Hi guys I am new here but not to diesel's. First I would like to say that this is a very nice forumn with lots of info, which leads me to my problem. I have a 2005 with the infamous 6.0 with 163,000 miles and I am one of the lucky one's [ knock on some wood] that I have had no problem;s with it except for a FICM 2 years ago. The problem is that this summer the water temp guage went all the way up and the check guages light came on while I was climbing a grade pulling a 8000 lb trailer so I pulled over and the temp droped right down to normal with no loss of coolent . I might ad that the fan seemed to come on because I heard it and felt the slight loss of power. I then continued on my way with no issues and began to think it was a fluke, with no issues ever since untill last week end the same thing happened. I know that they are known for pluging the oil and EGR coolers and I plan on a EGR delete in the future funds are the problem so will have to wait, but could it be as simple as the fan or termostat, it only does it on hill and not all of the time on them it is hit or mis I am a little baffled.Anyone with some ideas ? Thanks sorry for the long story

 

I thought of that but do they not fail open? What ould be the best way to check it ?

 

Probably a thermostat sticking. Especially if it's intermittent.

 

Thanks for the reply, If I have a thermostat problem is it possible that it is only opening half way and that is why it runs fine most of the time, if so what would happen if I just took it out to see if that was the problem would it over heat because of no restriction? Just a thought.

 

Taking the thermostat out of anything is never a good idea. It serves a couple functions. One is to let the motor warm up faster. Once it's up to temp it opens up to circulate all of the coolant and regulate the temp. Most people don't understand it also restricts flow. If the coolant flows too fast, it will pass through the radiator and it will not bleed off enough heat. It could very well overheat without it in there.

My buddy is tearing his 05 down right now that had a sticking thermostat. It would get super hot and then drop temp by almost 80* instantly when the thermostat opened finally.

 

Yea I understand that but my truck is warming fine and will run fine for hours or miles and then very intermitenly it will on a hill as I crest it it will spike, If I am correct when the stat open after reaching temp should it not stay open or does it open and close through the trip as you are driving. Do not get me wrong I would love it to me the stat, that would be the cheapest, just because of it be intermitent it had to figue out. That is why I was asking about the fan.Thank Mdub707 hopfuly you or somone can help

 

Check your water pump, the impellar will spin on the shaft , it mught be a sighn of it starting to fail.

 

Is there any way to check the pump without taking it off?

 

No i dont believe there is. Its something u want to phyiscally look at, I just put one on my truck and the impellor was melted at the shaft, and cracked almost in half. I could still run my truck at 55 and it wouldnt get hot. I dont have an explination for it except for the cooling systems are excelent in these trucks. How many miles on the water pump? It is real easy to remove, espicially if you are having intermitten problems it is the first thing i would do.The last thing you want to do is get this thing hot.

 

wrench4it Thanks that might just be my problem it has 168,000 on the orginal one, its funny to an extent that it only heats up on long hills when loaded but not all the time, so do think I should check, and how hard is it to get to?