You are correct. I failed to explain further. Thanks in adding that information.



.

Charlie, what is this U-shaped pipe you speak of? Got a pic?



.

It would appear that you have your wires crossed about who said what.

But even though I didn't say that, I do agree with the gentleman who did. The 617.95 engine has a built-in vent in the thermostat housing which is intended to automatically purge air from the cooling system. In my experience, it seems to work as intended. However, given the relatively small size of the passage, it would be easy to envision a poorly maintained cooling system in which the passage was obstructed and incapable of functioning as designed.

Have you ever wondered about that small hole on one side of the thermostat gasket?

Tango you are right. I was refering to post #13, VSTECH. my appoloizes. :o

I don`t remember a little hole in the thermostat, but been a while since I have one in front of me to look at.
I know Diesel Giant shows drilling a little hole in one for a cooling problem,
but something I wouldn`t do, better to just fix the problem.

DeliveryValve, the little U tube I was refering to, is the one in the front of the head, that connects to the watter pump housing.
I was with JT20 up here in Portland, Or yesterday. looking at his 85 300TD, it also doesn`t have this tube.
http://i131.photobucket.com/albums/p...t/SSPX0407.jpg

Here is picture of what I was talking about. Thanks to SIRNIK84 in his currently running thread.

Charlie

I didn't say the hole was in the thermostat. It's in the thermostat gasket.

http://catalog.peachparts.com/ShopByVehicle.epc?q=1982-Mercedes--Benz-300d-Cooling--System&yearid=1982%40%401982&makeid=63%40%40MERCEDES+BENZ%40%40X&modelid=6190%3AMBC%7C1504%3AED%7C10 000135%40%40300D&catid=240909%40%40Cooling+System&subcatid=240977@@Thermostat&mode=PA

Ok, now Iam up to speed with you.

Charlie

Ah, I didn't realize not all 617.95x motors had this part. Interesting info.




.

Per FSM.


.

I have seen that little vent tube before when the hose was off. I wonder if all 617 engines had this, or was started some where in mid production?

Then why does every one say to burp the system? I usually fill the upper hose until I see the coolant come out the radiator, then slip on the hose.

Now I need to check the 240 to see what it has.

Charlie

Chamalu,

I replaced the U shaped tubing on top of the water pump and my understanding it that it is a Pump Vent to make sure the Pump is flooded. My U Tube was dripping. Phil had the tube.

This means it burps the Pump (Primes)but not the block passages. I never heard of "burping the block".

My 1989 325 BMW 325i has a needle valve Burping location on the thermostat housing.

I don't believe these MB have this but if they do it may be on the T Housing.

I'll have to look at mine.

Steve

Great Sketch. That shows it all. TY

BTW,

These U-tubes usually starting dripping in the back where U really can't see where it is cracked or corroded. FYI the tube is made out of steel not a yellow metal as I had thought. My Tube was just worn out from the inside from water flowing through it. I'd call it Erosion Wear. Now I don't use any cooling water at all. Before I had to add some once in a blue moon.

I agree.

from what i have seen, only the '85 / late '84 does not have it.

I had an '81 240d that did have it.

My 80 240 has the metal U-tube. I put one on the 85 a few years ago thinking maybe some one removed it. can`t hurt I guess.
I have a spare 84 engine, I`ll have the check it when I get back home.

Maybe they ran out of them ;).

Charlie