Overheating, need some help

[Cobra1956]

Tracked again for 4 days this week. This was my first time out with the mechanical gauges installed. Oil pressure was @ 60 psi when on track but the pressure bounces a bit and I attribute that to the stupid BMW pump design as I do have baffles and an accumulator. The high pressure on start up pressure creates a bit of an issue for me as once hot the pressure drops to @ 20 psi at idle which then has the sump feeding the oil to the car. Will have to develop a way to close off the sump while still at speed during a cool down.

My coolant temp on Monday was high, north of 200 with the aluminum radiator. Tuesday through Thursday the gauge would not read much above the low reading of 140. So it my be the pump going or the thermostat, another wonderful design. I was also thinking that the adapter I put in the top hose might also be an issue of a restriction in the flow of coolant but the ambient temps were never over 70. Started getting high temp warning on the dash of yellow and then red. At red I backed out of it and turned the heat on full as I have no radiator fan in there now. Was wondering if the plumbing and the electrical are tied together and without fan you don't get much water pumps flow?

Steps for me at :

Verify gauge works ( this now is an almost certain confirm as the car says it's hot!)

Look into running without the gauge using my old upper hose to see if the fitting is restricting the flow. Have a spare upper hose to use for this.

Ran the car hard for the first time. Assuming this drives the trans fluid up and actually put more heat into the system. Have a trans cooler I plan to mount where the ac condenser currently sits.

Replace water pump and thermostat.


Any ideas or suggestions are appreciated.
Thank you!

[spidertri]

Random thoughts I have:

1) Did you do the water pump bleed procedure where it runs for 12mins and pushes all the air to the expansion tank?

2) Any coolant leaks or evidence of coolant leaks? Something not tightened enough, aluminum weld not holding?

3) When my water pump failed a couple years ago I knew there was an issue because the stock rad fan ramped up and stayed at full speed. Since you don't have the radiator fan, is that throwing the system for a loop?

4) The N55 water pump ground bolt is a known issue where it can break off. Maybe yours is partially gone? https://www.fcpeuro.com/blog/bmw-n55...lt-replacement

[Cobra1956]

Originally Posted by spidertri

Random thoughts I have:

1) Did you do the water pump bleed procedure where it runs for 12mins and pushes all the air to the expansion tank?

2) Any coolant leaks or evidence of coolant leaks? Something not tightened enough, aluminum weld not holding?

3) When my water pump failed a couple years ago I knew there was an issue because the stock rad fan ramped up and stayed at full speed. Since you don't have the radiator fan, is that throwing the system for a loop?

4) The N55 water pump ground bolt is a known issue where it can break off. Maybe yours is partially gone? https://www.fcpeuro.com/blog/bmw-n55...lt-replacement

Water pump bleed was done. No sign of leaking after any run. I can still bear what I think is the pump run for a few seconds after the car is shut off. If could be the thermostat as the gauge is not working but the gauge could be bad also as I keep forgetting the thermostat is not on top like normal cars.

My hood is not vented and since this car has panel under everything that should probably high on the list also. Should not need a fan since the car does not sit still once it is warm but willing to add a small one. I checked codes and found none that surprised me just cant think of why on this. On the e36 I ran kidney block off plates and never had an issue.

I keep looking at ideas so new path :
Therm did not think to shoot top hose with infrared but hose was hot.
Pump both done as normal maint
Hood vent
Fan

Will check the ground as power runs neg to pos. Will run bleed again.

[Mach8-0]

Interested to know the coolant mix you're using. Tracking in the California valley in summer the biggest difference came from switching to 90% distilled water and 10% OEM coolant plus a bottle of water wetter. Temps still climb up but the ability to shed heat has vastly improved even in 85+ degree ambient temps. That said, I also have a CSF dual core radiator and three rather sizable hood vents. No limp mode this season yet but the big test will be Buttonwillow or TH when ambients start to exceed ~90-95F...

Big dual oil coolers are my theoretical next step considering how much time the oil and coolant spend in close proximity to each other.

Fwiw I do run the MHD max cooling mode on track and it does seem to make a difference relative to how it acts on the street.

[Cobra1956]

Originally Posted by Mach8-0

Interested to know the coolant mix you're using. Tracking in the California valley in summer the biggest difference came from switching to 90% distilled water and 10% OEM coolant plus a bottle of water wetter. Temps still climb up but the ability to shed heat has vastly improved even in 85+ degree ambient temps. That said, I also have a CSF dual core radiator and three rather sizable hood vents. No limp mode this season yet but the big test will be Buttonwillow or TH when ambients start to exceed ~90-95F...

Big dual oil coolers are my theoretical next step considering how much time the oil and coolant spend in close proximity to each other.

Fwiw I do run the MHD max cooling mode on track and it does seem to make a difference relative to how it acts on the street.

Good info, thanks. I ran Evans in the last car and I think what is in the car now is close to a 50/50 mix. So I will up the distilled water. I have the CSF radiator. Ordered hood vents today and do think that improves the air flow a ton over the oem design. My mechanical gauge took a dump but the vendor shipped a new one today, but I am convinced the gauge is just a coincidence as it read high on a cool wet day not being driven aggressively. I have dual oil coolers and oil temps were normal. What I don't like it the oem thermostat settings that I think are fine on the street but a recipe for disaster on a track only car. Lots of extra heat being generated with nowhere for it to go. A fan should be no help at track speeds as the air flow produced by any sot of speed greatly exceeds any fan.
Ordered a pump and thermostat and will replace and play with the old unit and even use a flow limiter if necessary as this car is no longer street legal. There is an MHD tune on the car but it was not transferable so that issue may need some work in the future and I have considered getting a tune from Epic to see what can be done.

Since I had just installed the coolant gauge, thought it ran high but did not know if it is the pump or what. Convinced it is combination of therm, pump and air flow and will track again May 2 so I will have more to report back on then. How were you collecting your coolant temps or just monitoring the idiot lights on the dash? I had never seen the yellow or the red until last Thursday and have tracked the car a bit since November.

[Cobra1956]

Quick read on the MHD would lead me to ask how it affects anything since the thermostat is higher than you would like?

[Cobra1956]

Different engine but I think this gives you some insight, from Bimmerworld
BMW's M54 engine was a solid step forward in the development of power, efficiency, and lower emissions, but that lower emissions came at a price. The factory thermostat is electronically controlled to keep the engine running between 80-103°C, whereas we like to maintain 80°C or less for maximum power. The thermostat in this kit is set for 70°C. Additionally, the mechanical failsafe doesn't open up until the coolant temperature reaches 110°C, or 230°F, which is about the point when we turn our race cars off and park them - it's no wonder so many M54 engines get overheated and killed!

The Mishimoto M54 Competition Thermostat Plate Kit is designed to give the control of proper engine operating temperature back to the owner/builder by replacing the stock electronic thermostat with a manual unit (replaces BMW part no. 11 53 7 509 227). The thermostat in this kit is set for 70°C and cannot be changed. If you need one with a higher opening contact us for other options. A lower temp opening allows the engine to run at the proper, and much safer, operating temperature, improving engine longevity, reduces stress from high-temp operation, reduces heat soak, and increases power!

Cover on the sensor plug harness may require removal to clear the fan once installed. A trouble code will show up in your engine computer due to the absence of the electronic control, but this is only visible to a diagnostic tool, and does not show on the instrument cluster.

Notice of Emissions Non-Compliance. This product is intended only for vehicles that may never be used, or registered or licensed for use, upon a public highway. Removing, disabling, or altering emissions equipment on a pollution-controlled road vehicle is illegal. Installing devices or software that trick, disable, or modify emissions controls and monitors on a pollution-controlled road vehicle is also illegal. This product is sold only for racing, competition, track, hobby, or other off-road use. It is not legal for installation or use in California on any pollution controlled motor vehicle. It is not legal for installation or use on any pollution controlled motor vehicle in any state, province, or jurisdiction governed by, or which has adopted, CARB or EPA regulations. Some suppliers have shipping exceptions to certain states or territories, requiring extra delivery time. We will advise you of any delays.

[Mach8-0]

I am logging the temps through the MHD logger, I can send you a few if you're interested. I keep track of a lot of temperature parameters since this has been one of the biggest bottlenecks in terms of really pushing the car. It's is still fairly streetable but if I really wanted to go full tilt then removing the A/C condenser in the front would vastly improve airflow through the radiator. The other thing I am considering doing is removing or modifying the kidney ducts to route more air down behind the bumper bar. From factory they seem to be focused on directing more air up to the intake snorkels and it leaves a significant portion of the condenser and radiator hidden from frontal air loads.

I used to have vents cut in the belly pan just aft of the radiator to promote airflow out of the engine bay but the car was also starting to feel a little squirly at higher (140+) speeds and I can't imagine that was helping. A local show also destroyed the belly pan while doing an alignment (thanks Valley Motorwerks!)

I forgot to mention I'm on an N54 but close enough for the sake of comparison in this situation.

[Cobra1956]

Originally Posted by Mach8-0

I am logging the temps through the MHD logger, I can send you a few if you're interested. I keep track of a lot of temperature parameters since this has been one of the biggest bottlenecks in terms of really pushing the car. It's is still fairly streetable but if I really wanted to go full tilt then removing the A/C condenser in the front would vastly improve airflow through the radiator. The other thing I am considering doing is removing or modifying the kidney ducts to route more air down behind the bumper bar. From factory they seem to be focused on directing more air up to the intake snorkels and it leaves a significant portion of the condenser and radiator hidden from frontal air loads.

I used to have vents cut in the belly pan just aft of the radiator to promote airflow out of the engine bay but the car was also starting to feel a little squirly at higher (140+) speeds and I can't imagine that was helping. A local show also destroyed the belly pan while doing an alignment (thanks Valley Motorwerks!)

I forgot to mention I'm on an N54 but close enough for the sake of comparison in this situation.

On my s54 car I actually had the Kidneys blocked off and never had any issue in temps up to 100 with an 8500 red line. I think the thermostat is an issue as there will be tons of extra heat to get rid of and in a track setting you would not want the higher temp. I think the fact that there is something sold with lower temps by BW supports this but it could just be marketing also. I also think that taking a street car and using it in track situations as we do pushes the design parameters past what they design for in some cases. Since the electric portion of the thermostat is designed to open the flow at a lower temp based on load or speed this would support modifying the thermostat. I think this is added to the many ways mfgrs try to reach CAFE standards at the consumers expense. If I am correct then I can have the tuner adjust the fuel map later, I would think. Any info you log I would love to see. Does it show a drop in coolant somewhere in your track sessions?

[spidertri]

I have a 128 but I log my coolant temps on track and the thermostat always targets lower temps when pushing the car hard.

At CMP, sitting in grid before going out my coolant will be in the 207F range, once I'm on track at speed the temp drops to the 184F range (seen it as low as 172F). As soon as I start a cool down "lap" and drive normally the temp goes back up to the 207F range.

[Cobra1956]

Originally Posted by spidertri

I have a 128 but I log my coolant temps on track and the thermostat always targets lower temps when pushing the car hard.

At CMP, sitting in grid before going out my coolant will be in the 207F range, once I'm on track at speed the temp drops to the 184F range (seen it as low as 172F). As soon as I start a cool down "lap" and drive normally the temp goes back up to the 207F range.

Thank you. I was seeing much higher temps last monday with car being driven by a student in the wet. I was surprise at the mechanical temp readings which were north of 200. Think the gauge failing and the pump failing are just freak occurrences. What I have found is that the thermostat is higher than what you are reading. I think the 207 is what the thermostat is set at and I will assume that the map portion takes over and allows the thermostat to open early. Cool down lap might simulate no load so it reverts back to normal temps....I think. Will play with the old thermostat once I replace and consider just running a flow restrictor or drilling a few holes in the therm to help flow.
Appreciate the info!

[Cobra1956]

I have found a few map graphs but do not know if they are an accurate indication of the map BMW uses. If they are then it would appear that the high load regardless of speed would open the thermostat in the 85 to 90 F range or way lower than their mpg map. Hope the new parts correct and might also drill a hole or two in the actual thermostat to lower closed temps

[Cobra1956]

I have the pump and the thermostat replaced. The old parts appear to be working okay and will be saved as spares. Found a couple of codes but the only one that would pertain is no fan which is no issue. While in there we addressed a few air leaks in the intake and there was a code that was electrical that had me stumped as it says the ecu dropped power. The issue came to me on the way home. I had disconnected the battery in the trunk and just lowered the deck lid. The bouncing in the trailer causes the lid to lock and now I cant get at the battery. I use a jump box under the hood to power up the locks. This is what throws the code based on the way the ecu is powered so no issue there.

The thermostat housing is held together by three torx screws. It is sealed by a rubber gasket and an o ring and you can just pry it apart slowly so nothing gets destroyed. Once apart you can slowly work the thermostat off the heating element. I plan to test the element by applying voltage to the two pins and see what happens. My ultimate goal is to replace the oem thermostat with something that opens much lower, 180-190 range. I think this route would be better than running a restrictor as the car would still be subject to a near normal warm up on cold days. My assumptions are that once you are on the track you generate enough stimulus that the thermostat map would/should kick in opening the unit at a lower temp.

[Cobra1956]

Mishimoto Thermostats MMTS-E90-07




Fits in the plastic housing. 74c

You need to pull the center pin to get the pin from the housing to slide in. Question now is is it too low? It should help cool the dct also. Not for use on the street

[Cobra1956]

Quick update, the thermostat from Mishimoto failed to open in boiling water so it never made it to the car. They are sending me a replacement but it will have to pass the same test a frog would to be useful in the car. A little research found that the electric operation of the thermostat would cause the car to run much hotter than I would prefer and way higher than a track only car. Based on load, rpm, and oil temp the thermostat will open anywhere from @190 to 225f. This is also to be said to be the reason we do not have a coolant gauge as it would drive you nuts watching the huge swings. If addition the current situation and set up of my car could actually cause the thermostat to close during a cooldown lap as I already have dual oil coolers installed.
If the Mishimoto product does not work I have two work arounds, the first being to drill a few holes in the oem therm to allow some coolant to flow when close. The second is a mechanical thermostat number 33048. This opens at 180f and is just slightly larger than the oem unit but should be able to made fit in the housing.

[Cobra1956]

Okay, I was working on my IDIOT merit badge and it finally hit me as to why I am not getting the desired result with the OEM thermostat and the Mishimoto unit. The answer lies in the pictures of the oem thermostat two posts up. This thermostat will never open, nor will the replacement. I was too focused on the pin or post in the oem housing which works as a heater when triggered by the map. What I failed to realize is that like a conventional thermostat there is a pin of some sort but it pushes off a bridge and when the wax pellet expands the force against the bridge is what opens the thermostat. Normal mechanical thermostat with bridge. In our cars the housing serves as the bridge along with the heat source when the ecu says it's time to cool down. So by sitting there boiling water I would get nothing as the pin is most likely moving but against nothing.

Sewing the badge on now!



Housing in hot water just prior to boiling.



Daylight courtesy of the wide open thermostat