Why am I running cold?

[hheynow]

Today I drove all day and the coolant never rose above 185*F. I have the 203*F T-stat and a real water gauge. The ambient temps were in the high forties. This low reading of 180-185*F occurred last week also. Usually and always once warm I see 200-205*F. First I though of the t-stat sticking open. If it was stuck open the truck would take forever to reach operating temps but it climbs steadily from stone cold to 180*F then plateaus there. Yesterday it was at 200*F. Coolant level is right on. I have a spare dieselsite 203*F should I NEED to change it.

 

[97powerstroker]

i guess the cooling systems in these trucks are really good!. too good to be true.

 

[95_stroker]

Im going to go out on a limb and say, change the thermostat with the spare you have and see if problem vanishes Richard.

 

[hheynow]

i guess the cooling systems in these trucks are really good!. too good to be true.

Yeah but in my case I NEED HEAT for my vegoil system to be hot. I was hesitant at running vegoil with the coolant at only 180*F but I did only because my vegoil was at 180*F (with the help of two 12v heaters!).

Mike I hate throwing parts at my truck.

 

[95_stroker]

Mike I hate throwing parts at my truck.

I would agree, but this is a part you already have in inventory, if it doesnt solve the problem then the part you took out is still good.

 

[hheynow]

OK so where do I start? I've never changed my t-stat before. There's gotta be a sequence to do this. Do I need to drain some coolant first?

 

[Crumm]

Yes drain out a couple of gallons. Remove upper radiator hose from thermostat housing and pull it out of the way. Remove three bolts holding housing on. Remove thermostat. Clean housing up real good. Reinstall everything in reverse order with new thermostat and gasket(o-ring). Does not hurt to use a little silicone to seal up the housing. I tried four times to get mine to seal without silicone and it would not seal even after installing new housing and gasket.

 

[BJS]

A standard thermostat does need changing every couple years. Dieselsite even alludes to this on their site or did last time I went and read it. It is possible that there is some deposits keeping the current tstat from closing completely.

 

[dpantazis]

hhey-
there is a wiki page on th t-stat changing. have a peek there.
spend $3 on the single use permaseal waterpump/tstat goo and forgo the 3x-4x tries me 'n crum did.
dp

 

[hheynow]

Spoke to Bob at dieselsite today about the t-stat. Replacing it after three years seems to be the prudent thing to do. This is a good time to drain and replace my coolant (3 yrs also) so if I don't remove the two plugs in the head and just let the radiator run dry how much coolant mix will I lose? I need to know how much coolant and distilled water to buy. I don't even know what the total capacity is of the system.