Hi
For all those who took an interest in my old 85 300 SD non turbo, i' ve moved here to Diesel Discussion after being told off by one of the members. Sorry about that.

My first sunday where i was able to really take a hard look at the engine and do an oil change, i spotted four main areas which are serious and need fixing. Would really appreciate any tips or direction to existing material links

1. Main shaft bearing oil seal, which is flingin oil onto the fan belt inner side

2. Water pump bearing. Do you change a water pump bearing or the whole thing?

3. Gear shift, which is an absolute bugger. You practically need Houdini skills to get from 2 to 3 gear. Would really like to replace the whole thing but if there is a repair which can be done, i' all ears.

4. Steering. Feels a little heavy. Should i be thinking about flushing out all the ATF and replacing with with power steering fluid? How are the power steering units on these old w126s? Are they normally quite heavy by today's standards?


A big thanks in advance for those who are kind enough to give me some help here.

And for those curious about its history, it was a luxury taxi which has got 650,000 kms on the clock.


cheers

MJ in Morocco

No idea who told you off, there are nicer ways to suggest moving to the DD subforum. This is definitely the right subforum for talking about diesels though, there's quite a brain trust in here and the guys who know everything rarely venture to the other subforums.

1: You'll need to replace the front main oil seal. I'm not well versed on the 617's in that area, so you'll need to wait for one of the 617 guys to fill you in on the details.

2: Change the pump. It isn't worth messing with just the bearing. Buy a Graf or Laso pump with a cast impeller. It'll last you another 30 years.

3: I assume this is a manual? If so, you need to rebuild all the shift bushings. MB gear shifters never had a great feeling from the factory and a worn out one is simply HORRIBLE to drive. There are aftermarket kits to replace the rubber bushings with Delrin plastic and is said to greatly improve the shifting experience. If you search this forum, there is a writeup on how to rebuild the shifter, including pictures (assuming they weren't hosted externally and now gone).

4: The heavy feeling is normal for a W126. It shouldn't be set in concrete, but it should still require a bit of effort. If coming from a modern car, it would be easy to think something were wrong. Just keep an eye on the fluid. If it's murky and brown, change multiple times until it runs clear. ATF was the original fluid and is what should go back in it. There's a filter in the bottom of the reservoir that probably needs changing too.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Thanks so much for your help.

My engine is actually a 603, not a 617. Don't know if that makes any difference to changing the seal

For the power steering, is it correct to assume that the fluid is constanlty circulating?

thanks again




QUOTE=Diseasel300;4115361]No idea who told you off, there are nicer ways to suggest moving to the DD subforum. This is definitely the right subforum for talking about diesels though, there's quite a brain trust in here and the guys who know everything rarely venture to the other subforums.

1: You'll need to replace the front main oil seal. I'm not well versed on the 617's in that area, so you'll need to wait for one of the 617 guys to fill you in on the details.

2: Change the pump. It isn't worth messing with just the bearing. Buy a Graf or Laso pump with a cast impeller. It'll last you another 30 years.

3: I assume this is a manual? If so, you need to rebuild all the shift bushings. MB gear shifters never had a great feeling from the factory and a worn out one is simply HORRIBLE to drive. There are aftermarket kits to replace the rubber bushings with Delrin plastic and is said to greatly improve the shifting experience. If you search this forum, there is a writeup on how to rebuild the shifter, including pictures (assuming they weren't hosted externally and now gone).

4: The heavy feeling is normal for a W126. It shouldn't be set in concrete, but it should still require a bit of effort. If coming from a modern car, it would be easy to think something were wrong. Just keep an eye on the fluid. If it's murky and brown, change multiple times until it runs clear. ATF was the original fluid and is what should go back in it. There's a filter in the bottom of the reservoir that probably needs changing too.[/QUOTE]

Found this thread here for the front main seal replacement on a 603
http://www.peachparts.com/shopforum/diesel-discussion/167759-603-front-main-seal.html

Embedded in this thread is a link to the online MB service manuals for the 126 and 603.
If that link is dead this one is still good. It's for the 124 but it has the 603 engine manuals in there.
http://www.w124-zone.com/downloads/MB%20CD/W124/Main.html

Beware on the water pumps, don't get a Chinese one or you will be doing it again in a few months.

The steering on these is the old school recirculating ball system with a steering gear box. It is not like the newer models (starting with the W210) that went to a steering rack like on all modern cars. There are threads on here about rebuilding the steering gear box. A fluid change is definitely indicated. Easiest way to do this is pull the return (low pressure) hose off the reservoir, stick it in a container, and feed fluid into the pump reservoir. *DO NOT* let the pump cavitate (run dry) or it will be damaged. Have a helper turn the wheel back and forth with with their other hand on the key to kill the engine if you can't get the fluid in fast enough.

Tip for this forum (since we appear to be stuck in 2003 or so with this software, are del.icio.us and StumbleUpon even a thing anymore??), click the Search up in the title bar and then in the window that appears use the Advanced Search, it is much better.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Changing the front main seal on a 603 is a bit of an undertaking. The flywheel must be locked with locking tools (available on eBay) and the front crank pulley removed. The through-bolt is extremely tight, something like 300nm, you will need a very long cheater handle to break it loose and a very large torque wrench to reinstall it properly. Be aware that the 603's are known to wear a groove in the pulley hub where the seal rides. If you have a groove in your hub then the new seal will need to be mounted slightly further back in the bore, or a speedi-sleeve installed on the hub to give a new surface for the seal to ride on if you wish to avoid leaks with the new seal.

Fluid does constantly circulate in the power steering system. It works like any other hydraulic power steering system, there's just that extra filter in the reservoir that many other makes don't have.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Agree with the above and in my experience 617 is even worse because you have to get the dowel pins right and stuff

When you lock the crankshaft then put the balancer at tdc so that the keyway will be pointing up.

anyway the locking tool is ~$36 shipped (for those of you that live in the us):

https://www.ebay.com/itm/JTC-MERCEDES-BENZ-FLYWHEEL-LOCKING-TOOL-M102-M103-601589024000-JTC-4732/182765731036?hash=item2a8dafbcdc:g:YAkAAOSwvTBZuvrF

thats great. I'm enormously grateful. But after reading all the comments about the main bearing oil seal, i can't help feeling there must be a way to reduce the leaking. I wonder what the shade tree solution is. I don't have specialised tools and it sounds an absolute bugger getting out the main bearing. Probably this was the main reason why the taxi company sold the old girl. Too much work.

Teh water pump has to be done though. no question although that also invoves removing the serpantine belt and then retensioning.

I will for sure download those manuals.

cheers

MJ

There's no shortcut on a leaking main seal. You either live with the leak or you fix it properly. The leak is due to hardening of the rubber and wear from use. There's nothing you'll do to slow that leak that lasts for more than a trip around the block.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

The only thing that will permanently slow down a leak is to run thicker oil.

But that's not a real solution to the problem and the right thing to do is to just fix the seal.

15W-40 is already heavy oil (assuming he's running the correct oil in the engine). If it's slinging oil from the shaft/seal interface, anything thinner than roofing tar is going to continue to sling from the shaft/seal.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

i was thinking of trying single grade 40 oil, in fact, for that very reason

don't do it.

it's the same as 15w-40 when hot.

And when cold it will be too thick and could damage your engine. I think the thickest single grade oil that mb recommends is 30 weight.

find some diesel rated 20w-50 or 15w-50. the latter number is the hot viscosity.

But as we said before it's not a real fix and you will still have a leak.

Other things that make oil leaks worse: plugged pcv system or a hot running engine

Lucas makes an additive (and some 'high mileage' oils have it too) that might slow down the leak by reinvigorating the brittle seal.....obviosly better to replace it but maybe throw a quart of the lucas stuff in there and see?

LUCAS 11100 ENGINE OIL STOP LEAK HIGH MILEAGE TOP OFF ADDITIVE 1 QT 049807111007

__________________
0o==o0

James 4:8

"...let us put aside the blindness of mind of those who can conceive of nothing higher than what is known through the senses"
-Saint Gregory Palamas, ---Discourse on the Holy Transfiguration of Our Lord God and Savior Jesus Christ


Centrally located in North East Central Pa.

Subscribed .

Trust those here who have done a particular repair .

LUCAS snake oil isn't going to help and you may ru8n the entire engine by not fixing this properly .

If you're not comfortable doing this job, farm it out and have the shop replace the water pump at the same time .As mentioned, do not use nor allow to be installed, a Chinese water pump ! .

ASK FOR THE BOX IT COMES IN .

As a retired Journeyman Mechanic I always appreciated the few Customers who took the time to clean the engine before delivering the vehicle for repair ~ no one likes to swim in oil and that's what's required to properly clean and old, leaky engine before fixing the leaks .

it usually takes several passes before it's anywhere near clean, I wear a pair of overalls with nothing in the pockets and no trousers underneath because by the time I'm done I'm always covered in old oil degreaser and road/engine grime from head to toe .

Good luck with it and keep us posted .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

The w116 and w126 Diesels were export to North America cars only. The '85 came with the OM617 and was only available as automatic.

So it would appear that your car was refitted with the 603 and Manual trans by a previous owner.

__________________
'83 SD, 2x '85 SD
You are entitled to your own opinions, you are not entitled to your own facts.