Electric pusher fan no high speed - Resolved

[g300d]

I'm chasing an increase in average temps on the 3.0i.

Its going 95-96c average when it used to be 92-93c.

I just drove the 4.6is and the pusher fan is noticeable when it goes to high speed, and temps drop.

I notice that on the 3.0i the pusher fan doesnt go to high speed. It turns on when the AC is on but at low speed only, and most all of the time it's off.

Checked fan via INPA and it goes to high speed when actuated.

No errors stored.

I know the basics in that the fan is PWM and speed is controlled via DME. Any tips on troubleshooting this?

Resolved: Fan activates to cool coolant at 95 degs C, at the radiator outlet. Ktemp is different (at the cyl head) so cannot be used as a reference for fan activation.

Radiator outlet temps can be checked via INPA.

[crystalworks]

Probably not related, but when was your coolant last changed? Thermostat?

[upallnight]

Originally Posted by g300d

I'm chasing an increase in average temps on the 3.0i.

Its going 95-96c average when it used to be 92-93c.

I just drove the 4.6is and the pusher fan is noticeable when it goes to high speed, and temps drop.

I notice that on the 3.0i the pusher fan doesnt go to high speed. It turns on when the AC is on but at low speed only, and most all of the time it's off.

Checked fan via INPA and it goes to high speed when actuated.

No errors stored.

I know the basics in that the fan is PWM and speed is controlled via DME. Any tips on troubleshooting this?

Nothing wrong with your fan if you can command it to go to high speed. You will need an oscilloscope to see what type of PWM carrier signal is being sent to the fan. You can compare the signal to the 4.6 signal and see if they are the same. Most likely they are not. Because the 4.6 is a V8 and the 3.0 is just an I6, there is more heat generated by the 4.6 so the programming for the fan speed will be different.

[g300d]

CW, coolant is a few weeks old, changed it out when I did the water pump which was weeping a bit.

Thermostat is still OE.

Up, agreed, just my observation that in the same ambient temps the 4.6 fan goes to high speed but the 3.0 does not. The V8 is definitely hotter with peak normal at about 108c. compared to peak 96-97c with the 3.0.

Ive been looking at INPA analog values trying to make sense of the situation. Radiator outlet temp is about 25-30c lower than coolant temp. I read that the DME engages the fan at 90 or so C, would that be Ktemp or rad outlet temp at the lower hose sensor?

[crystalworks]

Originally Posted by g300d

CW, coolant is a few weeks old, changed it out when I did the water pump which was weeping a bit.

Thermostat is still OE.

Up, agreed, just my observation that in the same ambient temps the 4.6 fan goes to high speed but the 3.0 does not. The V8 is definitely hotter with peak normal at about 108c. compared to peak 96-97c with the 3.0.

Ive been looking at INPA analog values trying to make sense of the situation. Radiator outlet temp is about 25-30c lower than coolant temp. I read that the DME engages the fan at 90 or so C, would that be Ktemp or rad outlet temp at the lower hose sensor?

Sorry I was aiming at the temp issue, and not the fan triggering. I assumed the fan was doing what it always has and you were seeing an increase in temps now.

As upallnight says... fan is good, need to figure out what temp the DME is supposed to trigger it at to determine if DME is to blame. I'm doubting it though with only a 2-3c difference.

Edit: thermostat is still original and I'm guessing the heater control valve is still original?

[g300d]

CW, main issue is the temp increase, and the fan is one of the things I am looking at.

Yes, original thermostat and heater valves.

Funny you should mention the heater valve, I have no heat from the left vent that I am also wondering if related.

I researched on the valves and my system has the tandem valve. I checked INPA analog values for heater core temps the other day.

Right side core temps go up and down when activating/ deactivating the heater via AC panel right temp control switch. I have heat from these vents.

Left side heater core temps dont change when adjusting temp with the left side switch. Left core temps will increase over time but I think its just heat crossing over from the right side. No heat from these vents.

I believe the left valve is stuck or dead.

[crystalworks]

Originally Posted by g300d

CW, main issue is the temp increase, and the fan is one of the things I am looking at.

Yes, original thermostat and heater valves.

I believe the left valve is stuck or dead.

Heater control valves are extremely common failure. The rubber inside them degrades and gums up the valve.

Could be reduced coolant flow from the thermostat or heater control valve. Usually heater valves won't cause engine temps to rise noticeably... but 2-3c may be possible (I'm really not sure). I've run cars with completely clogged heater control valves, and also completely open (gutted the valve to get heat into the cabin) and never saw a change in the dummy needle in the cluster.

Another possibility is the new coolant. If it's not exactly a 50/50 mix or you changed brands, etc. I could see something like that making a slight difference as well.

[g300d]

Update...temps are starting to peak at up to 99 degs in stop and go traffic, and getting harder to get temps down.

I took a look at the heater valve and it is stuck closed with the rubber deteriorating.

Bypassed it by connecting the heater valve supply hose with the heater core return hose with a barbed connector. Temps still reach 99degs peak but it goes down to 86 and back up to 96-99, which is better than before. Still wondering what causes peak temps to increase like that.

Rad outlet temp is ok which is probably why my electric fan does not engage. Ktemp is from the cyl head sensor...with rad temps ok but head temps sometimes high, I'm thinking that maybe a flow restriction is the problem?

It being a periodic problem makes me think it may be a soft failing thermostat that is reluctant to open. But I've never seen any mention of this happening on M54's. All the thermostat problems seem to be being stuck open and temps being too low.

[bcredliner]

Originally Posted by g300d

Update...temps are starting to peak at up to 99 degs in stop and go traffic, and getting harder to get temps down.

I took a look at the heater valve and it is stuck closed with the rubber deteriorating.

Bypassed it by connecting the heater valve supply hose with the heater core return hose with a barbed connector. Temps still reach 99degs peak but it goes down to 86 and back up to 96-99, which is better than before. Still wondering what causes peak temps to increase like that.

Rad outlet temp is ok which is probably why my electric fan does not engage. Ktemp is from the cyl head sensor...with rad temps ok but head temps sometimes high, I'm thinking that maybe a flow restriction is the problem?

It being a periodic problem makes me think it may be a soft failing thermostat that is reluctant to open. But I've never seen any mention of this happening on M54's. All the thermostat problems seem to be being stuck open and temps being too low.

I wouldn't worry about an increase from 92 to 95c. That's not much and it may not be enough to turn the fan to high. Since you changed the water pump I suggest bleeding the system again with the heater on max. You may still have some air in the cooling system.

[g300d]

Yup, will be doing some more bleeding. I'm happy to see the normal temp fluctuations now after bypassing the heater valve.

Normally upon reaching peak temp the system will work to bring it down to about mid 80s, then it goes back up and cycle back down, and so on. Peak used to be 96. It became 97 to 99, and starting to stay there instead of cycling down.

As I understand fans turn on at 95 deg, but measured at rad outlet , not ktemp.

I have a dead aux water pump so bleeding is a bitch though.