W124 Question - PeachParts Mercedes-Benz Forum

psaboic · #1 06-14-2021, 08:01 PM

Hi all,

My son has a line on a 1990 300D that he is looking at buying. He told me the car has 145,000 miles on it, runs well, and according to the owner it needs shocks and glow plugs.

Now I have been a W123 guy for 20 years, and do not know a ton about W124's. Since it has a 2.5 Turbo engine I would assume it is an OM602, correct? Now if I remember correctly, I heard in the past that changing the glow plugs on these is a royal PITA, and involves removing the intake manifold.

That said, if he does get it (asking price is $2500) I'm going to be doing a lot of the wrenching on it. Sooooo

Good deal or no? Anything particular to look out for? How hard are they to work on and are they reliable like a good old W123?

THanks for any and all help......the more answers the better.

Phillytwotank · #2 06-14-2021, 09:14 PM

Some have said they have been able to change the glow plugs with the manifold on. It’s really not that big of a job to get the manifold off and get tot he glow plugs easily imo.
Over the years of wrenching on benz I have come to the conclusion that if the work instructions say to take such and such off to get access to whatever... do it. Effort to do so < the effort to try to work arround such and such.

bkc · #3 06-14-2021, 09:23 PM

I love the 300D 2.5. It is indeed the om602.962. You can change the glowplugs fairly easily without removing the manifold, just be prepared that you will need different extensions, wobble, etc for each one, due to getting around things. As Phillytwotank said, though, it is quite straightforward to R&R the intake manifold, just need to replace the gasket as an additional cost.

shertex · #4 06-14-2021, 09:56 PM

I know my mechanic is able to replace glow plugs without removing the IM.

These are fabulous cars. If it has been well maintained, $2500 strikes me as very fair.

Recommend that you do the pressure wastegate conversion....it will save you a lot of headaches down the road.

psaboic · #5 06-14-2021, 11:57 PM

What is the pressure wastegate conversion....never heard it mentioned before.

300D85 · #6 06-15-2021, 12:18 AM

http://www.peachparts.com/shopforum/diesel-discussion/212097-wastegate-actuator-swap-om602-962-a.html

tjts1 · #7 06-15-2021, 12:58 AM

Quote:

Originally Posted by psaboic

Hi all,

My son has a line on a 1990 300D that he is looking at buying. He told me the car has 145,000 miles on it, runs well, and according to the owner it needs shocks and glow plugs.

Now I have been a W123 guy for 20 years, and do not know a ton about W124's. Since it has a 2.5 Turbo engine I would assume it is an OM602, correct? Now if I remember correctly, I heard in the past that changing the glow plugs on these is a royal PITA, and involves removing the intake manifold.

That said, if he does get it (asking price is $2500) I'm going to be doing a lot of the wrenching on it. Sooooo

Good deal or no? Anything particular to look out for? How hard are they to work on and are they reliable like a good old W123?

THanks for any and all help......the more answers the better.

Changing the GPs on the om602 really isn't that bad. It's the on606 with its pencil GPs you have to worry about. You do need to pull the intake manifold but if you can wrench on an OM617 you can wrench on an OM602. I wouldn't worry about it.

OM602 especially the 89+ is a great engine. If condition checks out I wouldn't hesitate to buy it.

Usaguy · #8 06-15-2021, 02:44 AM

Quote:

Originally Posted by tjts1

Changing the GPs on the om602 really isn't that bad. It's the on606 with its pencil GPs you have to worry about. You do need to pull the intake manifold but if you can wrench on an OM617 you can wrench on an OM602. I wouldn't worry about it.

OM602 especially the 89+ is a great engine. If condition checks out I wouldn't hesitate to buy it.

How did they improve the 602 in 89?

tjts1 · #9 06-15-2021, 02:51 AM

Quote:

Originally Posted by christuna

How did they improve the 602 in 89?

Mercedes diesel 89 thing when they introduced angled injectors, particulate filters, after glow etc.

Quote:

A second 124-series turbodiesel was put on display in September 1988 at the Paris Motor Show. The 250 D Turbo was powered by a turbocharged 2.5-litre OM 602 engine, the one also used in the compact class. However, the unit used in the 124 series was a modified version developing 93 kW (126 hp) at 4600 rpm; the top speed was around 195 km/h. The engine design was revised with the aim of improving the combustion process to reduce particulate emissions.
The most important means of achieving this was the use of a new prechamber featuring oblique fuel injection. This ensured more efficient combustion and also boosted output by 2.9 kW (4 hp). Together with the 250 D Turbo, the 300 D Turbo also had its three-litre engine revised. Finally, in 1989, in connection with the “Diesel ’89” initiative, the non-turbocharged diesel cars also were fitted with revised engines. The improved models gave off 40 percent less particulates than their predecessors and thus met the stringent US standards even without a particulate filter.
From October 1990 onwards, as an optional extra Mercedes-Benz additionally offered an emission control system featuring an oxidising catalytic converter and exhaust-gas recirculation. Initially an option for conventional diesel engines, it also became available for turbodiesels at the start of 1991.

https://media.daimler.com/marsMediaSite/instance/ko.xhtml?oid=9361301&filename=Diesel-engines-in-Mercedes-Benz-passenger-cars

Usaguy · #10 06-15-2021, 04:04 AM

Interesting article.

But for a 602 buyer the pre 89 602 is just as good as a post 89 602.

You're not gonna feel the 4hp difference on a turbo engine.

And while the lower emissions were important for mb it's not that important for an average old mb buyer. Unless you're concerned about emissions. But in that case you should probably choose a completely different car.

300D85 · #11 06-15-2021, 08:15 AM

https://www.youtube.com/watch?v=5Hr9irfd92o

https://www.youtube.com/results?search_query=+w124+e300+diesel+

https://www.youtube.com/results?search_query=w124+300d

https://www.youtube.com/results?search_query=w124

tjts1 · #12 06-15-2021, 08:37 AM

Quote:

Originally Posted by christuna

Interesting article.

But for a 602 buyer the pre 89 602 is just as good as a post 89 602.

Pre 89 the 602 turbo had the same design flaw as the 603 turbo with the #14 head. You just don't hear about it much around here because they didn't ship too many to the USA.

back-seat-driver · #13 06-15-2021, 10:34 AM

Recently changed out my glow plugs on my 91 250TD without removing the intake manifold.

Initially the last one (number 5) seemed impossible to remove. However with the right combination of patience, extensions, and sheer bloody mindedness*, I was able to change the last one.

*i'd just had an operation done on my left foot and was going nuts with the whole "lie in bed with your foot elevated" routine.

filp · #14 06-16-2021, 02:46 AM

Be mindful the 124 cars are rarely well maintained...,because there is a long delay until things start going bad.
Bought my car on the cheap and had to spend way more (x3) to get it to reliable daily condition, even though everything seemed fine when buying. It was daily driving that really made the parts yell for replacement. Of course every person has their own standard of what is acceptable condition to them, mine is on the higher end, but very far from concours

R.Diesel · #15 06-17-2021, 12:00 AM

I would say that they are as reliable as the old 617 save for the occasional head gasket. The interior parts holding up seem to be the biggest issue. They are better interstate cars.