Overheating once again, this time after "Fan delete mod"

[Fusion]

So I was running the 88/92° tstat and switch during the wintertime and all was fine, sometimes the temp went a little over halfway, which was cured by manually tuning on slow or fast fan. I have a separate botton for each.

Now I decided to install the 80° tstat and switch, bled it, but now I have a problem. The temp is perfect while driving, no fan, 20°C outside its a little under halfway just the way I'd like it to be, sometimes it gets to halfway but drops again (thermostat opens probably).
The day of the install when I got home the temp went up to almost 3/4 mark, I manually turned on the fast speed fan, nothing much happened so I decided to turn the car off. With the old setup I would turn on the fan if it got hotter and the temp would drop after I revved the motor a bit. 30 seconds of high speed fan was all it needed.
Today I checked the coolant level before starting the car, added only a little that was missing. On the way home I stopped on the side of the road to see if it would heat again, but nothing. I sat there like five minutes, no fan, temp OK. Then I get home and again it starts to go heat up in the driveway, the same as last time, and again I end up turning it off with the temp at the 3/4 mark.

So now I have no idea what to do. I'm sure the tstat is OK, the sensor doesn't start the fan by itself, which I will check later, but I always did that manually. System should be bled well.
Any ideas?

[bejbis]

I manually turned on the fast speed fan, nothing much happened so I decided to turn the car off. With the old setup I would turn on the fan if it got hotter and the temp would drop after I revved the motor a bit. 30 seconds of high speed fan was all it needed.

System should be bled well.
Any ideas?

Just from that it really sounds like your waterpump may be cavitating. Could be caused by the impeller not being 'mated' to the shaft 100%, maybe having broken blades, or it still having air in the cooling system.

[MattM]

so you dont have any fan other then the manually activated highspeed one, and you expect to never have to turn it on? this is a false expectation. the radiator uses the cold air blowing through it to cool the car, its not nearly as effective when there is no air blowing past it, hence the reason to have some style of fan. Even brand new cars, if they have electric fan(s) you can hear them come on within minutes of the car sitting idling.....

My car sits dead on the halfway mark no matter how long i leave it on. If i stop moving the fans turn on within minutes keeping bang on the halfway mark. as soon as i start moving again they shut off.(im running the stock 90* thermostat that came with the engine)

[Fusion]

I have a manually activated low speed and high speed (two buttons). I don't mind having to turn them on and I did so in traffic.
I don't think it's the pump because everything was fine before before the tstat/switch swap.

The only thing that comes to mind is that the driveway is a little uphill, if that has anything to do with it overheating only when I get home. I'll try bleeding again tomorrow.
Also the temp went up to 3/4 a few months back, but I found out that I forgot to put the cap back on the exp. tank after checking coolant level, so I was driving around with an open exp. tank, *self slap*. The cap is on this time ;)

[Wh33lhop]

Why not just use the stock aux fan wiring? I finally wired up a SPAL pusher I just got with a Z3 temp switch, low speed comes on a little past the halfway mark and even with limited airflow (I'm retaining AC) it seems to be okay when I'm at a standstill (finally).

How new is your water pump? Did you change it out when you did the swap?

[bejbis]

You should really put your fan on a temp switch and relay. You are going to feel REALLY bad one day you forget to manually switch your fan on and you crack your head. It will happen with the way your going.

I'm still voting on air in the system or faulty water pump.

I have a manually activated low speed and high speed (two buttons). I don't mind having to turn them on and I did so in traffic.
I don't think it's the pump because everything was fine before before the tstat/switch swap.

Also the temp went up to 3/4 a few months back, but I found out that I forgot to put the cap back on the exp. tank after checking coolant level, so I was driving around with an open exp. tank, *self slap*. The cap is on this time ;)