Well this all started when I flushed the cooling system. After that it has been running around 90 to 100c before the flush it was running around 80 - 85c. (And that was in the summer time.) Now I've replace thermostat, radiator, temp sender & radiator cap and still running around 90 - 100c and its only 70f outside. On a 240D should I be able to see the coolant flow with the radiator cap off and running the engine above an idle (temp gauge at 90+)? I know I can on my Chey but this MB I don't see any water flow???? Any thoughts about the water flow? Is my water pump bad?

Thanks,

Bill

Bill

If your 240d is an early, pre "80", model they are prone to air trapped in the system. I put the front of the car up, make sure the heater valves are open, squeeze the upper radiator hose and try and "burp" the system while its running. You did open the 13 mm bleed nut on the T stat housing? right. I always wind up fiddling around getting the air out of my '78" and "79" but the later 240ds do not seem to have much trouble. Also I have gotten new bad T stats.

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

We have had a lot of people say they got bad thermostats...

also.. be sure if it has a hole in the edge that the hole is up... or drill one if you need to..

Also... check your lower rad hose,,,, if the spring starts to rust out. it can close since it is under suction ....

On the early cars, I drill a .5mm (.020") hole thru the thermostat flange, (the part that doesn't move), and put the hole at the top when remounting the thermostat. Thatusually takes care of the bleed problem. Are you running too high a concentration of Anti Freeze? Anything over 50/50, you loose cooling efficiency. Chris

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My Truck.. 2007 DODGE, 5.9 Cummins, 6spd stick, 4X4. My car..1977 240D, OTHER WHEELS...1955 VW Oval window bug, European Delivery (Holland) with a 1700cc, 2 barrel, Porsche drum brakes. 1939 WILLYS Pick-up. 1967 Triumph 200cc Tiger Cub. 1976 Honda 550F 4cyl Motor Cycle.

Forgot to mention that its a 1982 240D. The heater works good and I had it on a hill when I filled it. The thermostat did not have a hole in it nor did the one I took out. Guess I'll pull it and add a hole to it. Would it have air trapped in the system and still have the heater working good? I thought I would at least be able to see water movement in the radiator, through the cap or do MB not move much water? The mixture is a little less then 50 50 more to the water side. Upper hose is hot and lower one seems cool to cold after it warms up (90+) and idling in driveway. All new Hoses also when I replaced the Radiator.

Thanks,

Bill

Unless it is LOCKED UP... a water pump failure mode is just Leaking... so I don't think that could be it...You have a good stumper here...

I'm sitting here wondering about the radiator. Was it a new one? If it were used did you get it to a radiator shop for check out prior to installing it?

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Jim

mrBil240D,

You did not mention why you were flushing out the coolant system, and how you actually did the flushing (what flushing media, the flushing path, etc.).

It seems to me if your pump were the problem, you would not have an issue with a few degrees Centigrade. The pump essentially either works or it doesn't. Sounds like you replaced the essential elements of the system that would regulate temps, so you probably have a flow problem. This can arise from the thermostat being defective (test the old one - boil it in water with a thermometer and watch it open, note the temp) which has been noted already. I would also remove the one presently installed and compare its response in boiling water to the old one.

It is also possible the flushing procedure loosened some corrosion particulate that has been redeposited in the radiator, restricting flow. In general, at idle you should not see much flow from the engine through the radiator at idle as even if the temps are up to normal the heat load is low, and the thermostat will regulate the flow to stay in the normal range. With a low heat load, low rpm on the impeller, you have no real reason to expect a significant flow rate.

By the way, will the car's temperature at idle creep up to the higher mark, or does it stay in the normal range?

Good luck, and I hope this helps, Jim

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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

I have a 83 240d and when I flush the system out I normally go back and fourth a couple of times with the garden hose at front and rear hose connections to do the best job I can to get the most crap if any out and also take my air compressor to blow thru it . It is a little extra but worth it to me. when refilling take your time and check it a few times after it cools. Hans.

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A couple of Ford pickups F 150,250, 350 missed.
1983 240 D 256,000 miles ,auto, ac.

Flushed the system because it was a little rusty looking not bad but since car is new to me I wanted to start fresh. Took off top and bottom hoses and removed block plug and flushed both directions till clean. Just used plain tap water to flush with. Then after that it started to run hot so been troubleshooting (Shot Gunning mostly if feels like) since then.

Yes, radiator is a new one (part of my troubleshooting, replaced it after thermostat and temp sender)

Pulled off the thermostat and checked it with old one. It opens at 180 and old one opened at 190 so it should be a cooler running engine with new one. Also noted that both old and new have the same measurement open and closed.

Yes the temp creeps up to 90+ at idle.

Pulled top hose off and tested for flow and have flow which seems good plus it gets better when engine RPM increases so that does not seem to be a problem only it bugs me that I could not see the flow through the cap. (Oh well)

My next idea is to get a friends laser temp gun and see if maybe the gauge is way off.

Any other ideas????

Thanks for all your help so far.

Bill

I think the checking the temp by other means is a good idea. You can ck the temp with the radiator cap off and put a dial thermometer in the radiator fill neck. I have also checked the temp guage sensors by removing them, extending the wiring to reach a work table, get a hot plate, pour some light oil in a pan and slowly heat it with the key turned on and a reliable candy thermometer in the oil. Compare the readings to see if the guage or sender is off. Chris

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My Truck.. 2007 DODGE, 5.9 Cummins, 6spd stick, 4X4. My car..1977 240D, OTHER WHEELS...1955 VW Oval window bug, European Delivery (Holland) with a 1700cc, 2 barrel, Porsche drum brakes. 1939 WILLYS Pick-up. 1967 Triumph 200cc Tiger Cub. 1976 Honda 550F 4cyl Motor Cycle.

I think you need to pressure back flush the radiator with it upside down....

Well would you look at this.

Water Temp going into Radiator is 180 and heater hoses are at 180 and thermostat housing is at 180. So tried Motorheads idea and used old temp sensor and pot of hot 180 water and temp gauge shows 95. SOOOOO I guess I have a bad temp gauge not an overheating problem at all. Next time I’ll try this method first. One must be sure that ones gauge is actuate FIRST! This one had me going in circles, since it started with a radiator flush and went down hill from there. Any one have a good temp gauge?

Thanks for all your Ideas.

Bill