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I recently replaced my water pump (OEM) and thermostat (OEM) on my car. my car is still overheating I’m thinking it’s the Radiator as of now but just curious to see what you guys think. My old water pump was a lil moldy and my thermostat definitely needed the replacement. I also bled the coolant after installing the Pump. I’m no expert and appreciate any responses. Thank you.
I recently replaced my water pump (OEM) and thermostat (OEM) on my car. my car is still overheating I’m thinking it’s the Radiator as of now but just curious to see what you guys think. My old water pump was a lil moldy and my thermostat definitely needed the replacement. I also bled the coolant after installing the Pump. I’m no expert and appreciate any responses.
Thank you.
The cooling system requires to be filled under vaccum to prevent the overheat condition you're experiencing.
Flush then refill under vacuum - - - Problem solved or steem engine revisited?
Last edited by CaliBenzDriver; Apr 23, 2023 at 10:32 AM.
You can get this, when you do.... there is a flat seal you need to remove from the MB specific cap. I got this one. I never use the vacuum feature though, I use my electric vacuum pump. https://id.aliexpress.com/item/40011...yAdapt=glo2idn
When you said your replacement water pump and thermostat is OEM, what brand is that ? Show me the link.
W212 thermostat mechanically opens at 95Celsius, but can be sooner when assisted by the heater.
BMW uses 103C version. I hope your OEM is a 95C unit.
What coolant did you use? Did you replace chem pack in the system as well?
This is the 1st MB engine that I hear needs coolant bleeding, but MB cooling systems are usually well overbuild, (and I drive in 120F weather) so something must be terribly wrong when it overheats in mild temperatures.
I recently replaced my water pump (OEM) and thermostat (OEM) on my car. my car is still overheating I’m thinking it’s the Radiator as of now but just curious to see what you guys think. My old water pump was a lil moldy and my thermostat definitely needed the replacement. I also bled the coolant after installing the Pump. I’m no expert and appreciate any responses. Thank you.
When does it overheat? Does turning on the heat lower the temperature? Can you check the temperature sensor? Put it in boiling water and measure the resistance.
When does it overheat? Does turning on the heat lower the temperature? Can you check the temperature sensor? Put it in boiling water and measure the resistance.
It overheats when it’s on for about 10 min, also forgot to mention my heater isn’t working m it just blows cold a/c. That is the reason I thought it was my Thermostat.
It overheats when it’s on for about 10 min, also forgot to mention my heater isn’t working m it just blows cold a/c. That is the reason I thought it was my Thermostat.
this is called an "air pocket"... need to use the vacuum service procedure to exchange your engine coolant.
There may be an expert mode to burp the air out of this engine cooling track.... not impossible but unlikely -
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Last edited by CaliBenzDriver; Apr 25, 2023 at 01:21 AM.
Too bad there isnt a high point vent bolt like on previous versions of my truck. For some reason in 2014 my truck they got rid of it but kept everything else the same. Super annoying.
Just FYI not saying this is correct but in my truck I would squeez the upper rad hose several times then refill overflow tank. Repeat several times. This forced enough water thru to get rid of large air pockets and allow normal flow to fill everything else. Not sure if this would work or be effective on these vehicles.
Most people do not realize that ( based on M276 ) the ENGINE's REAR COOLANT OUTLET to HEATER CORE INPUT is the highest point of coolant route in the car, hence vacuuming will help.
Pressure can help too, I use pressure more often than using vacuum.
Heater core return is also very high position, next to EVAP's TXV.
Height information, M276 3.5 NA
Below is M276 3.0 Turbo, but it is the same as M276 3.5NA. This is the coolant hose from engine block rear to heater core via firewall interface hose.
If heater core is not flowing hot coolant and engine overheats, that also means the coolant pump is cavitating from too much air bubbles in cooling system.
When i use pressure instead of vacuum, I apply pressure for 30 minutes to compress air void and hence coolant can fill those air void. It is a slow process.
Usually need a few times of pressurization as the coolant level in the reservoir bottle will slowly goes down...............meaning the coolant has gone to fill those air voids.
Radiator while it looks high position for its input hose from engine block, its output hose is very low position. So air trapped in radiator is actually not so much, even when thermostat is closed shut.
The coolant reservoir is Tee-ded to radiator output & coolant pump suction hose.
One strike against using pressure bleeding... is the MB plastic expansion tank likes to split open - Also the coolant circuit features a heat exchanger with ATF inside radiator... a common MB failure when tranny runs on mayo.
Pressurized to 15 PSI or 1 BAR is safe.
System design is 1.4BAR as per pressure cap.
Vacuum down is the same as being pressurized from outside. Let say -12 psi vacuum, that means all component get pressurized by ambient air crushing it so to speak.
This thread only brings bad memories of the days I owned (helped other with) Renault vehicles overseas. It was a pain to get the air pockets out of the system. It was night and day difference once the system was purged correctly.
In fact, the Renault 18 (1600cc engine) had a small valve on the upper radiator hose that was used to let the air out. Though it helped, it introduced another failure point in the system, i.e. the hose used to fail at the valve. I thought the days of removing air pockets from cooling systems were gone, and it was an aberration from the French engineers of the day .
In old days, on American cars I installed flushing connectors on heater core hose. They cost very little at any automotive store.
Now, none of my MB require bleeding, but why not install one of those connector there and use it for bleeding?
I have flushed my 2010 E550 engine coolant twice. I have never heard of vacuuming the system. All I did was fill the reservoir with the coolant from the dealer mixed to distilled water 50/50 and let car idle filling the reservoir until it stops loosing level. I had the temperature set to MAX HEAT so the valve to heater core is full open and coolant can circulate freely thru the heater core.
After a day or two I added some coolant as the level had dropped some but I have not had any problems with this. And as S-Prihadi already explained, vacuum is not the force, the force is the higher pressure on the other side of the "membrane'. Vacuum just makes it possible for the higher pressure to form.
By my experience there is no need to use pressure or vacuum when filling the cooling system.
I recently replaced my water pump (OEM) and thermostat (OEM) on my car. my car is still overheating I’m thinking it’s the Radiator as of now but just curious to see what you guys think. My old water pump was a lil moldy and my thermostat definitely needed the replacement. I also bled the coolant after installing the Pump. I’m no expert and appreciate any responses. Thank you.
I also had a garage replace the wp and thermostat. Engine would temp gauge would redline after about 20 minutes of driving. Took it back and the garage burped it. Removed an air pocket in the colling system. Now it almost hits the red line
after 20 minutes and the radiator fan runs on high speed constantly after the 20 minutes. Not sure what to do now. It is not overheating the way it was but still now running properly. And this is in the winter when it is cold out. The fan never ran
in the winter before at high speed only in summer.
double check with your scanner that the temp sensor at rear of bank-2 is reading correctly without jumping around in steps... concider poor GND for that circuit.
In other words ask yourself if the redline display matches engine reality?
I used to have a chevy that would run the radiator in winter 10mn after start! The brand new aftermarket temp sensor what mismatched. I then purchased dealer part to escape the stupid games.
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