Expansion tank cap pressure

[The Warden]

Hello! I've been needing to replace my metal coolant tank cap for a while now. I suppose I can't call it a radiator cap, as it doesn't sit on my radiator. When ordering my hazard light switch, I decided to also get the cap from Fastlane. However, on getting it, I noticed that it had a 124 part number, and is rated at 1.4 bars. Is this correct for a 617 engine, or can damage ensue? I had thought that a 1.2 bar cap was appropiate for this setup...

Thanks!

That is correct, it is the updated cap. I thought it was a little odd too, when I replaced mine a few months ago, but was told it is the updated cap.

[The Warden]

Okay, cool...was I right though, that the original cap was rated at 1.2 bars? If so, I presume the cooling system can handle the extra pressure?

Ehh, I needed to flush the system and replace the upper and lower radiator hoses anyways

I think you are right about the original cap being rated at 1.2 bars. Tbe cooling system should be able to handle the extra pressure.
It would be a good idea to flush out your cooling system, that is something I need to do sometime the spring or summer.

[rickjordan]

I went through a similar thing, with regard to "updated" parts. When I ordered a new Star for the hood, the one I received had a 201 part number (190 series) and the round base was a tad smaller than the original. As it turns out MB says this is the offical replacement part for the 123 series hood ornament. If anyone replaces their expansion tank will go throught the same thing. I replaced the one in my father's 123 sedan and the new one had a hole in the side that required buying a plug for it. This hole would be for a coolant level sensor, in another car like a W126. I am guessing as these cars "mature", that this will become common place.

The updated part that I like the most, is the starter. I just replaced my starter witht the updated model, and it starts up so fast. I always thought since it was a diesel that it would crank and start slow when cold. I was wrong

[The Warden]

Originally posted by 123c
The updated part that I like the most, is the starter. I just replaced my starter witht the updated model, and it starts up so fast. I always thought since it was a diesel that it would crank and start slow when cold. I was wrong

I know what you mean; when the starter went out in my truck, I replaced it with an updated one...in this case, it was a Mitsubishi gear-reduction starter. My truck turns over so much easier now it's not even funny.

The 300D's starter hasn't been replaced yet as long as I've had the car, so I would assume that it's not an updated unit...

Actually, on the expansion tank, I noticed that mine has a 126 part number. I always thought that was interesting...not a problem, though

Originally posted by The Warden
The 300D's starter hasn't been replaced yet as long as I've had the car, so I would assume that it's not an updated unit...

You should look into it sometime, when you do notice that your car turns over slowly. The starter was only $134 plus $60 core charge from FastLane. It's just a pain to get the old starter out, until you have down it once . Now I think I can replace the starter in less than an hour now

[gsxr]

Mercedes has increased the cap pressure from 1.0 or 1.2 bar on most older cars to 1.4 bar. So yes, the 1.4 bar cap is correct. I think some of the really new cars may be rated even higher, I vaguely recall something about 2.0 bar (??) but that could just be my imagination. Don't worry about the increased pressure, as long as you engine runs cool like a diesel should (below 105C) the pressure will probably never get anywhere near 1.4 bar. Don't forget to use MB anti-freeze only if you have a plastic and/or aluminum radiator! A bottle of WaterWetter never hurts either.


Regards,