stuck crank

Author
Discussion

Petarah

Original Poster:

5 posts

98 months

Saturday 16th April 2016
quotequote all
hi. rebuilding a 924 turbo thats been stood for 24 years. just taken cam case off to replace the belt. the crank is stuck. how much pressure do i use to free it or is there something else i could do?

E-bmw

9,247 posts

153 months

Saturday 16th April 2016
quotequote all
You don't, you check the sump, plugs etc to see if there is any oil/water/crud etc in there and plan to strip the engine down if that shows up nothing as the engine sounds like it is likely seized.

CrutyRammers

13,735 posts

199 months

Saturday 16th April 2016
quotequote all
As in, the crank won't turn at all?
Is it just the engine or is it connected to the rest of the car - if it's still in the car, could be that the clutch plates have siezed together. You can sometimes free them by bumping the engine on the starter but not if you've taken the cambelt off. Try jacking the rear wheels off the ground, putting it in 1st, and seeing if it'll turn then. If so, you can then get someone to hold the clutch down while you turn the crank - if the wheels still turn, then the clutch plates are stuck together.

If it aint that, or the engine's out of the car and the crank simply won't turn, then I'd be stripping it down and replacing all the crank bearings & piston rings.

So - 1st step, work out if it's the engine which has siezed or something in the drivetrain. Then you'll know what to fix.

E-bmw

9,247 posts

153 months

Saturday 16th April 2016
quotequote all
Good point there too.

PaulKemp

979 posts

146 months

Saturday 16th April 2016
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More than likely it's the rings stick to the bores if it hadn't been turned by hand for 24 years
If it was the crank then it would be the main bearings
Anyhow a bit of oil down the spark plug holes could make a difference but in all honesty 24 years in a damp garage with all that condensation in the engine, I would start to strip it down.
You could put in neutral, raise the drive axle, turn the drive wheel, if it won't turn could be clutch plate.
Bar on socket on front crank pulley bolt, turn, if it turns and the wheels turn, clutch.
If it doesn't probably rings or mains, you could loosen the main caps a little and see if it will move a tiny bit but don't spin the bearings.

Old Merc

3,494 posts

168 months

Sunday 17th April 2016
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Even if it does "free up" are you really going to try and run an engine that has been laid up for 24 years.
I'm afraid it's engine out and a strip down.You never know after cleaning everything,bores,pistons,rings,valves etc etc,all it may need is new gaskets and oil seals.

DrDeAtH

3,588 posts

233 months

Sunday 17th April 2016
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Pour some hot engine oil down each bore to help release the pistons/rings

tapkaJohnD

1,945 posts

205 months

Friday 22nd April 2016
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My patent mixture for this purpose - white spirit and engine oil in equal measure.
No need to any fruit or paper umbrellas, just leave it in the bores for a few days.
Then lean on the crank, both ways, until it'll jiggle to and fro.
Continue to increase the movement - it'll eventually turn all the way, with luck.
John

kev b

2,715 posts

167 months

Friday 22nd April 2016
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The opinion on many old engine forums is that a mix of atf and acetone is the most effective.

I've only tried it once and it did the trick.

ColinM50

2,632 posts

176 months

Wednesday 27th April 2016
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Take out the plugs pour some diesel down each plug hole. Leave overnight. Next day turn engine over with plugs still out but put a cloth over the plughole or you'll get covered.

Betcha it works, 'cos I've done it on three or five engines now and every one a winner.

oakdale

1,807 posts

203 months

Wednesday 27th April 2016
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Most likely corroded rings but after standing for 24 years, anything other than a full strip down is a bodge.