85 300D wetted parts

[Graham]

Is there a place somewhere on the net that lists the materials that parts of our cars are made from?

In particular, on my 85 300D cooling system, what are the wetted parts made from. Rad, pump, block, head, heater core, etc.

[84-300dee]

Not sure of a material source, but having put my hands on all of the above I would say:

Radiator- Aluminum and Thermoplastic

Water Pump- Cast Iron Body/Mild Steel Impeller and Shaft

Block/Head- Cast Iron

Heater and Evaporator Core- Aluminum

[BillGrissom]

I agree w/ post #1. I recall that water pumps can have an impellor made of cast steel/iron, plastic, or sheet-metal. Heater plumbing is a steel tube and rubber hose. Don't forget the steel head gasket, since they can corrode. Also, the plastic reservoir runs at the coolant pressure, which doesn't give me confidence though it doesn't get as hot as the plastic in the radiator.

We all wonder why you ask. Perhaps choosing a coolant?

[84-300dee]

Get the green stuff out if that's what your running. That and lack of changes by the PO is what killed my TD prior to me getting it. (Cracked head due to overheat). Had fancy wheels though! More rust than coolant in the system, blown heater core too.

Use only MB coolant or Zerex G-05 (what I use)

There is a lot of aluminum parts in the system like the tstat housing and coolant hose flanges/piping. Even some copper in the tstat itself. Potential for all kinds of dissimilar metal corrosive action.

[uberwasser]

Metal compatibility is, by the way, only part of the reason to only use MB coolant or Zerex G-05. Zerex is also the only off-the-shelf coolant I know (i.e. available at your local auto parts store) that has the cavitation protection needed for the diesel engines.

[Graham]

Originally Posted by BillGrissom

We all wonder why you ask. Perhaps choosing a coolant?

I didn't really want to get into another coolant discussion (I know that was wishful thinking ) I was really just hoping to find an on-line source that lists the actual materials used in the cooling system for different models.

For example, the M117 engine that I have in my '72 107 has gone through various iterations, including cast iron and aluminum blocks in later versions. Perhaps same thing has happened with the W123s?

We often talk in general terms when our cars may be quite different.

Regarding getting rid of that green stuff. I was thinking about it and that started me thinking and prompted this thread.

Mind you, I have had both 107 and 123 for 25+ years and they have always used green coolant. Never a coolant problem on 300D (430k km). Did notice some pitting on tstat housing on 107 (looked like erosion) but otherwise good (160k miles). There are of course many types of coolant that are green. More to it than color. I imagine our W123s used something equivalent to green ethylene glycol based coolants when new.

By the way, I read that the current MB coolant is not same as G05. It is now blue-dyed HOAT (Hybrid Organic Acid Technology) G48, Part Number
BQ 103 0004 and is good for 15 years in cars that have a little top up silica bag. Another odd thing. The blue G48 and the yellow G05 are compatible. But when you mix them, the resulting mixture is green!

[BillGrissom]

If the concern is avoiding corrosion, you can't do better than the Evans Waterless Coolant I put in both my 300D's. Downside is cost ($42/gal), though never needs changing so probably a wash in the long run. Other downside is less heat-moving ability (specific heat), though seems to be enough since my cars don't appear to run any hotter. You won't have the issue of corrosion reducing flow in the future. The main limit on heat removal is probably in the radiator-to-air interface anyway. Upside is less worry about losing your heater core and other expensive and hard to replace parts (head gasket, ...).