" bought one from a wrecked 300D....and bought a car to boot."--Carrameow

I think that is great.... now you can rebuild this one with no time pressure.

leathermang .....
I agree with you. However you do have a choice. As I mentioned you can just just replace rings under the right conditions.
As for the pistons ...did you red this in the manual...
-The piston top is covered with an aluminum oxide coating.
-The piston skirt and the top land are graphite treated.
That means no scraping , brushing, scratching,

I never follow the rules.
I make new ones ........

__________________
2003 SLK 230 (85000)
1999 E300 Turbo Diesel (388,000)
1991 350SD Turbo Diesel (185,000)

There is a man down near Austin that is tearing the hair out of his head......................

If there is significant wear in the cylinder you will not be able to see the old cross hatch, it is worn away. I have seen this in many cylinders.

You can probably get a machine shop to stick the micrometers in the cylinders for free 'cause they want your business. If you can find an engine that is not worn-out and that has a reliable service history you save big money.

That is correct......Most engines there is no cross hatch visible at all. And there is a significant ridge as well. There just worn out..... 90 percent of the time they need to be bored oversize. In some cases after a 30 over bore the ridge will still be present. In that case it needs to be cut away or it will break a new ring as soon as you start it.

"The function of crosshatching is to aid in the seating (wearing in ) of the new rings”

This statement is partly true. If you read my previous post carefully ...... As I previously stated, it is the rings that have a coating for break-in so the cylinders need to be a very smooth finish
Honing the cylinders will achieve the smoothest surface possible.
An engine that still has a crosshatch visible with no ridge or very little, would be a good candidate to just replace the rings. That all I’m saying…… Ok so use a little “Sctoch-brite” and make your own rule…
The hone will tear, fold, and rip the bore finish if not done correctly causing premature failure.
Synthetic oils will not allow the rings to seat so you can only use dino oil for break-in.

"If you can find an engine that is not worn-out and that has a reliable service history you save big money."
Thats all I'm sayin dude ....................

__________________
2003 SLK 230 (85000)
1999 E300 Turbo Diesel (388,000)
1991 350SD Turbo Diesel (185,000)

Anthony, the more you post the more it looks like your experience has been with American gas engines as compared to our 617 diesels...

Crosshatching does not provide the "smoothest surface possible". The walls need to be rough with a cross-hatch to seat new rings. Polishing will provide the smoothest finish, and NO ONE polishes cylinder walls to install new rings. If the walls are polished, it doesn't matter what rings you use, they will never seat. Perhaps the only exception to this would be in the manufacture of a NEW engine where the cylinders can be specified perfectly round, and chrome rings can be used for long life. But I'm not sure about that.

__________________
'83 240D with 617.952 and 2.88
'01 VW Beetle TDI
'05 Jeep Liberty CRD
'89 Toyota 4x4, needs 2L-T
'78 280Z with L28ET - 12.86@110
Oil Burner Kartel #35

http://i16.photobucket.com/albums/b1...oD/bioclip.jpg

OLD300D, You are absolutely correct... the statement by Cerami "The hone will tear, fold, and rip the bore finish if not done correctly " is actually close to the Advertizement which goes with the wire abrasive hones... the idea IS to tear the wall (in a controlled fashion )...and the combo of that and the crisp surface on the edge of the new rings Wear in together...
If you start out with a smooth bore it will never seat the rings...
I have known other people who thought they made their own rules... they would do things like install rain gutters without regard to slanting them downhill... and would spend the summer wondering why there were mosquitoes buzzing around their head all summer.

Is anyone aware of a piston that has fractured after extended use in a 617? I would be interested in a situation where the pistons were reused after an overhaul and did not go the distance.[/QUOTE]


Yes, I have in my boxful of mechanical memorabilia, a piston from my 240D with ring land failure and other cracking. It came out of the original engine after 380,000 miles.

There are a number of people who have posted on this forum over the years that they have reused pistons in a resleeved engine, but I personally feel that it's not worth the risk after seeing that piston. If you are dealing with a standard bore engine, you can bore the original sleeve oversize and replace the pistons. The pistons will indeed be an added significant cost, but the machine shop bill will be less since they will simply bore the block, rather than replace the sleeves and then bore to fit.

A piston in a diesel engine lives a really tough life. Rather than a CR in the area of 8 to 10 to 1, you are dealing with a CR of 18 to 22 to 1. In addition to that the diesel piston deals with IMPACT pressure rather than the relatively gradual pressure increase of a proper running gas engine. You can hear that impact pressure. It's heard as diesel knock.

My $0.02,

Hey, I've met Tony and he knows his stuff. Like me he is also an engineer You got a problem with America there Tex??

__________________
Bill Reimels
Now down to one:
1972 300SE 3.5 W109 (Euro delivery)

OLD300D, You are absolutely correct...I agree. I have rebuilt many engines in the past This process is critical. After you hone a cylinder check it out with a high migification eye loupe. Youll see what I mean.
Ok so now that we beat this to death..... Who is gonna help pay for this sleeve , bore, hone job.?

__________________
2003 SLK 230 (85000)
1999 E300 Turbo Diesel (388,000)
1991 350SD Turbo Diesel (185,000)

Lol, not me Henny Penny.

__________________
'83 240D with 617.952 and 2.88
'01 VW Beetle TDI
'05 Jeep Liberty CRD
'89 Toyota 4x4, needs 2L-T
'78 280Z with L28ET - 12.86@110
Oil Burner Kartel #35

http://i16.photobucket.com/albums/b1...oD/bioclip.jpg

LOL.......
Ok no problem ...Im speaking to the grop.
Ok my shop is available ...Hoist, Engine stand....etc
Carrameow Is a stone throw from me ...............Lets do this ......

__________________
2003 SLK 230 (85000)
1999 E300 Turbo Diesel (388,000)
1991 350SD Turbo Diesel (185,000)

You guys with all this talk of new pistons, weather to re sleeve or re ring, has got me thinking about rebuilding the 616 I have on the stand. I bought new O/C pistons and had new sleeves bored too fit on the one I did last. Like someone has already said, "something nice can always be found to put it in" Anyway It seems new pistons would be a good idea if your gona do all the work of a rebuild, not a huge expense with a non turbo.

Lots of good input in this thread, Thanks

__________________


1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

Billrei, Earlier today you said "I guess I will try some Trans-X snake oil at some point and see what happens."

Since the concept of dissolving Varnish built up in the tiny holes in a transmission is very simple....and that is all the Trans-X is proffered to do... and since as far back as 1975 it has worked for me , sometimes dramatically, your " vouching for " Anthony is suspect.

I will put up my position with regards to what Anthony said using logic and references from accepted sources...

My first point is that the Factory Shop Manual is not for putting the engine together WHEN NEW...

It is for rebuilding....... and since it is for rebuilding.. the very specific specifications which are listed are meant for making the determination as to whether one needs new pistons or not. And the cost of Turbo Pistons is not a small matter when building an engine.

I notice that those suggesting using new pistons ( without regard to whether they pass the specifications listed in the manual ) don't suggest that one take apart an engine when it reaches a certain mileage.... If they were really worried about some etherial ' stress' which can't be measured... and certainly we have not had a swelling of posts saying that their ' old' pistons fell apart...I would remember that and we would have spent a lot of bandwidth on it...