[Rosie]

I've had an elusive oil leak for about a year, and I finally tracked it down to a valve cover gasket screw that was also holding had an Adel clamp.

It was leaking through the screw threads but I couldn't see it because the oil was leaking out right down the Adel clamp holding the metal-sheathed EGT wires: the oil wicked into the metal sheath and 'disappeared'.

My hangar-mate pulled all his covers since he too had a leak he couldn't track. His engine has ~500 hours since new and mine had ~700 hours since overhaul.

Here's what he found Rosie

 

[Ironflight]

Hey Rosie, I was always taught not to tighten the valve cover screws quite as tight with the silicone gaskets as we did with the old cork gaskets, because the silicone will just extrude - sort of like what you have. Just curious if the screws were way tight or not. From Rosie: Not way tight at all.

And remember, if a Lycoming isn't leaking oil SOMEWHERE, it means that you have no oil left!

Paul

 

[Don Jones]

Lycomings don't leak oil.......they just mark their territory

 

[Lars]

Question for all you experienced Lycoming guys-

This sort of thing is hardly unique to Lycomings. Auto engines have had the exact same valve cover/gasket problem for decades.

On the small block Fords with which I'm familiar, Ford solved the problem several years ago by designing gaskets consisting of rubber vulcanized to a metal core. Lay the gasket in place, install the cover and torque the screws to spec. You can't squish the gasket out anymore. The oil pan gasket is somewhat similar, though it's all rubber with steel sleeves vulcanized into the bolt holes. Same effect: you torque the fasteners without worrying about extruding the gasket. No more secret techniques or throwing salt over your shoulder and gesticulating to the nearest oil well in the hopes that you got the bolts just right. The aftermarket (Fel-Pro among others) has responded with gaskets constructed similarly.

Has anyone heard of such a thing for Lycomings? Seems to me it would eliminate the uncertainty of how "tight is too tight", and might even move the leakage to another part of the engine

 

[Don Jones]

Never seen them for lyco's lars, they are nice gaskets, but even those leak. We do lots of oil pan gaskets on Fords with the gaskets you are talking about. Intake gaskets on both Ford and GM are made like that too and those are making my retirement not look so far awayIt's not really the gaskets fault in this instance though, it is the stupid plastic intake manifolds

 

[gasman]

No more secret techniques or throwing salt over your shoulder and gesticulating to the nearest oil well in the hopes that you got the bolts just right.

Seems to me it would eliminate the uncertainty of how "tight is too tight", and might even move the leakage to another part of the engine

These gaskets come with instructions and a torque spec. If installed properly, they will not leak.

 

[jetjok]

In addition to proper torque, the surfaces must be absolutely free of oil. When I did my Pacer and RV, I cleaned the rocker cover and cylinder head with lacquer thinner and the gaskets with grease and wax remover.
The Pacer now has 300 hours on the gaskets with no leaks.

 

[Lars]

These gaskets come with instructions and a torque spec. If installed properly, they will not leak.

Are you referring to silicone or cork gaskets, or both?

For what it's worth, I've installed dozens of old-style automotive valve cover and pan gaskets over the years, both cork and rubber, with a pretty good track record for not leaking. Not saying it can't be done. My point was that the gasket designs I mentioned make it less of an art, something perhaps more important in automotive compared to aviation applications. They are obviously designed for mass production applications, whereas aircraft engines aren't. Still, anything that makes it easier seems to me to be useful.

 

[gasman]

These are the gaskets....

 

[Lars]

These are the gaskets....

I figured, and those appear to be silicone. I know better than to assume though.

And if the bolts have been overtorqued, the valve cover mating flanges under the bolt heads are probably distorted. In which case torquing to spec isn't gonna help. Again referring to the automotive world, the solution is to peen the flange flat prior to reassembly. Same thing here?

 

[JonJay]

Hey Rosie, they look a bit overtorqued

Just judging by the deformation of the gasket.
I believe the torque value is something like 15 or 20 in.lbs. I use to torque them with a torque wrench but now have developed the "feel" with a standard driver. It is not much pressure.
I double check them everytime the cowling is off and every once in a while, a few screws need a bit of a bump up, but not much.

As stated, mating surfaces and gasket absolutely clean. I use MEK.
Lay the covers on a very flat surface and if needed peen them flat. They are probably in need of this judging again from the torque it appears they suffered.

The beauty of this; it is a nice easy fix.

PS- The silicon gaskets most often carried are the "REAL" brand gaskets. They are quite a bit thicker and wider than the OEM gaskets. If you did not make your baffle with the "REAL" gaskets in mind, they will be too wide and interfere with your baffling around the head. This will lead to improper torque. I can only use the OEM gaskets on my machine.
I can't tell from the picture what type yours are.

"JJ"

 

[drmax]

what torque silicone gaskets?

I found this...http://www.chiefaircraft.com/rg-75906.html
and then from here I read 20-25" lbs. What is the torque value for these newer silicone gaskets? I am leaning towards doing what is writen in the link I posted. Thx for any info. DM

 

[az_gila]

Here are the instructions for the ECI silicone gaskets.

They call for a re-torque to 20 in-lbs on a warm engine.

http://www.eci.aero/pdf/03-3.pdf

The allowable use of Loctite 242 is probably a good idea. I wonder how many of us over-torque to make sure those built-in star washers on the screws work...

 

[drmax]

Here are the instructions for the ECI silicone gaskets.

They call for a re-torque to 20 in-lbs on a warm engine.

http://www.eci.aero/pdf/03-3.pdf

The allowable use of Loctite 242 is probably a good idea. I wonder how many of us over-torque to make sure those built-in star washers on the screws work...

thank you for looking that up.

 

[drmax]

?

re-torque after using Loctite initially?

 

[BillL]

Bad situation, good ( heavy duty engine, not aviation) design practice uses small compression sleeves at each fastener to allow proper retention torque for the fastener and at the same time provide proper compression of the gasket. Silicone is just too tender for much compression. I don't know if there is enough room for a sleeve with the large fastener and small radial clearances. Maybe a step stud (1/4 X 10/32) kit with sleeves offered by Anti-Splat. Are you listening Allan?

 

[az_gila]

re-torque after using Loctite initially?

Good point...

Re-reading the ECI document, I think I will go for 20 in-lbs on a warm engine and use the Loctite at that time...

Badly put, but you could read "re-torque" as remove, add Loctite and re-install to 20 in-lbs...

 

[jetdriven]

If you remove the screw to put Loctite on it, its not really "retorqued".

FWIW our 250hr factory Lycoming IO-360 sprung a pretty big leak from the bottom rear corner of the #4 valve cover, right where the adel clamp goes to hold the plug wires on. I replaced it with a fake "real" gasket from Spruce, and I cleaned the gasket and the cylinder / cover with lacquer thinner. Hopefully it doesnt leak further.

 

[drmax]

probably now will have wished I just gotten the simple cork gaskets and been through with it. I haven't read the instructions yet...but does ECI state to us the Loctite, or just mention it can be used?

Do the regular cork gaskets use Loctite?

 

[jrs14855]

Gaskets

I believe the problem is that the gasket was not properly aligned and the damaged areas were caused by forcing screws into place after several screws had already been at least partially tightened.
I install two of the upper screws thru the cover and gasket. Then engage these screws just one or two threads. This allows alignment of the remaining gasket holes. In turn each screw is installed just one or two turns. When all screws are installed, tighten evenly finger tight and then torque. I have a torque screwdriver that starts at 10 inch pounds.
If you have a screw that is holding a clamp, tighten all screws finger tight without the clamp, then remove one screw and install clamp.

 

[drmax]

I believe the problem is that the gasket was not properly aligned and the damaged areas were caused by forcing screws into place after several screws had already been at least partially tightened.
I install two of the upper screws thru the cover and gasket. Then engage these screws just one or two threads. This allows alignment of the remaining gasket holes. In turn each screw is installed just one or two turns. When all screws are installed, tighten evenly finger tight and then torque. I have a torque screwdriver that starts at 10 inch pounds.
If you have a screw that is holding a clamp, tighten all screws finger tight without the clamp, then remove one screw and install clamp.

sounds like you have accomplished this a time or 2. I'll go with your instructions. Did you then use the Loctite (permatex blue) product, or not?
Thank you

 

[az_gila]

probably now will have wished I just gotten the simple cork gaskets and been through with it. I haven't read the instructions yet...but does ECI state to us the Loctite, or just mention it can be used?

Do the regular cork gaskets use Loctite?

Check the ECI link provided, it's only a single page.

Exact words -

3.3.1 LOC-TITE 242 or equivalent product may be used on the screw threads as required.

It seems to me what they really want is 20 in-lbs on a warm engine - defined as over 100F.

 

[drmax]

what a job

That old cork **** has got to me as old as the engine, so about 8 yrs. VERY hard to dig off. Just gotta be patient and use the plastic scrapers...and light on a razor blade. I'm got 1&3 done and torqued cold to 25 lbs. It does squish out some, and perhaps more than I thought, but going by the instructions. I'll post back with my results after the run tomorrow. DM

 

[PerfTech]

Bad situation, good ( heavy duty engine, not aviation) design practice uses small compression sleeves at each fastener to allow proper retention torque for the fastener and at the same time provide proper compression of the gasket. Silicone is just too tender for much compression. I don't know if there is enough room for a sleeve with the large fastener and small radial clearances. Maybe a step stud (1/4 X 10/32) kit with sleeves offered by Anti-Splat. Are you listening Allan?

.....Yes! I am listening. We actually have a product that is the answer to this and all other valve cover issues as well. We have made and tested the prototypes and they are a true thing of beauty. Just installing these on your airplane will make it look much faster and make you look more attractive as well (see indisputable proof below). These direct bolt on parts also offer several functional benefits over what is currently available. We have made these new, very precision, "Billet Aluminum Valve Covers" that incorporate an imbedded silicone o-ring in the face of the cover. They reduce valve train noise, never need gaskets, will never leak no matter how many times you R & R them, you tighten them down all the way with no sealer of any kind. You will never need to clean or scrape a gasket off the head surface again. The very intimate contact of the cover to head surface with no gasket insulator provides some extra cylinder head cooling as it acts as a heat sink removing some heat directly from the head. They will be available soon in polished, clear, red, blue and black hard anodized finishes and we will most likely offer some custom engraving just to sweeten the pie! Now! Hows that for listening? Keep an eye on our website for new products and services coming to an RVer near you. Thanks guys, Allan...
.
ME, before ASA Valve Covers

.
ME After installing ASA Valve Covers
.

 

[DanH]

.....Yes! I am listening....We have made these new, very precision, "Billet Aluminum Valve Covers" that incorporate an imbedded silicone o-ring in the face of the cover.

That is an extremely clever idea.

 

[drmax]

finished

Well, those old cork gaskets were 8 yrs old and a booger to get off. (used a few drops of new oil on the old material and that really helped loosn up the junk) I put the silcones on eng room temp, say 80 F. Torqued 25 lbs and this took more that one time around each cover...more like 5 times. With that finally done I ran her to get her hot. Afterwards, this is where the instructions say to ck torq. at 20 lbs. I did and they all were under 20. Again more that one time around each valve cover, being anal but wanted no hassles with possible leak, and that was my result! Wanted to point out...the ignition wire clamp at the bottom of each cover (on my setup) I discovered best to use another washer to get the clamp surface out away from the flange of cover. I could see where this may not give a propper torg. So far so good. No thread locker used. DM

 

[NTex]

Silicon gaskets

Has anyone else encountered a problem with cylinder #4 and the gasket fit?

I purchased silicon gaskets at the advice of my tech counselor, and when replacing the cork ones noticed that that gasket for #4 did not line up. It appears to "sag".

The 4 gaskets appeared identical in size when I compared them. Here are some photos:
Side by side

I'm at a loss - hope that it's just the gasket, but am I missing something and for some reason is cylinder #4 different?

Also, Alan - I couldn't find the covers on your website.

 

[drmax]

Did you lay the gasket on the cover to see if it had the same shape?
Is it torqed properly? It can easily be over torqued causing the rubber to squish out. I did not have any issues with my 0-320 lyc.
Torque procedure is necessary and time consuming. Doesn't seem like much (maybe 25" lbs...don't quote me on that) then you gotta run it, then recheck)

Has anyone else encountered a problem with cylinder #4 and the gasket fit?

I purchased silicon gaskets at the advice of my tech counselor, and when replacing the cork ones noticed that that gasket for #4 did not line up. It appears to "sag".

The 4 gaskets appeared identical in size when I compared them. Here are some photos:
Side by side

I'm at a loss - hope that it's just the gasket, but am I missing something and for some reason is cylinder #4 different?

Also, Alan - I couldn't find the covers on your website.

 

[DaAV8R]

Send a message to Guy Gibney at [email protected] . He can sell you silicone gaskets which are thinner (about .090) with a reinforcement in the silicone. They will not ooze our when you torque.

Robert

 

[N941WR]

Here's a dumb question. Why not use cork gaskets?

Based on this thread, they sound just as good as anything else, short of Allan's milled covers.

 

[RVnoob]

I'm at a loss - hope that it's just the gasket, but am I missing something and for some reason is cylinder #4 different?

Also, Alan - I couldn't find the covers on your website.

Looks like you have the gasket upside down.

 

[NTex]

still unsure

Originally Posted by NTex
Has anyone else encountered a problem with cylinder #4 and the gasket fit?

I purchased silicon gaskets at the advice of my tech counselor, and when replacing the cork ones noticed that that gasket for #4 did not line up. It appears to "sag".

The 4 gaskets appeared identical in size when I compared them.

Did you lay the gasket on the cover to see if it had the same shape?
Is it torqed properly? It can easily be over torqued causing the rubber to squish out. I did not have any issues with my 0-320 lyc.
Torque procedure is necessary and time consuming. Doesn't seem like much (maybe 25" lbs...don't quote me on that) then you gotta run it, then recheck)

-yes, I overlayed the gaskets and they appear identical. It's hard to say with precision if they are EXACTLY the same size because the gaskets are not rigid, but there's not a obvious, gross misfit I can see.
-Unfortunately, these are not torqued at all. I was test fitting them in place and it was immediately obvious the fit was different than the other 3 cylinders. The other three gaskets went on and fit great out of the box. The screws are not even finger tight, just enough to seal the two surfaces. When I was working on #4, I noticed I had to shift it around to get it to even line up right.

-thanks for the torque value, I'll tighten them before first engine start and retorque hot. I see that ECI has a specified torque value that I'll steal when the time comes.

Send a message to Guy Gibney at [email protected] . He can sell you silicone gaskets which are thinner (about .090) with a reinforcement in the silicone. They will not ooze our when you torque.

Robert

-thanks, might go that route if this gives me any more trouble. But, these have not 'oozed'. there is no torque on #4, it is misshaped. Like I said, I'm wondering if there is unique geometry for #4 (or I have the wrong cylinder?) because the gasket is the same as the other 3.

Here's a dumb question. Why not use cork gaskets?

Based on this thread, they sound just as good as anything else, short of Allan's milled covers.

-I wish I didn't remove the cork ones that were in there! Too late for that now. Also Alan does not appear to sell milled covers on his website.

Looks like you have the gasket upside down.

-I thought so too and tried both orientations. Of course, if you look at it the gasket is symmetrical so there is no "upside down". Swapping it had no effect.


Thanks for the replies - I'm hoping someone has seen this before and it's something dumb I'm overlooking!

 

[aerhed]

There IS an up side, and #4 is upside down.

 

[Ironflight]

I have to agree with Aerhed - flip the #4 top to bottom - the rocker covers on a parallel valve Lycoming are not symmetrical in that direction.

 

[rvbuilder2002]

I use the silicone rocker cover gaskets exclusively on all of the Lyc powered RV's I maintain (7 at the moment), because properly installed, they assure no oil leaks at the covers. With the cork gaskets you are assured to get a leak... the uncertainty is when.

I agree, the photo shows a gasket installed upside down.
If you remove the cover you will see that even on a parallel valve Lycoming the covers are symmetrical (mirror image) left to right, but not top to bottom.

 

[Kahuna]

I've had an elusive oil leak for about a year, and I finally tracked it down to a valve cover gasket screw that was also holding had an Adel clamp.

Rosie. I assume you had washers between the adel and the cover for a flush even distribution of torque. Otherwise it will get catty whompus. And of course what Paul said.

 

[NTex]

Doh!

Guys,

Thanks for the replies!

I swear I flipped the gasket around...but this is definitely a relief. Much rather feel like a fool and have an upside down gasket than an a distorted cylinder.

Must have been luck I got the other 3 in without any mishap