Cylinder head removal

[colin addison]

I now have the seized engine out of my 1950 MM Tourer. Am having a problem removing the cylinder head. Have soaked the studs in both WD40 and AC90 and managed to remove x4 of the studs, 2 from each end. Still cannot budge the head. Does anyone have any tips please? I would rather not break the head because although a spare came with the car it is an earlier version and the fittings are not the same ie distributor mounting. I am thinking that it is probably rusted-in studs that are holding it and that really the rest need come out.?? The engine is seized so I think taking the sump off and hitting the head from below is probably not a goer, it is almost certainly rings rusted into the bores which means this might not be a good idea.

[mike.perry]

Try hammering under the thermostat housing on one side and under the small projection on the opposite side of the head, then if you can get a gap between the head and block you can lever the head up with a long screwdriver, working on either side of the head

[leyther8008]

The old mechanics used to have a set of thin walled pipe drills that had minimum clearance around the studs and where used to drill down through the 'clearance' between the stud and the head drilling out the corrosion, but I hav'nt seen a set for years might be worth a e-bay search.

[mogbob]

Colin
I've not come across AC90 myself...but I swear by Plus Gas as a releasing agent.
Screwdrivers or old chisels are likely to cause damage to the head, unless you are extremely skilled.
Remove as much rust/ crud as you can around the offending studs, using a wire brush/ sharp pointie
tool ( needle / skewer ).Apply your releasing agent and leave for a good while.

Mike's suggestion " under the thermostat housing projection "is a good one.I'd also suggest hammering/ tapping gently
with a block of wood between the hammer and the metal the studs.
With a good inspection light you should be able to see the releasing fluid moving around the perimeter of the stud as you hit it.Move the blows around from different angles.gently does it.As it disappears ,add more releasing fluid.
With a larger lump of wood, you can "cover " one side of the head and tap sideways with a club hammer.Then try the other side.

You are trying to induce "very slight " movement of the head...enough to let the releasing fluid get between the surfaces.
Keep moving the wood cushioned blows all around and eventually it will give.
Bob

[Veitchy]

I saw an old mechanic I used to work with remove a cylinder head by leaving the car hanging on an engine crane by the head so the full weight of the car was going onto the studs over an Easter weekend break (about 5 days) with a liberal amount of vinegar poured into the head bolt tunnels. The theory was that the light acid in the vinegar would work on the corosion over a period of time. When we came back on Tuesday it had moved about 1/4 inch and with some CRC and elbow grease it came off.
I don't know if it was luck, coincidence, or tallent but we had been trying to get the head off all afternoon without it moving at all but leaving it that way it moved !

Goodluck,
Graham

[RobThomas]

Can you remove plugs and feed rope in through to the piston tops? Rock the car with the gears engagaed and it shoves the head up from underneath.
Worked on my pre-war 850 cc sidevalve Morris engine but the bores are shagged. Anyone got a pre-war engine?

[colin addison]

Thank you for the various suggestions. As luck would have it my other 1969 Moggy was being MOTd last saturday and in discussion Hugo gave me a spray can of Wurth "Rost-off". So I have been spraying this into the stud gaps for a few days. I now have the side away from the manifold free and lifting just 2 or 3 mms. However the manifold side is proving a bit more of a challenge and I am still working on the studs. I screw a nut onto the stud and tap all the way round it with a hammer, then add spray and repeat, and more spray and leave. Then repeat morning and evening. On several of the studs, when spraying, the liquid coming off/out is brown in colour which I take to be rust being dissolved out. I guess patience is necessary?
I am thinking how I might hang the complete engine from the cylinder head, that sounded like a good idea, but not so easy!

[orb596]

When we were trying to get the head off my 1936 Austin 12/4 we had the whole weight of the car hanging on the engine for a whole week with no effect. We tried diesel down the studs but that didn't work. We ended up using a hammer and a coal chissel and carefully hitting it until it finally gave way. Turned out not to be rust holding it on but carbon in the end.
Good luck with it - it will come off eventually.

[mike.perry]

If you have a gap on one side keep tapping a blade into it then tap the head down then up etc and hopefully the head will gradually lift. Do not force the blade into the gap and keep working on the other side of the engine as well as the back and front.
If you can get a blade through the middle of the head gasket it will prevent the head or block getting damaged

[rayofleamington]

If you really want to keep the head, then I would attack the issue from the piston side.
As the engine is seized, you may need a lot of effort to shift the pistons, but you wont be re-using them!!

You can try hammering the pistons up the bore from below and once they can be made to move a little, you'll be able to get them out.

You probably only need to remove one piston from the end where the head won't budge - with any luck this piston may be free anyway.

[horologiumwatches]

I had a hell of a job getting the head off once. In the end I used lifting eyes welded to old spark plugs wound into the number 1 and 4 plug holes, jacked the car right up, tied the head to the beams in the roof and let the jack off.
I believe there was actually a tool similar to this set up avaliable for this job. Left it there about 2 days with loads of WD40 sprayed all round, and bobs your uncle! It did nearly pull the carport down though I'm not sure the screwdriver under the head is a good idea, unless you are having both surfaces skimmed after.....
Cheers
Tommy

[colin addison]

Hello
Well, after about 3 weeks off came the head, in one piece, with much bashing. Seemed that the soaking in "Rost-off" helped. I've now got the engine apart and am reviewing what needs doing.
The seizure was just one piston, which came out fairly easily, couple of days with Rost=off down the bore and then a gentle tap and out it dropped. The rings are stuck in their grooves and I have it soaking in diesel. One of the other pistons had a broken top ring which just fell out as it was withdrawn. So I will have to buy the full set of rings, which means I have plenty to replace those from the seized one. The pistons all look good. Bore size is on the maximum +.060".
One problem, the gudgeon pin clamp bolt was loose on number four, and the pin has worn tracks in the bore, I will probably hone the bore and keep fingers crossed. More importantly the bolt now has a couple of worn parts in it, does anyone have a spare good clamp bolt please?? It's a strange size with a square head. Are the small spring washers available? ESM don't have either.
The bore with the seized piston in it has cleaned up reasonably well, but there is a badly pitted area low down, the piston had seized almost at the bottom of the bore, and water must have collected just above this area. The top half of the bore is good, which means the first stages of combustion will be at max compression, but I guess if reassembled as is there may be some oil burning. What do the experts think about this?
All bearings and journals are good, but I will replace the big-ends as a precautionary measure, as the engine is in bits. The mains are -0.010" and this size is not available from ESM. The big ends are -0.020" and are available.
Valves are all out and have cleaned up reasonably well, exhausts are somewhat pitted but the sealing area has ground in OK.
Well, that's it for now
Colin

[MarkyB]

My main concern would be any pitting that the rings have to travel over.