E70 N55 X5 - Blocked Radiator Causing High Coolant Temps

[Skers 05]

Looking to connect with others who have an N55 powered E70 X5.

Specifically, I'm looking for data points from others who have logged coolant temperatures. I had an issue the other day with a temp sensor on the thermostat being partially backed out of the connector and providing an intermittent connection. I never got a fault pointing to the sensor wire being disconnected, just received a yellow coolant light on the dash followed by the rad fan running on max speed.

Has anyone ever logged coolant temps? Steady state driving on the interstate for the last 4 hrs at an indicated 77mph and indicated 86* ambient temperature, my coolant temp (as indicated by ProTool) is 241* and oil temp (as indicated by ProTool) is 244*.

I appreciate any input the community can provide!

2021.06.15 Update - Problem Solved
Hopefully my findings can assist others in the future if they are experiencing similar symptoms.

Source of Problem
Previous owner used incorrect coolant which reacted with the BMW coolant I used causing solids to form in radiator, thus creating a blockage.

Action Taken
Replaced radiator with new Nissens radiator from FCPEuro.com and flushed coolant.
https://www.fcpeuro.com/products/bmw...533472#fitment

[Thecastle]

Seems a little high, but nothing out of family yet for an e70. Normally the car should Be around 105c during steady state driving in normal mode, or about 225f. Eco mode will run the engine at a hotter temp at 111c or 231. I’ve seen these cars hit 115-118c in stop and go traffic (n62.)

It would seem your cooling system is marginal. N55 coolant pumps are a known wear out/failure item.

I’d have it checked.

How many miles.

[Skers 05]

Originally Posted by Thecastle

Seems a little high, but nothing out of family yet for an e70. Normally the car should Be around 105c during steady state driving in normal mode, or about 225f. Eco mode will run the engine at a hotter temp at 111c or 231. I've seen these cars hit 115-118c in stop and go traffic (n62.)

It would seem your cooling system is marginal. N55 coolant pumps are a known wear out/failure item.

I'd have it checked.

How many miles.

Thanks for the reply.

I bought the vehicle with 61k mi and the 1st thing I did was replace the thermostat and water pump with OEM parts from the dealer as I was aware of the issues you describe. The vehicle currently has 79k mi. This means the WP and t-stat have less than 20k mi. It would be likely for this to be the problem, but definitely not completely ruled out.

In the same driving conditions, my 2008 N54 135i (converted to 1M, so 1M front bumper cover) will have coolant temps right around 210-215* F. The 240-250* F I'm experiencing in the N55 E70 X5 just seems high to me. I hope it's not the vehicles way of telling me there is an issue.

[msan]

My n55 x5 driving around town the oil is usually 223 -230 F. Coolant is always at or slightly below the oil temp. Ambient around 70F

Hope this helps.

[Lviv777]

Seems a bit high, mine is anywhere from 212-222. SoCal Normal city driving.

[Skers 05]

Wanted to provide an update on this page. Hopefully it will help someone out in the future.

- Still having problems with the fan turning on high during normal highway driving as well as stop and go. Sometimes I will even get a ORANGE overheating light on the cluster.
- I replaced both the water pump and thermostat with genuine BMW parts and the performance has not improved since the install
- The local weather has cooled off here (65-70 F) and I'm still having the fan coming on high multiple time during a 15 min drive.
- Found a way to datalog with Bimmergeeks ProTool this evening. I created the graph below to document my findings.



Datalog above was taken while the vehicle was stationary in my driveway. You can see @ #1 the temperature delta between the "coolant target temp" and the "coolant actual temp" is 5 deg F. Once it rises to 243 F @ #2, the fan (not shown in the log) and the water pump (yellow) turn on full speed. This is what I'm hearing during my drives. So at a minimum I can confirm that the DME is doing one of its jobs to protect the engine from overheating. What I don't know, is why the coolant temp is deviating from the target temp and the water pump speed is not changing until the temp reaches the safety threshold. I would appreciate any input from any engine guys.

Thanks!

[BlackBitch]

I'm going through a overheating situation right now...lol, as I'm typing. My experience with the fan on high is a bad lower radiator temp sensor...the one for the fan. What are those temps s your warming up.and driving.if you unplug that same sensor, your fan will default to high. Right now I have a leak on the passenger side of engine bay. You can clearly see the drip drips. Anyway,log that sensor and see what those temps are. Especially when the fan engages.

[dang2407]

Might depend on the model but my understanding is that the main water pump is mechanical, and the electric pump is secondary - used for cabin heating and possibly to increase flow. Can anyone confirm?

The mechanical pump is sized for 'normal' running so it would expect to be at higher engine speed anyway, then the electric pump cuts in for out of the ordinary situations. For the sake of User comfort and noise emissions, manufacturers may prefer to not increase noise due to pumps etc until absolutely necessary, so a swift sharp action rather than a consistent increase in noise....

[BigHunk]

Possibilities: fan clutch, sensors, radiator fan switch, did you bleed system properly etc

[Papogator24]

I'm trying to pressure test the coolant. I have the bmw coolant adapter and the radiator test kit. For some reason, I tried to pressurize the system and it doesn't want to pressurize, eventhough I don't see any leak. So, I went ahead and tried the adapter on my 335d and I was able to build up pressure.

Is there something I'm missing with the x5?

[Skers 05]

I wanted to update this thread with my recent findings...

After taking datalogs to verify the coolant pump, e-fan and thermostat were operating as they should, I suspected the only thing left in the system I had not investigated was the radiator. At this point I suspected something was potentially plugging the radiator causing insufficient cooling even though the thermostat was fully open, water pump spinning as fast as possible and the e-fan to be at full PWM. I ended up purchasing a new radiator from FCP Euro (check 1st post for P/N) with plans to replace it. When I removed the old radiator from the vehicle I found this...



I'll report back in a couple days once the weather has warmed up and I can try to excite the behavior again.

[Skers 05]

I was able to confirm the blockage in the radiator was in fact the reason for my fan running on high quite often by datalogging several parameters both before and after the radiator swap.

Run #1 - Pre Rad Swap | 70F Ambient
Run #2 - Pre Rad Swap | +80F Ambient
Run #3 - Post Rad Swap | 70F Ambient
Run #4 - Post Rad Swap | +80F Ambient

All data was collected with the cruise control set @ 80mph on the highway.

[Thecastle]

Sorry to see that. Yup, coolant had gelled. Plus corrosion from not being changed. You can clean the gelling out of the rest of the cooling system by mixing soap and water and running it through. Then flush and replace with fresh coolant. Coolant should be replaced every 2-4 years depending on climate. The rest of your cooling system will have junk in it just like the radiator. without cleaning and flushing it will just dislodge and end up in the radiator again. Your whole system looks like that.