Temperature creep under load

[8000RPM]

Creating a new cooling system thread since my issue is a little different than the other.

My problem is temperature creep under load going up a hill. It warms up as it should to the point there the needle sits roughly in the middle 89-92c on the OBC. I can idle and the needle/temp doesn’t seem to move. Under load up a hill the temp gauge moves to toward the right dot (never fully reaching) hitting 96-97c. Books says within range, my experience this is not normal as my other two M’s never did this. When back on level road, the temperature returns to the center.

1. New Saleri water pump (metal impeller)
2. New Borg Warner thermostat
3. Full cooling system flush with distilled water/BMW blue (radiator, block, hoses, heater core); no grit or particles in flush
4. New upper and lower VNE temp sensors
5. Original radiator
6. New OE Mahle fan clutch
7. Tested front electric fan with scanner at multiple speeds and works properly

Since I don’t get any over cooling and the problem only seems to happen under load, do you think its a case of the metal impeller not being able to flow? Radiator lost efficiency? Where would you look first?

Ideally I would have used BMW brand but FCP listed these as OE originally. In hindsight I would not have bought them.

I have Schwaben scanner, no codes in 30 miles.

[WOLFN8TR]

How many miles are on the car? This seems pretty normal in temps under 110 degrees. Temps over 110 my car would easily hit 210-215 degrees uphill under load. I daily drove my car the last three summers, anything over 110 degrees you have to keep a close eye on the coolant temps.

This was during the 120 degree week we had last summer. 🔥

[COVID-19]

I believe your problem is going to be the radiator. A lot of crap gets caught between the radiator and condenser.

[8000RPM]

I’m kicking myself for not removing and cleaning out the fins while I had everything apart.

[S14]

How many miles are on the car? This seems pretty normal in temps under 110 degrees. Temps over 110 my car would easily hit 210-215 degrees uphill under load. I daily drove my car the last three summers, anything over 110 degrees you have to keep a close eye on the coolant temps.

This was during the 120 degree week we had last summer. 🔥

What did your coolant temp due when it was over 110 degree's? Your OIL temp in that picture looks totally normal, especially with 122F outside temp!

[WOLFN8TR]

In 120 degree temps I was running around 205 degrees on the freeway and around 215-220 under load up a incline. I usually shut off the AC on the inclines in those extreme temps.

[S14]

In 120 degree temps I was running around 205 degrees on the freeway and around 215-220 under load up a incline. I usually shut off the AC on the inclines in those extreme temps.

The photo you show is the engine oil temp gauge. How are you sourcing your engine coolant temp numbers?

[COVID-19]

The photo you show is the engine oil temp gauge. How are you sourcing your engine coolant temp numbers?

You can check it on the hidden OBC menu.

[WOLFN8TR]

[S14]

oooh, that's neat.

What is your stock coolant gauge doing when 205F what about 215-220?

My coolant guage is ticking over to the right dot at and indicated 185. I don't think that's correct.

[0-60motorsports]

In 120 degree temps I was running around 205 degrees on the freeway and around 215-220 under load up a incline. I usually shut off the AC on the inclines in those extreme temps.

You shouldnt have to. My car used to perform flawlessly in 125f+ temps with high humidity until recently where i have had a coolant temp issue with AC on if outside temps are above 104F

[Zekarus]

I'm on vacation and it's my first hot summer and I have the exact same behaviour. Will install a new radiator and a spal fan with the N15 design brackets when I'm back home.

I'm also experiencing that the water temp will go to the left when I'm off throttle and driving a long road down.

[8000RPM]

I want to bump this up again. I’ve spent some more time in the car and have more info to add.

The temperature will creep under load even when its not hot outside. It has the same characteristics no matter the temperature (80F - 110+F). Going down a hill, the temperature will even dip below middle point of the gauge. You can see the gauge climb under load and drop going down a hill. So the temperature swing happens quickly. Would this be a sign the thermostat isn’t doing its job?

BTW, I have a foxwell handheld to backup the temperature gauge. I’ve never had this problem on an M before and its driving me crazy.

Reminder on what I’ve done:

1. New Saleri water pump (metal impeller)
2. New Borg Warner thermostat
3. Full cooling system flush with distilled water/BMW blue (radiator, block, hoses, heater core); no grit or particles in flush
4. New upper and lower VNE temp sensors
5. Original radiator
6. New OE Mahle fan clutch
7. Tested front electric fan with scanner at multiple speeds and works properly

[COVID-19]

My vote still goes to the radiator.

[0-60motorsports]

I want to bump this up again. I’ve spent some more time in the car and have more info to add.

The temperature will creep under load even when its not hot outside. It has the same characteristics no matter the temperature (80F - 110+F). Going down a hill, the temperature will even dip below middle point of the gauge. You can see the gauge climb under load and drop going down a hill. So the temperature swing happens quickly. Would this be a sign the thermostat isn’t doing its job?

BTW, I have a foxwell handheld to backup the temperature gauge. I’ve never had this problem on an M before and its driving me crazy.

Reminder on what I’ve done:

1. New Saleri water pump (metal impeller)
2. New Borg Warner thermostat
3. Full cooling system flush with distilled water/BMW blue (radiator, block, hoses, heater core); no grit or particles in flush
4. New upper and lower VNE temp sensors
5. Original radiator
6. New OE Mahle fan clutch
7. Tested front electric fan with scanner at multiple speeds and works properly

Same here. I just installed the main coolant sensor under the airbox but ran out of time so I’ll be buttoning up the car on Monday and then will test. Maybe it’s a blessing issue. I am not sure either.