overheating while towing

[Johnny5]

Just looking for some thoughts on my overheating trouble.Last summer I towed my trailer to a wedding 10 hours away and it was nerve racking as I could not go over 50mph or the temp gauge would climb almost all the way to the red zone on the temp gauge and at some points my warning would come on my dash.as soon as I would slow down to 40mph it would drop instantly.anyway a little history on my truck its a 06 6L with about 205000 miles on it.And I would use the tow haul button while towing. My trailer is about 8500lbs..last year I had a new egr cooler put on from warranty.I,m not loosing any coolant and I did stop and buy a new degass bottle cap as I read it may be lossing preasure but didn't help and I blew the heck out of my rad and that didn't help either.My clutch fan would come on all the time as I could hear it.Also I have an edge programmer and it didn't matter if it was in stock mode or programmed. at times the temp would reach 245degres and I would panic and slow right down but hard to go 20mph up a hill and hold up tons of traffic? Just had my truck in for an inspection as warranty was up and they said everything is fine. Any thoughts?

[van-boy]

clogged oil cooler?

bailey

[dannyboy950]

What was the ambient air temps at the time, what was the tranny temps?
When towing the tranny works harder and the oil gets hotter and the radiator has to displace that heat also and it justed doesn't have much extra margain the cooling system is too small. Engine coolant capacity is 11 qts + 11qts coolant in radiator to exchange out when the thermostat opens and a total system capicity of only 28 qts, do the math, it don't take much extra heat to cause problems.

[Johnny5]

The temp outside was pretty warm about 30 degres celcius.I was watching all my gauges and the tranny temp did not move on my dash at all and to be honest not sure what it was on my programmer as I was focused on the engine temp.The bummer part was I had a buddy pulling a trailer double the distance than me with his dodge diesel and I texted him if he was having trouble from the hot weather and he said no that it was pulling like a dream and when I was getting fuel a guy pulled up with a Chev diesel and his trailer was double the size of mine and I asked how his pulled in the warm weather and he said no problems at all. Just seems soon as I hit 50mph it would climb fast.

[Johnny5]

could it be my thermostat?

[RedBKM]

Most of the time a bad thermostat stays open, meaning full flow. This would only help your situation.

Don't worry about the other guys. Your truck will pull that load and more just fine in those temps once you fix this.

If it appears to be road speed related I would double-check your fan and look for junk in grill or radiator. I got a grocery bag stuck once. Also make sure your fan shroud is functioning.

[Johnny5]

Thanks, I do hear a rattling (clinging sound) coming from the fan clutch so I;m checking ebay for a replacement. Any advantages to a snow plow fan clutch or would a regular be fine?

[1fastTRX]

Maybe the waterpump? I had a bad fan clutch and noticed temps increased when I would stop, but dropped as soon as I started moving. It would be a good idea to check oil temp vs coolant temp (when unloaded and at operating temp) to see if your oil cooler is clogged.