Finally got around to bypassing my front fuel tank the other day. My front pump took a crap and since I’m ready to daily this thing I just dropped it and set it aside for a project later on. I plan on putting it back on the truck but for now I used an old fuel pump and chopped the metal fittings off and then welded the ends to create a plug that would fit just as the factory fuel pump did. I have been battling constant lean codes with the front pump and would notice the engine overheating which I thought was in part due to the strain the engine was enduring trying to accelerate on the front tank. Recently I actually blew the upper rad hose and decided that it certainly was an issue for both tanks. As it turns out a PO had removed the pipe fitting where the ECT sensor (sensor not sender, so the one shown on a scanner) and plugged both the hose and the fitting. I was able to pull a sensor and fitting at a scrap yard and wired it up. While I was doing this I pulled the thermostat as well as I have read it is a common failure point. Interestingly it was stuck open. I replaced it with a motorcraft thermostat and replaced the upper rad hose. Topped off with concentrated antifreeze that I diluted to 50/50 with hose water. When I overheated I pulled over and checked my scanner. Engine coolant temp sensor gave me a reading of 240 F. What’s the next best place to start? Pressure test? Fan clutch? Water Pump? Any tests I could do (maybe pull rad cap and check for bubbles)?

 

When cold pop the cap off and check for bubbles and when the stat first opens feel across the face of the radiator to see if it is heated evenly.
If not even then the radiator is partly plugged and needs to be replaced.

Take it you have AC and a clutch fan if so do you have a shroud and does the clutch fan work as it should?
I would also get something else to measure the temp other than your meter and that sensor so you know it is true.

You did not say if it runs hot at speed or sitting at idle?
This can tell us where to look deeper.
BTW lower radiator hose have a spring in it?
Dave ----

 

Okay sorry let me add some more detail. The truck runs fine at idle and does not seem to overheat, it’s typically during start and stop city miles where it really racks up the temp. My friend and I were driving yesterday and observed that from a dead stop and no throttle input from the driver, the vehicle will actually get all the way up to about 30mph (not quickly but still). We are wondering if this could be in any way related. Regardless, I have also replaced the lower rad hose and noticed no spring in it. I have pop
ped the cap to check for bubbles and observed maybe one or two but it was just the air pockets leaving in the radiator.

I will test the fan clutch tomorrow and check if it has sufficient viscous resistance. If it is obvious I will replace it.

 

UPDATE: I ordered a gates water pump and a GDP aluminum fan clutch from Rockauto. Cost about $80 + shipping not bad at all. Fan clutch was leaking oil and had lost some viscous resistance. I also discovered the water pump had failed internally with two holes in the "turbine wheel" on the part that pushes coolant through the system. I refilled with water and added some LiqiMoly radiator flush and idled and then drove around. I am going to drain the radiator again tomorrow and refill with concentrated standard green from prestone that I will dilute to 50/50. I hope this helps someone! I will post pictures and add part numbers for anyone doing this in the future!