Mercedes-Benz Forum banner

1 - 11 of 11 Posts

·
Registered
Joined
·
372 Posts
Discussion Starter #1
So with my current spending of gas every week, I've been considering buying a diesel Benz. Now I spotted a '87 300D Turbo with the 3L 6 cyl. TD engine and while looking up, I read about the weak heat resistance and that trap oxidizer which kinda scares me... so I figured perhaps you guys in the know could tell me if it's a good engine.

I also spotted a few W201's with the 2.5TD, OM602.

So which one is the better engine, the 603 or 602?
I'd rather the W124 because of the comfort and space but I could also live with a W201.
And anything to check on these cars/engines? I've never owned a diesel car before...
 

·
Registered
Joined
·
1,336 Posts
The 603 is the rarer of the 2 engines and the cylinder head is more prone to cracking. The 602 had a longer production run and I think the only potential issue was head gaskets...

Both cars require you to idle for ~30 s before shutdown so the turbo lubricating passages don't coke.

Though the 602 is more "utilitarian" it would be my first choice from a purely pragmatic standpoint.
 

·
Registered
Joined
·
372 Posts
Discussion Starter #3
There used to be a 2.5TD for sale but it seems to have gotten sold recently...

Does the 603 remain any good? It didn't seem to last long in production either. Only a year in the W124, which can't be good news. The guy does want about 4.5K for the car so it's not exactly cheap either. Or am I truly better off with the 602?
And from what you say, the 602 might also be more reliable than the 603?
 

·
Registered
Joined
·
1,336 Posts
The 603 is definitely a very good engine if the trap oxidizer issue was addressed early but due to the head cracking issue I would shy away from it. There is simply no way of knowing how the PO treated the car with regards to the special considerations that have to be followed with the TDs of that era.
 

·
Registered
Joined
·
1,336 Posts
Things to check for are condition of the vacuum pump (is it noisy), pull the glowplugs and check that there is no carbon buildup in the pre combustion chambers.

Also, your fuel cost savings will partially be offset by higher cost of basic maintenance as oil change intervals should be ~2500 miles (severe service) with Dino if you have a TD engine.
 

·
Registered
Joined
·
372 Posts
Discussion Starter #6
^ Thanks, I'll check that.
As for oil, is that the only maintenance interval that changes or does the car need much more regular service? And is that with regular oil or synthetic? (i.e, if it is synthetic, can I run it for 5000 0r 7000 miles between changes). I also guess that this is all TD engines, including the 602, correct?
 

·
Cruise Control
Joined
·
52,233 Posts
Both are great engines, but the 602 gets the nod due to the 603 head cracking issue. Although, some 603s go to 400k without a problem. Here in the states, the 602 didn't show up in the 124 until '90, so its a three year newer chassis, and one that includes a number of features and options that weren't available back in '87. As to the point about coking in the turbos; that's primarily an issue with gasser cars. Many MB turbos last the life of the engine, irrespective of the time the owner takes to let the engine idle before shutdown. I've observed that Mobil 1 will quiet down noisy lifters in these engines, but synthetic isn't a requirement. The vacuum pumps on both these engines are an issue, so I wouldn't take that lightly. If I were to purchase another of these engines, one of the first things I'd do is to preemptively remove the VP and determine its condition visually. Does it have the updated pump (external screws on the cover)? If no; replace. Does the injection timer ramp show wear? If yes; replace both the pump and timer.
 

·
Registered
Joined
·
285 Posts
Thoughts

My 603 has been...well, expensive. However, most of my cost have been my replacing things for preventative measures rather than because they malfunctioned. Today I replaced my Vacuum Pump (Old one developed crazy leak), and Fan Clutch. Recently I also redid the rear multi links. I could have gotten away with 2 on each side, but I did them all. Before that a starter and front crank shaft seal.

All this obviously added up to a pretty penny BUT, this was from years of fixing stuff ONLY when it broke (Previous owner). So I have been nursing it back to heath. Some of it has been frustrating and tiresome but all of these things are really not related to the 603 engine itself. I do have a #14 head which apparently is a time bomb. I knew this before I got the car so the first thing I did was check the cooling system. I initially had to replace a resistor so the electric fan would engage properly.

Now, I do not know tons about the 602 but there was one in the shop I go to (mostly for parts and advice) and there was a 1992 with a 602 in it and it was LOUD in comparison with my 603. I switched to Mobil 1 Truck Diesel Fully Synthetic 6 months ago and it quited down the chatter a lot. I am also pretty sure mine is a bit quicker with the extra 6th cylinder but I could be wrong.
 

·
Registered
Joined
·
1,336 Posts
There's also the 606 engine which is probably the most balanced MB diesel powerplant @ the time. The naturally aspired version was only in the 95 but they also used TD versions in subsequent E-classes.

If I could find one in decent shape the 606 would be my first choice.
 

·
Registered
Joined
·
372 Posts
Discussion Starter #11
Thanks a lot guys!

So I did see the 300D with the 603. Surprisingly, it is not as anemic as I thought it would be. Power was respectable. Car seemed in shape but the paint bugged. Interior was clean but I feel like the car was repainted and I can't help but not like that.. Minor rust. Mind you the car is supposed to have 210K KM or around (~131K miles), the car really showed it's 21 years. Suspension was soft and will need replacement, sunroof engine seemed tired too, transmission shifted roughly, etc. Car was a bit noisy but honestly, it wasn't as bad as the stories I heard of diesel engines.

So yeah, the car might be worth the trouble for 1, 500$ but not for 4, 450$ so I'm passing this one!

Thank you to everyone who helped here! I'll keep looking for a diesel Benz and hopefully find a good one soon... ....or take a bullet and get a Civic. Gas is raping me!
 
1 - 11 of 11 Posts
About this Discussion
10 Replies
5 Participants
Funky Mad
Mercedes-Benz Forum
BenzWorld.org forum is one of the largest Mercedes-Benz owner websites offering the most comprehensive collection of Mercedes-Benz information anywhere in the world. The site includes MB Forums, News, Galleries, Publications, Classifieds, Events and much more!
Full Forum Listing
Top