My coolant tank was broken in an accident, then I bought a new one and installed it successfully. Of cause, I refilled the coolant MB325, and it took about 1.7 gal.


Today I found that the temp seems a little high. It is 31F, but the coolant temp is high to 90~100 ℃. And when I stop and open the hood to touch the coolant system, all are how but the radiator is as cold as the body.


But the warm wind is OK.


So I think there must some air in the radiator. It stops the coolant enter the radiator.


Then, how to drive air out from the radiator?


Thank you.

 

first, i'd check and make sure coolant is topped off on the radiator...

 

Sorry, I missed to mention that, after filling 1.7gal coolant, the tank is full.


And, how to make sure it's topped off on the radiator?

 

when engine is cold remove radiator cap and check the level...
normally, when u flush coolant, u have to drive a bit and then top off again...

 

Excuse me, I don't find the radiator cap. Do I need to remove something to make it outside? What does it look like?


Thank you

 

is this the radiator cap?

if yes, the level is as high as overflow.

 

I think more is going on here than you're aware of...


What was damaged in the accident.. the white plastic coolant *reservoir* bottle?


If you replaced this and refilled, it holds nowhere near 1.7gal of coolant/water.


The entire radiator and coolant reservoir combined hold approximately that much. So that tells me that you replaced the reservoir, but filled the entire radiator too.


Questions:
1. Are you sure the radiator didn't have a leak also? Was it completely undamaged?
2. Did you check the hoses also, and/or do a pressure test on the system to make sure it's undamaged?
3. Were you adding just coolant or 50/50(coolant/water)? Because if you added 1.7gal of coolant alone, you don't have enough water in the system.. your entire system is now full of mostly just coolant and no water.

 

i don't recall... if there isn't one, check coolant reservoir level...

 

There is no 'radiator' cap on these vehicles. The only cap is on the reservoir.


As long as the reservoir is filled to the 'full cold' level when cold, things are properly topped up.


If you suspect you have air, remove the reservoir cap when cold, then start the truck and warm it up. You need to have all of the heat vents blowing hot inside the truck (heat on high) to know that the thermostat has opened properly. Rev the engine a few times also.


Then put the cap back on and you're done.


If that doesn't fix it, the problem lies elsewhere.

 

Checked by myself and two body shops, we all confirm that the cooling system is alright except the expansion tank. Radiator, hoses, are all OK.

According to the owner's manual, all the coolant system need 9.5 L coolant, about 2.5 gal. Also, after the accident happened, I drove it about 10 miles until I found the expansion tank is damaged. So I think coolant should run out to empty during this travel.

The owner's manual says that the only coolant option for this ML350 is MB325.0 that I fill 1.7 gal into the tank. Should I mix it with water?

 

I just drive back.

The coolant temp reaches about 90 ℃, in 6 miles and about 10 minutes from a complete cool down. Maybe it is normal?

But after I just stop the car in front of my house and left the engine on, I opened the hood, touched the radiator again, it's cold. But the hoses are warm.
Then I opened the cap, some coolant ran out. At least it proves that there is no leak.

The thin hose connected with the top of the tank seems return the steam back to the tank.
Can I try to pull it out to remove the air.

 

90C is normal...

 

OK......And the cold radiator is normal too?

 

90C for cold radiator?

 

Yes, when the coolant is 90C, the radiator is cold.

 

must be thermostat then...

 

excuse me, is the radiator near the grill or the fan?

 

should be in front of the fan...

 

Forgive me, I just know that the cold one is the radiator for AC. And the Radiator for the engine I haven't touched yet.

 

I think you're touching AC parts not the radiator. If coolant temp is 90C the radiator should be that temperature also. But because of the cooling vanes it may feel cooler. Still should feel a bit hot, not room temperature.


I wouldn't worry about it though. Based on what you're now telling us, things sounds normal.


90C engine temp, no leaks, system holds pressure, hoses are hot... these are all good signs.


Just watch that the temp doesn't go to 100C or higher (unless it's a really hot day, your idling in traffic with AC running, etc.) and you're fine.

 

In general if you have air pockets in the cooling system after a system drain and refill, the air pockets should disappear after a few (3 to 6) hot-cold cycles. When the engine heats up the air pockets fill up with steam and when the engine cools down the pockets of steam contract considerably and suck coolant fluid into the space where these pockets occur.


Be careful not to allow the engine to get above normal operating temperature during the first few cycles after a refill when the amount of coolant in the system is still less than it should be. Top up the cooling system every time before the start of the next warm-up cycle. Continue to do this until the coolant level doesn't drop anymore after a few hot-cold cycles.