Well I just finished talking with my mechanic. I asked him to put new rings and seals, gaskets and whatever ells needed. Today he told me that I need new pistons. I dont understand this, because the engine runs fine in the summer. In the winter it will start hard, and thats the winter. Can it be the pistons are that bad? Never have problems in the summer, and it never blows smoke from the exhaust, except when I floor it. I am unhappy because this will cost a lot of money. Can anyone tell me what a set of pistons with rings might cost? Thank you for your time and help. -Nick

Many times when rebuilding an engine new pistons are needed. Your old ones must be worn around the edges or somewhere on them. Pistons do wear, so not, it is not uncommon to replace the pistons when doing this work. Someone else with more experience may chime in here and disagree. If someone does, listen to them.

Thanks
David

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2000 Honda Accord V6 137k miles

1972 300SEL 4.5 98k miles

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With only 156K on the clock, you have a right to be skeptical.

Ask the mechanic why he wants to change the pistons. Report back on exactly what he says. Write it down so you get it perfect.

There are good reasons to change pistons, and there are good reasons to keep them. I have not priced them lately for the turbo engine, but, with the exchange rate the way it is, I would not be surprised if a set runs close to $750.00

He must provide specific info on what is not within spec. This usually is related to the ring grooves.

Report back with what he says.

I wonder why you need the engine work, just because its hard to start in the winter? Is the compression low? It's possible a new set of rings would raise compression if that is low, but are the cylinders in good shape? There are those who reuse pistons and those the refuse to. A lot of mechanics say the metal gets fatigued and material is brittle.
I can understand why you are not happy "Piston Set 90.90mm w/rings $945
I went with new pistons on a total engine rebuild (cylinders bored first oversize) because I planned to keep the car and because I needed pistons to match the new bore. The other approach was to replace the liners with std size and reuse the pistons but replace only the rings. I was advised that the latter approach was less reliable. Going on 2 years later and the engine is excellent, it burns no oil, no smoke and starts with a flick of the key.

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!

most of the engines i have rebuilt we (the mb diesels) used the old pistons. the exception is if the piston has excessive wear on the sides or if the lands (the ring grooves) are worn too much. i would ask him why new ones are needed. he should be able to tell you what the acceptable specs are and what your pistons measure. the factory lists go no go specs. i usuallly play it a little safe if it is within say 30% of the no go dimension.

it seems that the new pistons are from 50 to $75 ea. not sure though. it is a significant expense but one not to shirk if the specs are not met.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Not for the turbo engine. They were a bit over $100. each, but, now, with the exchange rate, they are above $150.

My mechanic told me that they are worn out. I asked originaly to just replace the rings and seals, gaskets and what not. The engine leaks oil like hell. I already took the engine out of both my cars. I just was paying him to do any replacements and to plug the enigne back in, because I have no time to finish it myself. He was charging me $600 for the labor not including cost of rings and seals etc.. I think $600 for labor is fair enough. After he told me about my pistons I just felt horrible. I really love this car and want to keep it for a long long time. I am not changing my decision on rebuilding. Only now I have to have patience. I dont make much money in a month. I was not planing on new pistons. So now I must wait longer to build up some savings. This will take about a month and a half.

Yes I felt the engine needed a valve job and new seals and gaskets. Also new engine shocks/mounts. Anything worn I woudl replace. It's just now this piston deilemma is hurting me..

$150 Each!

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Dear "Mechanic":

Could you kindly explain to me exactly what is "worn out" on the piston. What have you measured (please show me the data) and what is not within specification? This will help me to understand why we need to change pistons.
Thank you.

This cost is conservative....
After many, many diesel rebuilds I would do the following :

Install new liners and ask the machine shop to clearance the cylinders to each numbered piston.

Piston wear will vary slightly and 0.0005" larger clearance than factory is safer, if in doubt.
My machine shop bores STD liners to 0.0007" piston wall clearance for new pistons.....

On a turbo, I increase this to 0.001".
The turbo pistons are tough and as long as the engine has not been subject to thermal overload, used pistons in new liners will work.

You can increase your engine compression pressure and reduce blow by if you use Total Seal Rings. If you buy a STD ring set, Total Seal will machine your second groove rings for you.

I have over 30 engines running on Total Seal rings and some are well over 100,000 miles now.

The Total Seal difference is this..1993....customer had a Nissan diesel car....engine old and hard to start....I installed Total Seal rings and set of gaskets....customer moved to Columbus Ohio....first winter there he calls me....he's so proud he's the only diesel on his street running after a night of 20 inches of snow.....without plugging in block heater.

And no, I have no affiliation or re numeration from Total Seal.
They tell me another company makes something similar with an 'overlapping ends' type second ring.

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I have tested compression pressures on these rings and most pump over 500 psi at sea level ( Injectors and glow plugs not installed. )

The only problem is, you need to be very clean and careful when installing these rings...you will need the 'ratchet' type ring compressor to close these up prior to install....whatever anyone tells you, do not install piston/ring assembly dry. Use Rotella 15W40 and run 100 to 150 miles non-stop to break them in. Do not let the engine idle for over 5 minutes before driving it.

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[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ]

"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."

Where are you getting turbo diesel engine pistons for $50-$75/ea.

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Jim

I did a complete rebuild on my 82 and finished about a year ago. I spent $675 for a complete set of Mahle pistons and rings. I'm sure it's quite a bit more now. The area that will most likely necessitate new pistons is oversize ring land widths on both compression grooves. If only the top groove is over, you could use a ring set made by Deves that has wider top rings to compensate. If the second groove is too big, I think you are out of luck. On the pus side, a properly rebuilt engine really runs great. And starts on the first glow at -2F without a block heater.

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

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

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

Yeah ! Inquiring minds wanna know .




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[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ]

"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."

Friends in the Parts department getting a five finger discount.

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Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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Section 609 MVAC Certified
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"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

It was clearly just a guess. Probably right on the money, in 1983.