Dominator head oil leak

Previously wrote:

Hi,

I have a irritating small oil leak on my 88SS cylinder head. It is three cooling fins up on the right hand side.Is this a common problem and is there a fix ?

Thanks

Colin

Hello Colin, Yes it's coming from the pushrod tunnels where the head meets the barrels and leaks by the gasket. You need to take the head off and remove the studs at the front and flatten the head off with a coarse file - but before you do that, try using some engineers blue paste then you can see the high stops in the head? When replacing the head, use STAG wellseal jointing conpound on both side of the gasket, leave to dry then fit the head. Don't get any compound in the small oil hole at the back of the right hand barrel - and check to see if it's clear. - Hope this helps you?

Anna J Dixon

PS. if you can't get engineers blue then call me on 01430 430831 I have a Big tin full I can post you some ?????

Three fins up is a common place to find oil on Commando heads. I'd suspect that the 88 head is the same. It is the height where the cooling travels through the centre of the head so any oil from above can find it's way down the sides or the back and mysteriously appear here.

Usual suspects are the rocker spindle retaining plates. A dribble from there can wick down almost unseen. Other possibilities are from the inlet rocker cover or centre nut and even the exhaust rocker covers if it is being blown backwards.

Previously wrote:

Thanks for the advice Anna.Not quite ready to remove the head yet as enjoying the good riding weather whilst it lasts.I will make this a winter project .

regards

Colin

Previously wrote:

Hi,

I have a irritating small oil leak on my 88SS cylinder head. It is three cooling fins up on the right hand side.Is this a common problem and is there a fix ?

Thanks

Colin

Hello Colin, Yes it's coming from the pushrod tunnels where the head meets the barrels and leaks by the gasket. You need to take the head off and remove the studs at the front and flatten the head off with a coarse file - but before you do that, try using some engineers blue paste then you can see the high stops in the head? When replacing the head, use STAG wellseal jointing conpound on both side of the gasket, leave to dry then fit the head. Don't get any compound in the small oil hole at the back of the right hand barrel - and check to see if it's clear. - Hope this helps you?

Anna J Dixon

PS. if you can't get engineers blue then call me on 01430 430831 I have a Big tin full I can post you some ?????

you might try re-torquing the 10 head studs.depending on the type of gasket,they can settle over time.I say 10 due to TRIUMPH mechanic has been known to miss the 3rd nut between exh.rockers.

Quite a lot of the big Norton twins have cylinder heads that leak from the 3rd fin up of the right. On many of the Atlas and Commando heads this generally corresponds with a small area near the headbolt hole that is immediately behind the spark plug. Youhave 3 serious amounts of plumbing carved outof this chunk of the headthat allconverge leaving a thin walledsection prone to pinhole leaks or worse still, cracks.

Like most annoying cylinder head oil leaks, itgenerally only shows itself when the engine isrunning and hotwhich makes ithard to spot. If this is the source of the drip, the simplest temporarycure is to thoroughly clean the area and then, with difficulty,spread a layer of one of the propriety metallic, heat resistant filler pastessuch as JB Weld.Some of these DIY goos are actually work very well and if applied well will do the trick.

Looking elsewhere, there are a few other potential drippy bits of the head which would be worth checking out.

Top of my list is leaking rocker covers. Nearly everybodymakes the same mistake with these. ie. They fit new gaskets, then clamp down the covers with overtightened nuts. Sometime later they reset the valve clearances and attempt to re-use the same gaskets which by now have been crushed to death. The misery is quite often compounded by the overtightened nuts which pull up the the studs leaving a raised metalring which then in turn stop the cover from sitting flush on the gasket. The end resultbeing hot oil vapour blowing through the gap and heading for somewhere tostain.

Lots of choices here as a cure. Stone the respective faces flat. Use new gaskets, Don't be so heavy handed with the spanner, or my favourite. A thin layer of RTV Silicon on one of the gasket faces.

Someone else has already pointed out that the rocker spindleend platescan also drip. Usually for a similar reason as above. The very coarse bolt threads, holding the plates,also offer alternative routes foroil to flow through. Some sealant on the threads wil help here.

Don't forget to check the rocker feed union bolts. These really need freshly annealed copper washers each time they are disturbed.

Lastly, the cylinder heads can leak around the pushrod tunnel mouths. It generallycaused bycheap head gaskets and bad torquing of the nuts in this area. I find that a tiny ring of gasket goo or RTV Silicon around the pushrod eyelet holesalways helps with this problem.

Agreed Phil.

Verifying and fixing the rocker feed pipe and its bolts cured an oil leak that I suspected coming from the cylinder head.

It may not cure your problem, but it's an easy and hopefully effective first step.

Previously wrote:

Quite a lot of the big Norton twins have cylinder heads that leak from the 3rd fin up of the right. On many of the Atlas and Commando heads this generally corresponds with a small area near the headbolt hole that is immediately behind the spark plug. Youhave 3 serious amounts of plumbing carved outof this chunk of the headthat allconverge leaving a thin walledsection prone to pinhole leaks or worse still, cracks.

Like most annoying cylinder head oil leaks, itgenerally only shows itself when the engine isrunning and hotwhich makes ithard to spot. If this is the source of the drip, the simplest temporarycure is to thoroughly clean the area and then, with difficulty,spread a layer of one of the propriety metallic, heat resistant filler pastessuch as JB Weld.Some of these DIY goos are actually work very well and if applied well will do the trick.

Looking elsewhere, there are a few other potential drippy bits of the head which would be worth checking out.

Top of my list is leaking rocker covers. Nearly everybodymakes the same mistake with these. ie. They fit new gaskets, then clamp down the covers with overtightened nuts. Sometime later they reset the valve clearances and attempt to re-use the same gaskets which by now have been crushed to death. The misery is quite often compounded by the overtightened nuts which pull up the the studs leaving a raised metalring which then in turn stop the cover from sitting flush on the gasket. The end resultbeing hot oil vapour blowing through the gap and heading for somewhere tostain.

Lots of choices here as a cure. Stone the respective faces flat. Use new gaskets, Don't be so heavy handed with the spanner, or my favourite. A thin layer of RTV Silicon on one of the gasket faces.

Someone else has already pointed out that the rocker spindleend platescan also drip. Usually for a similar reason as above. The very coarse bolt threads, holding the plates,also offer alternative routes foroil to flow through. Some sealant on the threads wil help here.

Don't forget to check the rocker feed union bolts. These really need freshly annealed copper washers each time they are disturbed.

Lastly, the cylinder heads can leak around the pushrod tunnel mouths. It generallycaused bycheap head gaskets and bad torquing of the nuts in this area. I find that a tiny ring of gasket goo or RTV Silicon around the pushrod eyelet holesalways helps with this problem.

i have been told that alloy can be pourous, many t150 / 160 ( cough cough) heads are notoriously prone to it , but VAPOUR blasting the head not only brings it up more shiny than new, the shot inthe mix is cushioned by the water and peens over the surface of the alloy and stops the pourousity , i have not seen it first hand but have heard from a number of sources.