Help diagnosing high water temps at track - Resolved? (not really!)

[BigRussia]

My 2004 M3 had a somewhat strange issue yesterday at the track with running hot. During a session when I started driving 10/10th and shifting at 8k redline I noticed my water temp had creeped up to the 3/4 mark after only a couple laps of really pushing the car, a little bit later it climbed more and touched the red zone of the water temp gauge (did not go into the red zone nor did the light turn on). Naturally I backed off and let the car cool down the rest of the session, once I did that the temps came back to just under the 3/4 dot.

Ive never had this issue any of the times I've taken the car to this same track, and the weather was cooler than usual and rainy. No leaks or issues with the cooling system when I returned to the garage, e-fan working, coolant expansion tank cap was dry and coolant level good. Everything seemed fine, so I went back out for a open session (where I could drive slowly with less cars), with the heater on and short shifting at 6k rpms the water temps never went past the 3/4 dot. So it was only when I would try to set a fast lap going 10/10th and redlining that the water temps got dangerously high going past 3/4.

My cars entire cooling system was refreshed in July 2016 (but less than 10,000 miles ago). New OEM water pump, thermo, coolant expansion tank, silicone hoses, CSF alum radiator, and Mishimoto e-fan. Any ideas of what could be the cause?

Update: Issue was resolved, see post #108 for details. It was the CSF radiator apparently.

07/22 Update #2: Issue not really resolved, while CSF radiator was big culprit, car still sees water temps climb on track. The quest continues!

[sapote]

How was the oil temp?
Either the engine had developed more friction on some critical moving parts (crank/rod bearings, pistons/cylinder walls), or something changed in the coolant system (radiator blocked with debris, rag; air in the system; thermostat not full open or wax motor electrical heater was bad). When it reach 100*C, grab the radiator lower hose and see how hot; if lukewarm then radiator has less flow.

[BigRussia]

How was the oil temp?
Either the engine had developed more friction on some critical moving parts (crank/rod bearings, pistons/cylinder walls), or something changed in the coolant system (radiator blocked with debris, rag; air in the system; thermostat not full open or wax motor electrical heater was bad). When it reach 100*C, grab the radiator lower hose and see how hot; if lukewarm then radiator has less flow.

Oil temps were pretty high when I was driving hard and pushing, got near the 3/4 dot (which I believe is around 250 F) but never touched or passed it. I have the CSF oil cooler as well, and pretty disappointed with it as I dont believe its done much to keep the max oil temps down (the stock one would get to around same temps). I think all it does is cool down quicker when I let off and let the car cool down. But I cant remember for sure if last time at the track with the CSF OC if the oil temps were slightly lower and then now this time, along w/ the high water temps, were higher than before..

I checked radiator front for blockages, there was no leaves or debris.

Yeah I am thinking it might be a combination of slightly lower than max coolant, and air in the system. After looking at the coolant dipstick in the expansion tank yesterday the top circle was just under the neck of the filler. Weirdly the dipstick only has one circle at the top, it doesn't have another to signify Max and Min levels like other BMWs. I tried finding a surefire answer but I guess the top circle just has to be flush with the filler neck? I posted pics of where it was sitting after the car was fully cooled down over night.

I'm going to do a fill and bleed today, but wont be able to really test unless I go out and drive the car hard on the street. As driving normally on the way home from track everything seemed fine.

Ive also suspected a sticky thermostat as well... but then the oil temps also seemed higher so now I'm worried could be more than that.

[Rich022]

Chances are you're just pushing the car harder / on the gas earlier. I went thru this same struggle this past summer and swapped out a bunch of parts with nothing to help on track coolant+oil temps.
Do you still have your AC? If so, I'm told removing the ac condenser is the biggest help in cooling. Higher coolant temps also affect oil temps. I don't want to remove AC and am thinking of going with hood vents.

[BigRussia]

Chances are you're just pushing the car harder / on the gas earlier. I went thru this same struggle this past summer and swapped out a bunch of parts with nothing to help on track coolant+oil temps.
Do you still have your AC? If so, I'm told removing the ac condenser is the biggest help in cooling. Higher coolant temps also affect oil temps. I don't want to remove AC and am thinking of going with hood vents.

Yeah I thought that too, but my lap times weren't even close to my previous PB lol. But track was also a bit damp on I was on street tires and pads this time so who knows in regard to that. I too thought maybe the higher water temps and hotter engine could be contributing to the higher oil temps.

Yes still have full A/C and other creature comforts, my cars is more of a street car that sees track time, than an all out stripped out track car. Living in sweltering South Florida removing A/C is a non starter.

[BigRussia]

Update to this ongoing running hot saga, as I am still trying to nail down and resolve this and would appreciate any insight:

After that last track day end of November in my original post I figured the coolant may be old and did a full flush, w/ 1L BMW coolant, 1 bottle Redline water wetter, and rest distilled water (so about 90:10) ratio, bled multiple times w front of car raised to get all the air out of the system. I also hosed down the front of the car both radiator and oil cooler in case of any debris, while the front bumper was off.

Went back to the track Feb 6th with cool weather, first session had just rained so on a wet track I took it easy and kept revs under 7k rpm and never downshifted past 3rd gear. Temps were fine and I was feeling confident to push next session.
Next session I push, 8k redline shifting and downshifts to 2nd on the slower corners, after a couple hard push laps water temp needle started climbing, and got neat the 3/4 dot until i decided to back off. So even fresh coolant with mostly distilled and water wetter was still not even enough to resolve this issue

I did more reading and researching and things starting pointing to a bad/failing headgasket. Even though the car runs flawlessly on the street with no issues after the two track days. Engine feels totally healthy and strong, no weird oil mix on dipstick, no smoking, and no fault codes pulled. But seeing pictures how thin the HG is between bores I saw how it could be possible, especially on an old high mileage motor that happens to be a long inline 6 with an aluminum head lol.

So I did a compression test, almost confident I will find 2 cylinders down on compression, which would be bittersweet (solves the mystery, but an expensive laborious job).
Test done with the engine warmed up, throttle open, 10 cranks each cylinder and these were my results:

Cyl 1: 175
Cyl 2: 175
Cyl 3: 180
Cyl 4: 180
Cyl 5: 180
Cyl 6: 180

Pretty damn good for a 180k+ mile motor, I should have been ecstatic but I wasn't... it was almost too good to be true, those numbers were so shocking.
So I redid every cylinder again, this time only 5 cranks and these were the results:

Cyl 1: 170
Cyl 2: 170
Cyl 3: 170
Cyl 4: 170
Cyl 5: 170
Cyl 6: 175

Again very consistent, so I will assume the headgasket is not the reason of the running hot issues. But the mystery still continues.

I'm starting to believe that being an older motor and getting tired, maybe just something inside is causing it naturally start running hotter from years of buildup, maybe some sludge or clogged oil passages? Ive been diligent with my oil changes, and I'm confident the PO i bought the car from was too, but who knows how the other owners were the previous 130,000 miles?

Not really sure what to try next, as mentioned before the car runs absolutely flawless on the streets, I can get on it for long periods of time without any issues. No missing, no hesitation, no cooling issues. These issues only come up on the track, and only when pushing hard.
Definitely would appreciate any ideas, only things I can think of is either faulty/sticking thermostat (but wouldn't that throw a code?), or maybe the mishimoto e-fan cant keep up? OEM Aux fan seems to be working too as I see it running when I pull into the garage.

[Obioban]

I bet if you put an OE rad in, you'd go back to trouble free operation. The fan isn't impactful at speed, so I wouldn't worry about that.

What's the tune situation on your car? I don't actually know how it works, but poor tuning can absolutely make it run hot.

[slavik1988]

I bet if you put an OE rad in, you'd go back to trouble free operation. The fan isn't impactful at speed, so I wouldn't worry about that.

What's the tune situation on your car? I don't actually know how it works, but poor tuning can absolutely make it run hot.

I am having the same issue with my car. New OE rad didn't help my situation. Went and bought a new A/C condenser over the winter since my fins are really damaged on my condenser. Haven't tested that just yet but hopefully this will resolve my issue. I only have 59k on mine.

[BigRussia]

I bet if you put an OE rad in, you'd go back to trouble free operation. The fan isn't impactful at speed, so I wouldn't worry about that.

What's the tune situation on your car? I don't actually know how it works, but poor tuning can absolutely make it run hot.

Yeah my thoughts as well on the fan since at track speed there's alot of air flow. Homestead Miami is a fairly high speed track, its an infield so all long straights to tight corners.

The tune is a custom TTFS, remote tuned by Frank himself with the car on the dyno. So I would figure its safer than an off the shelf tune? I was told the previous off the shelf tune I had was actually making a few cylinders run lean! I can post the TTFS dyno sheet if needed if you want to see the AFR's, this was back in May 2019 iirc.

[Obioban]

Yeah my thoughts as well on the fan since at track speed there's alot of air flow. Homestead Miami is a fairly high speed track, its an infield so all long straights to tight corners.

The tune is a custom TTFS, remote tuned by Frank himself with the car on the dyno. So I would figure its safer than an off the shelf tune? I was told the previous off the shelf tune I had was actually making a few cylinders run lean! I can post the TTFS dyno sheet if needed if you want to see the AFR's, this was back in May 2019 iirc.

Try flashing to to stock for an event and see how she does, before changing anything else. TTFS and track use... often don’t get along (I’ve had two friends have engine failure with their tunes on track, because of the tune). Both were custom dyno tunes.

[enjoy_m3]

You can try blasting the heater on at the track to see if it helps. If it does, you still may have air in the system. I'm also assuming you bled with heater core valve open? Do you happen to have underdrive pulleys? I experienced the coolant temp needle rising after putting the larger water pump pulley. Went back to stock and it fixed the problem. Also to add, plug an obd reader to see what are you actual coolant temps are. Mine would move past half before 3/4 but the obd was only reading 204 - 206 degrees. Sot it actually wasn't as serious. Also, just double check the water pump for any play. It's not common but I've seen water pumps fail prematurely, either bearing failed or plastic fins broke (again not common).

I haven't seen too many people in the US report failing head gaskets but the m3cutters forum seems to be more common. The head gasket actually fails between the cylinders, not near the coolant passages. The m3 guys in the UK say that a symptom would be low compression between 2 joining cylinders and can sometimes mimic a misfire.

Good luck! hope this helps and you resolve your issue without being too serious.

[thegenius46m]

Try flashing to to stock for an event and see how she does, before changing anything else. TTFS and track use... often don’t get along (I’ve had two friends have engine failure with their tunes on track, because of the tune).

Yup. Dump the TTFS tune. I've seen nothing but problems first hand with their tunes from precats being disabled entirely, drivability issues, etc. Also, up your water to coolant ratio to 80/20 if you havent already AND run the heater full blast during the session. My water temps never move past the middle on track and only oil creeps which will be addressed soon. Only other culprit could be the rad if it was one of the earlier CSF variants that had manufacturing defects that prevented coolant flow. Also do a leakdown test. That tells you a lot more than a compression test. Start with the water to coolant ratio first and drain the entire block not just the rad.

[slavik1988]

You can try blasting the heater on at the track to see if it helps. If it does, you still may have air in the system. I'm also assuming you bled with heater core valve open? Do you happen to have underdrive pulleys? I experienced the coolant temp needle rising after putting the larger water pump pulley. Went back to stock and it fixed the problem. Also to add, plug an obd reader to see what are you actual coolant temps are. Mine would move past half before 3/4 but the obd was only reading 204 - 206 degrees. Sot it actually wasn't as serious. Also, just double check the water pump for any play. It's not common but I've seen water pumps fail prematurely, either bearing failed or plastic fins broke (again not common).

I haven't seen too many people in the US report failing head gaskets but the m3cutters forum seems to be more common. The head gasket actually fails between the cylinders, not near the coolant passages. The m3 guys in the UK say that a symptom would be low compression between 2 joining cylinders and can sometimes mimic a misfire.

Good luck! hope this helps and you resolve your issue without being too serious.

Blasting the heat didn't help me to keep the temps down.😕

[Estoril]

My primary focus would be the non-OEM radiator choice.

[thegenius46m]

Blasting the heat didn't help me to keep the temps down.😕

That means you have a big restriction then. Make sure the tstat is opening and my first thought would be the radiator. Also are you running two fans? If so delete the aux fan and run just the rear electric fan. You're sacrificing a ton of airflow. Also check the ac condenser area for debris because that will also block a ton of airflow and make the cooling system have to work harder. Could also be air in the system, but you would have to have a massive amount because the S54 coolant tank is self bleeding (at a slow rate) so eventually the air should work its way out if its small.