Best way to unseize an engine

savageseadog said:
For a really serious and large case I suggested a hydraulic hand pump coupled to an injector or glow plug port.
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If that was going to work, it wouldn't have filled with water and seized in the first place!

Also it takes a great deal of steady force to move something compared with the shock of tapping it with a hammer. A combination of steady force and the ringing of hammer taps often has the most effect for least damage.
 
Sandyman said:
Dont bother with all that expensive plusgas etc etc

Take yourself off to your nearest supermarket / shop & purchase some coca-cola and
fill the pots with that for 24hrs. Has to be the real stuff. Not diet.

It works. Has for me on a number of occasions.
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Whoever actually worked in a mechanic shop knows that this is the right answer. It has always freed seized engines since WWII when that miraculous "beverage" (is it actually drinkable???) was exported all over the world.

Daniel
 
Scorpiokent said:
I have a Single cylinder BMW D7 that sprung a leak on the head gasket so now full of water which has seized the piston, anyone got any good tips on the best way to un-seize this without causing any damage to the bore and piston?
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On Classic Car Rescue this week they tried to save a Ford Mustang engine by pouring boiling vinegar down the cylinders. Didn't work for them but who knows... ? :D

Boo2
 
Put diesel on the piston and leave it for a few days, if diesel wont help it you have serious problems.

Personally I dont like the idea of hitting the piston, I'm in favour of turning the crank with a spanner and seeing if there is any amount of movement. If the piston is TDC you will cause damage with the hitting method.

IMHO

Tom
 
I rather think that if you need to hammer a piston out, you're into serious rebuild territory and should start with a bottom end strip so that the only thing you're moving when you clout the piston is the piston itself. I also advise using a wooden or plastic drift. (Not Oak or Teak as it can be harder than the piston).

I've only once had to do this to an engine and it was soaked in Plus-Gas and warmed in the oven before being thumped with the hammer. Just as well I'd budgeted for a re-bore......
 
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I've hammered the pistons out of a few old motorbike engines.
Variable results.
At best, the rust cleans up ok, clean the ring slots in the piston and it will run for many miles.
At worst, the rings break and score the bores. But they may have been broken to start with, hence the engine being discarded years before.
I remember in one case, a Honda CD175, we only wanted to get the barrels off so we could use the gearbox, but the pistons and barrels came out usable.

I've stripped a few drowned outboards, in one case the piston was not responding to a spanner on the crank, but it tapped out quite easily.

When you don't have the option of buying all new parts and doing a perfect job, you have to make the best of it and live with the consequences.
Or, give up gracefully and get a new one on HP.
 
From personal experience I can tell you that with a little modification to the engine bearers a Beta 10 will fit in only slightly more space than the D7. Not a difficult job to do. Worst bit was lifting the engines to and from the boat.
 
Boo2 said:
On Classic Car Rescue this week they tried to save a Ford Mustang engine by pouring boiling vinegar down the cylinders. Didn't work for them but who knows... ? :D

Boo2
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But that engine was just a pile of scrap iron - as, in fact, was the entire car - as, in fact, was the entire car that the replacement engine car from! And these guys want $5000+! :confused:

Richard
 
Heat the engine/crankcase, spray wd40 on top of the piston, tap gently the top of the piston with a soft mallet and rotate the engine from the flywheel end (use a large socket and a lever if possible). There is always the danger of braking the piston rings; so don't use sudden force.
 
While we've been wittering about this, the corrosion has presumably been getting worse!

WD40 is an OK penetrating oil, main problem is it is quite volatile, can be a bit lively if you apply a lot of heat!
 
I think there's a danger of getting hung-up on the idea of hitting the piston. Just to put it into perspective, you'd have to hit it damned hard before you got anywhere near the sorts of forces that routinely happen right on top of it on every power stroke when it's running! I agree about not hitting it if it is at TDC or BDC, but when the head is off, it will be pretty obvious whether it's in either of those positions. Only important thing is to do it via a plug of soft wood so that the forces are spread over as much of the crown as possible.

Remember also that the barrel comes off a D7 very easily (keep the shims from under it) so depending on where in the stroke it has stuck, you might find it easier to take the while piston out by undoing the big end and then at least you can take piston, conrod and barrel back home to work on them.
 
penfold said:
The D7 is a fairly horrid engine even when functional; do you really want to expend this much effort fixing it?
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Based on a Hatz 673 engine: I have one in my genny. Some Parts are very hard to come by. try Gary at Bryco www.bryco.co.uk who is very helpful - and he will put requests into Hatz in Germany, but not many parts are available for these obsolete engines
 
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