Hi all,

I have searched the forums but can't find an answer to this one. Basically when towing up steep long gradients, the fan will come on as the engine starts to get hotter, as you would expect, but then goes off allowing the engine to get hotter rapidly then comes back on again when it gets really hot!. Any clues as to what may be causing this.

It initially comes on when ECT gets to around 206 - 207 but then cuts off and doesn't comeback on until around 220....... By this time, it can't cope well and I have to back off to under 20psi boost to keep the temps down.

Thanks

Andy

 

Do you have an EGR delete? Is the valve still in place and plugged in? If it isn't plugged in, the fan doesn't operate properly. First, pull the codes, hard and soft. If there is anything there concerning the cooling fan, it's likely that the fan has partially failed. I have had two fail on my rig in the last year and I keep a spare in a tool box. On your scangauge, monitor FSS and see what speed it's at when the temp approaches 217 degrees. It should begin to ramp up at 215 and max out at 3000 rpm at 217, quickly blowing it down to under 215-210. I tow a 11k TT, when I'm climbing grades I sometimes see 225 degrees, depending on how hard I push it.

 

Hi and cheers for that.

Still has egr cooler and valve is plugged in. The fan comes on and cycles as it starts to heat up then stops..... There are no codes or pending codes, deltas are good. Ii thought perhaps itt may be a sensor as for no reason it stops. Even when it starts getting hot the fan is still cycling. I need to take more notice of how it is behaving. Temps have hit 240 and the fan is running but don't know what speed

I am off on another trip in about 10 days and will monitor it more accurately. I didn't really take much notice as it did come on and thought the computer knew what it was doing! Can I wire the fan to an upfitter switch and then it on manually?

Thanks again

Andy

 

down shift the truck to force the fan to come on by the increased RPM. You may have a failing water pump.

 

The fan doesn't come on at X temp and off at Y temp. Depends on engine and vehicle speed also, and a lot of other stuff.
220 is not that hot. If the coolant is mixed correctly it wont boil till 240, add pressure and you are around 260+ before boil.
When the fan does come on does it cool down quickly?

 

Yes, when the fan is on it cools rapidly, same if I back off a bit. Maybe it's just the ambient temps, 40+°C..... I just thought the fan would stay on after it initially kicked in...

 

The fan is on but spinning slowly at low temps. I'm recalling from memory, so don't hold me to these numbers. They will be close. As the temps get above 200F, the fan should be around 800 rpm if the engine is around 2000 rpm. At ECT of 210F, the fan should be spinning around 1100 RPM. The fan will not lock up until 217 or so. Mine kicks in and turns around 2200 rpm at ECT of 219F. When it does, it sounds like a turbo prop and the ECT drops rapidly to around 210 F.

However, never has my ECT hit 240 F. I'm more concerned about that than I am a ECT of 220 F. If you tow, you'll hit 220 often, but it should come down very quickly when that airplane prop on the front of hte engine starts spinning 2000 rpm.

I don't know how a properly functioning coolant system hits 240 ECT (Thus Watson's comment about the water pump). Are you sure you just didn't read that wrong?

 

How much and how fast are you trying to pull this load and how steep is the grade?

 

I'd second on the check you numbers. ECT at 240° would put the oil at or above 250° and at 253°, truck defuels to cool down. You would have known when you get that hot, dash probably would have lit up.

 

Ops, miss-read, sorry

 

Yes, these temps are towing usually 10 -12,000 lbs, ambient temps 95-100F and long gradients (5 -20 miles) reaching 7% at around 56 mph (90 kmh). 240 is correct although I back off now to 45 - 50 mph and don't see more than 225.

Should have mentioned at 240 it pukes... New degas bottle and cap

 

I don't think that's outrageous for the ambient temps, length and grade of pull, and speed. Where do you keep the coolant level in your degas bottle and are you studded or stock head bolts?

 

The level is at the minimum, as recommended? The head is on stock bolts.

 

I have about a 3 mile 6% grade with lots of turns to get to my house. Both fords I have owned will get to 220 deg F with ambient temps above 70 towing about a light (2,500) load. By the time I stop the fan is full on at idle.

 

Ummm, stock torque-to-yield head bolts and puking? Sounds like the bolts are letting the pressure escape at 240*. Have you checked for exhaust gases in the coolant? Have you pulled the EGR valve to look at its insides?