E36 Coolant temp weird problem?

[dirtdiggler]

Ok I just refreshed my whole engine gaskets/cooling system ect and put a aftermarket temp gauge in my car. The sender was put in the right side of the thermostat housing but driving on the street it gets up to 210 just normal driving? The weird part is I put a lower temp fan switch 80c 176 degrees and it comes on right about the time the gauge hits 210 degrees. I understand the gauge sender is right next to the head and the fan switch is in the radiator so they will be slightly different but it seems like a big difference?

I just thought it should sit about 195 and I don't want to damage anything, By the way I am also still using the stock clutch fan if that matters?

Could the gauge be wrong? anyone else have their sender in the same location and what are your normal driving temps?

[Carpy2]

With AC on sitting in 90F+ traffic my coolant temps sit anywhere between 200 and 230. At the track, in 90F+ conditions at high altitude I run anywhere from 230-240 degrees coolant, and about the same for oil temperature even with an oil cooler.

My experience has been that the stock buffered gauge in the cluster begins to move past half way at ~230 degrees, and stops at the 3/4 line at ~245. I monitor my coolant temps and make sure I don't go over 250 degrees (or my stock gauge doesn't go past the 3/4 mark). That's with 50/50 water/coolant with the 80c thermostat and lower temp fan switch, no clutch fan, and I removed the AUX fan and replaced with a Spal 16" puller fan.

Normally I run way more water with a bottle of water wetter during track season (only 10-25% coolant), but I've been lazy these first few sessions so I'm seeing the higher temps listed above. No Issue, 210 is perfectly fine.

[dirtdiggler]

With AC on sitting in 90F+ traffic my coolant temps sit anywhere between 200 and 230. At the track, in 90F+ conditions at high altitude I run anywhere from 230-240 degrees coolant, and about the same for oil temperature even with an oil cooler.

My experience has been that the stock buffered gauge in the cluster begins to move past half way at ~230 degrees, and stops at the 3/4 line at ~245. I monitor my coolant temps and make sure I don't go over 250 degrees (or my stock gauge doesn't go past the 3/4 mark). That's with 50/50 water/coolant with the 80c thermostat and lower temp fan switch, no clutch fan, and I removed the AUX fan and replaced with a Spal 16" puller fan.

Normally I run way more water with a bottle of water wetter during track season (only 10-25% coolant), but I've been lazy these first few sessions so I'm seeing the higher temps listed above. No Issue, 210 is perfectly fine.

Ok thanks that makes me feel much better, I have never ran a gauge so I have never really know the actual temps. My weather right now is about 90+ and I am at about 2600 feet and using about 75 water and 25 coolant do you think water wetter helps at all?

Going to be doing a track day really soon so I would like to hear at about what temp would everyone stop for a cool down?

[Carpy2]

I do a cool down lap or two when my coolant hits 240F (basically when the stock gauge looks like it wants to go past 3/4 way). Is it better to run your car cooler and take more cool down laps? Yes, but it's up to your discretion, imo 240F and below is A-Okay. If you want to stay at 230F and below, that's fine, no need to risk anything on an open lapping day since there's no F1 scouts or trophies at the end At 5300ft, with my oil cooler, my coolant temperature is the limiting factor, my oil never goes over 240F.

I think 75 water and 25 coolant is perfect, and yes, water wetter definitely helps. I always do a bottle of water wetter when I do a coolant flush. If I'm running more than 75% water, I run two bottles of water wetter. I can be out there balls to the walls for about 25 minutes straight without cooling issues, then I use the last 5 minutes to do two cool down laps (we generally do 4x 30 minute sessions here on open lapping days, unless there's only like 10 people then we have the full 4 hours to do whatever). I've done a multiple 45+ minute sessions with just the last 5 minutes as cool down sitting at the temps described above (240F coolant, 240F oil) with no issues.

Letting your car idle for a minute or two in the pits helps cool your car down as well when you are done/in between sessions. The key to good coolant temps is a reliable fan (clutch fan is nice to keep in there for redundancy, but not required), 50% or more water, a clean radiator, and good ducting to your radiator. Just some metal baffles to help force air from your kidneys and front grill to your radiator makes a big big difference if you find you need it. NeilM on the forums here has posted pictures of his radiator baffle, I like the design a lot and will be copying some of it sometime this season.

Technically, if you live in a place that never sees temps below freezing (or don't mind doing a coolant flush twice a year), there's nothing wrong with running 100% water, that will have a much better cooling capacity than any water/coolant mix. Since I'm in CO, the winters here suck and I'm pretty lazy so I run 50/50 and try to get away with it as long as I can during the summer lol. But I'm sure you're fine, and since you have an actual temp gauge (good move, I was also surprised once I installed one how much it varies, but the oem gauge never moves), you can keep track yourself and see how your cooling system is performing.

[DrftKingIII]

I have the my sensor directly in my cylinder head next to the factory water temperature probe. Putting around town (here in South Texas where it's very warm) I'll see temperatures fluctuate between 195-210. I have the 80/88* fan switch as well and it kicks on my big SPAL puller around 204-206 cylinder head temperature. Using an infrared thermometer I've read the side of the radiator and fan switch sensor and it would be in the high 170's/low 180's so it seems that the system is all operating properly.

Up to speed on the track, in 110* ambient, it's never gone above 218 and even that is on the warmer side for my preference, so I'm working on a remedy for that.

When you say that the sensor is on the thermostat housing, do you mean right side as if you're standing in front of the car and looking at the engine or the other way around? If it is on the passenger side of the thermostat housing, I'd be sort of concerned as that's the cold side, letting in water that is just cooled by the radiator and in theory is the coldest the water is in the entire system.

Do you still have the factory fan shroud with your clutch fan?

[fbirch]

My car has no AC cooler in front of the radiator, the slightly thicker OEM radiator, Euro E36 M3 OEM oil cooler mounted under the radiator, OEM mechanical fan with factory shroud and fairly decent shrouding around the radiator/oil cooler inlet. To get accurate temps on the hot side, I bought an inline coupler with a threaded hole for a temp sensor. I cut the radiator inlet hose mid span and inserted the coupler with temp sensor installed, wired to an Autometer gauge. Down here in south Louisiana, it gets quite hot and humid in the summer. At a test and tune day earlier this week, ambient temps were around 90 F and it can get into the upper 90's F later in the summer. Summertime water temps run about 190 - 195 F on track and maybe 205 -210 F if it sits idling in the paddock.

[olemiss540]

Did you replace the fan clutch as well hopefully? Make sure the motor mounts are nice and tight to prevent it from hitting your radiator/hood and exploding. Street driving can actually be tougher on a cooling system IMO due to AC use, lower speeds, and sitting in traffic. Mine runs 180-185 with the LS swap but I believe it's mainly due to no AC, no AC fan/shroud, and hood venting.

[jayjaya29]

Everything is working as intended on your car. I have an aftermarket temp gauge with the sender in the side of the head and the lower 80c fan switch. The fan kicks on when I see 210 on the aftermarket gauge. At steady state highway cruising the gauge reads about 190f (88c thermostat), in traffic it will creep up to 210 then the fans kick on and it will cool back down to 190f.

The fan switch is on the cold side of the radiator and you are measuring the hot coolant coming out from the engine. You're looking at the temperature differential across the radiator.

[Z-Thrizzle]

I found that having the temp sensor by the right side of the thermostat to not be really helpful. I have a sensor in the head and the cool side of the radiator. The temps there have been consistent and made sense.

[dirtdiggler]

Thanks everyone for all your help, I am guessing that where I have the sender is at the hottest place to measure temp. I went for a long drive in hot weather and it never went over 210 so I am guessing if I had a problem it would have kept going up and up but it didn't

For on track is water wetter really worth it? I track in 100f +

[aeronaut]

My personal experience with water wetter is that it made no difference in coolant temperature. This was on track, thermostat open, back to back sessions, one with 100% water, one with WW added. Exact same peak and stable temperature reached both sessions. BUT, I still run a little bit of WW for the anti-corrosion properties.

[Haifisch M3]

210 is OK in my book, 230 and up I would stay away from.
Maybe I'm wrong ...anybody know at which temp the head-gasket lets go?

[jayjaya29]

maybe i'm wrong ...anybody know at which temp the head-gasket lets go?

240f

[aeronaut]

That feels about right. I went higher once (skidpad, no fans, 7000rpm @ 6.7 mph, was laughing too much to worry about the flashing lights). It didn't blow a gasket, but I felt very lucky.
Yea, 210 is a non issue.

[ewrjontan]

Sorry to thread jack. But I’m a little curious. My sensor is on the right (drivers) side of the thermostat as well, measuring the hottest coolant. Track days I’ve always tried to keep under 220 but it basically means 1 hard lap, followed by a cool down lap or two. Street temps hover around 195-208 or so.

I am worried about head gasket failure so I have my gauge to warn me at 220 but when you say head gasket failure around 240 degrees, we are talking block temp not head temp right? So my measured 220 degrees after the thermostat is in theory a good bit under 220. Does that mean I should up my warning to about 235 or so?

[olemiss540]

I personally wouldn't want to routinely run over 220-230 or you are setting yourself up for a HG replacement IMO. My personal experience is that the car with the proper equipment and ducting in place should have no issues running in this region even on track during summertime heat unless there are other issues.

Try running straight water and water wetter instead of coolant mix. Eliminate as much shrouding behind the radiator (spal fan conversion) and ensure as much shrouding in front of the radiator. Upsized radiator, upgraded Stewart pump are much cheaper than replacing HG's.

[ScotcH]

Yeah, a proper street setup can work, but really for hot track days, it's marginal at best. A fully race prepped setup, on worst case conditions (street course, concrete walls, in traffic), our e46 sees 95C max (203 F). On wide open tracks, with low traffic, I struggle to keep it above 70C (160F), where our "warm-up" map end.

On our e36 with s54, it seems to run 95-100C all the time, regardless of conditions ... that setup is basically OEM style, just with a huge PWR rad, and race thermostat.

Front ducting to the rad is SUPER important. Also, mesh in the grill will really impact cooling ... we had it on the lower grill, a 1/4" wire mesh, and once removed, it brought down temps 15C. We believe it is because it causes turbulence in front of the rad, and so not as much air makes it cleanly through it. Putting the mash right in front of the rad is much better, but obviously the rock protection is severely compromised ... But just another data point, that something so simple can make such a difference.

[ewrjontan]

Yeah, a proper street setup can work, but really for hot track days, it's marginal at best. A fully race prepped setup, on worst case conditions (street course, concrete walls, in traffic), our e46 sees 95C max (203 F). On wide open tracks, with low traffic, I struggle to keep it above 70C (160F), where our "warm-up" map end.

On our e36 with s54, it seems to run 95-100C all the time, regardless of conditions ... that setup is basically OEM style, just with a huge PWR rad, and race thermostat.

Front ducting to the rad is SUPER important. Also, mesh in the grill will really impact cooling ... we had it on the lower grill, a 1/4" wire mesh, and once removed, it brought down temps 15C. We believe it is because it causes turbulence in front of the rad, and so not as much air makes it cleanly through it. Putting the mash right in front of the rad is much better, but obviously the rock protection is severely compromised ... But just another data point, that something so simple can make such a difference.

Super interesting. Can’t believe the mesh makes that much of a difference. I am running an oem pump, oem thermostat and a z3 m radiator with no ducting. I have a motion motor sports underpanel and it sounds like grabbing their radiator baffle is the way to go.

Before replacing my oem radiator with the z3 s54 one (which is a tad shorter but thicker) temps seemed a little lower so I guess some baffling would certainly make a difference.