Morris Minor Owners Club

had loss of power in the moggy, stopped to check to see what was going on, took leads of of spark plugs individually. the first one, while it was running only lowered the engine very slightly. the other 3, there was a noticeable difference when taking plug wires off. I think i may have a head gasket gone bad, as there is a bit of oil as well.

would this cause the loss of power bad head gasket?

Ben

[Moved to Mechanical Section]

Possibly, but it would be worthwhile putting in a new plug to No1 - if that cures the problem then it could be that the plug was fouled by oil &c... Further investigation will be required.

A compression test on all cylinders could show up a failing head gasket, although it's more likely that one of the valves is going west due to the unleaded fuel.

oh it has had unleaded conversion fitted, and i change spark plugs, think its definitely head gasket as mate says he has had his do same thing, so i may be changing head gasket on Xmas eve in my garage....!!!D:

i am unsure what to do next? how hard is the head gasket to change? i have the whole head gasket kit i ordered, it arrived from ESM today.

Check the valve clearances first - maybe (forlorn hope i know) just needs gap setting. Easy enough to change gasket - have done it at side of road using only simple hand tools (ie no sockets) in just over an hour. But you would be crazy not to take the time to grind in the valves when the head is off. You say there is 'oil' around - where from ? Is there any sign of crankcase pressure - to test - take oil filler cap off and run the engine. Plume of oil smoke would suggest piston/ring problems.

yeah had oil filler cap off and good back pressure from there. where do i start on the head gasket? my haynes manual hasnt arrived yet that i ordered.

is it wise to do the timing chain gasket while i am doing the head gasket?

My money is on a slightly burnt exhaust valve- a burnt gasket is more likely to be 2 cylinders missing. As said above do a compression test.
you will remove the head, and head gasket as part of the job to change the valve anyway. Only need to change the timing chain gasket if its leaking badly.
check there is a good spark to that cylinder as well- it may just be a faulty spark plug lead- they don;t last forever! Try swapping the lead from the faulty cylinder for a knolwn good one.

Least likely is piston/ ring problems.

Phyllis lost compression on No3 cylinder last year - the exhaust valve had chipped. She had an unleaded head fitted, so it can happen.

If there is 'good back pressure' then afraid it sounds like piston/ring problems. Timing chain is no-where near head gasket - stick to one problem at a time ! To remove head - first undo the exhaust pipe connection and unbolt the carb from the inlet. then off with rocker cover - and drain the water off - easiest to just pop the bottom pipe off the water pump, and take off the top hose and the heater feed pipe from the back of the head. Then undo the 4 rocker pillar nuts - and only then undo the 9 head nuts. Lift off the rockers - and shake the push rods to stop the followers coming up as you pull them out - undo the bypass hose - and lift the head complete with manifolds off the block. Then - indoors for Christmas Dinner !!