Turbo Failure after 200 miles

I recently purchased a rebuilt turbo for my 1986 300SDL.

I had my certified mercedes mechanic remove hte old and install the new.

The previous turbo has seized.

As is required a new oil line was installed, and oil pump checked for proper operation.

While drive on the freeway at 70mph, the turbo failed. I immediately drove to my mechanic. There was a "rattling" noice coming from the turbo. After the turbo cooled he removed it. Upon inspection he found the inner shaft to have been snapped in two. There was no smell of burnt oil, there was a large amount of oil inside the turbo, and when the engine was cranked a proper amount of oil flowed from the oil line.

When the rebuilder recieved the turbo, he pointed the finger at the car and the mechanic, saying that either the mechanic installed it improperly ie: didnt use new oil line or the oil pump was not working properly. That the lack of oil was the only reason a failure as mentioned above could have occured. He stated this was further established as the break in the "shaft" was exactly at the point oil came into the turbo.
(not sure what,if anything, this has to do with it, but he said it did).

My problem as you can see if that I am caught in the middle here, and havent a clue what to believe. My mechanic stood to make more money if he stated my oil pump need to be replaced, but stands firm that it is operating properly and is strong. He says the "shaft" was faulty or the turbo wasnt rebuilt properly.

The Turbo rebuilder says if he has to replace the turbo this time, he will NOT warranty it further (not sure he can legally do this if the car was an is operating under proper spec's).

I dont want the turbo to fail again, and am not sure what to do here. Do I replace an oil pump my mechanic says if functioning properly just to appease the turbo rebuilder?

Can anyone offer me some advice? Has anyone had this problem? Anyone familiar with the inner workings of turbos?

Thanks,
Chris

The turbo can fail either way (shaft failure or loss of oil pressure) What happened to your first turbo?? Also what was your oil pressure at the time they both failed?

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Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
LEAD TECHNICIAN FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

My mechanic's shop is closed at the moment, so, I am not sure what the oil pressure was, only that my mechanic (Mercedes certified) said it was with-in spec's, and was NOT the cause of the turbo failure either time. I can only assume he is telling me the truth.

The first turbo completely seized.

A mechanic friend of mine says it was because the turbo was never allowed it to cool off before it was shut down, and that my quick off the line before the turbo was warm didnt help either (never knew these things till now), thus the oil crystalized and accumulated over the years till the turbo (which had an easy life before I got it)seized.

My mechanic says that if the oil pressure was as low as it would have had been not to lubricate the turbo, that there most likely would have been resulting damage to me engine as well. And actually now that I think about it that is what the Turbo Rebuilder guy said, that I was lucky that the first one seized, because that helped save the engine, and that since my oil pressure must be SO LOW (according to him) that severe engine damage will occur (yet, it runs fine).

Just so I know before I speak with my mechanic, what should the oil pressure be on a 1986 300SDL?

As you can see I am just trying to educate myself here, as either of them can say whatever they want, and I am clueless. I want to be able to decipher what is fact from double talk if I can.

Thanks,
Chris

At idle when warm, The oil pressure should be at least a bar. When driving, right off of idle it should go to the 3bar limit and stay there. When the oil pump or the shaft go, The turbo is the first to dye. These engines are known for oil pump failure. Also I have seen bolts fall into the oil pan from the windage tray and get sucked right through the screen to the oil pump pick up and into the pump. When that happened it killed the pump.
And yep the turbo went south.

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Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
LEAD TECHNICIAN FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

I have heard about the above failure from
several of my friends. I repeat what I said
a few days ago: Diesels from 86+ are just
not the dependable well engineered cars that
is the case with the 220D, 240D, 300D, and
the 300SD. It bothers me badly that I can-
not update in the future with a diesel that
will LIKELY be dependable from MB. I talk
to too many people who have the newer diesels;they are having unnecessary problems!

Benzmac - What is Mercedes doing about the oil intake screen mesh size, or an oil intake screen, if there is not one there?
Is Mercedes aware that they have a problem.
Is there an aftermarket modification that could eliminate the problem of sucking such large debris into the oil pump?

What actually happened was, the screen held the bolt back for many 1000's of miles then eventually the back and forth rubbing action allowed the bolt to cut a hole in the screen and enter the pump: KILLING THE ENGINE! It wasn't a problem with the pump or the pickup but with the bolt that did not have loc-tite on it from the factory and fell into the pan. The last one I took apart had 4 bolts that had come loose, but it only takes one to kill it!

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Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
LEAD TECHNICIAN FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM