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Old 18-09-2019, 13:26   #1
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Oil leak from valve cover

Had a small but persistent oil leak from the valve cover which I wanted to address before heading north for the summer.


The first mistake I made was paying a mechanic to replace the gasket while I devoted my time to provisioning the boat. The result was it leaks more now than before.


Details:


- Like most boat engines it is mounted at an angle.
- The leak seems to be only at the low end of the cover but then that's where oil will collect when the engine is running. It appears as small puddles on top of the head right next to the cover that then run down the block and all over the pan under the engine.
- There are no gouges, gaps or obvious problems with the head or cover. Checked both with a straight edge and no noticeable warping on either.
- The "expert mechanic" cleaned head and cover, applied some kind of goop and installed a new gasket. The goop is red and has the consistency of silicone.


Silly me thought installing a new gasket was all it took but apparently not.


So how to fix this? Maybe use more or different goop? I have looked at the local NAPA and determined there's about 4,000 different kinds of Permantex. Some to actually make gaskets, some to seal a gasket, some fuel proof, temperature proof. Maybe I need to find a grade of Permatex that's idiot proof.


One more thing, talked to the excellent mechanic that works on my Yamaha outboard and he suggested a clogged vent hose from the cover to the crankcase could cause a leak.


Anything else I can check. Things to look for that might contribute to the problem?


Thanks
Skip
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Old 18-09-2019, 13:34   #2
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Re: Oil leak from valve cover

We went to a nitrile gasket and new rubbers in the valve cover. The new rubber inserts were very soft compared to the old ones so I ended up going back after a few hours of motoring and retorqued them until no leak. Problem with permatex on the valve cover, is you should really be in there annually doing regular checks. Not sure which engine you have but see if a nitrile gasket is available as theyre pretty cheap and better than cork and really crank down on the cover bolts but don't distort the cover. I was really surprised as how much the new rubbers compressed without damaging the cover or the inserts.

Clogged vent is an easy check, but also if the air filter is equipped make sure it is intact. A torn filter could cause lack of suction on the vent hose and increase pressure.
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Old 18-09-2019, 13:38   #3
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Re: Oil leak from valve cover

HI RBK,


Thanks for reminding me to mention this. The engine is a Westerbeke W58 which is just a Perkins 4-154 painted red.


The valve cover attaches to four studs coming up from the centerline of the head, not with bolts around the edge.
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Old 18-09-2019, 13:46   #4
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Re: Oil leak from valve cover

Also, the new gasket I used is not cork but some kind of rubbery material so probably nitrile.


I did check the vent on the cover and that's clear. Not at the boat but will check the hose to the crankcase tomorrow.


Hopefully not making myself sound too ignorant but why would I need to check under the valve cover every year? Adjusting the valves is all I can think but I might run the engine 40 hours a year (it's a sailboat ) so assumed the valves would be OK.
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Old 18-09-2019, 13:51   #5
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Re: Oil leak from valve cover

My favorite gasket goop in this case is Hylomar Universal Blue.
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Old 18-09-2019, 13:51   #6
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Re: Oil leak from valve cover

Quote:
Originally Posted by skipmac View Post
Also, the new gasket I used is not cork but some kind of rubbery material so probably nitrile.


I did check the vent on the cover and that's clear. Not at the boat but will check the hose to the crankcase tomorrow.


Hopefully not making myself sound too ignorant but why would I need to check under the valve cover every year? Adjusting the valves is all I can think but I might run the engine 40 hours a year (it's a sailboat ) so assumed the valves would be OK.
Maybe make a "stiffening" bar from a steel angle that can put more pressure on the valve cover . say a steel angle that has holes for all the 4 c/l bolts and can be arranged to put pressure on the ends of the valve cover.
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Old 18-09-2019, 13:53   #7
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Re: Oil leak from valve cover

We have a 4108 so might be similar. Same two center studs run up through the cover and (they may be painted) rubber insets with washers on top to compress the cover (these get hard and don't work as well over time)

https://www.parts4engines.com/perkin...tud-seals-set/

Sounds like you have a nitrile gasket already but look at the above link, the 4 rubber bits (stud seals) are the inserts for the valve cover. As for annual maintenance, valve tip clearances as well as check the collets for proper seating, check head bolt torque, broken/cracked springs ect. Catch any of those early and you'll save a world of hurt and takes no time to take the cover off IMO. Good luck
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Old 18-09-2019, 14:05   #8
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Re: Oil leak from valve cover

Quote:
Originally Posted by rbk View Post
We have a 4108 so might be similar. Same two center studs run up through the cover and (they may be painted) rubber insets with washers on top to compress the cover (these get hard and don't work as well over time)

https://www.parts4engines.com/perkin...tud-seals-set/

Sounds like you have a nitrile gasket already but look at the above link, the 4 rubber bits (stud seals) are the inserts for the valve cover. As for annual maintenance, valve tip clearances as well as check the collets for proper seating, check head bolt torque, broken/cracked springs ect. Catch any of those early and you'll save a world of hurt and takes no time to take the cover off IMO. Good luck

Thanks. Yes sounds like the same setup, just four studs instead of two. I did check the rubber inserts and they're good. The leak is definitely around the bottom of the valve cover.


From your comments I have clearly been neglecting some inspection details in the valve train area.
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Old 18-09-2019, 14:07   #9
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Re: Oil leak from valve cover

Quote:
Originally Posted by geoleo View Post
Maybe make a "stiffening" bar from a steel angle that can put more pressure on the valve cover . say a steel angle that has holes for all the 4 c/l bolts and can be arranged to put pressure on the ends of the valve cover.

Good idea. I am a bit nervous about overtightening the nuts on top of the cover for fear of warping or causing some other damage that could make the problem worse. With this I could torque down a bit without risk of damage to the cover.
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Old 18-09-2019, 14:18   #10
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Re: Oil leak from valve cover

Quote:
Originally Posted by sailormed View Post
My favorite gasket goop in this case is Hylomar Universal Blue.

Well I'm not where I can access specialty goops. Guess I could order it from Amazon but I want instant gratification. Think the Permatex blue would substitute?
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Old 18-09-2019, 14:28   #11
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Re: Oil leak from valve cover

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Originally Posted by skipmac View Post
Good idea. I am a bit nervous about overtightening the nuts on top of the cover for fear of warping or causing some other damage that could make the problem worse. With this I could torque down a bit without risk of damage to the cover.
The cover can take a fair bit of pressure. And you really end up compressing the inserts more than you'd think. The only real issue with the above is the cover should 'float' on the gasket and the inserts, this could transfer a lot of vibration to the cover and eventually lead to cracking. Maybe the stiffening plate and a chunk of cork under to reduce vibration?
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Old 18-09-2019, 14:39   #12
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Re: Oil leak from valve cover

Quote:
Originally Posted by rbk View Post
The cover can take a fair bit of pressure. And you really end up compressing the inserts more than you'd think. The only real issue with the above is the cover should 'float' on the gasket and the inserts, this could transfer a lot of vibration to the cover and eventually lead to cracking. Maybe the stiffening plate and a chunk of cork under to reduce vibration?

I'm wondering if the pro I hired to do this just didn't torque the cover down enough. Rough guess on what's appropriate?
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Old 18-09-2019, 14:47   #13
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Re: Oil leak from valve cover

Valve cover gaskets are done a little different. You glue the gasket to the cover so it won't leak. Then use nothing between the gasket and the head surface. This allows you to remove the cover and still use the gasket again. You could use some non setting gasket dressing on that side if you wanted.
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Old 18-09-2019, 14:49   #14
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Oil leak from valve cover

OK, lets start from the beginning, most of the time if a sheet metal valve cover leaks, its because its been overtightned, what happens is the area around the holes distorts a little, the hole gets bent inward, what you do to fix this, and is a good idea to do anyway, is to take a ball peen hammer and with the pan held upside down and the edge of it on a table ledge, place the peen end of the hammer in the hole the stud goes through and hit it with another hammer, hit it pretty hard.
This bends the cover back to straight, or actually a little bend opposite does no harm, just a little though.
If the cover leaks after a new gasket I can almost guarantee its distorted, further tightening usually almost always is not the answer it usually makes the leak worse, and if it gets worse with tightening its almost guaranteed its a distorted pan, distorted pans are very, very common and very easy to fix.
What is happening is the gasket is not tight against the head between the studs.
Hot rodders used to use cast valve covers because they dont distort, or bend, but if you get stupid they will break.
You only want to tighten the nuts as if they were screws, use a nut driver, that will keep you from overtorqueing, almost always the problem is over tightened, not being too loose.

Goop is never the answer, especially silicone, hydrocarbons, oil or gas or diesel will attack the silicone and break it down and youll have what looks and feels like slimly bass worms.

Way back in the day people used to use contact cement and glue the gasket to the valve cover, this works fine, but you really need a wire brush in a grinder to clean off the glue, but if you have a wire brush in a grinder you can clean a cover up in short time and the gasket surface looks new.

But never, ever put any kind of sealer between the gasket and the head unless you want a mess and it screams this guy doesnt know what hes doing.
You wouldnt use a granny knot to attach your sheets to the jib would you? Then why would you use goop on a valve cover gasket?

If you ever pull an oil pan, dont even consider reinstalling it without Peening the holes, its cheap Insurence.

Personally I wont glue any gasket, paper ones like water pumps for instance or timing chain covers Ill use grease to hold it in place, but if you glue one, it can be hell to clean off the next time.

Good valve cover gaskets will last many removals, we used to run roller rocker arms on drag cars and were pulling the covers all the time to adjust valves, there is no pressure so its not hard for a valve cover gasket to seal, as long as there is a flat surface.
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Old 18-09-2019, 15:11   #15
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Re: Oil leak from valve cover

A64Pilot makes some points points however I have found it difficult to restore the integrity of the trueness of the cover when it only uses centre line bolts.

The leak has been persistent in the past which suggests to me the cover is distorted when tightened down. So it isn't just a gasket or torque issue any more.

I know you have checked the cover for trueness but that was only done off the engine. I think the cover is designed to have a certain degree of spring to compress the gasket when correctly tightened but if it has over torqued in the past, that spring has been compromised. Put another way, the cover is no longer true when tightened.

How to fix? I used the following method sort of successfully for the rocker covers on old Morris A series engines - the same design vintage as a Perkins I believe.

Use some flexible "form a thick gasket" product (experiment with what is available in your area).
Apply thickly to the cover lip.
Allow to set a bit with cover upside down.
Fit proper gasket on top of the product.
Turn the whole cover right side up and place on a very flat surface.
Add some weights to the top of the cover around where the centreline bolts are. Again some experimentation is needed to get the right weight.
Allow the product to cure.
Then fit to engine and torque gently.

There are likely to better and more professional ways but my DIY method has worked for me.
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