What does it mean when the engine block does not have a serial number stamped on it? This is regarding a 617.951 that appears to be a replacement motor on a '82 300SD because it has a couple of later model year parts on it.

The engine does not have the "Original Mercedes-Benz Tauschaggregat" tag found here in this thread for rebuilt motors. mystery 617: "Original Mercedes-Benz Tauschaggregat" = Replacement motor?

And where the serial number usually is (located behind the oil filter housing, on a flat surface on the block just below the head), the area looks like a factory casting with no evidence of it being ground off.

So am I looking at a possible "New" factory replacement motor? The other thing to note is upon looking down into the oil fill cap, the cam still has the machined ribs on the lobes given the car has over 300,000 miles on the odometer.


Any opinions?


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__________________
1983 123.133 California
- GreaseCar Veg System

May be - just may be it is a block built under license in another country????? (Wild guess - if you can't see a serial number anywhere else)

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

This is what I’ve found on this subject but nothing directly related to the 617 but with the OM603.97 3.5L engine found on the 350SD/SDL rod bender. There have been posts that people have purchased their cars second hand and also found that their engine with no serial # at the factory locations. Some respondents have concluded that these engines are factory new replacements given they came with the # 22 head. Some new motors had a tag at the bellhousing to indicate the new serial number while others reported they did not have such a thing. Some other folks received rebuilt units for factory replacement 3.5L engines. They could tell from the MB remanufactured plate attached to the side of the block.

Again if somebody has some information on this subject, it would be interesting to hear.
The other thing would probably find the servicing dealership of the car and ask for the service history which should tell for sure if any factory replacement was done. But some dealerships are not that willing to do so just out of the whim and the challenge is if you don't know the history of the car, then where is the servicing dealership as in the case of this car in questioned?





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__________________
1983 123.133 California
- GreaseCar Veg System

Yes dealer it is if that Russian database still is not working...

In my 38 years with MB, the only way to get an engine W/Out a number is by replacing either the short block OR "block fitted with pistons" with new MB parts!

__________________
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MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

Thanks for your response to the thread. I assume your answer is for new factory short blocks. And would that include new long blocks?

Also if the engine was a factory rebuilt, would they grind off the original serial number on the block.


Thanks again.

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__________________
1983 123.133 California
- GreaseCar Veg System

That's interesting. I bought a 350SDL with ~250,000 miles on the odometer, minimal wear to the interior indicating to me that it is likely correct mileage, and no numbers on the block except for a bar-code sticker on the top of the bell-housing flange on the engine.

This engine had a #22 head, but the cylinders and pistons showed some scuffing, so I assumed it is an original block, ... maybe not?

I've never seen visible wear in cylinders on a 603.96x with these miles, can't imagine that this was a recent new engine.

__________________

Gone to the dark side

- Jeff

Only on new only! only new short blocks or new bare blocks fitted w/ pistons.

All MB reman units were given their own number.
MB never offered a NEW long block for those cars.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

Didn't the original engine (starting around the mid-'80s) get a VIN sticker like the major body panels?

__________________

Gone to the dark side

- Jeff

What I've read is any 603.97x without a stamped identification number by the injection pump is not the original block.

I know for the 603.97x motors is it is not uncommon for it to be burning oil at less then 100,000 miles on the clock. So the cylinder wear you are seeing is not surprising in my view. You were probably looking at the beginning of the motor's demise.



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__________________
1983 123.133 California
- GreaseCar Veg System

Its demise was coming into my garage with a #22 head, now the block's just in the way. No cast-in numbers anywhere, just the VIN sticker on the back.

Amazing the difference in cylinder wear between identical mileage 603.96x and .970 engines.

__________________

Gone to the dark side

- Jeff