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Trying to fault find why my 1938 Austin Seven Ruby won't start I discovered that I had no compression on cylinders 3 & 4. I have removed the valve cover and can clearly see that the valves 5 & 8 are both stuck open when I turn it over on the crank.
I am going to start further investigation this weekend but i wondered if anyone else has experienced this and iaf there is a possible solution?
I can't understand why only 1 valve on each of these cylinders is affected.
Location: Rochford, Essex
Valves sticky in guides. The common cure for this used to be to trickle a little UCL (redex) into the inlet manifold with the engine running.
But not anywhere near your neighbours!
Whatever the cause within reason, should be able to prise the valves close thru the plug hole, crank, and persuade sufficiently free to start.
Location: Auckland, NZ
A dose of redex might cure it, but rather than follow the advice of bodger bob, I'd take the head off, remove the valves and find out what the real problem is.
Is there a problem using Redex because it is not the same as it used to be? Following some earlier posts on here I bought some 2 stroke oil, which looks and smells almost the same as 'proper' Redex and am using an old Redex dispenser to use one squirt per gallon of petrol. There is no smoke and the engine seems to run better. I should mention that the engine has just reached 1000 miles after a rebuild.
Location: Near M1 Jtn 28
I think Bob's solution is worth a go on the grounds of simplicity. Especially if it turns out to be just carbon build up on the valve stem/guide.
I had the same problem last year, and the culprit was very difficult to find. Eventually it was a cam follower that had cracked at the top where the conical adjuster screw goes, causing the follower to expand when tightened and seize in the bore. I managed to change it without removing the block.
Location: Bonnie Galloway
As I said before- coca-cola down the plug holes,replace plugs ,turn engine over,leave overnight. I obtained lasting result ,this tip was given me by an ex-team Lotus man. Worth a try surely?
Ian, can you explain how poking a bent screwdriver through the plug hole to try to free a stuck valve will bend the valve head?
I'm not suggesting sticking a crow bar down you know. And if appreciable resistance is felt, stop and 'fix it properly'.
It's worth a shot.
Location: Bonnie Galloway
A bodge might free the sticking valves but for peace of mind I would take the head off and strip the valves out, first of all to determine why they had stuck and secondly to regrind the seats.
I had a stuck exhaust valve after doing my mega run to the top of the Col de la Bonnette and whilst the engine was still running OK it was a bit short on power on the way home. Even that little hiccup had enabled the exhaust gases to burn the seat.
Old adage - do it once, do it right. (I think it was Jack Reacher wot said it)
Not as simple as a blown head gasket
Location: Oakley, hants
To answer the original query: the two valves are both exhaust valves, so they have that in common, also they are to the rear of the engine which usually means they run a little hotter than the other two.
So maybe the deposits on the stem are a bit harder, so they are more likely to stick.
Location: On a hill in Wiltshire
Thank you everyone for your advice. Sounds like the valves could coked up a bit. I have decided to take the head off etc and check nothing is bent or damaged and hopefully all it will require is a bit of a clean.
Will let you know when 'Ivy' is back running around my local lanes.
Check that the cam followers drop away from the valves if you think you have stuck valves.
I have seen a few instances of split cam followers caused by overtightening the adjusters. the cam followers jam in the guides holding the valves open.
when you have a look at the followers, if split it will just look like a small vertical scratch. you need to pull the followers out and tighten the adjusters to see if a split opens up. or use a dye test kit.
you could try to loosen the tappet adjustment lock nut on the offending valves and see if it makes thing move.
Austin valves rarely jam in the guides unless they get bent.
Please report back on your findings.