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  #1  
Old 01-23-2008, 03:04 PM
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How good are the OM602 2.5 liter turbo engines?

There are tons of posts about how reliable the 61X series engines are and lots of posts about what to look out for on the 603 series engines, but hardly anybody talks about the 602 series.

What is the story on the 602 engines especially the turbo version? I have a line on a 1987 300D 2.5T and I have no idea on how these cars and the engine stacks up to a 617 powered 300SD or a 603 powered 300SDL. Do they have overheating issues? lubrication problems? anything?

Are the W124's as good as the W126's? (I know I've opened up a can of worms here!)

HELP

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  #2  
Old 01-23-2008, 04:33 PM
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Great car

I have all three cars as you can see by my signature line. The 92 300D 2.5 is the best of them all in my opinion. Better handling...and almost as smooth a ride as the 300SDL but it is quieter and gets 8 mpg better than either the 300SD or the 300SDL. It has 210k miles and I have had no motor problems at all.
The only significant repair I have made to the car is replacement of the evaporator and that was a pretty tough 20 hour job (look it up here in the forum).
My only question is are you sure that it is an 87? The 87 300D's only came with the 6 cylinder 603 in the USA. 300Ds with the 2.5 602 were sold in the USA in 90,91,92 and 93
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  #3  
Old 01-23-2008, 05:18 PM
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Depends on how large a boat you want to anchor. It might be a little lighter.
Actually the 2.5s seem to enjoy a fairly good reputation. Much superior to the 3 litre engines of the period. Given a choice there is no contest in my mind. No chronic expensive problems that I personally am aware of. I still do not know how hard the glow plugs are to change when thats required.
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  #4  
Old 01-23-2008, 05:30 PM
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OK, in the same area of questioning, can anyone give a comparison of 2.5 to the 3.0 in the 124 car?

An 87 model with a 603 compared to a 90 model with a 602. The cars would have to be virtually identical, so exactly how do the two motors compare in virtually identical cars?

Jeff
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  #5  
Old 01-23-2008, 07:20 PM
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the 603 makes around 25hp more and 35 ft/lb more than the 602.

The 603 seems to have problems with cracked heads and the 602 doesn't.

They are basically the same engine, but the 602 just has a cylinder chopped off. I also think that the 602 gets slightly better fuel economy.
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  #6  
Old 01-23-2008, 07:35 PM
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The 603 IMO has problems if overheated, with the head cracking. The manual shows an improved head gasket to fix early gasket problems with oil leaks and coolant leaks, same with the 602.

If you don't overheat the 603, it'll treat you fine. Plenty of them around with 300,000+ miles and original head.

The 602 engine is great also, the only significant difference being the later car's electronic boost (wastegate) control, which opens in the absence of vacuum, some have backdated to the earlier system which defaults to closed wastegate. Look for a lack of boost on '90s 300D cars.

I'd take either one. The later car has nicer interior panels and some nicer features along with the plastic lower-body panels to update it, the earlier more power. So far I've stuck with the '87 for the power, but if the right one comes along I do miss the interior of my '91, I'll buy another.
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  #7  
Old 01-24-2008, 12:12 AM
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Quote:
Originally Posted by hughet View Post
My only question is are you sure that it is an 87? The 87 300D's only came with the 6 cylinder 603 in the USA. 300Ds with the 2.5 602 were sold in the USA in 90,91,92 and 93
Maybe it's an 87 190D 2.5t. Rare beast.

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  #8  
Old 01-24-2008, 07:34 AM
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Sorry... it is a 1993 300D. I am looking at so many cars to replace my 300SD that I got confused.

I have seen some 190D 2.5 NA cars, but only one with the turbo. I was bastardized with a gasser instrument cluster and other things that made me run away

Speaking of the 2.5 NA... how does that stack up? I think it only has 73 Hp so I havenot really looked at any 190D's with that engine. Anybody with a 190d 2.5 5 speed? How do they drive? I am looking for something to take on the highway so I don't want a car that is a slow as a 240 D


Thanks for the help
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  #9  
Old 01-24-2008, 07:51 AM
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The 190D 2.5NA 5-speed is as fast as a turbo 82-85 300D and gets much better economy. My used car boss owned one and it was very fun to drive on the few occasions I got the chance to do so.
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  #10  
Old 01-24-2008, 08:14 AM
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Quote:
Originally Posted by ForcedInduction View Post
The 190D 2.5NA 5-speed is as fast as a turbo 82-85 300D and gets much better economy. My used car boss owned one and it was very fun to drive on the few occasions I got the chance to do so.

Cool, they are now back on the list! Did you drive long distance in them? I do 330 miles one way each weekend. I know I can't do that in the BMW without feeling like I was in a fight with Mike Tyson. I have driven a 190e for short distances, but how are they (190 class) on long trips?
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  #11  
Old 01-24-2008, 08:46 AM
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Quote:
Originally Posted by LUVMBDiesels View Post
Speaking of the 2.5 NA... how does that stack up? I think it only has 73 Hp so I havenot really looked at any 190D's with that engine. Anybody with a 190d 2.5 5 speed? How do they drive? I am looking for something to take on the highway so I don't want a car that is a slow as a 240 D
The non-turbo 2.5 has around 90HP IIRC, I drove a 190 2.5 5 speed for around 5 years as a daily driver. It was a rocket ship compared to a 240D and it would routinely deliver 36-38 MPG on the open road. The 201 chassis is a bit cramped, especially for taller driver (like over six feet tall) - I currently have a 91 300D 2.5 turbo and its a much more comfortable long distance highway car. It consistently returns 34-36 MPG on the highway.
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  #12  
Old 01-24-2008, 08:55 AM
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I would be careful of the 190d's with the NA 2.5 if you want too much speed. Of course mine was an Automatic. But it was very slow off the line. I had to up shift on hills most of the time. But it was a nice little car.

The 87 300d w/603 Turbo I have now is a dream to drive. I can't picture a better MB to have or other car for that matter. The newer stuff may have more power but this thing's easier to work on and purely mechanical in function. I like it!
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  #13  
Old 01-24-2008, 11:32 AM
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602.962 2.5 Turbos

- Similar reliabilty to the 616/617
- Less maintenance than 616/617 (no valve adjustment)
- Same power as 617 turbo, quicker due to less weight
- Quieter and less smoke
- 37 mpg

Only thing is the 2.5 turbos appear to be very rare in the US.
IIRC only 12,000?

More:
W124 diesels, the good, bad and the ugly?
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  #14  
Old 01-26-2008, 09:12 PM
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Quote:
Originally Posted by TimFreeh View Post
The non-turbo 2.5 has around 90HP IIRC, I drove a 190 2.5 5 speed for around 5 years as a daily driver. It was a rocket ship compared to a 240D and it would routinely deliver 36-38 MPG on the open road. The 201 chassis is a bit cramped, especially for taller driver (like over six feet tall) - I currently have a 91 300D 2.5 turbo and its a much more comfortable long distance highway car. It consistently returns 34-36 MPG on the highway.
Good info. Couple questions for anyone with knowledge:


1 - Anybody have a link to a list that shows the HP and torque ratings for each of the engines, in a list?


And 2 - Will the 5-speed that comes mated to the 2.5 NA bolt directly on to the 2.5 turbo version?


Thanks to anyone who knows.

Jeff
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  #15  
Old 01-26-2008, 09:16 PM
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Or for that matter, how about the 5-speed that comes on the 601 4cyl (in the 190D). Will that bolt-up to a 2.5 turbo?

Thanks

Jeff

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