So a little back story. Did the oil cooler a couple of years ago as the deltas were getting high. Coolant flush and new Ford gold. Also welded EGR shut and had PHP reprogram. That was approx 25k miles ago.

Well now I have to fix the EGR because it won't pass smog. But my truck is running hot again BUT only when climbing a grade while towing my toy hauler. As soon as I crest the Temps come down fast. Also my deltas are fine normal driving, which was not the case last time I did oil cooler. My deltas were off all the time.

Also when I shut the truck off and stand in front of it after driving I can hear the coolant system gurgling.

I will be tearing my truck apart next week to fix the EGR and was thinking of doing the oIL cooler but don't want to waste money if that is not the issue. How do you tell if the water pump is bad? Also the fan is working according to scan gauge but doesn't have the big whoosh and squeal like it used to.

 

It helps if people know what your driving and any other possible mods.

 

Would also be good to know what the temps were.

 

Ficm 40 tune and a very mild tow tune from PHP and egr delete. Other than that stock.

Temps would get into the 240's. Hit 250 once that I saw and backed out.

 

I would start by replacing the coolant cap. A cooling system running under pressure will have a decreased boil point. What ect and eot is running hot? Do you hear the fan at all?

 

Sorry just seen the temps. Ground the light blue wire going to the fan and see if the fan starts running at full speed.

 

Is that coolant or oil temp?

 

Yo would start with the new coolant cap, and even measure pressure to rule out a small head gasket leak. I would also consider gauges what is FANVAR at what temps, as the coolant once it hits 215 to 217 should ramp right up, and that should pull temp down, if that's working, the head gaskets spcheck out, you can hold 15 psi in the coolant system, then the next thing I am thinking is water pump. We also need to know mileage, and oil temps and coolant temps together.

 

What's the loaded weight of the toy hauler? How long and % is the grade when it's hitting 240° ? Is the tune a 8,000lb. Tow Tune? The tune may just be over fueling for all the weight. Did you try going back to stock and seeing if the temps come down?

 

We're you using tow/haul?

 

Toy hauler is 10k loaded. Tune was written for that load. I do not have the option of going back to stock. Coolant temp was in the 230's.

What is FANVAR? Is that the same as FSS on a scan gauge? The FSS would get to 3500 is at the high temps.

I did replace the cap when I did the cooler. I will see about getting pressure tested and a new cap. Also have a new t-Stat I never installed.

I will check those things before I tear into it.

 

How fast were you going when climbing the grade, how long was the grade, and how steep was it?

 

Not sure how steep the grade was. Hey 50 from Sac to Tahoe if your familiar. Constant climb through the mountains. From 250 ft to 7000 ft in 90 MI or so. Most of it was fine but on one climb is where it got to 250 was a section probably 3-4 miles where it is a steady climb. Probably doing 55-60.

 

If the coolant was at 230, the fan should have been screaming full speed. Please let us know if it was. Once the temps hit 220, the fan kicks in full speed and the ECT should kick back down below 215 very quickly. If it's not, either the fan is not working properly, or the water pump is not working properly.

IF your deltas are good when not towing, and the fan and water pump checks out, it could be your oil cooler bypass valve is faulty causing oil to bypass the oil cooler prematurely. Yes, the oil will bypass the oil cooler under heavy demand. This is normal. The only way to change the oil cooler bypass valve is to change the oil cooler cap (oil filter base). You cannot buy the valve separately (although its about time someone made one to install with every oil cooler job). It can't cost more than $5 to make the parts to replace only the valve.

Having said all that, your 230 ECT temps point toward a fan clutch, radiator, thermostat stuck, or water pump issue. If its high miles, it could be the water pump.

Under extended high load, a 20 degree delta does not surprise me because the the oil cooler is being bypassed. Nobody knows what Percent load the oil cooler bypass valve opens (I believe its a 20 psi pressure difference), but based on my towing and watching ECT and EOT, I would guess the valve opens around 85% engine load and around 95% load, it is wide open. I can only say this because I KNOW my coolant system is clean enough to drink out of and my oil cooler has less than 5k miles on it.

In summary, I personally do not suspect your oil cooler. But, I've been wrong before.

 

Do you have anything mounted to the front of the truck the would restrict air flow to the radiator? Is the AC condenser in good shape?