The Diesel Stop banner
1 - 8 of 8 Posts

·
Registered
Joined
·
200 Posts
Discussion Starter · #1 · (Edited)
Just got back from a 1900 mile round trip to New Mexico. On the way there I noticed that the temperature gauge started 'creeping' up and then suddenly falling back to its normal temperature. This was at a steady speed of 70 mph pulling our 5th wheel. Wind was a quartering tailwind. As we drove I-25 from Colorado Springs and started up to Raton Pass from the Colorado side it went to just shy of the H (still not to the red though) and then went down to normal operating temperature (express - just as if the thermostat had just opened up). It did this several times more while we were on the trip. This Tuesday and Thursday, driving solo back here in Kansas, no hills, just a fairly level 20 mile drive, I noticed the temp gauge do the same thing albeit not to the higher extreme as when it was under the load.

So, after all that said, here is the delimna. In the 'old' days when I could work on the vehicles (before all the computers and pollution stuff), this activity indicated, to me at least, that the thermostat was dying and needed to be replaced stat. I called my selling dealer and was told that I needed to drop the truck off so that they could evaluate it - problem could be several things and they would need to test multiple items? Local diesel shop told me it was a thermostat. No radiator leak(s), both antifreeze reservoirs are at or above the cold fill lines. I don't see anything obstructing air flow to the radiator nor are the fins bent (that I can tell).

Truck only has 17700 on it so don't want to do anything to void engine warranty.

Suggestions as to what it could be, if not the thermostat?

Thanks.

Ron
 

·
Registered
Joined
·
2,869 Posts
What was outside temp?

Sounds totally normal to me.
When I am pulling my big trailer in 110F here in Phoenix, my temp gauge will move up, then I can hear the fan kick in and then it comes back down.
It cycles like this over and over.

No big deal.
 

·
Premium Member
Joined
·
4,205 Posts
I'd suggest getting a device to see the temps thru the OBDII port.
 

·
Registered
Joined
·
259 Posts
Sounds like your cooling fan kicked in and did its job.
 

·
Registered
Joined
·
200 Posts
Discussion Starter · #5 ·
Temp in the 90s and then dropped into the 80s, even lower during a rain storm. Heard fan kick in several times but that did not seem to cause the drop in temp as the fan came on sometimes when the gauge was already back down, other times when the temp was topped out. ??? Only has 17.7K on it so will let the dealer have it. Just wish they wouldn't keep it so long
 

·
Registered
Joined
·
200 Posts
Discussion Starter · #6 ·
Well, just to update. Truck is still at the dealers - second day which is nothing compared to what others report on here. Regardless, I swear these things have chips in them where they know that they are at the 'Doctors' and they get well. Bottom line is that they found nothing to substantiate my trouble ticket; they are thinking maybe a computer flash might do something so they were (are) trying to download two of them. Supposedly having issues doing that.

I told them that it did it under towing load (they just test drove it on a local highway for a few miles); I had just taken our 17500 lb RV to Kansas City and had it do the high temp, drop to below middle, climb to middle temp, stay a while until the next hill, then climb, drop, .... Oh well, guess the Ford idea is to break down in the middle of no-where and wait for a tow truck (being facetious of course but it is irritating.) End of rant!!

Hoping everyone is staying safe in this heat.
 

·
Registered
Joined
·
2,869 Posts
I personally don't think there is anything wrong so I am not surprised they haven't found anything.
 

·
Registered
Joined
·
2 Posts
Mine does this same thing when towing my trailer. Usually when climbing steep grades. In my experience it is normal for a vehicle to climb until the fan kicks on. I can distinctly hear my fan when it kicks on.
 
1 - 8 of 8 Posts
Top