How to Fill With Coolant 300SD - 1983 - PeachParts Mercedes-Benz Forum

rhodes2010 · #1 08-28-2007, 10:37 AM

Anyone ??

I am under the impression that my 300SD from 1983 has air in the coolant.

The overflow tank has liquid and can't take anymore.

Still, I hear air and gurgling in the passenger compartment.

Is there an easy way to bleed out all the air from the cooling system ?

Searches tuned up lots and lots and lots of discussions, but no simple solution.

SD Blue · #2 08-28-2007, 10:48 AM

Could it be the air and gurgling is due to the system being overfilled? There is a max. level line on the reservoir.

vstech · #3 08-28-2007, 10:55 AM

The SD should have no issues with filling. the vented radiator should keep air out of the system. if you are hearing gurgling, you may have problems with your a/c system, or possibly the heater core may have some air in it.
squeeze the upper radiator hose, watch the expansion tank. does air or water enter it?

jim messina · #4 08-28-2007, 10:58 AM

I had air in my Sd got good advice here. I removed the top hose(car running) to the radiator filled it to the top and quickley put it back on. Also try running defrosters in park for about 10 minutes. Hope this helps...Jim

rhodes2010 · #5 08-28-2007, 07:59 PM

Searching previous posts I fond one that talked abot the highest point in the
system being a host by the firewall.

Poster disconnected this hose and vented air out.

I seem to remember specific references to bleeding air out on
the Turbo models because we have no radiator cap on the radiator.

Long and short of it, I am running warmer than I should.
After the thermostat change I refilled the coolant but feel like it is low.

This weekend I will pull the radiator and replace it with rebuilt.

LUVMBDiesels · #6 08-28-2007, 08:04 PM

What I did is a three step process.

1) Get the car pointed uphill or put her on ramps.

2) fill the block by removing the top radiator hose from the radiator and puring coolant (Zerex G05 only please) into the hose until it was filled to the top. Then I attached the hose to the radiator.

3) Filled the rest of the system from the expansion tank. I then started her up and ran her with the defogger on until she came up to temp. Once she was at temp, I checked the expansion tank and added coolant if needed.

Doing it this way has eliminated the air for me.

If you have already filled the radiator, try getting her up on ramps with the cap off. Turn her on and run it to normal temperature with the defogger on.
This should force any air out the expansion tank.

DieselAddict · #7 08-28-2007, 08:14 PM

By defogger I assume you mean with the heater on (not the rear electric defogger

) Otherwise your procedure is pretty much the same as what I use. I would just add that some cars have a bleed bolt near the upper radiator hose. After you fill the system it's always a good idea to remove this bolt and let any remaining air out. Be prepared to reinstall it quickly once the liquid starts coming out.