617 overhaul - PeachParts Mercedes-Benz Forum

PanzerSD · #1 10-13-2007, 01:14 AM

If I tear down my 617, what are the odds that my 400+k engine would need new pistons?

I may have posted a similar thread in the past....

#2 10-13-2007, 05:30 AM

Pretty good chance that the ring grooves are past the reusable limit.

t walgamuth · #3 10-13-2007, 05:41 AM

In tearing down mb engines I have been able to reuse about three out of four times, but none of my engines have had nearly that many miles on them.

I would say small chance.

Tom W

Stevo · #4 10-13-2007, 12:03 PM

Quote:

Originally Posted by PanzerSD

If I tear down my 617, what are the odds that my 400+k engine would need new pistons?

I would replace the pistons with HALF that millage. With the compression ratio of these engines the pistons take a hell of a beating and to go too all the work and expense of a rebuild and not replace the pistons would, IMO, be a waste of time and $.

bgkast · #5 10-13-2007, 03:07 PM

Quote:

Originally Posted by PanzerSD

If I tear down my 617, what are the odds that my 400+k engine would need new pistons?

KM or MI?

Hatterasguy · #6 10-13-2007, 04:20 PM

If it runs good why tear it down?

Whiskeydan · #7 10-13-2007, 05:22 PM

Quote:

Originally Posted by t walgamuth

In tearing down mb engines I have been able to reuse about three out of four times, but none of my engines have had nearly that many miles on them.

I would say small chance.

Tom W

Tom, Did you replace the sleeves in each case? If so, what's involved?

Also, Anyone have a good 617.951 piston? I may need one depending on what I find...

Chris Bell · #8 10-13-2007, 06:49 PM

Quote:

Originally Posted by PanzerSD

If I tear down my 617, what are the odds that my 400+k engine would need new pistons?

I may have posted a similar thread in the past....

If your gonna go through all the trouble of tearing down the motor you might as well replace the pistons, cylinder liners and rings, see links below. For approximately $1,840.00 you get new cylinder liners, new pistons and new rings.

Chris Bell · #9 10-13-2007, 06:52 PM

Quote:

Originally Posted by Stevo

I would replace the pistons with HALF that millage. With the compression ratio of these engines the pistons take a hell of a beating and to go too all the work and expense of a rebuild and not replace the pistons would, IMO, be a waste of time and $.

^^^ What he said. Is it really a rebuild if you don't replace the pistons, rings, & sleeves?

t walgamuth · #10 10-13-2007, 07:49 PM

Quote:

Originally Posted by Whiskeydan

Tom, Did you replace the sleeves in each case? If so, what's involved?

Also, Anyone have a good 617.951 piston? I may need one depending on what I find...

We have resleeved in every case except my 280e which did not need it. (only 140K). The proceedure is to have my favorite machinist measure the lands and if they meet the factory tolerances we reuse them. If not we have found a set of used ones that will work from my various spare motors with a rod hanging out the side. So far we have never bought new pistons for any of my benzes.

(I have a set of four 240 pistons that are reusable for sale on parts.)

If the factory bothers to take time to establish go/ no go dimensions why waste money buying new parts? Just buying the ones that are actually needed is expensive enough.

We don't spare the attention, either. He trues the block (they twist), and bores true to the crank line, then fits the sleeves to match the pistons. Of course we do valves, guides and springs as necessary. Chains as needed and guides (always). Oil pump gets new gears as needed too.

Although the 280 motor only had 140K on it the oil pump gears looked rough and I bought new ones. One came from Texas and the other from Germany. it turns out there are at least three styles of oil pump on the 280 motors.

Tom W.

Whiskeydan · #11 10-14-2007, 11:55 AM

Tom, Have you ever had to turn a crank? I see undersize brngs available but have always heard it's a not a good thing to do on these engines.

Also, can you explain the block twist? I'm afraid I will have a difficult time finding a machine shop around here qualified to do my work. Maybe if I describe the twist to them and see if I get the 'blank look' I'll know to go elsewhere.

PanzerSD · #12 10-14-2007, 05:17 PM

Quote:

Originally Posted by Whiskeydan

Tom, Have you ever had to turn a crank? I see undersize brngs available but have always heard it's a not a good thing to do on these engines.

Also, can you explain the block twist? I'm afraid I will have a difficult time finding a machine shop around here qualified to do my work. Maybe if I describe the twist to them and see if I get the 'blank look' I'll know to go elsewhere.

IIRC Mercedes uses some special hardening technique on cam and crankshafts and grinding the crank or cam takes off that layer of hardened material and serverely shortens the life of the part.

and the twist is one of the special features of owning an inline engine.

Use the term "align honing" or "align boring" and you won't see those blank looks.

t walgamuth · #13 10-14-2007, 05:23 PM

we turned the first crank. i have not heard about not turning them from what i think is a sure source (sorry).

actuallt align boring is related to the crank bearings, i think....usually not needed on a mb. truing the block is decking.

tom w