Commando Head Oil Leak problem solved!

That is really interesting thanks for posting it as i am putting an 850 together now.

JC - can you state if it was RH4 or RH10 stamped head? thanks

Previously john_cowie1 wrote:

Just a quick note to share this piece of good news with all you depressed, oil-soaked (1974, 850cc, Mk2) commando owners out there.

The symptoms: increasing problems with oil appearing around the front right of the engine (and then eventually, front left as well). Drips of oil hanging off the exhaust locking rings. Oil collecting down by the tacho drive. I havean old police fairing so there was always oil on the inside of this which was enough to cause puddles to form underneath when parked up! Evidence of oil coming out between the fins and collecting around the spark plugs. Even some travelling right to the back of the cylinder head and wetting the bowl of the carb. (I have a single carb conversion). Also, of course, frequent need to top up engine oil level.

Being a bit tight and ever the optimist, I tried all the usual fixes: checking rocker covers and spindle covers and getting an upgraded tacho drive with oil seal. Replacing the head gasket and putting some silicone around the pushrod tunnels. Putting thread seal around the cylinder head stud that breaks into the pushrod tunnel and evening devising a cunning dowty washer-like device to stop oil coming out here. - All to no avail.

In the end Andover Norton suggested I get the head checkedfor cracks by Norman White at Thruxton. Die penetrant testing showed cracks and the head was sent to EMP Tooling in Havant who used laser welding to seal them. The heat generated during laser welding is so localised that nodistortion occurs and the head can go straight back on. Since then - nice and dry!

Looking back at the amount of heart-ache and agro all this has caused, to anyone battling with similar problems, I would recommend a quick trip to see Norman. I think hecharged me £60, which has to be worth it even if it's just for the peace of mind. EMP then charged £360 which might seem a bit of a strain on the wallet until one finds out that a new head costs over £1000.

Apparently the fault lies with the manufacturers back in 1974 who changed their suppliers of cast heads and didn't keep an eye on the quality.

So there it is - a good news story which I really hope gives some relief to fellow commando riders. Happy riding. - John

That's interesting John.

My 825 head is more or less the same, mine is stamped RH10 I think?

I have little bits of rag(not seen) to stop oil being blown onto the float bowls!!!

My main problem is oil coming down between the in guide & head, this is because many years ago it was built by Hemmings and the valve angles & sizes were changed, I then had to have them reverted back as I couldn't buy the larger valves! Someone had them in stock, but they wasn't going to sell them!!! I won't say who!!!

My valve guides are now about 3/4" dia!

Paul

I can also recommend EMP Tooling. In my case they rebuilt the oil boss on my Commando crankcase after the heli-coils broke out. At the time they said they had repaired a number of leaking Commando heads. The laser welders are quite impressive and they were keen to show me around. The turn-around time was less than a week.

Graham