617 piston damage - Page 2 - PeachParts Mercedes-Benz Forum

mach0415 · #16 02-24-2011, 03:26 AM

Quote:

Originally Posted by layback40

Mark,
If you search for threads by konstan, you will find them. Maybe worth a PM to him, he can give you the lowdown on how the car is now going. He did complete set of rings & bearings.
If that bore would clean up & you could get some one on here to sell you a good piston, maybe you could get it going very cheap. Probably would be better replacing all rings & bearing shells.

Thanks. I sent a pm and am pouring over the thread. If one goes with a larger/smaller group number on only one piston, does that cause a balance issue? I know that VW diesels must have matched pistons.

Stretch · #17 02-24-2011, 03:31 AM

Quote:

Originally Posted by leathermang

MB Factory Shop Manual does not suggest that a bore can be ' cleaned up' .. and since it is easy to pull the sleeve and put a new one in...that should be the recommended procedure... the chances a used bore can be cleaned up to the extent that it would pass the MB specs for installing a new or used piston are very very slight... perhaps bordering on fantasy....

Hey leathermang

Having recently gone through this with my OM617 I was advised that it was not so easy to just pull the sleeve. Let me explain:- theoretically it is a simple procedure - you push out the old one and then push in the new - bore to the desired size, hone it and you're done.

However, if you damage the bore of the block when you remove the sleeve you can end up with a situation where you get pockets of air between the sleeve and the block. If this happens this will cause localised hot spots which will result in uneven heat distribution and more to the point uneven heat dissipation. In simple terms the bore will not wear evenly.

To avoid this situation I was told that it was necessary to bore out the old sleeve (whilst it is still in the block!) until most of its strength was gone, and then push it out. I assume a lip of metal is left at the end of the sleeve to left with the pushing. Freezing the new sleeve helps to prevent damage during installation. I've not seen it done - this is what I was told.

The story behind this was that with high Dutch labour rates it turned out to be cheaper not to replace the liners / sleeves in my engine, but to replace the (non turbo) pistons instead.

layback40 · #18 02-24-2011, 03:35 AM

The small difference between the 2 sizes will make little if any difference unless you are going to be using the car under extreme conditions. If you look at the allowed variation in compression & more over the variation seen in readings that people get from running cars, its not going to be much of an issue. Unless you expect to do 500k miles on the motor, its wont be an issue. With a quick fix, you will basically end up with a motor that has done the mileage that its done, not a reco motor.

mach0415 · #19 02-24-2011, 03:36 AM

Quote:

Originally Posted by layback40

I do agree with you leathermang.
It is always best to put things proper & right. If it was one of my machines that I make a living from I would be doing a rebuild.
Mark appears to want to get the car going reliably for as little $$ as possible. He doesnt appear to be wanting to do a full restoration or rebuild. That is why I have suggested that he may be lucky & get by with a hone / second hand piston / rings. He may be able to do that for under $200 in parts if he only rings that cylinder.
Heck its number 3, I suspect you could do it with out removing the motor from the car.
There is always a risk associated with that. He probably should inspect all 5 pistons out of the motor. I cant recall if he did a compression / leak down test. If the motor goes back together & runs ok, its a win !!

This is all correct. The engine is currently in the car as you said.

t walgamuth · #20 02-24-2011, 06:10 AM

I was assuming the OP wanted to try to do all this without removing the motor from the car. I don't know if the third piston can be removed without pulling it. I think it may be possible but I suspect it will be difficult with the main pan in place.

If the motor is pulled then it becomes much more acceptable to resleeve that one cylinder.

Of course if doing that it may make sense to go ahead while you are in there and do them all.

layback40 · #21 02-24-2011, 09:28 AM

Mark,
Your original intention to remove the pan turns out to have been a good idea.
Maybe some one can tune in & let us know if it is possible to undo the bolts on #3 rod bearing with only the pan off. If you can, I have never tried, then you may be able to just hone & replace that one piston without pulling the motor.
I have my fingers crossed !!!

Stretch · #22 02-24-2011, 09:33 AM

Quote:

Originally Posted by t walgamuth

I was assuming the OP wanted to try to do all this without removing the motor from the car. I don't know if the third piston can be removed without pulling it. I think it may be possible but I suspect it will be difficult with the main pan in place.

If the motor is pulled then it becomes much more acceptable to resleeve that one cylinder.

Of course if doing that it may make sense to go ahead while you are in there and do them all.

X2 on the upper oil pan.

I too think it is possible to remove the upper oil pan with the motor in place - although I'm not sure how easy it would be to get it nicely aligned when you put it back in.

Take a look here:-

OM617 Front crankshaft seal nightmare - should I re-align the upper oil pan?

I'm pretty sure my upper oil pan wasn't misaligned by Mercedes...

@layback40 - I've just seen your post!

I don't think you'll reach number 3 with just the lower pan out. I think you'd struggle with number 2...

layback40 · #23 02-24-2011, 09:37 AM

Quote:

Originally Posted by Army

X2 on the upper oil pan.

I too think it is possible to remove the upper oil pan with the motor in place - although I'm not sure how easy it would be to get it nicely aligned when you put it back in.

Take a look here:-

OM617 Front crankshaft seal nightmare - should I re-align the upper oil pan?

I'm pretty sure my upper oil pan wasn't misaligned by Mercedes...

@layback40 - I've just seen your post!

I don't think you'll reach number 3 with just the lower pan out. I think you'd struggle with number 2...

You dont still have your bottom pan off do you Army?
If the upper pan needs to come off, its an engine out of car job !!

Stretch · #24 02-24-2011, 09:41 AM

Quote:

Originally Posted by layback40

You dont still have your bottom pan off do you Army?
If the upper pan needs to come off, its an engine out of car job !!

You'll not believe it but I've actually got oil in the bloody thing!

I'll dig out some photographs - wait 1

Stretch · #25 02-24-2011, 09:51 AM

I do think you can get the upper oil pan off - you'd probably have to undo engine mounts and slightly lift the engine to clear the cross member that sits just behind the lower oil pan (so to speak). But like I say you'll have to be pretty good at aligning it to get it back on.

Anyway here is a picture of some sealing stuff - oh yeah and in the back ground you can see the position of the cylinders!

Please note - This is a non-turbo OM617 so the oil pump looks different!

But compare the position of this oil pump with the position of the cylinders when the upper oil pan is fitted.

mach0415 · #26 02-24-2011, 10:05 AM

Thanks for the pics on that. That settles it. If I am going to put money into this thing and also pull the engine, I wonder how cost effective it will be to repair vs replace with a good used, running engine?
I could then set this aside and eventually build it right over time after I sell this car to eventually put in my other 85 SD. Whatya think? I may just part this whole car out.

Stretch · #27 02-24-2011, 10:10 AM

Quote:

Originally Posted by mach0415

Thanks for the pics on that. That settles it. If I am going to put money into this thing and also pull the engine, I wonder how cost effective it will be to repair vs replace with a good used, running engine?
I could then set this aside and eventually build it right over time after I sell this car to eventually put in my other 85 SD. Whatya think? I may just part this whole car out.

I think if you are going to mess about with the upper oil pan you may as well pull out the whole engine.

A good second hand engine is always hard to find - there are many that are advertised as such... but I'm sure you can imagine how it goes... you need to find a reliable source with a reliable engine. That's a bit tricky.

barry123400 · #28 02-24-2011, 10:15 AM

Quote:

Originally Posted by Army

Hey leathermang

Having recently gone through this with my OM617 I was advised that it was not so easy to just pull the sleeve. Let me explain:- theoretically it is a simple procedure - you push out the old one and then push in the new - bore to the desired size, hone it and you're done.

However, if you damage the bore of the block when you remove the sleeve you can end up with a situation where you get pockets of air between the sleeve and the block. If this happens this will cause localised hot spots which will result in uneven heat distribution and more to the point uneven heat dissipation. In simple terms the bore will not wear evenly.

To avoid this situation I was told that it was necessary to bore out the old sleeve (whilst it is still in the block!) until most of its strength was gone, and then push it out. I assume a lip of metal is left at the end of the sleeve to left with the pushing. Freezing the new sleeve helps to prevent damage during installation. I've not seen it done - this is what I was told.

The story behind this was that with high Dutch labour rates it turned out to be cheaper not to replace the liners / sleeves in my engine, but to replace the (non turbo) pistons instead.

Check the old bores condition first. If it checks within the acceptable range just get a good used piston and rod or have your current rod checked out. you should be good to go from a mechanical perspective.

Rather than a resleve an overbore to the next piston size may be cheaper than a liner change if you can find an oversize single piston. Just machine some metal off to solve the pistons weight balance problem.

Any slight power increase will be insignifigant in my opinion. There are many reasons the piston may have failed. The engine must be checked for overfueling or advanced element timing of that cylinder compared to the others shortly after getting it up and running again. This could have caused the failure or is one area that can. The milli volt proceedure can do this.

Rather than machining liners to ease extraction. Running a small welding bead up the length of the liner will take a lot of the tension off and make them much easier to extract. A methology that has been used for almost forever on larger truck diesels to aid pressed in liner extraction. Certainly far more cost effective than machining the existing older liner down.

Generally speaking a good engine in a rotten or smashed body may be just as cheap to deal with as a replacement source. Thats if one can be sourced in your area at the right price. They are out there. Finding them is the issue.

I almost would expect some bore damage with that portion of the upper piston ring missing. Yet again you never know till you get the old piston out.

mach0415 · #29 02-24-2011, 10:17 AM

Quote:

Originally Posted by Army

I think if you are going to mess about with the upper oil pan you may as well pull out the whole engine.

A good second hand engine is always hard to find - there are many that are advertised as such... but I'm sure you can imagine how it goes... you need to find a reliable source with a reliable engine. That's a bit tricky.

At the same time I do not want to put a ton of money in this thing, as it is not my daily driver. It has a good body and interior...needs some paint, but is not too bad. Parting it out looks better and better. I wish I could get a feel of what I would need $$$ wise to put into it to determine where I go from here...decisions decisions.

Stretch · #30 02-24-2011, 10:20 AM

Quote:

Originally Posted by barry123400

...
Rather than machining liners to ease extraction. Running a small welding bead up the length of the liner will take a lot of the tension off and make them much easier to extract. A methology that has been used for almost forever on larger truck diesels to aid liner extraction. Certainly far more cost effective than machining the existing older liner down...

Great bit of information - thanks for that.