Oh noes another m50 overheating

[Mde36]

Well I have a vanos m50 and I'm using the m20 radiator. About 2 weeks ago my radiator decided to a meeting with the mechanical fan and it stripped off all the blades. There was no damage done to the radiator but the fan was basically a spinning nub. So I decided to go electric. Got a 16in Spal puller fan and installed it. Now on cool days (like the last few we had in Maryland 50's an 60's) the car ran right at the halfway mark as long as I was moving. When I was stopped for any period of time it would slowly start to heat up to the point where it was at the 3/4 mark on the temp gauge. On warmer days like yesterday and today (70's an 80's) it overheats much faster whether im moving or sitting still. It seems kinda backwards that when the engine isn't underload it overheats faster than when the rpm are up.

Has anyone had this issue and if so what is it and how do you fix it.

[FredK]

How is the Spal controlled? Did you just use the stock aux fan wiring? If so, it's entirely likely you'll have to use a lower temperature electric thermostat.

There are two effects at play here in terms of engine heat. When it is idling, it isn't producing much heat. When it's running on the highway, it is producing a lot of heat. The ability of the engine to shed heat depends on air passing through the radiator.

So, as you can imagine, even though there isn't much heat being generated at idle, there also isn't much air passing through the radiator. On the highway, plenty of air is passing through the radiator.

[Mde36]

The fan is simply wired to ignition so when the car is on it's running. I thought about a lower t-stat but when it's cold here I didn't want the car to run under operating temp.

[FredK]

How many CFM is that fan?

[Mde36]

how many cfm is that fan?

1300 cfm

[FredK]

I'm guessing you deleted the stock aux pusher fan? If so, 1300 CFM is too small.

[Mde36]

no stock fan is still there and functional. How much air does the mechanical fan move?

[FredK]

Is there any way that the fan is running in reverse right now? I run only a stock aux fan and I'm usually right in the middle, even if it's around 75 - 80 outside.

Are you sure the aux fan works?

[Mde36]

As of a few weeks ago yea it still worked but when I go on lunch from work I will check again as well as take a few photos. As far as the spinning direction of the fan it only goes one direction. There was just a power and a ground to wire it up.

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[MattM]

ive got twin 12" pumping 3000CFM through my rad, the temp guage drops like a rock when they kick in. my temp stays dead center sometimes creeps a notch to the right.

They usually come on after idle for 2 - 3 minutes, go off shortly after i get moving again.

[Mde36]

ive got twin 12" pumping 3000CFM through my rad, the temp guage drops like a rock when they kick in. my temp stays dead center sometimes creeps a notch to the right.

They usually come on after idle for 2 - 3 minutes, go off shortly after i get moving again.

So im trying to decide on a fix for this before sunday so I can make blown euros:

Either get a larger fan but clearance it already tight.

Get the aux fan back working but I don't know why it isn't working anyway

or

Go lower t-stat but I don't know how that would affect winter driving. (If I go out early in the morning when temps are still in the 40's or lower it actually runs a notch to the left for a while, then starts to overheat.)

[rosphill]

I am wanting to install a Spal 16 inch pusher fan 2700 CFM on my M50 swap, but trying to decide on what thermostat 75C or 80C ??
Does the 75C thermo make the heater not work as quickly/efficently in wintertime?
Can the stock pusher fan in front of the evaporator be replaced with just a large Spal fan?

[Mde36]

well I hoped that my thermostat was the reason it was overheating so I changed it out in the parking lot of the store for a 75 C. During the day it didn't overheat...as fast but it still made it's way to the 3/4 mark by the time I made it home. Checked the aux fan it doesn't work. So now i'm trying to trace that issue either the fan switch or the relay on the fan. so I'm just going to change both. Is there a local store that would sell the correct part? Checked the usuals AZ and AA but neither had it.

[MR E30 325is]

You have a bentley??

You can close the circuit on the electrical connector that connects to your thermostat on the passenger side. I think its brown to black for low speed.

I did that, and wired in a switch, so when the temp gets high i flick the switch and the aux fan comes on. Got rid of my overheating problems in my old M50 E30