is the 603 engine a sleeved block?or does a rebuild require boring and new oversize pistons?

Yes, the 603 is sleeved and crazy expensive to rebuild.

are the parts more expensive than normal or is it the labour involved?

About $1500 for the parts if using oversize pistons and boring for them. That is mostly for just the pistons and rings. About $3k is a good figure to use with the associated machine shop labor and the "other" parts. Maybe $4K if you are being thorough. The cost of pistons alone will set you back over a grand.
A resleave will cost more. Would still need to be bored to match the piston tolerances. Hard to get exited about reusing old pistons as they could too easily give out and you would have to start all over again.

603 Pistons are about $300 each (need 6) and the sleeves are about $70 each...
vs.
The 617.95x engine pistons are about $200 ea (need 5) and the sleeves are about $35 each.

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Over 21 years I owned several:
w108
w110
w111
w115
w116
w123
w124
w126
w212

Question: If you have the crankshaft turned, does this not make weaker bearing surfaces as the original heat treated bearing surface is removed from the turning?

If so, would it be worth renewing cylinder sleeves?

I'm in this same dilema as I am getting reday to rebuild my 603 engine. I have found piston sets for about $1200 and sleeves for $37 each. However I don't know if I need the pistons yet, even thought the car has 312k miles on it. The reason is that I have found that the head is brand new and it is possible that the bottom end had been rebuilt as well.

How can I determine if the pistons are new? I haven't had the head off yet, just took off the turbo, exhaust, and IP lines the other weekend.

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Michael LaFleur

'05 E320 CDI - 86,000 miles
'86 300SDL - 360,000 miles
'85 300SD - 150,000 miles (sold)
'89 190D - 120,000 miles (sold)
'85 300SD - 317,000 miles (sold)
'98 ML320 - 270,000 miles (sold)
'75 300D - 170,000 miles (sold)
'83 Harley Davidson FLTC (Broken again) :-(
'61 Plymouth Valiant - 60k mikes
2004 Papillon (Oliver)
2005 Tzitzu (Griffon)
2009 Welsh Corgi (Buba)

You can buy rebuilt 603 long blocks with a new head and rebuilt IP for $6k give or take. If you spend $4k on a good rebuild and another $2k on a new hed your still ahead with the long block because of the rebuilt IP.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Gee those are cheap pistons! The last set I priced was $2500!

Anyway, the only way to tell if the pistons are good is to measure and inspect them. If they are completely free of scuff marks and are the correct diameter, check the ring side clearance. If within spec, you can re-use them. Else, toss and replace.

Why are you rebuilding the engine? I would only work on it if it were seriously low on compression and a leakdown test indicated worn rings or if there were bearing noises, and you can rework the mains without removing the pistons. If you have serious oil consumption and blue smoke, check the turbo for a bad bearing FIRST, as it will blow copious oil both down the intake AND out the exhaust.

MB cranks have two regrind sizes. They are nitrided deep enough that you won't grind through it, and if you do, they can be re-nitrided and polished to size. You will not impair the quality. Not usually required unless someone ran it out of oil and seized it up.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

What about a good used engine? I keep hearing you can get good used 603's for $1,500-$2,000?

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

You can get a good used 603, I did!

If I had realized how much pistons cost new, I would have saved the 603 block I just took to the dump. I did pull one piston just to see the condition and it appeared to be in very good shape, same for the crank. But I needed the space!

Also, my 617 will likely be doomed too as I'm slowly tearing that down but will save the turbo, IP!

psfred is right. You won't know what you need until you disassemble, clean and measure. If it ain't broke don't fix it. I rebuilt my 617 from 2 engines because it had terrible blowby, wouldn't start and I loved the car. But it took a lot of time, cost about 2K and that was doing everything myself except boring and honing the sleeves and grinding the valves

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

thanks for all the great replies.i just purchased an 87 wagon with 310kkm.the engine is good low oil consumption and little blowby.but with the mileage i am concerned about longevity.i just love the way that engine runs and sounds!

Just keep it going! It is said that these engines can go a lot further with good maintenance.

Who know's, maybe you can go 2.+ million miles, just as the MB was reported this morning on CNN. The owner recieved a new MB free!

As for me, I'm rebuilding because I have a fist sized hole on each side of the block where the #6 connecting rod broke through. I have a replacement block sitting in my garage (with badly scored crank and no rods or pistons). Since the top end was rebuilt (replaced actually, with a #22 head), the bottom end may have been rebuilt as well. I may just need the replacement block, a connecting rod, bearing and seals.

__________________
Michael LaFleur

'05 E320 CDI - 86,000 miles
'86 300SDL - 360,000 miles
'85 300SD - 150,000 miles (sold)
'89 190D - 120,000 miles (sold)
'85 300SD - 317,000 miles (sold)
'98 ML320 - 270,000 miles (sold)
'75 300D - 170,000 miles (sold)
'83 Harley Davidson FLTC (Broken again) :-(
'61 Plymouth Valiant - 60k mikes
2004 Papillon (Oliver)
2005 Tzitzu (Griffon)
2009 Welsh Corgi (Buba)