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

[tnord]

I don't know that much about how the DME works in this application, but on my old race car we had to run HUGE radiators that you might find on like a full ton diesel truck. Reason being the stock computer would pull timing very aggressively at temps above like 205. No idea if that's a feature built into the BMW DME, but if it was disabled that's another pathway to running hotter than normal.

A restriction in the radiator is a restriction in the radiator and it would still be a problem at 6k rpm or 8k rpm. Same with the thermostat, but I'd still gut that thing on a track-only car just to remove the failure point.

[Obioban]

Is this a track car only? If so, you can gut the thermostat. Most of us did that on our SCCA cars, or just take it out entirely. I haven't looked at how the M3 thermostat is integrated so it may not be possible.

The other thing is on the tune, a lean condition makes the car run hotter. Check around for leaks past whatever air metering you have, or if the tune disabled knock sensors so it could run leaner that would be a problem too. I would suspect something other than the radiator.

The one on track engine failure TTFS (custom dyne) tune I have seen had the knock values turned way down, despite the owner requesting a safety over power tune-- and detonation was what led to his engine failure.

[tnord]

Is this a track car only? If so, you can gut the thermostat. Most of us did that on our SCCA cars, or just take it out entirely. I haven't looked at how the M3 thermostat is integrated so it may not be possible.

The other thing is on the tune, a lean condition makes the car run hotter. Check around for leaks past whatever air metering you have, or if the tune disabled knock sensors so it could run leaner that would be a problem too. I would suspect something other than the radiator with it being limited to higher RPMs. Could be fueling too if it's a lean condition causing the problem.

Stock water pump? High rpms can cause cavitation on an incorrectly designed impeller.

[BigRussia]

Do you happen to have a datalogger? I haven't had a chance to sit down and sift through some old sessions but my oil temps are running higher on the CSF cooler. This may sound dumb but the first thing that I would check are your underdrive pulley's and t-stat. Someone here may be able to correct me but a sticking t-stat will not throw any codes. I went through hell bleeding, re-bleeding, bleeding, x20 when I did a cooling system refresh (with a high quality aftermarket radiator) and ended up having to vacuum bleed the system (should have done it the first time) to get all the air out. You can get to the t-stat in minutes (considering you are running an e-fan) so that is a quick, but messy check. Boil it.

I wish I had more data on aftermarket parts vs. the OE parts so I could impart some advice but people with way more experience with this car swear by the cooling efficiency of the stock system, so I would defer to them.

I am in a similar situation as you are with respect to A/C. I am in NC and the car is driven to the track and back, so deleting the A/C is not worth the weight savings on a 92 degree day with %80 humidity, unless you want to go to a full cooling solution or die.

No no datalogger I was going to ask for suggestions on how to get one and set it up to watch the true water temps next time at the track. But honestly i dont think ill be able to hit the track again till I get this problem figured out.

I hope someone can chime in as well about the sticking t-stat not throwing a code, cause Im still leaning that might be my issue.. but yeah again no codes at all anytime I check for faults!

Agree on the A/C, Im in SFL and doing anything that comprises the cooling power of my A/C is a non starter for me haha

[Slonik]

do you have any faults on auxiliary water pump?
if you didn't tried it, i guess that this is it.

[Fresh1179]

Do you happen to have a datalogger? I haven't had a chance to sit down and sift through some old sessions but my oil temps are running higher on the CSF cooler. This may sound dumb but the first thing that I would check are your underdrive pulley's and t-stat. Someone here may be able to correct me but a sticking t-stat will not throw any codes. I went through hell bleeding, re-bleeding, bleeding, x20 when I did a cooling system refresh (with a high quality aftermarket radiator) and ended up having to vacuum bleed the system (should have done it the first time) to get all the air out. You can get to the t-stat in minutes (considering you are running an e-fan) so that is a quick, but messy check. Boil it.

I wish I had more data on aftermarket parts vs. the OE parts so I could impart some advice but people with way more experience with this car swear by the cooling efficiency of the stock system, so I would defer to them.

I am in a similar situation as you are with respect to A/C. I am in NC and the car is driven to the track and back, so deleting the A/C is not worth the weight savings on a 92 degree day with %80 humidity, unless you want to go to a full cooling solution or die.

[BigRussia]

Hey all sorry for the late response, work has been hectic and havent been able to check back here. Im going to try and respond to everyone's points as well as I can!

Obioban You and the others could be onto something about the TTFS tune... but since I got the car tuned, I've done 2 track days (Homestead and PBIR), 1 drag strip night with 4 passes, and 1 autox with it before these last two track days that I had high water temp. I cant say for certain if my water temps were dead center during those previous events, but def not like what happened in late November that made me make this thread. Unfortunately I dont have a stock tune to flash back to, my car came with the ancient AA tune from the previous owner, and the tune I had before the custom TTFS was Buildjournal's B-Spec...
I also posted the dyno graph, to show the AFRs, its a photo of the monitor so kinda grainy.

enjoy_m3 Yup did the bleed with ignition on 2 and heater running at max heat. Bled multiple times, with the front of the car raised, bleeder screw open, heater running, for at least 10 minutes. No bubbles whatsoever. And yes I actually do have underdrive pulleys, car came with AA power pulleys, but again these have been on the car my entire ownership. And yeah on M3Cutters is where I saw all the scary blown HG stuff lol. When i saw how thin the HG material between the bores was I was convinced that mightve been my issue, but alas solid compression!

I'm thinking as due diligence to have the entire cooling system looked over, especially water pump, thermostat, and if theres any clogs or blockages.

thegenius46m Yup i mentioned in my earlier post I did a full coolant flush, including the block drain plug. 1L BMW coolant, 1 bottle of RL water wetter, and the rest distilled water. My math isnt great but I assume that's at least 80/20, maybe closer 90/10? The CSF rad also came on the car from previous owner, so has been on the car my entire ownership. I can check when he bought it? It was around 2016 IIRC, is that within the time frame of those that had defects/issues?

Estoril Hmm i thought I had mentioned in my OP, but yeah the major running hot track day was this past November, on a fairly cool by SFL standard day and had rained earlier and was cloudy so ambient temps were good. Def not the hottest day at the track for the car. The early Feb most recent track day was also rainy but nothing crazy warm, maybe low 80s max. I tracked the car a couple summers ago in June and didnt see the water temp issue im seeing now (but may have been before the TTFS tune...)

[Estoril]

Shouldn’t matter with a healthy stock cooling system and good tune.

Agree - but he isn't on a stock system. On his setup - it does matter.

It would be helpful to know the baseline problem temperature to understand it in context. Temps in FL right now shouldn't be all that high.

[Obioban]

OP: you shouldn’t be tracking on that tune, if you don’t wanna pop your engine, you should get rid of that either way. But, I suspect you’ll want a stock rad, too.

[Obioban]

OP: You might mention the high ambient temp you are overheating at.

Shouldn’t matter with a healthy stock cooling system and good tune.

[Estoril]

OP: You might mention the high ambient temp you are overheating at.

[The M]

My OE radiator runs my car super cool at Sebring. Fellow E46ers with CSFs seem to always get really hot when ambient temps are mid 80s and hotter. Can you swap an OE rad in just to make sure?

[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.

[Estoril]

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

[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.😕