25 replies to this topic

[Ethel]

You're not going to tell which cylinder(s) are seized, short of unbolting them from the crank. A compression tester will give you an attachment - if you haven't got one you'll likely want one to help assess it once it is free. I wouldn't worry too much, one cylinder will be compressing another via the crank thousands of times a minute when it's running. Even if it was running moisture could have got at the valve gear almost as easily as getting at the piston rings, so it wouldn't be a waste of time to have the rocker cover off & give the valves a shove, or slip the timing chain off, especially if the radiator's already out of the way. At least you could tweak the cam pulley to see if any chain slack will swap sides.

[Drew McCrae]

Agree totally Ethel. If I have to go as far as head off, I'm assuming I will need a new head gasket??

[Ethel]

Yes.

 

An old gasket might seal well enough for de-seizing purposes, but you'll want a new one for it to run.

 

 

.... brings us back to draining the coolant.  Removing the bottom hose is the usual method. If you had the drain plug out, it's not unusual for them to be blocked with gunge. They're in a bottom corner where there won't be much flow.

[Drew McCrae]

Update is that I managed to unclog the block drain hole (Thanks to Morris Minor forum). Eventually a coat hanger shoved in with a tiny bend on it and in and out and round and round. This has enabled me to thermally cycle the block a little. Pouring boiling kettle in the thermostat hole a few times and it feels hot to the touch. I'll continue to do this regularly.

Also have refilled the cylinders with 50/50.
Also have tapped the valve stems with a small mallet. Cyls 3 and 4 definitely have open valves. But tapping valves cause spurt if liquid out the plug hole which is good news.

I'm still doubting if the pistons are seized and whether there's a possibility the gearbox is preventing me prying the flywheel and rocking the front wheel. Am I worrying unnecessarily?

[Ethel]

Gearbox could be eliminated  by holding the clutch out and seeing if you can roll the car in gear.

[Drew McCrae]

Gearbox could be eliminated by holding the clutch out and seeing if you can roll the car in gear.

Will try that 😁

Edited by Drew McCrae, 06 September 2026 - 02:54 PM.

[JH1212]

Mine was the same when I picked it up many years ago, although that had been sitting for 15 years.  I think it’s just the moisture in the atmosphere which cause the corrosion.

 

I tried all the same easy fixes, but in the end had to take the head off.  I knocked the stuck piston down with a block of wood, cleaned up the bore with some wet and dry and rebuilt it all.  15 years later it’s still running beautifully!

[Drew McCrae]

It never rains but it pours !
Bled the clutch in order to get to next release stage only to discover the clutch is stuck😩

Managed to discover that when the slave cylinder extends that it doesn't return fully. Loosening if the two nuts at the center of the cover shows me what looks like a bush slides on the shaft. By levering hard the slave cylinder back to its normal position I can see this bush appear (rusty brown). At least it slides but too stiff for the spring to return it. When this is free then I can go back to my intended issue.

At least it'll give the cylinders a longer soak

[Ethel]

In my experience it's usually the clutch slave cylinder that seizes, similar to an engine cylinder the bore rusts (because the fluid seal wipes it dry) then you pump out the slave piston on to the rust...

 

What I think what you're describing, with the 2 nuts, is the clutch plunger (where the ball end of the clutch arm seats) it's all one piece of metal. It could seize the same, but it's less likely. Either seizing, after the clutch pedal has reached the floor, would likely hold the clutch out (disengaged) so the car will push in gear without trying to turn the engine over as it rolls.

[Drew McCrae]

Press pedal, lever the arm back, press pedal, lever the arm back again and again freed it up. Some oil in to the centre of the bush and clutch working again. Definitely the bush with the socket as you described.

Think I'll have to use a grease gun at this stage for the cylinders. Fingers crossed

[Drew McCrae]

Feeling please. And fortunate that Amazon took their time delivering a grease nipple! The extra soak resulted in a tiny amount of movement at the crank nut. Gradually worked away at it and can now rotate 720 degrees. Only thing was when the stuck piston came back up it got stuck. tapping the spanner and then releasing and inching forward bit by bit got me through it.

Expecting that future work will be needed as a result but that can be done when valve seats are being my replaced. Lots of other restoration that my son has planned before then.

Thanks all for your advice.