Hi From Down Under

[Gregted]

Originally Posted by Fore and Aft

Gregted, could you somehow brace the engine against a wall and use a hydraulic jack to push the cylinder down or up?
Cheers

That will be an option if the whacking with a hammer doesn't achieve the desired results.

I did try this while the engine was installed but the engine mounts gave too much and I couldn't get the leverage I needed.

I still have the bush press idea as well, so the 62 year old bush mechanic vs the 40 year old marine engine battle continues....

I lost count of what round we are on so I'll guess current score is engine - 5, Me - 0..

[RaymondR]

One usually finds that forcing the piston down far enough to use a hone to clean up the cylinder and oil it before attempting to pull the cylinder upward is more likely to lead to success.

[Gregted]

Originally Posted by RaymondR

One usually finds that forcing the piston down far enough to use a hone to clean up the cylinder and oil it before attempting to pull the cylinder upward is more likely to lead to success.

Top idea sir.


One is hoping the rings are not broken or badly rusted enough to mark the bore as it is in reasonable condition atm.

[Wotname]

I once saw a bush mechanic free up a seriously stuck (rusted) piston/cylinder by filling the combustion chamber with grease, removing the pushrods and connecting compressed air hose into a custom fitting screwed into the spark plug hole. It was left connected anytime the shop air wasn't needed elsewhere.

Took about 3 months to force the piston out of the cylinder. Almost all things are possible!

[Gregted]

Originally Posted by Wotname

I once saw a bush mechanic free up a seriously stuck (rusted) piston/cylinder by filling the combustion chamber with grease, removing the pushrods and connecting compressed air hose into a custom fitting screwed into the spark plug hole. It was left connected anytime the shop air wasn't needed elsewhere.

Took about 3 months to force the piston out of the cylinder. Almost all things are possible!

My shop moto used to be, " The impossible we do immediately, Miracles take a little longer."


Might have to change that to, " Beating a dead horse is our specialty."

[RaymondR]

Machining a disc with an oring groove and a grease fitting and retaining it in the cylinder bore with a couple of bars held down using the head studs and using a grease gun to pump the cylinder full of, and then pressurising it, using a grease gun would probably be one of the gentlest ways of getting a stuck piston moving in a cylinder.

Assuming a 3" diameter piston and 1,000 psi pressure one would generate 1.5 x 1.5 x 3.1416 x 1,000 = 7,069 lbs of evenly distributed thrust on the piston.

[Compass790]

Have you tilted motor so cylinder is vertical & left your choice of penetrating oil sitting on top of piston?
You will have to get piston out of the head end as wont come out the bottom with the crankshaft in the way ( from memory )
If the bore is not rusty I wouldnt hone it yet until you have the piston out just to keep the hone even.
Now you have said the water inlet seacock is jammed open makes me think that it was probably being cranked with no start that caused the cylinder flooding rather than exhaust elbow.
You can install another ball valve in the line till you replace seacock on next haulout.
If you have left penetrating oil on top of piston for a few days I'd be surprised if it doesnt move with a few whacks from a 4lb club hammer.
Hang in there, the battle isnt easy but doable.
Looking forward to next installment in the saga.

[Gregted]

Originally Posted by RaymondR

Machining a disc with an oring groove and a grease fitting and retaining it in the cylinder bore with a couple of bars held down using the head studs and using a grease gun to pump the cylinder full of, and then pressurising it, using a grease gun would probably be one of the gentlest ways of getting a stuck piston moving in a cylinder.

Assuming a 3" diameter piston and 1,000 psi pressure one would generate 1.5 x 1.5 x 3.1416 x 1,000 = 7,069 lbs of evenly distributed thrust on the piston.

We will add that arrow to our solution quiver to fire at the beast if she fails to succumb to our gallant parries and thrusts.

[Gregted]

Originally Posted by Compass790

Have you tilted motor so cylinder is vertical & left your choice of penetrating oil sitting on top of piston?
You will have to get piston out of the head end as wont come out the bottom with the crankshaft in the way ( from memory )
If the bore is not rusty I wouldnt hone it yet until you have the piston out just to keep the hone even.
Now you have said the water inlet seacock is jammed open makes me think that it was probably being cranked with no start that caused the cylinder flooding rather than exhaust elbow.
You can install another ball valve in the line till you replace seacock on next haulout.
If you have left penetrating oil on top of piston for a few days I'd be surprised if it doesnt move with a few whacks from a 4lb club hammer.
Hang in there, the battle isnt easy but doable.
Looking forward to next installment in the saga.

Unfortunately, time was against us last Sunday. We started late on the day. I decided to destroy some perfectly good targets at the pistol club with my CZ and the son had a sleep in on his only day off.

By the time we dismantled the table, part of the seats and the sink cupboard, and finally managed to extract the heart from the chest of the Roberts it was 9.30pm and the son had to work next day.

We will definitely be back on Saturday to drain the oil/sea water from the sump and the remaining oil from the gearbox so the motor can be sat on it's side to allow us to either have a decent whack at the piston top or bottom or mix a concoction of ATF and acetone and let it soak for another week or so.

The raw water inlet will get a ball valve between the rusted/fubar seacock and the debris trap .

[Gregted]

Ok. So we ventured out to the Roberts today and drained the sump and gearbox.

We removed the conrod end and whacked on the conrod with some hardwood and then a bit gentler with an extension bar but the piston still wouldn't budge.

The good news there is that showed the conrod was not rusted to the crank which would have surprised me if it was the case.

We tried again to pound on some hardwood on top of the piston but still no movement.

We decided at this point to leave it sit for a week with a mix of ATF and acetone in the combustion chamber.

If it doesn't move next week, we might press against the piston top with the 20 ton jack now that we can fully support the other side without the engine mounts giving.

If we can't get enough leverage, I can't see any other option than taking the motor home and placing it on the press.

[Wotname]

Thanks for the update - it is a stubborn bugger.

A couple of random thoughts -

If you plan to pull the engine, you may want to remove the flywheel to make it considerably lighter to handle. If so, then now is the time to remove the flywheel nut as the stuck piston will hold the crankshaft from turning making it significantly easier to apply torque to the flywheel nut. It will be tight!. It is torqued to 35 kgs or ~250 ftlbs.

If you fill the water jacket with something CLR to remove the boiler scale and rust on the cylinder liner, the whacking the conrod might remove the liner as well as the stuck piston. The only thing holding the liner in place (with the head remove) is the boiler scale (calcium carbonate) and the rust. In fact, it may be to your advantage to use the stuck piston to remove the liner.

[Gregted]

Originally Posted by Wotname

Thanks for the update - it is a stubborn bugger.

A couple of random thoughts -

If you plan to pull the engine, you may want to remove the flywheel to make it considerably lighter to handle. If so, then now is the time to remove the flywheel nut as the stuck piston will hold the crankshaft from turning making it significantly easier to apply torque to the flywheel nut. It will be tight!. It is torqued to 35 kgs or ~250 ftlbs.

If you fill the water jacket with something CLR to remove the boiler scale and rust on the cylinder liner, the whacking the conrod might remove the liner as well as the stuck piston. The only thing holding the liner in place (with the head remove) is the boiler scale (calcium carbonate) and the rust. In fact, it may be to your advantage to use the stuck piston to remove the liner.

Yep. It is pretty comfortable in it's bed atm but an eviction notice is in the mail

If it has to come out, the gearbox will definitely be removed but hadn't thought about the flywheel. That would certainly remove some weight.

Trying not to remove the liner if possible atm. The ideal goal is to get the piston moving and attempt a restart although I doubt we will get any compression with the exhaust seat in the state it is in.

Would be nice to have the cutter on the pic attached but that price is just for the one 45 Degree cutter, not the whole set. Then you need a guide rod and handle so not that cheap for one valve seat.

I can get a new valve seat welded in for $100 if it comes to that.

I bought a brass ball valve from Bunnings today and was planing on fitting it in the raw water line on the weekend but I have been informed that bronze is the preferred material.

Not sure how long the brass ball valve and copper pipe will hold up to the sea water. Pic included. Is it even worth fitting?

[Gregted]

Something that surprised me was that after I removed the conrod end, I still couldn't move the starting shaft or turn the motor over with the P.T.O. shaft pulley.

When I levered on the starting shaft with a set of stilsons, the motor still wouldn't budge but sounded like the starting shaft slipped a tooth inside the motor.

Might have to pull the P.T.O. pulley and have a look inside.

I would have thought if the piston is locking up the engine that after the conrod end was disengaged that would take the stuck piston out of the equation and allow the motor to turn over the last bit of the piston stroke.

Maybe it is at BDC but I thought it had a bit more travel. That could explain why we can't move the piston down any further.

Might have to concentrate more on upward movement...

[Compass790]

Sorry Gregted should have said get a plastic or nylon ball valve for your raw water inlet line. Much less troubleome than metal. Grizzled old boatbuilder told me that. He tells all his customers that when replacing skin fittings.
Whats the big end journal like? If its rusty that is a problem, needs to be polished to a high shine.
Bit surprised you couldnt move piston but yea 20 ton jack will if whacking doesnt.

[Compass790]

The starter shaft has a sprag bearing on it ( clutch bearing). Better to use pto shaft alright to try & turn it. It maybe the problem is in the gearbox thats stopping it from turning but you can take front engine cover off & look at the parts in there.
Study the diagrams in your workshop manual. With water in the oil you need to check your injector pump is moving as well.