Piston Rings & Main Bearings

[Titan1995]

This is a follow on question to my previous post.

I have pretty well determined that I have a piston/ring failure on #03 cylinder
.
I am toying with removing the cylinder head [again] and checking this out.

My dilemma is that I cannot raise the Bongo high enough to drop the engine out and therefore would have to do the work in situation.

This would be working on the premise that the bores are fine but there is a piston and or rings failure.

In and ideal world I would drop the engine and rebuild the bottom end.

Is it possible to replace the main bearings with the crank in situation and auto gearbox attached?

[rita]

HI, What makes you think that the Crankshaft Main Bearing journals/shells are damaged.

[ELZE]

HI, What makes you think that the Crankshaft Main Bearing journals/shells are damaged.

They are probably not damaged but if he is intending to remove the piston from the bottom end, then the shell casings will be removed anyway in the process and of course it is always better to renew them all at that time. Thats my experience.

The thing that threw me was if he is doing this then why does he need the head off?

[rita]

HI, What makes you think that the Crankshaft Main Bearing journals/shells are damaged.

They are probably not damaged but if he is intending to remove the piston from the bottom end, then the shell casings will be removed anyway in the process and of course it is always better to renew them all at that time. Thats my experience.

The thing that threw me was if he is doing this then why does he need the head off?

He suspects that the Piston/Rings are knackered. You need the head off to perform this operation. And to check for internal cylinder and head damage.

[ELZE]

HI, What makes you think that the Crankshaft Main Bearing journals/shells are damaged.

They are probably not damaged but if he is intending to remove the piston from the bottom end, then the shell casings will be removed anyway in the process and of course it is always better to renew them all at that time. Thats my experience.

The thing that threw me was if he is doing this then why does he need the head off?

He suspects that the Piston/Rings are knackered. You need the head off to perform this operation. And to check for internal cylinder and head damage.

I gather he already had it off some time previously and unless it was a catastrophic failure then it should be OK. Pistons with the rings can be extracted from below by removing the conrod and gudgeon pin then positioning the crank to get the piston out but if unsure of the whole problem then a full strip would be the way to go and could not argue with your comment.

[BigPanzer]

Hi,

Purely a personal opinion, but I would take the engine out, even if it means paying somebody to do it.

I have removed and replaced a piston once working from underneath (Ford Kent engine) because I thought it would be easier than taking the engine out but it was almost certainly not the easy option.

Peter

[Titan1995]

Hi all thanks for the responses.

I was only asking about the main bearings in that I would want to replace them at the same time as the big ends and piston/ rings.

The head would obviously have to come off to facilitate the piston/rings replacement.

It really is only an issue of height that is stopping me dropping the lump out.

I am looking at a replacement short engine fitment now.

[ELZE]

Hi all thanks for the responses.

I was only asking about the main bearings in that I would want to replace them at the same time as the big ends and piston/ rings.

The head would obviously have to come off to facilitate the piston/rings replacement.

It really is only an issue of height that is stopping me dropping the lump out.

I am looking at a replacement short engine fitment now.

That's what I thought!

[helen&tony]

Hi
Out of pure interest, as I may buy a spare engine, has anyone got an idea what a quality rebuild engine would cost...that being a new head with all new parts, with rebored block, new pistons, reground re-hardened crank, and the whole caboodle balanced?....
Cheers
Helen

[teenmal]

Hi all thanks for the responses.

I was only asking about the main bearings in that I would want to replace them at the same time as the big ends and piston/ rings.

The head would obviously have to come off to facilitate the piston/rings replacement.

It really is only an issue of height that is stopping me dropping the lump out.

I am looking at a replacement short engine fitment now.

This can be done with most engines, you remove the journal cap and insert an appropriate rod through the journal oil hole, locate the hole in the upper shell and rotate the shaft towards the notch on the shell until you can pull it out.

PS make sure you rotate towards the notch.

Good Luck.

[Titan1995]

I was unsure as to whether the rear main bearing cap was part of any other other assembly as is the case in some engines, eg rear main oil seal housing which precludes removal with the gearbox attached.

So very very saddened with this failure. Bores looked fine when I replaced the head .

No history of oil consumption or poor performance in the 16,000 miles since replacement.

Only possible indication was an engine rattle that I could not traces.

Too light to be mains or big ends, guess it was the piston/rings starting to fail .

I live in Wraysbury and was flooded out in Feb. The Bongo on 18" wheels proved our saviour wading through well over 18 inches of water.

Even had to wade to it to make a cup of tea onboard when the kitchen was flooded in the house.

So I think "Boris" deserves a new lump at least.

[dave_aber]

How on earth do you remove and refit a piston / conrod past a crank that is still in place?

With the box fitted, you can't remove the crank, so surely can't get the piston out, never mind get a ring compressor in there to refit the piston & rod?

[ELZE]

Trust me it is possible. Many have done it including myself. I also remember in the early days it was demonstrated in Haynes manuals. The piston will not pass the crank with the conrod attached but comes out enough to tap the pin out. with the conrod detached the piston will extract further when you turn the crank to BDC giving the clearance needed to remove it. don't take my word for it ask an old mechanic. Obviously not done nowadays as it's often cheaper to just replace with a short engine. .

[dave_aber]

Neat - I would never have thought that was possible.

Refitting mus be a right fiddle!

[ELZE]

Well I never said it was easy and it is fiddley but weighing it against removing some engines might be the better choice depending on what time you have to send on it and how fit you are to remove and engine and/or roll around a floor.

Probably better to have a replacement engine installed, sit back and watch the footy.