Member
Recently swapped an S50 back into an M3 and I'm having the time of my life figuring out why it's overheating.
The engine never overheated before I pulled it, ever.
So far I have gone through 3 radiators, 2 thermostats, a new water pump, and 2 expansion tanks and I swapped the electric fan back out for the stock mechanical fan to try and sort out what is causing my issue.
Here is what I know.
- The coolant is bled (I'm pretty sure it is.)
- The aux fan does not come on because I don't have freon in the system and the bolt holding one of the ac lines onto the compressor is missing (but I don't see why the car would overheat without the aux fan.)
- The heat works and blows hot after bleeding it.
- I have about a 5x5 inch puddle that has made its way out of the exhaust.
Anyone have a similar problem?
Member
Does the puddle smell sweet like coolant (smell your fresh coolant to compare). Hopefully its just condensation leaving.
The aux fan does not rely on the AC system to work when controlling radiators temperature. To test that the fans work, unplug the sensor from the side of the rad, use a small wire to bridge the connector from center pin to one of the sides, then test to the other side (fan should come on).
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Member
Puddle didn't really have a smell and it dried fairly quick. So I think it may have been condensation.
Large Member
Under what circumstances doesit overheat? Can you give details?
Are there any blockages? Thermostat in the correct way?
Can you hook up a live data reader and watch the temp? Can you tell when the thermostat opens and coolant is flowing?
Member
Originally Posted by Auto Parts Guy
It's a fresh swap so Ive been just running it, haven't really driven it yet.
The thermostat is in the right way. Unfortunately, I do not have a live data reader.
It overheats after running for an extended period of time.
Member
does your plastic coolant tank show return to about the cold mark after running engine for extended period of time without removing cap?
i always have to bleed multiple times to achieve that.
smokes at gas stations
The aux fan does not rely on the A/C system being full.
When you swapped back to the mechanical fan, did you test the fan clutch?
Member
320i E36 1994, M50 engine
Mine had the coolant boiling and leaking out as it boiled. Turned out to be the clutch fan. Car had 121k miles on the clock which is about right for the part.
£30 of parts and 2 hours to swap (looked at the fan blades for 20 mins before I figured out I could palm bash the old clutch out) and test drive. No more boiling over.
Member
Turns out I had the coolant sensors on the head backwards, problem solved.
shade tree mechanic
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Moved from E36 forum to E36 M3 forum
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