I'm dropping a 603 in my w123 wagon. At least that's my intention. I've still got to pull the half a 617 out of the bay first and get rid of it. But while I've got the 603 in my garage I want to do as much serious preventative maintenance as I can before it goes into the car.

I've never owned a 603 before (I know, bold move). I've owned a 606 powered car and several 617s. So what work should I do before this thing goes in the engine bay?

It's a 603 from an 87 300TD, and yes it has a #14 head (and no, I don't have any budget to swap a new head). ~140k miles.

So far I'm planning on:

• water pump
• pulley tensioner/belt
• starter (came as a crushed one from donor car)
• valve cover gasket
• hot tanking and maybe painting the manifolds
• injectors

__________________
Onus probandi incumbit ei qui dicit, non ei qui negat

I recondition w123/w126/w124/w140/r107/r129/ steering boxes!


1984 300D "Elsa" odo reset 6/2011 147k
1983 300TD "Mitzi" ~268k OM603 powered
1995 E300 "Adelheid" 262k [Sold]

This Guy did it and posted a lot of really good pictures of the build... too bad it's in a different language.

Sladdprojekt W123 -83 OM603 Mynä. Nylackad och bromsad! - Sida 10 -


Even has some video....

https://www.youtube.com/watch?v=lmmqXeUBJGY

Even more... it's a beast...

https://www.youtube.com/watch?v=RZOxTlH3AVo

From my experience, replace the intake gasket... for that matter replace them all while it's out. Also, replace the front and rear main seals on the engine while it's out and easy to do. Check my 87 build thread, right after I got my engine in the car the front seal went... PITA. Pull valve cover and check the lifters. There is an updated design for them now. Focus on keeping that engine cool... that #14 will crack the first over heat. Good luck with the build, look forward to seeing it!

My #14 has been fine so far. Don't worry too much about it.

Check the vacuum pump.

Take the intake manifold off and replace the glow plugs, and clean as much crap out of the runners as possible. Disable EGR.

Consider sending injectors to Greazzer while they are easy to get at.

Upgrade to the plastic fan and new clutch.

Replace the temperature sensor with the lower temp version -- red top IIRC.

Thermostat. It's somewhat of a PITA in the car with small hands, next to impossible with larger hands, I imagine.

REPLACE THAT @&$% FLEX JOINT IN THE SPLIT MANIFOLD! Mine is leaking and I dread the job of getting that apart with the engine in the car...

__________________
RenaissanceMan Labs: where the future is being made today.

Garage:

2017 Chevy Colorado Diesel (nanny state emissions)
2005 Volvo S40 T5 AWD, 77k
1987 Mercedes-Benz 300D turbodiesel, 4 sp auto, 156k - 28.7 mpg
1996 Tracker 4x4, 2 door, 16v, 3 sp auto. 113k - 28.6 mpg

WARNING: this post may contain dangerous free thinking.

head gasket, new head bolts - really important for longevity of the head.

retorque prechamber retainers

check the turbo for radial and axial play

fuel preheating system

front and rear crank seal - prob not critical, but this is the best time.

reseal the IP - so much easier with the engine out and mani off.

__________________

I would do what is easy with the engine OUT. Change the bottom gasket of the IP, oil pan gasket and rear seal. May be the GP and clean rim the holes. The rest can be done with the engine in place so do them when something fails. I would not touch the rest unless you are planning an overhaul.

__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.

I'd give this a serious second thought. One hypothesis is retorquing head bolts can accelerate the progression of cracks. No reason to replace a #14 head that isn't showing symptoms, but similarly little reason to recondition and reinstall a #14 head that's off the engine.

Fresh set of injector line clips and rubber pads.

Make sure it has a later style vacuum pump. I have a couple available.

If you're going to do anything to the ALDA, do it while the intake manifold is off.

See if you can find a deal on a 603.971 (92-95 140 Diesel) exhaust manifold.

What are you doing for a transmission?

Sixto
83 300SD

I don't know how many of these heads I've taken off. - not like I've done it for 20 years in a shop though.

Often I have experienced that the bolts have a wide range of "de-torque' values. this is a mixture of the headgasket collapsing and the bolts losing plasticity in that range.

Primarily, the rear passenger bolts on the head will rust due to a failed HG at some point which will not be perceivable by visual inspection or testing of the coolant. this reduces the holding power of the bolts.

Fast forward, you now an have an aluminium head prone to cracking which is held against the block by uneven forces. then add high combustion pressures and heat. . . . well, uneven distribution of forces and internal stresses in the metal seem the most likely candidates for a cracked head, in my humble opinion.

__________________

Specifically, I did not suggest to "retorque the head bolts" on an old gasket.

I said to replace the head gasket (u new, uniform surface) and the headbolts then retorque.

__________________

Poor choice of words on my part. I meant any situation in which you release then reapply preload on the head.

Sixto
83 300SD

I do #14 head's all the time, have even welded a handful and they've all been fine. While, the best and preferred route is replacement with 17 and up heads, the welded ones have been doing fine (one has logged about 60k miles 5 years problem free, SO FAR lol).

Do absolutely as jt20 said and remove the head and use new head bolts with the updated gasket design if you intend on keeping the #14. You'll be doing yourself the favor as you'll be able to see cracking between valves / valves to prechamber while the head is off far forward of installing the motor. The cracks don't usually happen immediately either, they start to form primarily off the valve seats and work their way deep into the head. Catch it while you can.

See: W126: OM603 #14 Head-Ache, P.2 | Artisan

For pics of one I'm doing as I type this. This particular head has seen no overheating that the owner or previous owner has experienced, just 250k+ miles of heat cycles. The heads WILL crack, it's a porous cast. The late heads and especially the upside down #22's are absolutely fabulous compared to the #14's.


Reseal as much of the motor as you can. Don't waste time putting it into the car without front/rear mains, timing cover, pan gasket, etc. You've got a chance to do everything easily now, just get it over with. You'll thank yourself later.

Get a low temp tropical thermostat (special order from merc) and a 606 fan/clutch assembly if you have enough space to keep it. Otherwise a pair of 12" SPAL should be perfect.

Good luck.

__________________
Allen Kroliczek
Oak Grove Autosport | Oak Grove Autosport
01 G500, 82 300TD, quite a few more.....

its really hard to decipher all the anecdotes we have around here. So many factors are involved: did all those instances that you receive information from resurface the head and replace head bolts etc... when they re-installed?

hard to say. these factors could cause more problems than the previous condition if not all accounted for.

and I certainly would not doubt your experience on this matter. For piece of mind, the most straightforward solution I can suggest is bringing it back to ground zero. flat surfaces, an even gasket made with modern technology and new headbolts.

__________________

I have no plans at present to use a different exhaust manifold. Any reason I should?

I'll be using the 722 that was original to the donor car.

__________________
Onus probandi incumbit ei qui dicit, non ei qui negat

I recondition w123/w126/w124/w140/r107/r129/ steering boxes!


1984 300D "Elsa" odo reset 6/2011 147k
1983 300TD "Mitzi" ~268k OM603 powered
1995 E300 "Adelheid" 262k [Sold]

This seems quite unlikely. When you have bolts that are torqued as factory head bolts are there isn't any sudden, unexpected shift that would cause bolt "plasticity" to be "lost."

The Coefficient of Thermal Expansion differences in materials are already known long before anything makes it to the assembly line. If a failure was going to develop it would be because of a improperly cooled engine or due to lack of maintenance, neither of which I am concerned about on this engine. But those would cause other issues in most engines.

__________________
Onus probandi incumbit ei qui dicit, non ei qui negat

I recondition w123/w126/w124/w140/r107/r129/ steering boxes!


1984 300D "Elsa" odo reset 6/2011 147k
1983 300TD "Mitzi" ~268k OM603 powered
1995 E300 "Adelheid" 262k [Sold]

It depends on what you want to spend for preventative maintenance.

Oil pan gasket, not a bad idea, front seal, simple and cheap also, rear main seal, ... a little more work but well worth it to prevent leaks. A well-sealed engine is worth the effort. I'd replace the front seal in the transmission while it's out also, about a 10minute job with a small slide-hammer and hook on the end to extract the old seal.

If you're re-sealing the pan, pull the rear main and rod caps to look at the crank and bearings, wouldn't hurt to measure them to ensure you have a solid engine, replace oil-pump chain and sprocket bolt (have been a few failures), ensure that all is in good shape in there.

Timing chain, guides, and tensioner are also worth doing, and check to ensure at least a late-design vacuum pump.

Other suggestions here are good, I agree look at all IP seals, replace delivery-valve seals while it's apart, time the pump and make any adjustments while it's out. Depending on the size of the hole it's going into, the IP can be adjusted on the engine with the CC actuator removed.

The head gasket I'm not sure about, if you pull the head you have the opportunity to look at the condition of the bores, the head casting, and of course refresh the gaskets. This is however an additional day's work and $100+ for the gaskets.

Lots of "while you're at it", problem is that scope-creep comes in increments of $100s, best to stick with your plan and budget and decide what you do NOT want to find / deal with once the engine is in the hole, crank seals are on this list as they're easy and cheap when out, impossible when in the car, ... HG re-seal is slightly more difficult in the car but doable and the price is high, ... how well do you know this engine would be my decision point.

__________________

Gone to the dark side

- Jeff

Excuse me, I used the wrong terminology. Thats still no reason to throw away good food because you dont like the plate.

The bolts deform and do not provide the holding strength they once did. I have personal experience. You asked for help, I offered.


It appears you have much more specific agenda than that which you suggested in your original post:

"while I've got the 603 in my garage I want to do as much serious preventative maintenance as I can before it goes into the car."

this is serious maintenance. it is an issue. you have no clue how many stress cycles have occurred on this engine.

__________________