2.7 crd overheating on inclines

[JeanLuke]

Originally Posted by OffroadSpike

Hey guys, never got an answer. Is 100ºC common to see at highway speeds in this car? My mom has a the Mercedes C220 with the OM646 which is basically the same as the 2.7 CRD but with 4 cylinders instead of 5. Her car always runs at 87ºC no matter how hot or fast I'm going.

Apologies for missing this one. What RTB said - he's spot on.

If you are really worried you can get an 82 degree thermostat, but they are vary hard to find. Frankly, I would not recommend it.

[OffroadSpike]

Thanks guys. I decided to flush the system anyway and put the correct Mopar stuff in there. Upon draining the system I discovered a partially clogged radiator.



At first it looked like rust brown material, but after some flushes and water coming out transparent, there's some small white and brown/black pebbles comming out. My guess is they are mineral deposits, calcium and silicates.



I tried filling the radiator with vinegar overnight but it did almost nothing, still looks as clogged as before.





I don't really have time or money to install a new radiator, I've been trying to clean the system so I can put the correct Mopar MS-9769 and forget about it, but that stuff is expensive and I don't want to fill the system with a clogged radiator. I will try a citric acid flush tomorrow, some Mercedes Sprinter guys recommend it on their forums, and see what comes out. Any advice for or against it are welcome.

On another note, I tried finding the radiator drain plug as per Service Manual instructions, but it's non existent, so I just removed the bottom radiator hose. I have spent so much time trying to find the engine block coolant drain plug but I can't, it's anoying to do flushes because I have to get the engine up to temperature every time so the thermostat opens and I can get the water out of the block. I found a 17mm plug at intake/front side of the engine, but once removal only a couple of drops of oil came out and nothing else. Did you guys ever found the engine block drain plug?

[layback40]

Originally Posted by OffroadSpike

Thanks guys. I decided to flush the system anyway and put the correct Mopar stuff in there. Upon draining the system I discovered a partially clogged radiator.


At first it looked like rust brown material, but after some flushes and water coming out transparent, there's some small white and brown/black pebbles comming out. My guess is they are mineral deposits, calcium and silicates.


I tried filling the radiator with vinegar overnight but it did almost nothing, still looks as clogged as before.



I don't really have time or money to install a new radiator, I've been trying to clean the system so I can put the correct Mopar MS-9769 and forget about it, but that stuff is expensive and I don't want to fill the system with a clogged radiator. I will try a citric acid flush tomorrow, some Mercedes Sprinter guys recommend it on their forums, and see what comes out. Any advice for or against it are welcome.

On another note, I tried finding the radiator drain plug as per Service Manual instructions, but it's non existent, so I just removed the bottom radiator hose. I have spent so much time trying to find the engine block coolant drain plug but I can't, it's anoying to do flushes because I have to get the engine up to temperature every time so the thermostat opens and I can get the water out of the block. I found a 17mm plug at intake/front side of the engine, but once removal only a couple of drops of oil came out and nothing else. Did you guys ever found the engine block drain plug?

I think you will find the sludge is mainly aluminum hydroxide.
Its insoluble in cold water. This causes it to be in solution in the hot part of the cooling system & Precipitates on cool surfaces in the radiator.
If you were to place the radiator in boiling water & flush it with boiling water, it would all dissolve. Calcium hydroxide is also more soluble in very hot water but insoluble in cold water.

[FARWEST]

Im pretty sure no chemical 'easy fix' flush is going to help you if the radiator core is blocked....Sprinters had an overheating issue...blocked radiator just like you....because the heads werent completely flushed of casting sand at manufacture.....the casting sand worked its way clear with use...some times thousands of k's other times under 1k....and blocked the radiator core.....benz replaced radiators, water pumps and thermostats under warranty....same engines....same issues.....the radiator core will require having the 'tubes' cleaned with a wire rod....every radiator shop uses this method....anywayz......dont bother spending huge amounts on Mopar Coolant...or any Coolant for that matter....until the radiators been professionally cleaned AND flushed....a flush wont remove the hardened biuld up in the radiator core tubes......NOT a Jeep thing...a Benz thing

[JeanLuke]

Originally Posted by OffroadSpike

I don't really have time or money to install a new radiator...
...
Did you guys ever found the engine block drain plug?

I used one of these: https://www.supercheapauto.com.au/p/...un/656321.html

I have not found a block coolant drain.

[OffroadSpike]

I've been away from home for a couple weeks and couldn't continue working on it. I used a citric acid flush as recommended by Mercedes. 10% citric acid powder to 90% water, I did one heat cycle, about 30 min driving and when I stopped the whole coolant system was bubbling up because of the citric acid reacting. I flushed the system and a bunch of junk that dislodged from the radiator came out. The radiator is 100% clean after the citric acid flush. Flushed the system with tap water about 6 times to completely remove the acid from the system and so far so good.



Decided to change the water pump anyway, the old one was 10 years old, although functioning fine with no leaks I decided to do it now that I was going to put new coolant in it. Bought a INA branded water pump for the WJ 2.7, people say INA is a good brand and OEM part for some car models so I guess is good enough for the OM612. I received the water pump which looks almost exactly as the old one. The old one had a paper gasket installed with some gasket maker, the new one came with a metal and rubber gasket.The metal gasket has a ridge that fits the rubber gasket, but I see no ridge on the water pump or engine block where the rubber gasket could fit.



Found some thread on the Sprinter forums about some OM612/OM647 models having a ridge on the block that fits the rubber gasket. So i guess I'm not going to use the rubber gasket, question I have is should I still use the metal gasket with the ridge? I'm afraid of it leaking. How is the original OEM gasket?