Coolant temp at track

[andrebxp]

I noticed a huge improvement in on-track cooling performance by ditching the aux fan + clutch fan and switching to an E46 non-m electric fan + shroud I had. A SPAL fan would probably be better but I didn't have one on hand.

They're actually the same fan motor just a different fan blade and shroud. The aux fan shroud is honestly pretty restrictive and I suspect that is why I had issues. Other than that my cooling system is all new OE front to back (40:60 coolant to water).

Ditching the aux fan probably isn't great for A/C performance but that is less important to me than cooling system performance.

[Casa de Mesa]

New OE.

I run an event every year that is 99-101F and do not have a problem. I run distilled water for safety.

I was out last weekend at 89F pushing hard and zero temp creep on 2-year old OE.

Hey nice pic BTW. I miss that big oak.

[Casa de Mesa]

Decided to do the cooling system refresh minus the radiator and also install the csf oil cooler. Updates + some driver mod should be sufficient for the next track day. I'll follow up at the end of the summer with updates.

Keep us posted. I refreshed mine about 2 years ago after my water pump took a nap at 55k miles. Pretty early for the E46 pumps...

Be careful with the #8 O-rings that the thermostat housing attaches to:
https://www.realoem.com/bmw/enUS/sho...diagId=11_3010

Part no: 11537830709

I thought I was super careful, but botched one on install. I reassembled everything (EVERYTHING), filled the coolant and watched it start draining out of that front O-ring that attaches to the thermostat housing. I'd buy a spare O-ring or two just in case...

[Estoril]

Also forgot to mention under drive pulleys were added recently. I’m guessing this exposed the cooling system issue as it’s the only real change that directly effects the cooling system.

Any recs on radiators?

New OE.

I run an event every year that is 99-101F and do not have a problem. I run distilled water for safety.

I was out last weekend at 89F pushing hard and zero temp creep on 2-year old OE.

[Obioban]

Decided to do the cooling system refresh minus the radiator and also install the csf oil cooler. Updates + some driver mod should be sufficient for the next track day. I'll follow up at the end of the summer with updates.

I have a <10,000 mile csf oil cooler for sale if you’re interested.

[jk715]

Decided to do the cooling system refresh minus the radiator and also install the csf oil cooler. Updates + some driver mod should be sufficient for the next track day. I'll follow up at the end of the summer with updates.

[sc_tr0jan_m3]

i had a summer event a few weeks ago and it was about high 90's on the track. my coolant temps raised between halfway and the 3/4ths dot. i was running in the advanced group and our sessions are typically 30 mins each stint. i'm overall pretty happy with the stable temps. when i pulled off the track, i'd drive at around 20 mphs around the paddock for a slow lap and the temps would drop pretty quickly.

[Casa de Mesa]

I'd bet the goop in question is actually the result of mixing coolant types-- not the water wetter.

All else equal, hotter coolant temps aren't inherently bad-- higher temps = more horse power and more efficiency. Out of control/spec temps are bad. I've never seen the appeal of race (or no) thermostats for that exact reason.

But, yes, if you're in a situation where you're otherwise overheating, I 100% agree water wetter is running too hot (or having to slow down the bring temps under control). If you're not allowed to run coolant, it is probably also the lesser evil.

Before changing anything, I think it's always best to figure out why factory the way it is. Water wetter certainly isn't new tech-- I was using it a decade ago on our e36 race car, and I'm sure it existed long before that. Yet, the tech hasn't been integrated into coolant, which would undoubted help the OEs from doing things like install 8 radiators (:cough: M4 :cough.

The cooling system on the stock e46 M3 is pretty great-- including in terms of air pressure, if you look at all the sealed off ducting going into it.

You're probably right on the goop, that was my first thought too.

Funny you say that re: thermostats. I've always run one and replace them every year. Without them, I've seen cars run too cool. We're on the total same page here - a cool motor with cool oil temps at race rpms is bad news.

My old man has one of those guilty-as-charged M4s. Sick car. He's 76 and drives it like Paul Newman.

[Obioban]

Here is what I know. Some cooling systems, even the best, will struggle with high intensity sprint races during higher ambient temps (140F track temps).

A quick tangent: In the particular system I'm thinking of, it has an aluminum C&R rad, 6.5qt oil pan plus a 3qt Accusump (~10 quarts with plumbing, the Accusump serves as an artificial radiator when not mounted in engine compartment), Sebco oil cooler, P/S cooler, a properly blocked off rad to funnel air to it, NO fan whatsoever (blocks airflow), and a giant splitter that forced air through the rad, to a large degree. A well sorted cooling system.

Water-only regularly saw temps 225 to 230 and would rise above that if you're in close quarters. I stopped using only water. With water + WW, maybe it sees 210F, but typically 200 or less. The issue with cooling systems designed to flow large volumes of air through them, get in behind a car for a couple laps and airflow is diminished, that system will struggle. That's where WW has helped me significantly lower water temps, when the cooling system is under pressure. It has helped with lower-than-50/50 mixes (call it 60/40) in HPDE cars, albeit not as much. You might see only a 10F decrease, but 220F sounds better than 230F.

One other tangent (I'm horrible at this): People often put larger rads on a car thinking more is better, but the air pressure isn't enough to flow through rad and all of a sudden, their car won't stay cool. The entire system needs to work as a system - weakest link and all that.

Having wrapped up my verbal diarrhea, I don't know the S54 platform on track. You certainly do. I've anecdotally heard 10W60 is hard to keep cooler, but sounds like that's not the case with a fresh cooling system. Go BMW, go.

In the short Googling I've done during lunch (the internet is always right), it sounds like some people have experienced "goop" in their cooling systems after adding WW. Goop doesn't sound great to me either, but it isn't deposits - heat transfer killing deposits. Ironically, in my Googling, the Toyota pink coolant kept popping up. It's not been my experience at all, with any coolant type, however.

The other things I know:
1) I know that I know less and less the older I get - right when I think I'm right, I'm proven wrong.

2) I love chasing stuff like this down and will keep diggin on this.

I'd bet the goop in question is actually the result of mixing coolant types-- not the water wetter.

All else equal, hotter coolant temps aren't inherently bad-- higher temps = more horse power and more efficiency. Out of control/spec temps are bad. I've never seen the appeal of race (or no) thermostats for that exact reason.

But, yes, if you're in a situation where you're otherwise overheating, I 100% agree water wetter is running too hot (or having to slow down the bring temps under control). If you're not allowed to run coolant, it is probably also the lesser evil.

Before changing anything, I think it's always best to figure out why factory the way it is. Water wetter certainly isn't new tech-- I was using it a decade ago on our e36 race car, and I'm sure it existed long before that. Yet, the tech hasn't been integrated into coolant, which would undoubted help the OEs from doing things like install 8 radiators (:cough: M4 :cough.

The cooling system on the stock e46 M3 is pretty great-- including in terms of air pressure, if you look at all the sealed off ducting going into it.

[Casa de Mesa]

It does help cooling system performance in the short term for sure. That's just only beneficial if you have a shortage of cooling system performance to start with-- which our car does not not, when everything is functioning a designed. I have also run it when coolant wasn't allowed.

But if you're tracking, where coolant is allowed, and don't NEED it, I don't want the tradeoffs associated with it.

Here is what I know. Some cooling systems, even the best, will struggle with high intensity sprint races during higher ambient temps (140F track temps).

A quick tangent: In the particular system I'm thinking of, it has an aluminum C&R rad, 6.5qt oil pan plus a 3qt Accusump (~10 quarts with plumbing, the Accusump serves as an artificial radiator when not mounted in engine compartment), Sebco oil cooler, P/S cooler, a properly blocked off rad to funnel air to it, NO fan whatsoever (blocks airflow), and a giant splitter that forced air through the rad, to a large degree. A well sorted cooling system.

Water-only regularly saw temps 225 to 230 and would rise above that if you're in close quarters. I stopped using only water. With water + WW, maybe it sees 210F, but typically 200 or less. The issue with cooling systems designed to flow large volumes of air through them, get in behind a car for a couple laps and airflow is diminished, that system will struggle. That's where WW has helped me significantly lower water temps, when the cooling system is under pressure. It has helped with lower-than-50/50 mixes (call it 60/40) in HPDE cars, albeit not as much. You might see only a 10F decrease, but 220F sounds better than 230F.

One other tangent (I'm horrible at this): People often put larger rads on a car thinking more is better, but the air pressure isn't enough to flow through rad and all of a sudden, their car won't stay cool. The entire system needs to work as a system - weakest link and all that.

Having wrapped up my verbal diarrhea, I don't know the S54 platform on track. You certainly do. I've anecdotally heard 10W60 is hard to keep cooler, but sounds like that's not the case with a fresh cooling system. Go BMW, go.

In the short Googling I've done during lunch (the internet is always right), it sounds like some people have experienced "goop" in their cooling systems after adding WW. Goop doesn't sound great to me either, but it isn't deposits - heat transfer killing deposits. Ironically, in my Googling, the Toyota pink coolant kept popping up. It's not been my experience at all, with any coolant type, however.

The other things I know:
1) I know that I know less and less the older I get - right when I think I'm right, I'm proven wrong.

2) I love chasing stuff like this down and will keep diggin on this.

[S14]

If your coolant temps are elevating, it’s time for a cooling system refresh. Stock/healthy, they don’t really move.

Don’t subject your engine to water wetter if you can avoid it.

Oil temps elevating on track is normal. Coolant is not.

what actual coolant temps are you seeing while on track?

[Obioban]

Interesting. Have never heard that before, I'll do some research on it. I've used it [successfully] in diesel and gas motors. Also daily drivers. It's been in a Toyota truck motor for 100k+ miles and hasn't caused issues. But it's a Toyota - it could probably use Budweiser for the cooling system and be fine.

In a water only track car (coolant isn't legal for use in most road race sanctioning bodies), it absolutely helps regardless of how robust a cooling system is, but you also typically flush the system at least once a season.

I'll look into this more.

It does help cooling system performance in the short term for sure. That's just only beneficial if you have a shortage of cooling system performance to start with-- which our car does not not, when everything is functioning a designed. I have also run it when coolant wasn't allowed.

But if you're tracking, where coolant is allowed, and don't NEED it, I don't want the tradeoffs associated with it.

[Casa de Mesa]

Over time it builds up deposits on the coolant passages in the engine and/or on cooling system components. As always, with such things, if it was "only better" it would just be part of coolant to start with.

Interesting. Have never heard that before, I'll do some research on it. I've used it [successfully] in diesel and gas motors. Also daily drivers. It's been in a Toyota truck motor for 100k+ miles and hasn't caused issues. But it's a Toyota - it could probably use Budweiser for the cooling system and be fine.

In a water only track car (coolant isn't legal for use in most road race sanctioning bodies), it absolutely helps regardless of how robust a cooling system is, but you also typically flush the system at least once a season.

I'll look into this more.

[Obioban]

Curious as to why? Been running it in an all-aluminum setup (block, heads, rad) for 20 years and never had a hint of an issue. I've had race engine builders recommend it. I've done this in 50/50 mix setups (coolant/water) and pure water + water wetter (or equivalent).

Over time it builds up deposits on the coolant passages in the engine and/or on cooling system components. As always, with such things, if it was "only better" it would just be part of coolant to start with.

Since our stock cooling system, when healthy, is more than adequate to keep coolant well within range in pretty much any conditions, no reason to use it.

When you say refresh, just changing certain things or do you mean an entire coolant refresh kit such as FCP offers?

Radiator
thermostat
water pump
fan clutch
tubing
o rings
temp sensor
coolant (Bmw mixed 50:50 with distilled water)

They all get used up at around the same age, so you might as well do it all at once. I’d only use the stock and clutch and water pump, and would only switch rads to aftermarket if going to Zionville.

[ViN]

If your coolant temps are elevating, it’s time for a cooling system refresh. Stock/healthy, they don’t really move.

Don’t subject your engine to water wetter if you can avoid it.

Oil temps elevating on track is normal. Coolant is not.

When you say refresh, just changing certain things or do you mean an entire coolant refresh kit such as FCP offers?