Cam Cover sealing...again

[andrewh]

I have not suffered to any great extent from leaking from the cam cover gaskets until now. I have now got a leak and wonder what everyone recommends as the best technique for sealing these up. I had used Blue Hylomar but think I probably did not tighten it up enough when it was assembled. I didnt want to put too much load on the covers. Then when I did retighten it after the leak it had probably gone off and did not do the job. Anyway, surfaces all look fine. What do we think, Hylomar, Wellseal or other? The Hylomar had totally glued the gasket to the head and cover and has taken a good time cleaning it all off.

[cactusman]

In am sure others will offer sage advice but I used blue hylomar successfully. The vital thing is to ensure the head and cover seal surfaces are free of any remains of old gasket or oil so the hylomar seals the gasket surfaces to the head and cover. Even more vital is not to over tighten in the hope of sealing. Really all they need is a nip. Any more and you will crack the oh so fragile covers and then you have a whole load more oil leaking out...and no hope of a simple repair....tighten oh so gently and evenly....and replace or 're-anneal the copper washers below the dome nuts too....

[mgcjag]

Hi Andrew.....I have always had good results with wellseal.....but its not easy to use......i brush it on.....but on all 4 surfaces.....head, gasket both sides, cover...... Steve

[andrewh]

yes thanks Julian. That is exactly what I did last time and all the times before, but it leaks! I have checked for flatness and it looks good. The gaskets where black ones where as in the past they have been thinner and a blue material . I wonder whether this was the difference which caused the failure. Also, the hylomar glued them solid to both surfaces. Didnt think it was meant to do that!

[andrewh]

Hi Andrew.....I have always had good results with wellseal.....but its not easy to use......i brush it on.....but on all 4 surfaces.....head, gasket both sides, cover...... Steve

I like Wellseal and have a lot of faith in it, but its very messy and weeps for quite some time.

I wonder whether my gaskets were the wrong type. Included in the SNG kit.

[cactusman]

Hylomar will stick the gasket to the metal surface....my gaskets were cork not black....about 3-4mm thick from memory. Good layer of hylomar on surface that meets the head and on the head. Wait a few mins till it is tacky. Pop over the studs and ensure it lines up. Apply hylomar to the top gasket surface and cover. Wait a few mins till tacky. Gently locate the head without disturbing gasket. Pop on the washers and nuts and nip down....

[cactusman]

Just a thought....are you sure it is leaking from the gasket?....the blanking plate and rubber seal (exhaust side) can also weep and the oil runs down and looks like it is coming from the seal. Worst case scenario there is a tiny crack in the cover. With clean oil again you might think it is the gasket when actually it is a hair line crack by a stud and the essentially transparent film is weeping down the cover to the seal where it accumulates. Wipe a new tissue around all the nuts and around the blanking plate after giving the car a good run....Any oily stain indicates a leak...

[andrewh]

its bizarre actually. Where the oil is running is between the head and block on the exhaust side but starting from the front. It then drips down the block. It really did not look like it was leaking from the cam covers or the nuts but I could not see anywhere else it could be coming from . What blanking plug and seal are you referring to? Am I being a bit thick?

[Gfhug]

Did you use aerograde hylomar? It's what I've used rather than the standard grade.
Hope you get it fixed

Geoff

[andrewh]

no I didnt use that, as its not available readily locally.

[chrisfell]

I don’t use any sealant, just the standard gasket. Technique is to nip up all the nuts all round until finger tight. Then I wind up the lower of the nuts then the higher nuts, slightly less. Repeat using only slight pressure in the nuts. I never tighten the nuts to the specified torque, always very much less. The nuts are loose enough to undo with a screwdriver handled socket. No leaks, not from the cam covers. Leaks everywhere else, but not from the cam covers.

[andrewh]

INTERESTING! And quite possibly the answer. I will ponder on that and decide upon a course of action but that does sound viable indeed. Thanks for the input.

[cactusman]

Andrew. At the back of the exhaust cam cover is a hole similar to the hole on the inlet into which the tachometer generator is fitted. Obviously there is no need for two tachometer generators but the exhaust cover has a hole where it would fit. This is blanked off with a kind of half moon ish shaped plate he'd on with a couple of bolts and there is a rubber seal that basically bungs up the hole in the back end of the cam cover....at least there is on S1 3.8 cars. It is all a bit heath Robinson if you ask me. The plate keeps the bung in place. The bung is rubber? and age and heat I suspect cause it to loose its flex and if disturbed it is prone to fail to seal again. Oil weeps out behind the plate and drips down past the cam oil feed pipe area....incidentally the banjo unions can also leak....

[andrewh]

Oh yes, of course, No its not leaking at the back at all. Its just at the front. Above the alternator and then running down the seem between the head and block. Thanks for the input. I am going to put it all back together tomorrow and use Wellseal . Will report back.

[abowie]

I seem to have success with these.
You need to be sure your cam cover's mating surface is actually flat.
I use spray hylomar on both sides of the standard paper gasket. The Americans seem to like the Cometic gaskets but I've never used one.
I have an inch/lb torque wrench I use for servicing scuba gear. I torque all of the nuts up to 4 lb/ft. If it leaks I then go to 7 lb/ft.
If you still have trouble one trick is to use a quality silicone sealant in addition to the paper gasket. I put a thin bead on the outer edge of the gasket to try to stop excess ending up in the engine. I then seat it with the nuts finger tight, let it go off overnight and then torque up as described.

[andrewh]

thanks Andrew. I intend on checking my flatness this morning by fixing in place without the gasket and searching with a feeler gauge for areas where I have a problem. Not keen on using the hylomar again as it took me a long long time to clean off the gasket. Not sure what a Cometic gasket is but will look that up now!

[abowie]

The Cometic gaskets are crushable steel.

[andrewh]

ah, ok, thanks Andrew . No leaks at present but need to go for a run. I am sure ( doh!) that it wasn't the cam covers after all but that front corner on the head.

[E-by'eck]

With costly welding of cracks in the cam covers due to previous owner overtightening, I am considering the use of O-rings between the copper washers and the cam covers to improve sealing. I imagine not a new idea but I cannot find a reference to it on the forum. I'm no expert, but a read up on elastomers used for O-rings shows that technology has improved significantly. Neoprene used to lead the way but nitrile is now probably the most popular elastomer in the o-ring seal industry with excellent resistance to petroleum products. Its disadvantage is it only has moderate heat resistance.The latest & better option is FKM...All the properties of Nitrile and can also stand temperatures of up to 200C.
Branded as VITON, bags of 50 of the appropriate size are available on line from RS Components (part no BS 011 or BS 012) for £6 delivered. The slightly larger BS012 are better if the cam cover holes have been drilled out wider to accommodate the studs. These seals are only 1.78mm thick. With 50 in a bag they can be replaced pretty frequently if durability is a concern!
Opinions welcomed!!
Graham

[Gfhug]

Try Dowty washers, steel/nitrile/viton in one washer, much neater, unless you really need the look of copper washers

Geoff