A similar thing happened in an seven in which I was a passenger, sudden noise and then the engine stopped, it was locked solid and the worst was feared. The head was removed there and then to find....... a solid lump of coke from around a plug. No bigger than a current it has jammed between the head and piston. Had we known a reverse rotation of the engine would have shown that it was in fact free but an obstruction was present in one cylinder only.

I would try top gear and a gentle rock backwards with the plugs out and see if the beast will turn over! Good luck, I hope it turns out to be something very simple.

Location: Cotswolds

John, It sounds unlikely, but I had the identical problem, drove for less that a mile, and it locked solid. In my case, it was a big end seizure, but they were shells and not white metal. Harry Fox

Location: High Wycome

Thanks to all who have given suggestions as what may be causing things. My son suggested trying to rotate the rear wheels backwards whilst in gear but I don't know if the rear wheel will just spin. However I will give things a try.

John Mason

Location: Nottinghamshire

Take the sump off and have a look ! Forcing it may do more damage .good times .Terry.

An update on things. I have started to strip things down and removed the starter motor together with the fly wheel cover. Tomorrow I should have the engine and gearbox separated. So far I can see the flywheel has moved resulting in the teeth for the starter ring gear being in contact with the inside of the bell housing cover. Looks serious. Until the gearbox if off and clutch taken apart I don't know quite what I will find. I will update for people who maybe interested when this is done. I fear broken crank or damage to the key way, flywheel taper together with damage to the flywheel itself.


John Mason

Location: Nottinghamshire

My RN did the same a couple of years ago returning from the MoT , it was a snapped crank right by no.4 journal.

Location: Dorchester

Just to keep all up to date. The engine has now been stripped down and the problem has been found. No.3 piston seized solid with deep score marks on the opposite side to the split in the piston. The top 2 rings are also seized in there grooves and warn down to the piston.Likewise corresponding marks in the bore. The gudgine pin also seized solid in the piston. What I can't understand is how this should happen with plenty of oil going up the bores ( I run with the oil baffles taken out). The engine had plenty of oil and water before and had only been running about 5 minutes so could not be over hot. My next decision is how far do I go with the re-bore the engine is plus3 already. What is the maximum re-bore for an engine that is only used in a car for social driving. No competition or racing.

John Mason

Location: Nottinghamshire

Maximum size of bore is determined by the internal condition of your block John. I have had blocks that hole at +0.030" and some that show no signs of holing when boring out to fit a liner.

Standard pistons are available up to +0.080".

Have you done major work to this engine recently? If so, what did you do?

Thanks Ruairidh. Approx 12 months ago I stripped the engine down to replace the block to crankcase gasket and put right the oil leak. To do this I disconnected the big ends and kept the pistons and rods in the cylinder bores. Reassembly was the reverse on stripping down.Block back on then big ends re connected. I have done a few hundred miles since this before my current breakdown.

The cause of the seizure seems to be that the pin going through the piston and little end has seized solid thus making the piston move up and down the bore at an angle instead of parallel with the bore.


John Mason

Location: Nottinghamshire

I had it in my mind that you had done work to the block but clearly nothing to the pistons - I have experienced stuck rings but never a seized gudgeon pin. I shall be interested I knowing what caused it, good luck with your rebuild.