Cooling system PROBLEM!!! - PeachParts Mercedes-Benz Forum

racerx12367 · #1 08-01-2011, 11:26 AM

1992 300e The cooling system isn't working. I have tried taking out the thermostat, replacing the thermostat. The pump isn't leaking or making any noise. I have now removed the radiator to see if its clogged, it seems to be fine. I 've taken the serpentine belt off and the water pump feels okay. Also when the pump is spun by hand the coolant in the thermostat housing appears to move through the engine. I've also checked the fan, it spins about 1/3 of a revolution. I really don't think that the pump is shot, but I don't see what else it could be. What else should I check before I start ripping into a tough job.

Thanks in advance
Dan

oldsinner111 · #2 08-01-2011, 11:40 AM

head leak?Weak hose being suction in.

racerx12367 · #3 08-01-2011, 12:09 PM

It doesn't seem to be leaking at the head, I'm not losing any coolant. The hoses look okay too.

engatwork · #4 08-01-2011, 12:20 PM

What kind of temp readings are you getting?

racerx12367 · #5 08-01-2011, 12:55 PM

The gauge is pegged. The radiator when its done that has been cool, it doesn't appear to be flowing. The tank is full as well. Have also installed new cap and temp sending unit.

engatwork · #6 08-01-2011, 01:17 PM

The radiator should be pretty hot to the touch. Sounds like you are on the right path in regards to no flow. Was their any visible build up in the radiator? How did you check for flow through it? Did it just start doing this all of a sudden or did the temp creep up till it got where it is today?

Hirnbeiss · #7 08-01-2011, 02:30 PM

Check the fan and fan clutch too. The fan should "whoosh" when it's hot and you accelerate from idle.

Is it possible you have air in the system? I think 104's have bleed screws in the block. Also, see if you get heat from the heater core.

A symptom-free pump failure just doesn't sound right, especially when you get results with your hand test.

Here's a pretty thorough link (for Honda's) jsut to make sure you've covered all your bases. It shows a corroded impeller, but notes that this is a very extreme case.
http://www.tegger.com/hondafaq/overheating/index.html

racerx12367 · #8 08-06-2011, 06:14 PM

I was still pretty skeptical about the water pump being the problem. After checking many old posts I thought that the radiator made the most sense.
I just finished replacing (supplied by Phil) and it worked like a charm. Now the temp stays at the 80° on the gauge. Thanks to all who helped me on this frustrating problem.

big dog 2 · #9 08-07-2011, 12:49 AM

I suspect the fan clutch may be the culprit too!

benzme · #10 08-07-2011, 09:30 AM

Just to help with my own diagnosis - when you say it stays at 80, is that in stop start traffic as well?

Thanks

mpolli · #11 08-07-2011, 12:27 PM

Ummm.. I think it's fixed

benzme · #12 08-08-2011, 05:21 AM

I meant diagnosis with my own car's heating problems

- the thread helped anyway.

oldsinner111 · #13 08-08-2011, 07:01 AM

Warning never use Bar stop leaks in import radiators.It will harden into a brick in your rad.
Alumia Seal works good.

racerx12367 · #14 08-08-2011, 01:04 PM

Benzme, The car stays at 80° pretty much all of the time now. Its a little higher if you stop at the store and stop the engine for a minuet but then goes right back to its normal operating temp. The fan was okay, good resistance when you tried to spin it by hand. Stops immediately when you shut down the motor. When I tried to flush the old radiator with water and air it did seem like it went through alright, then I reinstalled it. When the car started to get hot, I shut it down and used a laser thermometer to check different areas of the radiator. That indicated the radiator wasn't flowing (cooling) properly. Now its working well.