cylinder head oil leakage

After many years of "Nortoning" it seems to me that if you have a clean leakfree motor its quite likely that not enough oil is getting all round the motor, and the reverse is also true. That's not to say that with a diligent attitude you can't stop all the leaks. You can. It just takes  care and detective work. Back in the day minor leaks were seen as normal ,tolerated,and ensured that even if the oil was never changed the motor got a fresh drop now and again. Some parts of the machine even stayed rust free!, and when you worked on those parts you were gratefull for the leaks!.I did everything as per the "Book" when I built my 99 25 years ago ,and its seeped some since then. But it runs so well I don't intend to touch it until something gives out.Now with better sealants and hindsight its possible to give the "extra attention"to certain parts that the motor should not need if it had been really well designed in the first place. The alternative would be to buy an NSU or BMW.

I found through bitter experience with two 99s and a 650 that solid copper head gaskets did not work for me. They all blew out oil at the top of the barrel near the spark plug. Lots of people informed me that the problem was my poor annealing of the gasket or warped cylinder heads but this turned out not to be so. The problem appears to be the lack of force exerted by the head bolts compressing a 2mm copper gasket enough to make a good seal. I swopped/swapped my all- copper jobs for composite versions and cured all the leaks immediately. Now strangely enough, my Commando also had a solid copper gasket that I fitted with some Silicone goo smeared thinly over the top of the barrel. This was absolutely fine. Same size head bolts so why. 

I suspect that if I took the head off and used silicone everywhere I could even get by with  re-using the old composite gasket  and with less tightening sessions. But i'm used to seeing that smear of oil on the fins and re-assured that there is oil getting round!.

I used a solid copper gasket with a minimal smear of Wellseal around the pushrod tunnels on my 850m Commando and it was perfectly leak free. But it does have to be properly annealed - heated to dull red all over. In this state it will bend with virtually no pressure.

But others have different experiences.....

I have heard that the threaded holes in the barrel can be too shallow for the bolts, or have muck in them which stops the bolts from being fully tightened.  Check the depth with a depth gauge and compare that with the bolt's actual length, together with the head thickness at those points - or add a thick washer.  Easy to clean out the threaded holes with your trusty old, flat-blade screwdriver - the one you occasionally use as a cold chisel.

When heating a solid copper gasket make sure it is heated evenly or you will defeat the object of doing it.  No need to quench it.  In fat I would never do that - just let it normalise by cooling naturally as you would when normalising steel after welding.  With steel you would quench it in oil to harden it, but let it cool naturally to anneal it.

Those of you who were once thinking of buying a Rolls Silver Shadow will remember the saying - "If there's no oil on the bottom of the engine, there's no oil in it!  Walk away now!"

They always say - " only the slow ones don't leak oil ".  Cheers, howard  

"You had the head skimmed flat"

Did you reduce the height of the barrel spigots by the same amount at the same time? (being a 1950's model, I assume it has them?)

Not having spigots on mine, this is just a guess, but if the spigots are now appreciably higher above the gasket than the head recess is deep, you are going to have trouble sealing it as the head face will be jacked off the barrel?

Regards,

George.

I use thin copper wire threaded round the gasket on my ancient vet. It's held longer than usual so looks good. What I do like about copper gaskets is that they aren't likely to strand an air cooled engine by the roadside. They quack like a duck and lose power but aren't likely to blow out.

Despite getting it annealed at work, torqued and retorqued after 3 hot/cold cycles, it lasted exactly 14 miles before it blew out the side. Was 3 miles from home at the time and got to within 1/2 mile away on 1 pot when other side failed.

After approx 10 thou skim to clean up the head ( barrels were flat) a fibre gasket with flame rings (made specially for me by Reinz in Germany) was fitted and is still ok 14 years later!

The Imp uses Reinz head gasket too! I have about 5 stored up, cost  approx £30-£40 each!

John

For me was:

a/ I got a spare too.

b/ they phoned me to ask what materials the barrels and head were so as to put the correct coating on each side

c/ most importantly they were free!

The wonderful world of business contacts that you miss so much once you have retired.

Interesting that the leak is down the bolt thread. Jaguar XJ engines used to have acorn nuts with ground flat washers under the heads to stop leaks down the thread.

I once rebuilt an ES2 500 short stroke engine in a hurry. I had a pack of two pack epoxy adhesive intended to be used on jet engine repairs. As it was free, and it was there, I used it to seal the head, crankcases, chaincase, bearings. The engine never leaked a drop of oil, ever. The next owner was not pleased getting it apart, he used a blowlamp, and big hammer. He did mutter that he should have known anything I put together was never meant to come apart. I would use an annealed 60 thou thick copper gasket. Leave the bolt holes 20 thou bigger to allow expansion. Smear with high melting point grease. You might also need new makers bolts and nuts. Do not use Stainless Steel, they stretch and snap off. They need to be En8 or En16. I machine them out of 16mm studding as I have loads of metre lengths of it.

I would check the barrel face is flat, old engine and distortion sets in. More difficult with spigots, but not impossible. Hope you sort it Ok, Paul

Hi Jonathan....your comments about wonky top faces on the barrels makes sense and possibly explains why my Commando had no problems, with a solid copper gasket, whereas my Dominator hated them.  John Hudson once told me that the first 650 engines were so powerful that they distorted terribly on each firing stroke. The barrel side rippling and causing the rings to unseal.

On my Commando I put a light smear of Silicone RTV around the pushrod tunnels. On my Dominator barrel the head gasket gets a thin layer of Red Hermitite which works for me but does sometimes squidge out and end up in the sump plug.

Can you still get gaskets from Reinz?,  Does anyone in the uk make special head  gaskets  for one off engines? .