strange cooling problem on w104 - PeachParts Mercedes-Benz Forum

Bryan · #1 09-01-2006, 01:12 PM

I researched the forum and I can't find another problem exactly like mine.
I recently replaced my radiator due to the neck breaking off the top. So since I was already under the hood I replaced the thermostat with the correct beher replacement,the radiator cap and new hoses. The car ran just above 80deg, which is good since we have had some pretty hot days here in Cha. This morning I drove about 15 miles and noticed my coolant light came on, the resovoir tank was extremly low. I filled it back up to the line, and drove home. When I got home I noticed water draining from behind the water pump, and pooling around where the oil dipstick tube enters the engine, and when I took the cap off the bottle it seemed to be gurgling. I flushed the cooling system with some fresh water and then drove the car another 10 -12 miles, and now I,m not loosing any coolant and around the dipstick tube is dry. Now even though its not leaking, its still driving me nuts! Does anyone have any input on this problem, it would greatly appreciated.

david s poole · #2 09-01-2006, 01:46 PM

now that you have everything else shipshape the water pump is going to bite you too just for good measure.you will probably find that when it cools down o/nite it will leak again although not every nite. o ring at the rear where pump connects to block is prob flat and depending on pressure in system will leak.

Bryan · #3 09-01-2006, 01:48 PM

I knew it was probably to good to be true. Have you ever had to change one yourself?

Bryan · #4 09-01-2006, 01:51 PM

Sorry, about the stupid question. Since you own a shop youve probably changed plenty of them.

Bryan · #5 09-01-2006, 04:10 PM

I have a 93 300e with a 3.2 liter, so that would be a w124 right?

lkchris · #6 09-01-2006, 06:26 PM

Mercedes radiator hoses are MUCH better quality than those of us familiar with USA cars may be used to.

10 years is way too early to change them for "preventive" reasons.

Bryan · #7 09-01-2006, 06:47 PM

Thats good to know, I think german automakers take more pride in even they're lower end cars than some of our more expensive cars. Sometimes I think with the exeption of a few, american automakers are more about economy and quantity, than building a car that if maintained is as much fun to drive and look at with 300k on the dash as it was the day it left the dealership!

Ron in SC · #8 09-01-2006, 07:26 PM

It may be worthwhile to pressure test the cooling system with the engine cool. You may be surprised where the coolant leaks from. I did that on one of my 124s that was loosing coolant. . I thought it was only leaking for the coolant tank sensor. It turned out it was also loosing coolant from about 4 or 5 other places to. All were minor, loose or improperly seated hoses, some just due to age. One of the other larger leaks turned out to be the thermostat housing.

Bryan · #9 09-01-2006, 07:34 PM

what kind of tools do I need to pressure test the cooling system

Bryan · #10 09-01-2006, 07:37 PM

It looks like its leaking from that 13mm bolt on the bottom where the rear of the pump fits to the engine.

Ron in SC · #11 09-01-2006, 07:46 PM

The pressure testers are pretty generic. See post #13 in link.
http://www.peachparts.com/shopforum/showthread.php?t=152436

hs_300e · #12 09-01-2006, 07:59 PM

If you saw water leaking from behind the water pump, it is most likely from the weep hole in the pump and it is probably due for a replacement.

Bryan · #13 09-01-2006, 08:50 PM

Thanks for all the responses I'll start with getting some guages and probably a new pump.

Bryan · #14 09-02-2006, 01:07 PM

Well I've gained enough confidence to try and install the water pump myself.
Does anyone have any helpful tips on doing the job without going nuts. From searching the forum I've seen way too many mixed opinions on this change out!

Ron in SC · #15 09-02-2006, 04:40 PM

I've never done a water pump on a 103 or a 104 motor but I'd be willing to help you if I can; I'm always interested in learning something new.