Sorry in advance for the long post.

2006 Ford F350 DRW. The truck has 117K miles. I bought right after head studs and an EGR delete from a Ford Diesel shop near DC. I've done two trips from MD to FL in the last month pulling our 5th wheel RV 18,000lbs. On the first trip the temp gauge started dropping to 0, and the "Check engine temp" warning comes up; intermittently. After returning home I replaced the temp sensor, visually inspected the wiring, removed and cleaned all connectors to the modules. Flushed the coolant system and put in new coolant. The problem persisted.

I've monitored the engine oil temp via odblink and until our return to Florida last week I didn't have any high temps. Toward the end of this last trip, the temp gauge started going to max and the oil temp got up to 245. I'm also loosing coolant at a rate of 1 gal every 100 miles or so. There is evidence that it's coming out of the reservoir cap.

Had an Orlando diesel shop put in another coolant sensor and a new water pump, oil cooler, thermostat and reservoir, all OEM. On a short trip after the repair from Orlando to Crystal River (100 miles), it started acting up again after about 50 miles.
Coincidentally (?), my oil pressure gauge quit on that trip as well. I don't believe there is actually an oil pressure issue as it's my understanding these engines won't run without oil pressure.

Looks like it's also low on coolant again, but the coolant system seems to be holding pressure fine after shut down and there is no external evidence of leaking coolant. Exhaust looks normal.

When the truck is "overheating" it is very difficult to start, my guess is oil is hot and thin and doesn't build enough pressure to activate the injectors. Fires right up after 1/2 hour or so.

Since getting to Crystal River I've driven the truck 20 miles or so without the RV and haven't had any cooling issues. Though the oil gauge is still out.

I love my truck which is paid for, but the wife is threatening to make me buy a newer one that comes with big payments.
Any advice will be real helpful, thanks.
Joe

 

What did the transmission temperature do during all of the towing?

Not sure how good your scan tool is at reading codes, but have you checked for them?

Have you heard the fan "roar" at those temperatures? You should!

 

Trans temps were normal. Yes the fan has seemed to run more than normal, but not consistently when the temps are going up. When the temps go up it happens fast like in a couple seconds, then it will return to normal just as quick. If I didn't have trouble starting when it's hot, I'd really suspect it was just an electrical problem. In fact, I really did at first.

 

The fan should roar for a good while. Even in the winter when it's 35F outside when I'm pulling a long grade the fan will come on for about 15-20 seconds. It cuts in when the ECT hits 220F and will cut out around 213F. If its cutting in and out quickly thats an indication the fan clutch is not working correctly. Check the wiring first as it can get damaged, but it likely needs a new fan clutch and that might explain your overheating.

BTW at 220F ECT the fan is ROARING. You can't miss it. At 207F the fan will engage on low speed. That you typically can't catch unless you've got the radio off and are listening for it. I usually watch the fan speed on my scanner so I know whether it's coming on or not.

With 18k pounds behind it I would expect the fan to be operating quite often! With 8k in tow I'm usually hitting the 207F low-speed cut in running down the flat highway.

 

Hi Five, the fan isn't cutting in and out quickly, the temp gauge goes up and down quickly. Without the trailer I haven't had any issues, seems to run 205 - 213 consistently. With the trailer, went up to 245 and yes fan running hard.

 

205 + without towing is too high for coolant IMO. Starting to sound like head gaskets.

 

Don't fixate on specific temps for the fan - 5.0 said 220, but mine kicks in very consistently when ECT hits 13.8 in TorquePro. Because it takes a few seconds to wind up, ECT might be up to 15 before the fan actually roars, but it was triggered at 13.8. On the EOT side, it varies more, but usually around 223 when the fan roars. This is an Eseries though, although it seems similar to the Fseries I've driven.

I wouldn't keep driving up to 245. I've been as high as 232 and that was only because I didn't have a place to pull over sooner. Keep it at a high idle if you do pull over, until it cools down - gotta keep that coolant circulating. And the fan should be roaring even at idle at that temp, I'd guess.

 

On my way back from Florida to MD towing ~18K up I95. Keeping my speed under 65 ect has been between 200-2020 fairly steady. Fan comes on at about 210. I'd think this was okay as IHateCommieCars said, except truck would not start for 20 min after stopping for fuel. Couldn't build enough oil pressure to activate the injectors (P2291 - Injector Control Pressure Too Low - Engine Cranking). Once cooled starts right up. I'm also still loosing a gallon of coolant about every 100 miles. There are signs of leakage around the cap (puking).

Bismic you said, Okay, but should I see any other signs for this. And should the system hold pressure for nearly an hour after shutdown? If a head gasket was leaking wouldn't the pressure drop?

Thanks again.
Joe

 

Cylinder pressure is very high compared to the pressure in the degas bottle. It leaks combustion gas into the coolant because of that very high pressure. 15 psi isn't enough pressure to push coolant into the cylinders. The only significant pressure in the degas bottle should be from the coolant (liquid) expanding as it heats ... then dropping to zero (ish) as it cools.

 

The first question I would ask is why the studs at 117k? You won't be able to answer that by buying it afterward.

The second is if the heads were machined? Another one you might not be able to answer.

But if it were mine, I'd also follow the advice already given and look closely at the fan and thermostat, both of which could cause the issue. Mark is right to point out that 205 is too hot for the condition.

Lately, I finally put out a video of my theory of what is going on with these heads, which would explain your on and off again puking issue. Despite the work previously done, I think you need to add a pressure gauge into the cooling system and document how the pressure is changed due to the driving conditions. I suspect the heads were done poorly. I hope that s not the case.

 

Hi all, thanks for the advice so far. The truck has made it back to MD with the trailer. There were no new overheating issues on the trip, but I did still have to add coolant. I did develop a bad oil leak, from what looks to be the oil pressure switch, and considering the oil "pressure gauge" quit, I'm thinking it's a good bet. I'll be changing that in the next couple days.
I've also ordered everything I need to monitor the coolant pressure, so once I've done that I'll update here.

Also, TooManyToys, I started watching your video, very informative. Thanks.

 

One thing I learned when pressure testing my 2 stroke engines looking for crankseal leaks. Compressed gases will find there way through leaks much easier than fluids. I suppose that is the same for head gaskets. Combustion gases will get past the defects much more easily than coolant will.