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79 cj5 258 valve cover

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79 cj5 258 valve cover
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hattrck24

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Lawrencebug, Indiana
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Just purchased a 1979 CJ five with the AMC 258 i6 / 4.2l engine and a four-speed Transmission . It is leaking oil very bad, so I am hoping to replace the valve cover with a new one as well as gaskets. Searching the Internet and I cannot find any valve covers for a AMC 258 i6 / 4.2l that are not for the year 81 or after.

Is there a difference between the AMC 258 i6 / 4.2l engine from a 79 to an 81? Or would the same valve cover work?

Mine currently has a plastic one and whoever put it on last time couldnt get it to seat properly so they just used a ton of goop to try and fill the gaps and it is leaking oil.

Anyone know of a lead for a valve cover for a 79 AMC 258 i6 / 4.2l that is metal?

Any help would be appreciated

Thanks

Zac

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Can not help with the metal cover, but whatever route you go, FelPro Blue gaskets work quite well
 
Make sure the leak is from the valve cover. Mine leaked like the Valdez and I assumed it was the valve cover. Well it turned out it was a little from the valve cover but most of it was coming from the fuel pump gasket.


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I know they make 'em in aluminum, but can't remember where I've seen.
 
Make sure you have the correct PCV valve.
Be sure it's clean and working.
Gary
 
The only difference between a plastic valve cover and a metal/aluminium cover is the plastic ones only have 3 or 4 bolts around the perimeter and use plastic plugs on the cover that go in the other holes to keep it from spreading out. Over time the heat and such make it warp. Anyways, your only option would be to go with a new plastic cover or get a metal cover and tap the holes(the holes are there so no drilling), just no threads. If you go the metal route, you will need a bottoming tap, start with a regular tap til it bottoms out them switch to the bottoming tap to thread the rest. The holes are shallow, 1/2"-3/4" maybe. It's easy to do just take your time, don't force the tap, and careful not to get metal shavings inside motor. I want to say threads are 3/8-16 but i might be wrong...

PS: Morris 4x4, Summit Racing, QuadraTrac , Amazon, all sell plastic and metal/aluminium covers.
 
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My understanding is that the aluminum after market covers are designed to replace the plastic covers because they leak so bad. My 1980 AMC 258 i6 / 4.2l has a steel cover, and none of the cool new ones fit. The seat shape is different on the passenger side. Mine is squiggly as opposed to straight on the plastic and new aluminum ones. I've read about tapping new holes for some retrofits but don't have any experience. Good luck.
 
My understanding is that the aluminum after market covers are designed to replace the plastic covers because they leak so bad. My 1980 AMC 258 i6 / 4.2l has a steel cover, and none of the cool new ones fit. The seat shape is different on the passenger side. Mine is squiggly as opposed to straight on the plastic and new aluminum ones. I've read about tapping new holes for some retrofits but don't have any experience. The aluminum covers are available from Quadratec. Good luck.
 
hattrck24 said:
Just purchased a 1979 CJ five with the AMC 258 i6 / 4.2l engine and a four-speed Transmission . It is leaking oil very bad, so I am hoping to replace the valve cover with a new one as well as gaskets. Searching the Internet and I cannot find any valve covers for a AMC 258 i6 / 4.2l that are not for the year 81 or after.

Is there a difference between the AMC 258 i6 / 4.2l engine from a 79 to an 81? Or would the same valve cover work?

Mine currently has a plastic one and whoever put it on last time couldnt get it to seat properly so they just used a ton of goop to try and fill the gaps and it is leaking oil.

Anyone know of a lead for a valve cover for a 79 AMC 258 i6 / 4.2l that is metal?

Any help would be appreciated

Thanks

Zac
Click to expand...


Double check your engine data as to year it was made. Plastic covers started in ‘81 and later engines. Those are the ones that the aftermarket aluminum covers are made to replace cause they leak.

Up to 1980 they used steel covers, like mine. Believe it or not, after 6 years looking I finally found a replacement by Mr Gasket on Holley website in chrome or black. Currently out of stock.


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I've got a 1980 as well with the stamped cover. I resealed my valve cover when I first got it and it helps for 4 years. Now I've tried resealing twice in the last few months, cork gasket with black sealant on both sides and it leaks worse than ever. I'm trying to get it ready to sell but can't until I get it to seal better. Any advice?

DrDoc
 
DrDoc, I also have the stamped steel cover. Use a good gasket, also use just enough sealant to fill the porous surface of the metal and cork. Most people use to much. Use about 1/16 of an inch. That means, put a small bead down and then smooth it our with you finger, so that it is just a small film. Don't over tighten. Let sit for several hours, before you restart the engine. Worked for me, your mileage may vary.

PS: Put you valve cover on a good flat surface to check how straight it is. If bent, junk yard may have a replacement. Lots of AMC 258 i6 / 4.2l 's in AMC cars that are out there.
 
I'll check that again this weekend while it's off, but what's others experience, gasket with sealant or leave the gasket out?

DrDoc
 
DrDoc said:
I'll check that again this weekend while it's off, but what's others experience, gasket with sealant or leave the gasket out?

DrDoc
Click to expand...
I have the steel valve cover on my AMC 258 i6 / 4.2l also and when I replaced mine with felpro gasket I tried it without rtv at first and it still seeped. I redid it with just a slight film on both sides and it hasn't leaked since.

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I just resealed my plastic valve cover with Permatex The Right Stuff gasket sealer. So far no leaks. Others on the forums have had good results as well.
 
As a 1980 CJ5 owner, I have been wrestling with the valve cover gasket issue since I purchased my Jeep 20 years ago. As discussed previously, the AMC 258 i6 / 4.2l head went through a configuration change in late 1980/early 1981, and mine has the older bolt pattern with the steel valve cover that's curvy on both sides. The newer bolt pattern accommodated the plastic valve cover that's straight on the passenger side, and curvy on the driver side. Unfortunately, the only decent aftermarket valve covers I've seen are compatible with the newer pattern, intended to replace the plastic covers. STEER CLEAR of any aftermarket steel valve covers (e.g., Mr. Gasket, Spectre, etc.) because they are garbage. I have tried them all over the course of 20 years, and they just don't have enough interior clearance for the lifters, which will smack against the inside of the cover itself. When you hear that horrific noise for the first time, you'll want to tear the cover right off and throw it in the trash! A somewhat lesser issue with them, is the flange that goes all around the bottom perimeter of the cover. While a small thing, this is VERY important for keeping your gasket in place. Unfortunately, the flange does no good on the aftermarket covers, because it is bent UP...not down, like the OEM covers. This design flaw does nothing to contain the gasket, and allows it to spread out from under the valve cover, especially if you overtighten the bolts.

While the thicker of the two cork gaskets made by Fel-Pro seem to work OK, they start leaking 1-3 years after installation on my CJ, even after trying a few different OEM valve covers with every type of Permatex you can imagine. I have been told by several old-school Jeep mechanics that the solution to all this, is a combination steel and rubber gasket that is supposed to work wonders. However, these are apparently long-gone, and are nowhere to be found. Since the AMC 258 i6 / 4.2l was used on a wide variety of vehicles, I have to believe that these are available somewhere, but I have yet to discover any. As such, I would (I think we all would) appreciate it if anyone could share their experience with these gaskets, and where to find them. Thanks in advance, and hope to find a reliable solution!
 
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So the aftermarket steel cover for the 81 and newer are garbage or the 80 and earlier than that are garbage ?
 
Aftermarket steel valve covers for 80 and earlier (curvy on both sides), are garbage. I have had the same poor results on two different engines with four different aftermarket covers...two black, and two chrome. Results were the same with them all. For the 81 and later (plastic) covers, there is a wide variety of nice aftermarket aluminum covers, most of which seem to seal pretty well on the newer head. I guess I could change out the old head for the newer one so I could use the good aftermarket covers, but that seems like a lot of unnecessary time and expense for a problem that should be much easier to correct. On the other hand, I've been messing with this for 20 years....perhaps I should just bite the bullet and change out the head!
 
Well I have a 85 I rebuilt and I think AMC could have done a little better job on that one also, but I guess it is better than the older ones
 
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