2006 F350. EGR delete. SCR tuner with 50hp boost. Scan Gauges. Oil cooler, head gaskets (Motorcraft gaskets) replaced 3 years ago, ARP studs were installed. Coolant Filter, Work was done at 115,000 miles, it's now at 127,000 it's not a high use vehicle. In August of this past year, I noticed that my oil and coolant temperatures would at times run warmer by a few degrees more then they usually did, when pulling 15,000# trailer, on steep grades. Never got coolant over 218 and oil high was 225. Normally coolant and oil run no more than 10 degrees difference. Went ahead and replaced fan clutch and thermostat, then in November of this past year the "y" tube from the heads to turbo cracked, so replaced it. Seemed like everything settled down, and came back to normal.

Last trip out temperatures were erratic. Ambient air temperature 50. Coolant running from 188 to 200 under load at 65 mph, oil temperatures from 199 to 208. Sometimes on a grade the coolant and oil temperatures would come up, sometimes it wouldn't, the erratic part. On the last BIG grade before home coolant temperature went up to 212 and oil to 218, before falling back. Boost maximum was 28.9.

When I got in popped the hood to check things before putting it up, and the Degass bottle is covered in dried coolant. Up to this point I would occasionally find "little" trails that wiped off, but this time it puked it out pretty good. So now I'm concerned I might have a head gasket leak just starting. Any ideas out there what to check before I tear this thing down again????

 

Coolant level should not be above the min mark on the bottle. I always ran mine about a 1/2 inch below. I would also try a new MC cap and check the results. The caps have been known to malfunction. Your temps looked good to me.

 

Always run it at the minimum mark and never an issue. If it wasn't for the other suspicious temperature readings, I might agree on the cap.

 

225 and 228 oil temps... if the fan came on and cooled it down quickly (should have heard it), I'm with Mike. Coolant level in mine is up and down by the day about 1/4-1/2 inch, never above the min mark. Temps don't look suspicious to me either.... you were towing and pretty heavy, up hills and....

What are temps at 65mph, flat ground, unloaded for 15 minutes after reaching temp?

 

Scan Guage shows fan spooling up as it should. Normal temperature on flat ground towing yesterday at 50 degree ambient temperature was 188 to 195. Coolant level has always stayed within the minimum range til yesterday. Something happened that blew it out

 

If your EGR deleted, pressure gets to the degas tank only one way.

 

I'm afraid you're right, but you can always hope. Going to get an coolant/exhaust gas checker, and see if it will give me a positive reading. If it doesn't I'll pressure check the cooling system. I also might throw a new thermostat in, I think I might have used an aftermarket thermostat.

Spoke with ARP this morning, and didn't like the comment "our studs will slow down the incidents but won't stop them". Apparently there are still a lot of gasket failures after the installation of studs. Frankly I'm really kind of turned off at spending another $$$$ to fix something that I'll be fixing again down the road.

 

make sure the heads are sent out and checked for straightness... that will give the gaskets the best chance to succeed.

 

Been busy and hadn't been able to get back to it, but bought a tester to check for exhaust gas in the coolant. Negative on the test but I'm not 100% sure of the test, despite using the recommended fluid for diesel. Rigged up a pressure gauge and plumbed it in between the rear return line and the degass bottle. It's cool out today, so despite several runs up some steep grades, I couldn't get coolant temperatures past 190 and oil past 194. I did get boost up to 26#. Coolant pressure was running in the 14-15# range except at the tops of the hills it would creep up to 16-17#. I couldn't see any signs of puking out the cap, but since I'm not hooked to a heavy load, I don't have a way of maintaining a sustained load. Got back and checked the lower radiator hose - it was slightly warm, but no where near the temperature of the top hose. I changed out the thermostat about 6 months ago, but I swear it almost acts like a sticking thermostat. Coolant/Oil temperatures holding to within 10-12 degrees. Any thoughts????

 

What level is your coolant at in the degas bottle? Mines just below the new posted min line and I hold 10 psi at 200 degrees in the coolant

 

Refilled it to just below the minimum mark. How are you checking your pressure, and are you doing so in real time? Mine creeps up steadily as the coolant warms and seems to peak out at 15-16 #, but because of load and ambient temperatures, I haven't been able to get the coolant temperature past 190. My thinking is that until the thermostat opens, the a slight increase would be normal.

 

From what I noticed coolant pressure only rises with temperature unless you have exhaust gases getting in. I monitor in real time, no other way to do it. I run a 200 degree thermostat, before with a Ford thermostat at 186 on the coolant, my psi would be around 8. You say you don't have any puking out the degas? get the truck up to full operating temperature (190ish) and carefully remove the degas cap to vent all pressure and then close it again and drive some more. If you build more pressure but your ECT stays steady, you have gases getting in

 

The last time I drove it "under load" it puked out coolant once on a long a pull. Other than that it hasn't. I've had an ongoing issue for the past year with the temperature. Previously this truck would run from 195 to 200 on coolant, with the oil temperatures in the 200 to 205 unless you hit a long grade, and then it might climb up some. Now it will run normal for a bit, then will run 5-10 degrees warmer on both coolant and oil, then drop back to it's normal range. I'm going to try the your recommendation.

 

Keep us updated.

 

Guess it's back to the drawing board on tracing this problem. Bought a reliable gauge to add to my rig to check EC pressure. Ran the EC up to 190 oil to 194. Then ran it up some steep grades, with RPM up to 3k and boost up to 27#. EC pressure via the gauge was 13#. Opened the cap to relieve the pressure back to 0, and then ran the crap out of it over several miles with steep grades. Pressure on the EC never got off 0. Verified that by opening the cap again, no pressure. So can I assume that my erratic temperatures are not head gasket related??? If it warms up a little, I'm going to pull the thermostat and check it. Any other suggestions folks????