possible valve drop on my LD 28 engine locked please help?

[_blaylok]

Hi I am from Australia got an LD 28 in my Nissan Patrol MQ. Been happily motoring along for the last couple of years until 1 month ago i went to start it and and it just locked. First checked all things like possible starter motor locking etc. all good. My father and i now have it down to somewhere in the cylinder head. Locating service manual now and am about to pull off the head. Anyone out ther had any similar problems? Any help would be greatly appreciated.

[asavage]

Possible hydrolock? Water from the cooling system leaked into a cylinder, via a head gasket or cracked head.

Have you pulled the glow plugs and tried to turn the crank?

[_blaylok]

Hi again, Yeah not so sure about the possible hydrolock u suggested. Would that not mean that i would have had some overheating problems leading up to the engine lock i am having now. ie. cylinder head becoming extremely hot leading to blown gasket or cracked head? Engine had been running fine. My father and i were able to rock the vehicle and managed to get nearly 3/4 of a revolution out of the engine, until it reaches a certain point then locks itself again. We have drained the coolant and removed the radiator and fan, also IP cover. Removed IP belt, tensioner. Injector pump cranks. Removed rocker cover. All springs and clips seem to be in place. But there does seem to be a fair bit of play in two in particular one more than the other out of these two. Upon sussing about on this forum it says valve clearances should be .10mm and .12mm respectively. I dunno but the play or slack i feel in the one in particular is more than .12mm. Could that point to this one being my possible dropped valve?
thanks again
Chris

[_blaylok]

sorry i got that wrong in previous post
.010 intake
.012 exhaust

[asavage]

No, you would not necessarily have an overheating symptom prior to hydrolock. Corrosion can take out a head gasket, and is actually more likely on the LD which has cast iron head & block, as opposed to the L (gasser) alloy head.

Remove the glow plugs. With as much as you've removed so far, the GPs are a snap -- 15 minutes tops. If you can't turn the engine over with the GPs removed, the head will have to come off anyway.

[asavage]

Via email, the rest of the story:

removed all the plugs, still the problem, took off the head to find that one of the valve seats had dropped out of the cylinder head only to be mashed up by the top of the piston. kaput i reckon.

First I've heard of a valve seat come out of an LD head.