Replaced radiator 87 300D... right and wrong way to refill fluid????? - PeachParts Mercedes-Benz Forum

davidlee · #1 11-20-2013, 06:48 PM

I was in a small collision that ended up puncturing my radiator. radiator has now been replaced, I introduced new fluids into the system via the plastic overflow bottle on the passenger fender well, It took about 1 &1/2 gal.
I started the car and waited for the thermostat to open so I could finish filling the system, the temp started rising after a couple minutes and kept rising until the car was running much hotter than normal operations. perplexed I got out of the car and looked at the overflow tank and it was still full, I felt the top and bottom radiator hoses and they are cold, the hoses dont feel like they are holding any fluids, though Im not positive on the bottom one since it is a challenge to reach up to, but both are for sure cold, yet the engine is hot? Thats why I am wondering if there is a certain way to fill it up other than the way I did it.. Any advise would greatly appreciated.

shertex · #2 11-20-2013, 07:02 PM

Do you mean overflow tank or expansion tank? My experience with my W124s is that you can fill the entire system from the expansion tank....before starting, make sure you can feel coolant in the upper radiator hose. Turn heat on high before starting to get coolant in heater core. Sometimes I've found I have to put up on ramps with cap off to burp.

If this doesn't work on your W124, maybe also fill engine from upper radiator hose.

davidlee · #3 11-20-2013, 07:23 PM

I guess I mean the expansion tank, I put about a half gallon in the expansion tank and then started it and kept filling it up but it stopped taking fluid after about a gallon and a half, can I fill the engine block up the other water neck outlet or is there a thermostat there? I'm a little perplexed because I have had the radiator replaced before and never dealt with this, granted a shop did it and I do not know how they filled it. this car is never had an overheating issue

shertex · #4 11-20-2013, 07:28 PM

Maybe some 87 300D owners will chime in....your set up could be different than mine.

Why not try filling the block through the upper radiator hose and see if that works. Also, you have to fill from expansion tank slowly and not let that vent line get submerged.

davidlee · #5 11-20-2013, 08:28 PM

I took a look at the water neck and it doesn't look like a thermostat would fit under it, thats why I'm wondering where it is located?

sixto · #6 11-20-2013, 08:45 PM

The thermostat is where the lower radiator hose connects to the block.

Sixto
87 300D

davidlee · #7 11-20-2013, 11:56 PM

so basically super hard to get to. got it, well hopefully thats not the issue, will try disconnecting the upper hose and filling the block and radiator and get back to you all. Thanks!!