, all the way home.
But after I wiped it down and ran it, I could see the oil coming from the front corner of the crimped area.
Strange as to why the gasket want's to slide out there.
Gasket squirting out is usually a sign of over tightening. I put some blue reusable (Felpro) I think, gaskets on mine- and they've been great.
I've had great results with Felpro blues, too.
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Re: 426 Hemi Valve Cover gasket leak
[Re: 68jim]
#1254334
07/03/12 08:59 PM
07/03/12 08:59 PM
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Joined: Jan 2003
Posts: 2,431
USA
SSAAHemiFan
top fuel
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top fuel
Joined: Jan 2003
Posts: 2,431
USA
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RTV CAN cause gaskets to squirm when tightened - use weatherstrip adhesive or hi-tack. - make sure the covers are flat and not pulled thru or distorted at the bolt holes - snug them - drive for a bit and re-snug - repeat this until bolts stay tight 
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