Petter a problem

My Petter A runs really nice till last Friday when it stopped and seems to have lost compression.Checked head gasket lifted barrel and everything looks perfect no broken rings etc. and bore looks ok.Bit stuck as to what to check next and wondered if anybody has any ideas .Thanks Jim .

Valves and valve seats perhaps? if designed to run on leaded fuel the valves can get too hot and the seat becomes worn/ coked etc - a simple method (that costs a cup of fuel) to see if the valves are sitting right is to turn the head upside down and pour some fuel onto the head/ cylinder- with luck the fuel will stay in the head and not leak past the vales - if it does leak then at least you have found one issue to sort out - visually inspecting them may not allow you to see the issue..

the remedy can vary - from simple grinding paste to a little more engineering on the valve seats - but others on the forum may have a better idea of specific issues/ solutions..

Best

Hamish

Petter A was not designed to run on leaded fuel, any type of petrol will suit it fine.

well bang goes my theory

Reckon it's the tappet clearance...

Or lack of....

Thanks for all the suggestions and sorry for slow reply ,I have had an unexpected week in hospital.Definitely not the valves or tappet clearance,have checked and all ok.Is there a breather somewhere which could be stuck open?

decompression lever - if it has one? I cant think of anything else...

A blocked breather shouldn't cause the problem. I had the same problem with a friends Wolsley engine the other weekend and it turned out to be the valves.
If the bore,rings and head gasket are ok it can only be the valves. I'd check them out as Hamish suggested and if that doesn't work pop them out and give them a regrind.

Bob

I was going to suggest the decompression lever myself but could not see how it could happen. Having looked at the diagram I suppose that the decompression cam or shaft could have worked loose and be holding the valve open. But there again wouldn't that be obvious with the head off?

I'd still check the valves.

Bob

as the other lads say other than that is plug threads or plug leaking out compression or something blocking the airflow into head, sucked up something like clump of grass or even bit off a/your oily rag,easy to find out is turn the engine over in reverse and see if the commpression is back,