Hi. I bought a '92 190e for peanuts that overheats. The cooling system is a mess, full of chocolate pudding. I have the cooling passages clear for the most part, but it still overheats. I have heat in the car. The water pump pumps, but the radiator stays completely cold. I took the radiator out to clean it as much as possible. water flows from the top port to the bottom port with NO resistance. almost as if it is just bypassing the aluminum tubes and just flowing through the tank. The radiator has 3 ports and ive shot water in from every which way, but the main ports are on the same side. Is it possible that the radiator is broken internally? If water flows freely, but it doesn't get hot, it makes since that it is going straight through the tank.

Could be thermostat. I think the thermostat stays closed and only allows water through the engine block when engine is cold, and then opens and lets water through radiator when engine gets warm. It's probably not opening when the engine gets hot. Is it a 2.6 m103 car?

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Streetside: 1987 Mercedes 300E Petrol Blue/Green
2014 Ford Mustang Grabber Blue
1999 Ford Ranger Green

Dockside: 1968 Eltro 17
1985 Silverton 34C

Thanks for the reply. It does this with no thermostat. it is a m103

If you have chocolate pudding then your headgasket is shot, thats why its overheating.

My '84 2.3 just got a new heater core, radiator, thermostat, and water pump. It's all cleaned out inside, and has new antifreeze. When it's running, and all warmed up, the radiator isn't getting hot, either. The heater airflow is great now, and very hot.

I have a feeling that in cold weather, like we are having right now here in western North Carolina, the engine is not making enough heat for the thermostat to open for the radiator. The gauge reads that its running about 80-90 degrees C.

The heater core might be removing enough heat from the water to satisfy the bypass half of the thermostat. Does this make sense?

The car does not overheat, and never has. I've got a fan clutch thermostat switch ordered, as some other owner had it wired to run all the time, and removed it.

Am I on the right track with the multi-function thermostat? BTW, it's a Behr from the dealer.

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My first Mercedes Benz. 4/6/07.

1984 190E (201 024) 2.3L four.

This is completely normal, if the radiator was getting hot it would not be doing a very good job at cooling. Why are you trying to fix something that's not broken ?

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600SEL '91
300E 4Matic '88
240D '83
280SE '77
350SE '73
The most complex systems can fail in the simplest way.
Contra verbosus noli contendere verbis, sermo datur cunctis, animi sapientia paucis.

i don't believe in the lord! He's never bought me a Mercedes Benz.

The engine fan is really loud at highway speeds. If this doesent do the job, I havent lost anything but a few minutes time. Besides, this car HAD the clutch switch.

Bruce

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My first Mercedes Benz. 4/6/07.

1984 190E (201 024) 2.3L four.

So back to this thread... I replaced the Radiator and fan clutch, as well as the thermostat and most of the hoses. I thought everything was fine until I got plates for it and took it for a drive. Typically the temperature would stay around the 80 mark until I had to drive slow or idle. The needle would move very erratically between 80 and 110. It never hit the red mark or stayed high for very long. I suspected an air bubble, but I'm pretty sure the system is air free now. I had to bypass the heater core because it was peeing all over my feet. What Ive noticed is the radiator is still luke warm on the side opposite the hoses. The main hoses aren't even really very hot. The Hose that I bypassed the core is very hot though. Visually, there are no signs of overheating, no steam, nothing even really feels abnormally hot. I'm stumped. Now that I'm paying insurance on this thing i gotta get it running right.

My new radiator couldn't be clogged already could it? Maybe the temp sender went bad from bathing in oil for who knows how long. Thanks for any advice.

Did you flush it out really good before you refilled it? My car makes alot of heat on the heater lines, and some heat at the radiator.

Now that I got my fan clutch thermoswitch replaced and the wiring to the clutch repaired, my car runs at about 110 C on a warm day in traffic idling. The fan clutch kicks in at 110 C, and the temp stays right there. When I'm driving at moderate speeds, there is enough air moving thru the radiator to keep the temp between 80 and 90C.

Also with the new fan hook-up, the car warms up fast. That will be a plus this winter! My old temp sender would bounce the needle now and then. I bought a new sender since I was doing all the other work, and the new one doesent bounce.

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My first Mercedes Benz. 4/6/07.

1984 190E (201 024) 2.3L four.

It's possible that a P.O. had put in head gasket sealant (trying to fix the mudd issue) and has blocked some of the passages through the engine block that circulate water to the water pump. I found a large rubber O-ring jammed into one of my coolant passages when I did my head. Or, more likely, something is obstructing the flow to the waterpump intake (your impeller can also disintegrate in the waterpump and won't be able to force enough water through but will "act" normally). If your hoses aren't hot but you are getting heat, something is restricting or causing poor flow there. You should be able to feel the rush of coolant going through the top hose into the radiator and it should be "ouch" hot when you touch it after a good run. I have torn my completely down, did the headgasket and all so I know how these parts are supposed to work. Let me know if anything rings a bell here.

So I flushed the radiator out, problem still persists. I hit the gauge with my hand, it jumps back to normal, hit it again, it pegs to the top. Looks like I have an electrical problem. Thanks for the advice everyone!

The gauge shouldn't have anything to do with the cause of cool hoses or a lukewarm radiator. It just measures the actual temperature as far as I know...

the end tank with both outlets has a divider in it to force water to travel through the radiator, if that divider is broken or damaged (unlikely but possible) then water will short circuit from in to out, both pipes would be steaming hot but the rad core would be dead cold.

Had a VW Golf that did that.

Best way to check is to tilt radiator that is sits angled with outlet port towards the ground, pour some water (about a glassful) in the top port and see if water comes out the bottom port - if it does when its tilted towards the exit port, that divider is bust and you need a new radiator.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

The whole system got hot eventually. I was just afraid to drive it for long. It was a cool that day.

The original radiator had a broken divider. I had never seen that before. It appears all Is well now.

I've never had the good fortune to see a radiator with a divider, though, I understand why it would be used in a vehicle.

Glad you got it fixed.

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My first Mercedes Benz. 4/6/07.

1984 190E (201 024) 2.3L four.