Oil leak from valve cover

[skipmac]

Originally Posted by Ecos

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.

[rbk]

Originally Posted by a64pilot

OK, let’s start from the beginning, most of the time if a sheet metal valve cover leaks, it’s because it’s 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 it’s distorted, further tightening usually almost always is not the answer it usually makes the leak worse, and if it gets worse with tightening it’s almost guaranteed it’s 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 don’t 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 you’ll 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 doesn’t know what he’s doing.
You wouldn’t 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, don’t even consider reinstalling it without Peening the holes, it’s cheap Insurence.

Personally I won’t glue any gasket, paper ones like water pumps for instance or timing chain covers I’ll 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 it’s not hard for a valve cover gasket to seal, as long as there is a flat surface.

This could be as well. The Perkins has a second lip at the bottom of the cover to make it more rigid. This could also be impeding the seal if an improper gasket was used as it can limit the depth to which the cover can be torqued and is essentially bottoming out with a gasket thats too thin,which may be why the mechanic gooped it up? Other possibility is the mechanic actually read the permatex instructions and half torqued the cover then was letting it set up before final torque which never got completed?

[skipmac]

I was hoping you would chime in on this. Thanks.


Reading your suggestion about peening the holes in the cover are you talking about a cover that has the holes around the circumference on the lip of the cover? This cover has four holes that run longitudinally down the center of the top of the cover that fit over studs coming up between the rocker arms on the head.



Regarding the mechanic over tightening the bolts, when I removed them they were not extremely tight. I did have a socket wrench but could have easily removed them with a nut driver.


Regardless, even though it looks pretty flat checking with a straight edge I'm wondering if there is enough distortion or as you mention, loss in the spring, to cause the leak.

Originally Posted by a64pilot

OK, let’s start from the beginning, most of the time if a sheet metal valve cover leaks, it’s because it’s 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 it’s distorted, further tightening usually almost always is not the answer it usually makes the leak worse, and if it gets worse with tightening it’s almost guaranteed it’s 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 don’t 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 you’ll 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 doesn’t know what he’s doing.
You wouldn’t 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, don’t even consider reinstalling it without Peening the holes, it’s cheap Insurence.

Personally I won’t glue any gasket, paper ones like water pumps for instance or timing chain covers I’ll 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 it’s not hard for a valve cover gasket to seal, as long as there is a flat surface.

[Compass790]

Another good trick I use is to make up an o-ring say 3 mm thick. You can buy bulk 0-ring in any length you want cut & glue it using super glue or if you are fussy buy o-ring glue
Glue the o-ring to the rocker cover & voila a reusable gasket.

[skipmac]

Here's a photo of the valve cover. The downhill, leaking side is to the left.


While it is stamped sheet metal it is reasonably substantial and as rbk mentioned the lip around the edge has a double bend to add stiffness. That however doesn't necessarily mean it hasn't warped a little.

[Compass790]

Originally Posted by Wotname

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.

Sounds like a great plan to me Wotname

[skipmac]

Originally Posted by Wotname

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.

This may work although I'm thinking about a modified version of this idea. As mentioned, the engine is mounted on an angle which results in some oil pooling at the lower end of the head when the engine is pumping oil and this I'm almost positive is where it's leaking. So my thought is to focus on that end of the cover which might be easier and work better than trying to get an even seal all the way around. So build up some formagasket (yes I have some in the spares) just around that end of the cover, carefully tapering it away.


Idea #2 is to try some thicker, flexible o-ring material like suggested by compass790.


Idea #3, try to bend the end of the cover down a bit so it seals better against the gasket. I am very reluctant to try this as there could be a rist of damaging the cover and a replacement would be difficult to impossible to find.



Any other ideas? Any votes on which solution sounds best?

[model 10]

Plan B. The head surface is probably true. The bottom surface of the gasket is also true.You are never going to get the valve cover surfact true, so fill the space between the gasket and the valve cover with glue and assemble. Tighten tomorrow.

[Compass790]

Have you checked rocker cover against a flat surface?
If you follow Wotnames plan it self corrects for the warpage IF you have access to a flat surface. As Ecos says yr cylinder head is likely flat.
I have found just silicone works well too & I think using Wotnames method & putting silicone between gasket & rocker cover then letting it go off somewhat would work well.
As I said before fattish o-rings work good too but if your warpage is extreme maybe Wotnames method would be better. If he can stop a Pommy engine from leaking oil ya have to give him kudos for that.
More than one way to skin a cat

[Wotname]

Originally Posted by Compass790

......If he can stop a Pommy engine from leaking oil ya have to give him kudos for that.
.........

Well the OP's engine was probably manufactured in the UK, certainly it was designed in the UK so it should leak some oil. Absence of a minor oil leak is considered a defect (or a lack of oil)

[skipperpete]

There is a vague possibility that you have some rust pinholes through that valve cover and not a leaking gasket. The photo shows the area near the Lhs bolt hole is corroded and it looks like there might be another area of rust near and just above the sealing edge on the left.

[skipmac]

Originally Posted by Wotname

Well the OP's engine was probably manufactured in the UK, certainly it was designed in the UK so it should leak some oil. Absence of a minor oil leak is considered a defect (or a lack of oil)

I always assumed it was the British way to maximize the time between oil changes. Just keep pumping new oil in and out of the engine on a continual basis.


This reminds me of my theory of repairing some unknown, complicated piece of kit. If I don't have at least one screw or small part of some kind left on the bench after it's reassembled I must have done something wrong.

[skipmac]

Originally Posted by skipperpete

There is a vague possibility that you have some rust pinholes through that valve cover and not a leaking gasket. The photo shows the area near the Lhs bolt hole is corroded and it looks like there might be another area of rust near and just above the sealing edge on the left.

This is a possibility and will go look at that now. The PO did have a small, ongoing leak onto the rear of the engine from the anti-siphon valve which is one reason the cover looks so nasty.



In fact the whole engine looks like carp but it runs like a top, has perfect oil pressure, starts instantly and doesn't smoke at all so I hate to replace it. Then I run into a persnickety little problem like this and consider turning it into a mooring.

[skipmac]

After reading all the suggestions and sleeping on it (for a while I was not sleeping on it) I think I have a plan.


First I'll try and easy fix and see if I get lucky. Have cleaned the cover and gasket and will reinstall as is but with a modified tightening plan. I will snug down the nut on the leaky end firmly but the next one in line just more than finger tight. The next two I think maybe in between in how much I tighten them.



If that doesn't work I will try some method of increasing the contact pressure on the leaky end. Using a gasket making goop is one idea but I thought about building up the sealing area on rim of the cover with MarineTex or JB Weld. That has the advantage of being able to easily shape by sanding and filing but could still be sanded completely off if it didn't work or makes things worse.


Thoughts?

[Compass790]

Originally Posted by skipmac

This is a possibility and will go look at that now. The PO did have a small, ongoing leak onto the rear of the engine from the anti-siphon valve which is one reason the cover looks so nasty.



In fact the whole engine looks like carp but it runs like a top, has perfect oil pressure, starts instantly and doesn't smoke at all so I hate to replace it. Then I run into a persnickety little problem like this and consider turning it into a mooring.

Hell no! If it runs as good as you say just work on the problem at hand.Trust me, you'll figure it out in the end with the help of the hive. The problem is with the modern engines is they make it more & more difficult to repair yourself. Then they make sure they last for much less time.
Makes for more employment ( tho mostly for 'Bots these days ) & maximises the CEO's bonus. Funny that
Better to use sails where possible IMHO