e36 water tempature on track

I tracked my 97 M3 for the first time last month.  I was watching the water temp with a bluetooth OBD scanner.  A few laps into the session it would would be pretty steady at 220 and towards the end of a 25 or minute session it would hit 225 before dropping back to 220.  Ambient temp was in the mid 80s.

This seemed a little high, so I replaced my mostly missing undertray with an aluminum one, added some ducting under the radiator, sealed every gap I could find with foam and rebled the system.  Didn't seem to have any air in it.  I also added an oil temp and pressure gauge.  Water temp gauge didn't show up in time.

This weekend, I was at the track again and the car ran hotter.  Ambient temps were in the mid 90s.  After a few laps it would hold pretty steady at 230.  I would normally take a cool down lap once I saw 230.  I couple times though, I started a lap at 230 and saw 234 at the highest.  The dashboard temp gauge only moved when I got over 230, otherwise it was dead center.  Oil temps seemed a bit high at 260-270 but oil pressure seemed around where it was supposed to be, around 60psi on track, 10-15 at idle when hot.

On cool down laps, the temperature almost immediately started dropping.  If I hit traffic and backed off early and did a full lap at reduced pace, the temperature would fall to under 220.  Coming off track by the time I got to my parking spot, it was under 200.  Idling the car is at 188-190 and usually holds 194 during regular driving.

I've done just about everything I can think of short of hood vents or removing the AC fan and condenser.  I have a Mishimoto radiator, efan, and their expansion tank.  Stewart water pump, 80c thermostat.  I've ducted and sealed the radiator.  I'm running probably 80% water and water wetter.  The system holds pressure, when tested there is no exhaust gas in the coolant, oil analysis doesn't show any coolant in the oil.

I'm not sure what the next move is.  Reading around the internet you'll find people saying Mishimoto is worse than stock, you'll find people saying they run it in every car they have.  You'll see people say these engines run hot and 230-240 is perfectly normal but then there are people saying their car never gets over 200.

Temperatures here will be a lot closer to 110 if I do another track day this summer.  I'm willing to replace everything with OEM and see if it makes a difference but would like to get some more input.

Following because I'm interested in tracking my e36.

Seems like a silly suggestion, but do you have the upper radiator ducting attached? 

Yeah Mishimoto radiators are built around bargain-bin cores so it may not be a cooling upgrade even with extra rows(!), and their fan assemblies like many "racing" fan setups are really badly designed, with an extra-thin fan with flat blades and no shroud. These types of fan setups tend to cause cooling issues at least up to highway speeds. You don't want to run a thinner fan than necessary and shrouds are good.

The fact that it cools quickly on cooldown laps shows that the thermostat is working well and the problem is that the cooling system can't get rid of the heat as quickly as the engine generates it. Over 220 definitely seems too high for that car. If I had to guess at what you should try, it would be 1) Make sure all ducting is in place and 2) Get a better fan setup with the thickest shrouded fan(s) you can fit, that Mishimoto fan will only give you a sporting chance at not overheating in the pits.

In reply to EchoTreeSix :

The plastic that covers the core support and tops of the radiator and condenser?  I have it. I also have the plastic or rubber bits that seals up the sides of radiator.

In reply to GameboyRMH :

Ducting should be better than stock.  Looking thru the front of the bumper cover at the radiator, you can't see much without shining a light in there.  The bottom is of the grill to AC condenser is sealed with hvac sheet metal, as is the gap between the condenser and radiator.  The sides and top are sealed by the factory plastic bits.

I'd hate to have to go back the clutch fan.  It's so nice to be able to just pull the efan out if I need more room to do something.  I leaning towards doing the Z3m radiator, so I might have to do it anyways since I think I'm going to have to use the OEM shroud to mount the expansion tank.

Call BimmerWorld.  The cheap upgrade radiator is <90 bucks. 

And you get gummy bears.  

In reply to czerka :

Maybe take the stock mechanical fan's shroud and stuff the biggest thickest electric fan you can fit in there?

The mechanical fan on these moves a ton of air. I would leave it as long as it's working. 
 

I put a spal on my E36 and it was a big mistake. Awful compared to the mech fan. 

czerka said:

In reply to GameboyRMH :

Ducting should be better than stock.  Looking thru the front of the bumper cover at the radiator, you can't see much without shining a light in there.  The bottom is of the grill to AC condenser is sealed with hvac sheet metal, as is the gap between the condenser and radiator.  The sides and top are sealed by the factory plastic bits.

Is anything obstructing the exit of the heated air?

In reply to jmabarone :

The CSF one with plastic end tanks?

I might get the aluminum CSF radiator.  It'll set me up for a oil cooler down the road, looks like it has similar mounting tabs so I can use my current fan and expansion tank and it's closer in price to the OE z3m radiator versus the OEM one.

In reply to GameboyRMH :

There isn't much room for a bigger efan.  There is probably less than half an inch of clearance from where the mechanical would thread on to the current efans motor.

In reply to spandak :

Ah, that's disappointing.

In reply to L5wolvesf :

Other than the electrical fan and its bracket, no.  The engine is right there though.  I could see hood vents making a big difference in flow.

I'm thinking the move is to, swap radiators and see if that makes any difference on a back road on a hot day.  If not, put in a mechanical fan.  If that doesn't do it, cut the hood.  The OEM z3m radiator is $600 and sounds like it is getting close to being no longer available and is currently back ordered on FCP, the OE one is $200.  Both have plastic end tanks and I think I'm going to have to use a OEM fan shroud to mount the expansion tank which is going to add another $150 or so.  Versus an aluminum CSF radiator which is about $300 and I think I can reuse my current fan and expansion tank.

I cracked the head and blew a headgasket at 245 on my S52, so do please be careful.

Stock mech fan hurts horsepower but is a HUGE upgrade over pretty much any aftermarket setup on these.

Definitely leave the OEM clutch fan in place.  Do you have the MZ3 S54 radiator?  Everything ducted and sealed up?  Chances are you've already damaged the head gasket.  My 98 M3 was totally fine driving on the street and then after one track day it pressurized the over flow tank = blown head gasket.  Luckily no damage to the head.

In reply to docwyte :

The clutch fan had already been removed when got the car.  Car currently has a mishimoto radiator, I'm debating either trying another aluminum radiator from CSF or paying the premium for a OEM mz3 radiator, fan shroud, expansion tank and putting a clutch fan back in.  By the time I do all that, I'd have spent enough to put in one of Zionvilles options. 

Before cutting up the hood, does the hinge bolt to the hood in such a way that you could stick a 1" or so stack of washers between it and the hood to raise the back?

This helps extract air from underhood.  You can turd polish and stick yarn to the back of the hood and see which way it goes at speed... if the high pressure air at the base of the windshield is higher pressure than the underhood area and the air goes the wrong way, tape off the back.  The air will still vent out the sides.  For extra turd buffing action, put yarn all across the width, you may find if it goes the wrong way that it only does so in the middle half of the hood.

With a front hinged hood, I used to pop it on the highway on hot days.  At 80mph the underhood pressure would push the back up a couple inches!  This on a different chassis of course, but data is useful to get and washers and longer bolts are a cheap way to see if you are going in the right direction.

The cars stock were made to go at high speed indefinitely, after all... they may have required the clutch fan to help scoot things through.

What's your airdam situation?  If the car is lowered you may need a deeper airdam under the radiator, too, to get back some forced lower pressure behind the radiator under the car.

Another thing to try... short shift and see if temps drop.  It still may be a coolant issue, if the radiator is too restrictive then the water pump may be cavitating at higher speeds.  Cavitating pumps flow less and the lower speeds when you let off may be allowing the coolant to work, if it's dropping really fast after you back off.

I mean, if you wanted to really, really over engineer a testing rig you could check what the water pressure is on the inlet of the water pump 

In reply to Pete. (l33t FS) :

https://youtu.be/ZYsocpb_RJU?si=nQerDbPUsCbbO0dU

Here is a video of one of the sessions. Coming out of the grid car is at 192. About 10 minutes in it's 220s. Around 15 minutes I start a cool down and it immediately begins to drop. 

From the video it's pretty clear that the fan is a problem, especially from how slow it is to cool down when you take a gentle cooldown lap and go into the pits at the end.

I have not read the whole thread as I am away from home atm, but having the same issues. 

See my thread on this here - ‘97 M3

I have an S53 Z3M radiator and the biggest Spal you can fit (the water pump snout had to be machined to fit)  2300 CFM

Looking at going back to the clutched fan ... that means a new Stewart pump as I machined the threads off. PITA bit I think its the only way to survive the Florida heat. 

Guessing its not a fan issue since its cooling down at lower speeds well. Hate to say the worst, but if the system is up to date (and it sounds like it is), guessing you have a minor HG issue which is pretty common. Did you ever have an overheat condition prior to redoing the old cooling system? 

I really like the s54 oil filter housing/s54 oil cooler/s54mcoupe radiator setup. Cooling the oil will really help take the load off of the radiator. Also like the self bleeding e30 coolant reservior versus dealing with the BS stock bleeding proceedure and adds some volume to the system.

Have any residual pressure in the coolant cap once it cools down overnight by chance??

I'd also recommend calling Bimmerworld for a consult.  I've tracked my E36 M3 in hot weather and never had an issue with the stock setup, other than the frequent proactive replacement regimen.  

In reply to Olemiss540 :

I guessing it's not the fan either.  There are plenty of e36s on track without fans.

I've always worried about the head gasket.

It has overheated.  Going over a bump cracked the hose neck for the upper radiator hose.  Fortunately, I was really close to home and got it parked before anything happened.  I thought maybe I could get away with just tightening down the hose a little more than normal.  Next time I drove it, I got a few miles down the road and the hose loosened up.  I noticed it right away, got turned around and got some speed, and turned the car off and coasted as far I could.  Waited half an hour or so and did that again.  I've never seen any symptoms of a bad head gasket though and thought I got away with it.  Coolant has never been detected in a oil analysis, exhaust gas has never been detected in the coolant, coolant system holds pressure and doesn't bubble once it's bled.  Maybe that is what's going on though.

How hard is it to remove the fan?

If it's easy, take it off for one of your track sessions.  The fan just gets in the way of airflow at highway speeds.  See if your temps stay lower.  If so, put on the factory fan.

Edit to add...  is your electric fan turning the correct direction?

P.s. I have never met an electric fan that I liked for track use.

You want the stock clutched fan.  Yes, you've probably already cooked the head gasket.  At this point, I'd just pull the head, send it to a machine shop to have them check it for cracks and warping, then put in a new gasket and rebuild.

To explain why I think the fan is an issue, look at this cooldown lap for comparison. This is with a stock radiator fan assembly with 2 thick electric fans, but also an original 1-row radiator that's decades old. Also this ECU tune had a "hot spot" in it around 4krpm at medium/low load. I don't have a record of the ambient temp that day but it's generally in the 80F-91F range.

Pete. (l33t FS) said:

Before cutting up the hood, does the hinge bolt to the hood in such a way that you could stick a 1" or so stack of washers between it and the hood to raise the back?

 

This helps extract air from underhood.  You can turd polish and stick yarn to the back of the hood and see which way it goes at speed... if the high pressure air at the base of the windshield is higher pressure than the underhood area and the air goes the wrong way, tape off the back.  The air will still vent out the sides.  For extra turd buffing action, put yarn all across the width, you may find if it goes the wrong way that it only does so in the middle half of the hood.

 

With a front hinged hood, I used to pop it on the highway on hot days.  At 80mph the underhood pressure would push the back up a couple inches!  This on a different chassis of course, but data is useful to get and washers and longer bolts are a cheap way to see if you are going in the right direction.

 

The cars stock were made to go at high speed indefinitely, after all... they may have required the clutch fan to help scoot things through.

 

What's your airdam situation?  If the car is lowered you may need a deeper airdam under the radiator, too, to get back some forced lower pressure behind the radiator under the car.

I thought raising the back of the hood made airflow worse because the base of the windshield is a high pressure zone?