Temperature creep under load

[0-60motorsports]

Well guys, SSDD is all I have to say.

The only thing not changed is the radiator that has 40,000 km on it, it looks brand new and wasn’t even dirty but I cleaned it any way. I am at a loss. I don’t know what to do. I have changed every single cooling component on the car and it still over heats with AC on and under load. Car has 70,000 km on it.

[WOLFN8TR]

My car used to perform flawlessly in 125f+ temps with high humidity until recently where I have had a coolant temp issue with AC on if outside temps are above 104F

Well guys, SSDD is all I have to say.

The only thing not changed is the radiator that has 40,000 km on it, it looks brand new and wasn’t even dirty but I cleaned it any way. I am at a loss. I don’t know what to do. I have changed every single cooling component on the car and it still over heats with AC on and under load. Car has 70,000 km on it.

What temps are you seeing when it's overheating? Are you seeing overheating during normal driving on the freeway under load or up a steep grade under load?

I can idle all day long with the AC on with outside temps of 120. On the freeway my coolant temps are approx 200-205. On the freeway up a steep grade under load temps are approx 210-220 with the AC on, that's where I seen my temp creep. I usually shut off the AC when temps go over 220 because OCD kicks in LoL.

I did have an issue when I refreshed my cooling system which was caused by an undersized O-ring on the suction side of the water pump which caused the system to over pressurize. This caused all kinds of issues which led me to putting together the Hi-Temp O-ring Kits.

https://nam3forum.com/forums/forum/c...cooling-system

[0-60motorsports]

What temps are you seeing when it's overheating? Are you seeing overheating during normal driving on the freeway under load or up a steep grade under load?

I can idle all day long with the AC on with outside temps of 120. On the freeway my coolant temps are approx 200-205. On the freeway up a steep grade under load temps are approx 210-220 with the AC on, that's where I seen my temp creep. I usually shut off the AC when temps go over 220 because OCD kicks in LoL.

I did have an issue when I refreshed my cooling system which was caused by an undersized O-ring on the suction side of the water pump which caused the system to over pressurize. This caused all kinds of issues which led me to putting together the Hi-Temp O-ring Kits.

https://nam3forum.com/forums/forum/c...cooling-system

The temp goes up only when ac is on, standing still and under load. I already have the O ring kit from you so I should be good in that regard.

So I’ll give you an example: today at around 8:45am it was 41c and the car was going over the half way mark for the water temps standing still with AC on....meaning water temps 95c as displayed on the bluebus and gauge just starting to move past half way mark.

It wasn’t even the hottest time of day, which would be after 11am till about 4-5pm. We’ll be checking again in about 2-3 hours but I am sure it’ll be the same frakin result. I’m getting so tired of this.


I am going to change out the dryer today possibly and then check how the car is tomorrow in the afternoon. Let’s see what happens when we recover the AC gas today and see if it is low or normal. The AC performance is perfectly fine.

[WOLFN8TR]

Interesting. I had this same issue on my old Chevy 1500 years ago. It was a set of power pulleys that were causing the issue. The under sized water pump pulley was the problem.

If the dryer doesn’t fix the issue I wonder if the AC compressor is going bad causing more of a load on the system when the clutch engages on the compressor?

[0-60motorsports]

Interesting. I had this same issue on my old Chevy 1500 years ago. It was a set of power pulleys that were causing the issue. The under sized water pump pulley was the problem.

If the dryer doesn’t fix the issue I wonder if the AC compressor is going bad causing more of a load on the system when the clutch engages on the compressor?

Yeah we will check it out. Denso compressors online from ecs and fcp and pretty affordable but if I do the compressor I’ll do the ac evaporator as well just to have the comfort of it being completely new and nice. Let’s see what tomorrow turns up if anything.

[Johnvu]

I remember reading on M3F that the Saleri/aftermarket water pumps don't move the coolant as well as the OEM pumps. Something to do with the internal fin design not being as efficient. Here is a link to M3Cutters that references M3F: https://forums.m3cutters.co.uk/threa...er-pump.40701/

I was going to go the aftermarket route for cooling but after reading so many horror stories, and experiencing issues with aftermarket components myself, I will just pay the price for OEM. I am not one to just spend money when a perfectly good aftermarket variant is available, however for things like valve clover gaskets, or critical components, the S54 really does need OEM parts.

This won't be easy but try swapping out the pump to an OEM version and see if that solves your issues. This is obviously a last resort, due to the amount of work. Keep us updated and good luck!

Edit - I just realized you have the OEM clutch fan. I had the same overheating issues with mine until I swapped it out for the Mishimoto electric fan kit. That has solved all of my problems even in 112 F weather with AC on full blast, and it does not over-cool either. I would try this first then swap the water pump.

[0-60motorsports]

I remember reading on M3F that the Saleri/aftermarket water pumps don't move the coolant as well as the OEM pumps. Something to do with the internal fin design not being as efficient. Here is a link to M3Cutters that references M3F: https://forums.m3cutters.co.uk/threa...er-pump.40701/

I was going to go the aftermarket route for cooling but after reading so many horror stories, and experiencing issues with aftermarket components myself, I will just pay the price for OEM. I am not one to just spend money when a perfectly good aftermarket variant is available, however for things like valve clover gaskets, or critical components, the S54 really does need OEM parts.

This won't be easy but try swapping out the pump to an OEM version and see if that solves your issues. This is obviously a last resort, due to the amount of work. Keep us updated and good luck!

Edit - I just realized you have the OEM clutch fan. I had the same overheating issues with mine until I swapped it out for the Mishimoto electric fan kit. That has solved all of my problems even in 112 F weather with AC on full blast, and it does not over-cool either. I would try this first then swap the water pump.

Thanks for the insight in the pump. I’ll check it out. Electric fans do not do the job in our water vs a fan clutch.

[0-60motorsports]

One of my friends was just telling me that the radiator has a valve on it and it can be bled by unscrewing it. Is that true guys?

I don’t recall seeing anything on the radiator itself, only the bleeder screw in the top radiator hose.

[WOLFN8TR]

No valve just the bleed screw on the top of the radiator hose.

[0-60motorsports]

Ok today's update is that after monitoring AC pressure during warm up and overheating the pressure goes UP. So first thing to be changed and easiest will be the drier and Expansion valve (later). I will be picking up the drier today. Updates to come by Saturday or Sunday.

[WOLFN8TR]

Good Luck...🤙

[8000RPM]

I’m interested in seeing how this goes!

Ok today's update is that after monitoring AC pressure during warm up and overheating the pressure goes UP. So first thing to be changed and easiest will be the drier and Expansion valve (later). I will be picking up the drier today. Updates to come by Saturday or Sunday.

[0-60motorsports]

Won’t know till Saturday noon time. Will update.


Sent from my iPhone using Tapatalk

[8000RPM]

Quick update: I did a compression check on the engine today. All cylinder psi consistent across the board.

1. 152
2. 151
3. 154
4. 151
5. 150
6. 154

The AC is cold in the cabin but I can hear the compressor cycle on/off a lot. I’m wondering if its the compressor causing drag on the motor after all?

I still need to install my new radiator, I’ll do that sometime tomorrow along with cleaning out the AC condenser.

To the op. I would recomend that you pressure test the coolant circuit, test the coolant for combustion gasses and peer down each cylinder looking for a super clean piston crown.
Possible headgasket breach...small at this time.

[old///MFanatic]

Well not that this would be a fix (but a mask) for the issue. But BMW Motorsport makes a 55° thermostat instead of the 80° for anyone who might actually need it for their driving needs. I had it in my car years ago but changed it back since it was doing more street driving than track. part number 11-53-1-417-215

This would just open sooner but would not likely fix someone having issues with lacking heat transfer from a system that had a part not functioning correctly.