M2 cooling challenge

[jimk]

Where was the temperature taken on the radiator? I ask because I think I see both the upper and lower radator hoses on the right side of the radiator. You can get "short circuited" water flow thru only the section of tubes on the right side of the radiator, thereby not get full use of it's cooling capability.

Unless it is a double-pass radiator, where the top and bottom sections are partitioned off.

This has top and bottom tanks. Plus I wouldn't think it is that sofisticated.

[Ian]

This has top and bottom tanks. Plus I wouldn't think it is that sofisticated.

Oops, good catch. I missed the top tank

[ahlem]

On our e30 M3 I was having problems overheating and found a PO removed the low/high thermo switch. Are you running a one speed fan? Is it turning on? If it isn't turning on you don't have coolant circulating by the switch.

[teeb]

So the first time I checked temps on the radiator, I did so at the top pass side, and bottom pass side. Hot, cold, respectively. The illustration of the double pass makes sense triggered something in my memory. Last attempt (after adding some Preston to the water) the driver side bottom of the radiator was hot. This was the first time I measured this, and it was hot. Hmmm...circulation issue?

I don't have the fan switches hooked up yet. I simply ran a toggle switch in the cockpit for the interim while sorting the systems. I wonder if I can pull some conductivity or current numbers off the switches to watch to see if it trips open? Maybe keep track of time and temps at the thermostat?

[jimk]

If there are no divider plates in the top and bottom tanks, it is not a multipass cooler. With the inlet/outlet arrangement, it would be a 3 pass if multipass.

[M3M3]

So the first time I checked temps on the radiator, I did so at the top pass side, and bottom pass side. Hot, cold, respectively. The illustration of the double pass makes sense triggered something in my memory. Last attempt (after adding some Preston to the water) the driver side bottom of the radiator was hot. This was the first time I measured this, and it was hot. Hmmm...circulation issue?

I don't have the fan switches hooked up yet. I simply ran a toggle switch in the cockpit for the interim while sorting the systems. I wonder if I can pull some conductivity or current numbers off the switches to watch to see if it trips open? Maybe keep track of time and temps at the thermostat?

s14 tstat has two ports on it. put fan switch in one of them and you can use the other for an extra temp gauge.

[Brendan]

With all the fanciness abounding here, I haven't heard anyone mention the heater core.

Did you open the valve for the heater or disconnect the hose at the core? That's the high point on my cooling system. If you didn't burp the core or open the valve, you may still have air in there that's moving around.

Brendan

[M3M3]

With all the fanciness abounding here, I haven't heard anyone mention the heater core.

Did you open the valve for the heater or disconnect the hose at the core? That's the high point on my cooling system. If you didn't burp the core or open the valve, you may still have air in there that's moving around.

Brendan

from the op's first post that started the thread

" It doesn't have the heater box lines hooked up"

[teeb]

Correct Marshall. I do not have the heater on line. I have the ability (hoses) to do so, it was a matter of really wanting to hear the engine roar ; ) I plan to include it in the system...

I really thinking the hose bends are reducing some of the flow. If you look at the casual loop Marshall created at the bottom of the radiator, it seems like a good idea. I just have a hard time thinking a slight 10% pinch on a lower hose could do this.

The head return line and no expansion tank adds complexity to solving this dynamic issue. It seems a lengthy deductive trial and error work day, and careful observation and notes might lick it.

More later.

[M3M3]

found a pic of my current configuration. the custom radiator had a straight back outlet and was more over to pass side of car so simplified the lower hose routing.

[teeb]

Problem solved!  The new M3 thermostat was working as per a boiling water sink test.  The issue was flow, even after a new water pump- I determined it must be in the thermostat.  I pulled it out of the system and it ran cool!  Problem solved!!  Thanks for all you words of wisdom!  It was a lucky find.  Not sure what would cause the low flow - but done!  I'll be at VIR this weekend! Let's hope I can resolve the clutch issue! ~ Teeb