sudden engine failure 1098

[eng622]

Not had the car long but engine was very peppy and an Ivor Searle according to the plate on it. Anyway thought I would check the spark plugs and they looked good all straw coloured. Started the car the next day and it ran very lumpy thought it may have been too much choke but no. Seemed to have little power and rapidly got worse, stalled and would not restart. RAC managed to get it going by cleaning the plugs. Limped home (RAC following me).
Now the bad news. Did all the normal checks on leads but noted it has electronic ignition and did not check the timing. But did a compression test and not good. Cylinders 3 &4 ok around 140 psi but cylinders 1 & 2 both ZERO.
So something very bad has happened without any prior warning. Took the rocker cover off and the pushrods operate the valves and the rockers do have free play they are not tight. To get zero compression could I have melted the pistons.
There is only normal colour smoke from the exhaust.

[svenedin]

I'd be suspecting the head gasket especially as the affected cylinders are adjacent although it is more common for the gasket to fail between 3 and 4. Head gaskets don't always fail with steam coming out of the exhaust. You say the pushrods are opening and closing the valves. Presumably you were turning the engine over with the starting handle whilst watching?

I can't see how you could have melted through two pistons and if you had there would be tremendous blow-by and oil leaking from all over the place at the bottom of the engine.

Don't panic. It probably isn't anything terrible.


Stephen

[Bill_qaz]

Zero compression is unusual.During test did you have all plugs out and full throttle?
If you put you finger over the plug hole and turn the engine do you actually feel nothing?
If you put a screw driver down the plug hole and turn engine by hand can you feel the pistons rising on the no compression cylinders?
Do you have access to a borescope to look into the cylinders?

[ManyMinors]

Agree with Stephen. Most likely the head gasket - and more usually between cylinders 3 and 4 because they are the least well cooled I guess but that is still the most likely in my opinion. Ivor Searle engines usually pretty good
Probably got to whip the head off. Not a big job though.

[eng622]

When you blip the throttle there is a brief metallic chattering noise which sounds from the front of the engine, read that is typical of a blown gasket between adjacent cylinders. There is a small oil leak from the front NS but cannot see if from the tappet chest cover or the head. There are no fumes coming out the oil filler. Worried getting a compression of zero but guess this can happen with a bad leak between adjacent cylinders.
Any advice on new gasket, copper or other type.

[simmitc]

Copper every time. Hopefully you did not run the engine after the problem appeared. If stopped straight away, then likely the only damage is the gasket. Prolonged running can result in damage to the surfaces of the head and/or block - make sure that you check both with a straight edge.

[svenedin]

Definitely fit a copper head gasket.

You may also wish to replace the manifold gasket at the same time (because you will be detaching the inlet/exhaust manifold to remove the cylinder head). It is also a good time to replace the somewhat notorious bypass hose (because access is so easy with the head off). You can buy a gasket set which used to be known as a "Decoke set" from ESM and other suppliers.

Best of Luck!

Stephen

[ndevans]

I think you'd know about it if you had got the engine hot enough to melt 2 pistons! I'd be surprised if it ran at all, much more likely to be seized.
Head gasket failure is most likely, however piston ring failure also possible, as are damaged valves/valve seats, though unlikely on 2 cylinders concurrently.
Worth checking the bores for scoring, and while head is off, see if you can detect any damage to the valves.
Good copper gaskets are the way to go, Payen is a good brand. Buy from ESM or Moss, don't be tempted by an ebay cheapie.

[myoldjalopy]

And fit gasket copper side up.........and grease both sides first.

[eng622]

Thanks for replies starting a new post on head removal