Rush of blood to the head....

[James W]

With a typically stupid rush of blood to the head, I lost my patience when I couldn't separate the cylinder block and piston on the MD1B on the boat today. I need to get the block into the shed to clean out the cooling channels but the sod decided to stick itself fast, leaving me with a piston half out of the block, still attached to the crankshaft below.

So......not wanting to admit defeat, I applied some (a lot of) leverage in the form of a rather large bit of wood, and eventually the block pulled clear.

There are two problems now (apart from my ongoing blatant stupidity):

1.) There is a small dent in the base of the piston where it hit the crankcase in the melee (obviously will need filing down but surely not terminal?)
2.) The large bit of wood splintered slightly and despite having covered the hole with a rag, some splinters escaped into the crankcase.

So, in short, have I completed shagged the engine or are these old lumps able to take a bit of strong in arm and thick in head mechanics?

Thanks.

 

[Seajet]

Not sure what you mean by a dent in the base of the piston, but going by what I hope is the gist I think you'll get away with it.

 

[CAPTAIN FANTASTIC]

The piston can be smoothed out with a fine file and fine emery cloth; so not a problem, however, bits of wood in the crankcase could be a problem. I would pick the bits out as much as possible then flash out and repeat as many times as possible. When all together start the engine and then empty oil, flash, check for bits of wood in the oil; take a view whether you need to flash out again; replace the oil filter

 

[James W]

Not sure what you mean by a dent in the base of the piston, but going by what I hope is the gist I think you'll get away with it.

It's just a small ding in the skirt really, but i'll be taking the piston off to examine closely for any cracks as soon as possible.

I know it's a bit late now, but i'm more worried about the effects of the leverage on the small end and big end bearings.

Very foolish behaviour.

 

[James W]

The piston can be smoothed out with a fine file and fine emery cloth; so not a problem, however, bits of wood in the crankcase could be a problem. I would pick the bits out as much as possible then flash out and repeat as many times as possible. When all together start the engine and then empty oil, flash, check for bits of wood in the oil; take a view whether you need to flash out again; replace the oil filter

Thanks for that, very good point. What would you recommend to flush the engine?

 

[VicS]

The coarse oil strainer should prevent any bits of wood being drawn ino the lubrication system. It will be as well to check/clean it after running for a bit.

 

[VicS]

Thanks for that, very good point. What would you recommend to flush the engine?

cheap engine oil

 

[James W]

cheap engine oil

Thanks Vic.

With all the help and advice on this forum, I will get this old engine running, and running well. So help me god!

 

[Avocet]

Check that the piston hasn't gone slightly oval during it's ordeal. As has been said, the dent can probably be filed out, but check the whole thing still sits nicely in the bore before reassembly.

 

[TQA]

It is an MD1B. Think agricultural mowing device not F1 mover.

File it smooth and if the piston goes back in the bore without squeaking it will most likely be fine.

Remove any visible LUMPS of wood. Ignore minor splinters.

An oil change after a few minutes running can do no harm but it is more for your peace of mind than the engines benefit.

 

[rob2]

Yes, you've a very good chance that it'll be OK. Mic around the skirt of the damaged piston to ensure it's sufficiently round to still work and smooth away the damaged area. Probably a good idea to check the rings are still free, too. I doubt you're puny human efforts put anything like the force of a diesel detonation on the bearings! Luckily the flywheel on these engines are pretty massive, so I shouldn't think any imbalance from the loss of material on the piston will show.

If you can drop the sump in situ, it would make cleaning any wooden debris much easier and you'd start with a really clean system.

Rob.

 

[Daydream believer]

Thanks for that, very good point. What would you recommend to flush the engine?

Castrol solvent flushing oil

 

[Daydream believer]

The initial problem suggests wear in the bore. The piston presumably slid up & down its normal stroke area but jammed when you tried to pull it past an unworn section of the cylinder. A bore gauge will demonstrate this but you may be able to feel the point with a finger. It may be however, that carbon deposits had built up & you will be able to clean these off
To replace the cylinder you will probably need to push the piston in from the top using a ring clamp to compress the rings .
Then you will need to re connect the con rod to the crankshaft
To do that you need the sump off, so I would expect that you need to remove the full engine on to a bench
I have never tried pushing the piston up from the bottom of the block & I suspect that you may damage the oil rings ( as opposed to compression rings) when you re assemble, although it may be that the block has tapered skirts to allow this
Removing the sump will solve the chips of wood issue
You have not said why you wanted to remove the block but in any event that is a major job - or a bit more savage than just changing the filters!!!- so I would have thought it a good idea to get the whole lot out of the boat. You may even consider a recon etc whilst you are at it

 

[VicS]

Yes, you've a very good chance that it'll be OK. Mic around the skirt of the damaged piston to ensure it's sufficiently round to still work and smooth away the damaged area. Probably a good idea to check the rings are still free, too. I doubt you're puny human efforts put anything like the force of a diesel detonation on the bearings! Luckily the flywheel on these engines are pretty massive, so I shouldn't think any imbalance from the loss of material on the piston will show.

If you can drop the sump in situ, it would make cleaning any wooden debris much easier and you'd start with a really clean system.

Rob.

Drop the sump ???? Not familiar with the design of the MD1B then!

If accessible remove the crankcase side cover plate and clean out the "sump" perhaps #11 :

 

[savageseadog]

I've used Kerosene to wash an engine out, central heating oil. Take care to re-lubricate, ie hand turn the engine with oil in before trying start.

 

[rob2]

Drop the sump ???? Not familiar with the design of the MD1B then!

Quite right, I have never owned a Volvo Penta or even worked on one! The general principle would have been good though. As the sump is apparently integral, a more apropriate option may be to hoover around with a Pela pump as well as flushing through.

Rob.

 

[Heckler]

It's just a small ding in the skirt really, but i'll be taking the piston off to examine closely for any cracks as soon as possible.

I know it's a bit late now, but i'm more worried about the effects of the leverage on the small end and big end bearings.

Very foolish behaviour.

Dont worry about it! Think of the pressures inside the combustion chamber when that fuel ignites! The ding on the piston, dress it up with a fine file. Check the piston and gudgeon pin are square to the con rod, I have straightened con rods in situe before now! The wood, pick it out as best you can, drop the oil, see what you can see in the crank case.
Stu

 

[chrishelen]

Just a small point, but I would remove the piston from the con rod before I were to file or sand out the dink.

 

[essexboy]

Just a point on " measure piston for roundness" pistons are not round, they have a built in out of round and are round when hot !

 

[James W]

Great stuff, thanks to all that answered and continue to answer. It's great to have the benefit of everyone's experience.

Much happier now that all will be well.....but I still won't be doing it again in a hurry!