Diesel 5 liter suddenly seized ......

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.... why ? 

So the ambulance has been getting a makeover, welding, paint job, exhaust, new springs, getting ready for the summer.

My mechanic hasn't been able to start the thing, and has been troubleshooting the starter motor / battery. Took him out a new battery, all we got was a click.

So I was there yesterday and said to him "In my day we would put it in second and rock it back and forth, maybe a tow start".

"Didn't think of that, surely the motor isn't seized"

We got a 27 socket on the front of it, and the motor wouldn't budge, clockwise OR anti-clockwise. 

Last time he had it running it cut out itself, he attributed it to not keeping the revs up for long enough, it was -9 celsius at the time, he'd run it for 45 seconds or so.

That was a month ago.

Hydrolock ? As in a cylinder full with diesel ?

Seized ? After a month standing still ? Surely not.

No signs of water in the oil.

He will be be removing the glow plugs / injectors to elimination the hydrolock possibility, then I guess it's a matter choosing which lubricant to spray in the glow plug holes to see if that frees it up.

Popped a valve maybe ?

Was a great motor, btw, no smoke, pulled like a schoolboy, to coin a phrase.

[Big_Richard]

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[TJ 450]

Yep, condensation would do it.

The first thing I would do is gain access to the combustion chambers and soak them with oil, WD-40 etc. You could have a coolant leak in one of the cylinders too, or as you say hydrolock from a pool of Diesel (that would clear in a while anyway, in which case you could turn the engine after some time).

Tim

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Update:

After a week of using some highly rated spray lubricant ( my mechanic mate has been working on it, while I've been away, er, working ), we bit the bullet and did a little towing in fourth and the engine turns now.

The starter motor also turns the block slowly now, which my mechanic friend attributed to being slower than due to higher compression having removed some of the tappet stuff to check the valves were ok. ( haven't completely wrapped me head around how that works )

So, put the thing together again, hope it starts and get back on to the paint job.

Currently going for the "condensation / rust" theory.

( Been pricing blocks in the meantime, rather cheap on the "hit and miss" second hand market, to a "naked" block from a reputable scrapyard, 140,000 km, € 600, one month guarantee  )

[Big_Richard]

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Here is the pic from when it was advertised for sale ...

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Damn, had totally forgotten about ( or subconsciously dismissed ) this incident ....

http://forum.w116.org/auto-torque/%28-w114-%29-exhaust-fell-off-oil-pressure-gauge-fluctuating/msg94786/#msg94786

... thanks again W116 forum, for being able to search my back posts for the "when was that?, what was that again?" type queries.