Cooling system struggles

[samthejam]

Newspaper? What's that? lol

dust off the playboys

[bigjae46]

dust off the playboys

Why would you ruin a playboy by sticking it in a fan?

[BTB]

Is consensus that OE is the best overall cooling package for street/track with A/C? Tired of having needle creep in hot Central Texas with A/C on. I have Bimmerworld C&R rad and Mishimoto electric fan, considering doing a refresh with all new OE (maybe aluminum expansion tank?). My heater hasn't been working recently so I may have an air bubble/leak somewhere, would like to get the car as close to bulletproof as possible. For what it's worth I've done a couple track days in fairly hot >90 F Texas weather and no issues at all, though no A/C running

[Dave092]

Is consensus that OE is the best overall cooling package for street/track with A/C? Tired of having needle creep in hot Central Texas with A/C on. I have Bimmerworld C&R rad and Mishimoto electric fan, considering doing a refresh with all new OE (maybe aluminum expansion tank?). My heater hasn't been working recently so I may have an air bubble/leak somewhere, would like to get the car as close to bulletproof as possible. For what it's worth I've done a couple track days in fairly hot >90 F Texas weather and no issues at all, though no A/C running

I do know that the overall consensus is that all OEM new cooling system components is the way to go for most use cases. What I don't know still is what the actual acceptable temperature range for coolant on these cars is. Considering the gauge will start to creep at 203F but many say it shouldn't creep I'm starting to think nobody really knows because 203F seems very very safe as far as I've always known.

[moproblems]

I do know that the overall consensus is that all OEM new cooling system components is the way to go for most use cases. What I don't know still is what the actual acceptable temperature range for coolant on these cars is. Considering the gauge will start to creep at 203F but many say it shouldn't creep I'm starting to think nobody really knows because 203F seems very very safe as far as I've always known.

Yeah my coolant temp on track was up towards the line between center and red and was extremely worried but then I realized that was barely 100c. Not really much of a worry. Still replacing everything anyways.

[dreamdrivedrift]

I have the same experience
Full OE setup: BMW radiator, OE water pump, 60/40 water/coolant + water wetter.

Multiple push laps shifting at redline at Laguna when weather is warm and it will be in the red, around 215F
I'll back off around there
Cooler weather it does OK
Thunderhill it does fine lap after lap

The problem with Mt Baldy is probably the altitude
I think really depends on air flow - don't think the E46 design flows air well enough

Possible solutions you can do:
Increase water/coolant ratio
Water wetter
Hood venting
Upgraded radiator: DO88, PWR. NOT CSF (that is 1000000% worse than OE)

[Mike RT4]

Another thing to check for is hydrocarbons in the coolant. S54s are known for doing headgaskets and this pressurises the coolant system and can give the symptoms you describe. Something that can then be eliminated very easily. If you have a failing head gasket, it doesn't matter how good your cooling system is, or what changes you make to it, it wil always overheat on WOT and cool back down quickly as soon as you get off the throttle.

Also the BMW gauge is just that (and a very rough "gauge" of the temps). I always monitor the temps on track via the OBD and iBus (displayed on my Avin 4). In the UK, it very rarely goes above 25°C, where I am seeing consistant high 80s/low 90°C (standard BMW set-up). HOWEVER, when on track, I remove the front number plate so that the front bumper has a completely unobstructed flow of air through it. I have always done this though, so not sure how beneficial it is, but it makes sense to not disrupt the flow to the radiator / oil cooler.

[prostcfc]

I was hitting the right-most dot this past weekend during afternoon HPDE sessions. Oil temps were left of the right-most dot. My phone said ambient temp was 85F though the car said 95F, so who knows. It was warmer than every HPDE I did last year. It would spike after the last straight and into a slow corner, and would slowly drop over the course of the lap until I hit the next straight; short shifting didn't change anything.

Car has 96k, and afaik has the same cooling system as when it rolled off the assembly line, so I think replacement is in order. Knowing that the right dot is still considered "normal", I wasn't too fussed about it, though I kept an eye on it, so lap times suffered.

[ramzM3]

I was hitting the right-most dot this past weekend during afternoon HPDE sessions. Oil temps were left of the right-most dot. My phone said ambient temp was 85F though the car said 95F, so who knows. It was warmer than every HPDE I did last year. It would spike after the last straight and into a slow corner, and would slowly drop over the course of the lap until I hit the next straight; short shifting didn't change anything.

Car has 96k, and afaik has the same cooling system as when it rolled off the assembly line, so I think replacement is in order. Knowing that the right dot is still considered "normal", I wasn't too fussed about it, though I kept an eye on it, so lap times suffered.

Knowing the right dot is considered "normal", is that a new thing? IDK, my car is a street driven car I've had for 16 yrs and it didn't used to go past center, except on occasion, just ever so slightly, on the hottest Florida days, but now, I'm having it go up to the right dot and a little more, in stop and go traffic on hot days more often than I can count on all my fingers and toes. I think that I either have some air in the system from when some cooling system parts were replaced and the system wasn't properly bled or some other component is failing and I just haven't found out which one yet. I've had the following components replaced over the past 5-6 yrs: fan clutch, fan blade, thermostat, water temp sensor, coolant expansion tank, water pipe O-ring, aux fan switch, lower radiator hose and coolant(a gallon at a time, when the lower radiator hose, coolant expansion tank, and coolant temp sensor were replaced).

[prostcfc]

Knowing the right dot is considered "normal", is that a new thing? IDK, my car is a street driven car I've had for 16 yrs and it didn't used to go past center, except on occasion, just ever so slightly, on the hottest Florida days, but now, I'm having it go up to the right dot and a little more, in stop and go traffic on hot days more often than I can count on all my fingers and toes. I think that I either have some air in the system from when some cooling system parts were replaced and the system wasn't properly bled or some other component is failing and I just haven't found out which one yet. I've had the following components replaced over the past 5-6 yrs: fan clutch, fan blade, thermostat, water temp sensor, coolant expansion tank, water pipe O-ring, aux fan switch, lower radiator hose and coolant(a gallon at a time, when the lower radiator hose, coolant expansion tank, and coolant temp sensor were replaced).

The manual says it's "normal" though I've only had it on hot track days. Normal driving I'm closer to the left dot and idling the center. I'm in the Chicago area so it's not oppressively hot here constantly.

[Pklauser]

The manual says it's "normal" though I've only had it on hot track days. Normal driving I'm closer to the left dot and idling the center. I'm in the Chicago area so it's not oppressively hot here constantly.

Glad this got attached. It's always been interesting to me that BMW says reaching the edge of the red is normal.

I've been facing hot water temps on track for years now. It doesn't even have to be very hot ambient for me to have issues. It was 90F at VIR yesterday and I was getting up to 107C and having to let off to cool down. Towards the end of the day I was running the heat, which seemed to help a bit.

I'm on new OE everything in the last couple years. Debating throwing a Do88 radiator at the problem and seeing if it helps.

I may also take off the mech fan today for science. Thinking that at speed all it does is impede air flow.

Also worth mentioning that by "OE", I'm on the new NRF radiator that comes instead of Modine now. Still not totally convinced it's a good part.

[OldRanger]

I may also take off the mech fan today for science. Thinking that at speed all it does is impede air flow.

Pklauser - both you and the OP have mentioned this. I never considered this. How about the radiator shroud for the OEM fan and the two side pieces?

(For track cars - I just assumed folks were taking off the OEM and replacing with an electric for reasons other than improved cooling)

[Altaran]

Pklauser - both you and the OP have mentioned this. I never considered this. How about the radiator shroud for the OEM fan and the two side pieces?

(For track cars - I just assumed folks were taking off the OEM and replacing with an electric for reasons other than improved cooling)

I took the whole thing off (mech fan and shroud) and am only running a spal fan. I measure my coolant temps directly, and those are stable at around 80°C (last week on the ring at 36°C ambient temps). But I do run without AC and no aux fan. Radiator and thermostat are stock.

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[Pklauser]

So I ended up not having time to pull the mech fan at the track today, science will have to wait.

In the meantime, can someone explain to me why we have the mech fan anyway? Is it a failsafe? I'm confused because the clutch seems set to clutch up only at very high temps. On old-school bimmers, the clutch fan was the primary cooling fan, and the efan was really just for AC, or high coolant temps when idling. On the E46 M3, the efan seems to be used as the primary cooling fan, and I never hear the clutch fan clutch up.

EDIT: Also, what temps do people see cruising at various ambient temps? At 80F, my coolant temps hover around 90C. Since the thermostat is rated to 80C, 90C seems high to me, but I'm not sure if this is just a factor of where the measurement is being made, or if I have something else going on here.

[bigjae46]

I had an electric fan on the back of the radiator - I would run at 185 for coolant temps. Removed the fan AND and now I run 170-175. Maybe 180-185 on really hot days and longer sessions. Yes, removing the fan significantly improved the coolant temps when paired with hood vents and relocating an aluminum expansion tank to the drug bin. Also consider that my CSF radiator is likely at the end of its life - lots of oil, grim, dirt, and stuff in it. I've cleaned it which helps but only so much. I used to run a whole session without the thermostat opening for any extended period of time in colder weather - used to run 170-ish in any condition.

Here are the downsides to removing the fan.

1. Need to be careful idling.

2. Need a lot more headroom between the operating temp and boiling point. Temps will spike if you come to a stop - go off and stall the car, red flag and stop on track, etc. A higher pressure cap helps - probably should install an aluminum expansion tank and eliminate as much plastic as you can or replace more often. Really need to be running in the 180s. I think coolant temps shot up to 223f during a red flag from (I think) the 170s - wasn't that hot out. So if you're running at 200 without a fan...you're asking for trouble.

3. Need to have a deliberate cool down lap. This is a much bigger issue at MSR Cresson which is a 1.7 mile course. COTA, not as bad as long as they throw the checker at Turn 11. Altaran on the Nurburgring on a tourist day lap - that could be an issue unless you back out well before getting onto the straight.

4. Oil temps will take longer to warm up. A LOT longer with a t-stat bypass in the oil filter housing.

5. Coolant temps will climb if you closely follow a car for awhile.

Removing all of the fans is not the first thing you should do, probably should be the last thing. There is management involved and very bad outcomes if it is not managed properly.

Other things in order based on my opinion:

1. remove AC condensor and pusher fan
2. cap the heater core feed and return (not looping...cap - costs $2 + high temp JB weld)
3. aluminum expansion tank
4. relocate tank to drug bin
5. hood vents - add a gurney flap for more extraction from engine bay (I verified - this works)
6. remove puller fan

On another note, I use a $1 freeze plug to cap the water pump. One the pipe that bolts to the head, I cut the end off, drill out the hole and insert another $1 freeze plug. I applied high temp JB weld to make sure the plugs don't pop out. I wish I could have found an aluminum freeze plug so I could tack weld the freeze plug in place.