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6.2 running too cold?

RNation

RNation

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St.Peters, MO
I think this is a very odd concern but my motors running about 30 degrees colder than normal.

I switched the fan clutch the other day because my motor was originally running between 195 - 205 and it hasn't even hit summer temps yet (that's with a load).

After switching the fan clutch the temp still fluctuated between 195 and 205 but hung out more at 205. I noticed the upper radiator hose was stiff at 200 so I thought maybe the thermostat wasn't opening.

I replaced the thermostat (195* stat) with a 180* stat and this is where it gets weird (weird to me anyway since I'm so used to this thing being on the hotter end of the comfort zone). When I start the truck it warms up to about 160, then when I hop on the highway and go over a few hills and such it gets too 175 ish. Then it seams to run between 175 and 185 and peaks rarely at 195.

Is this ok? I understand the motor is designed to run best at a certain temp but I don't know what that temp is. Also would the extra comfort of not worrying about over heating out weigh the motor not running at it's best.

Also I thought about the temp gauge being faulty but it was reading 205 one morning, then after swapping stats it went on the lower side later the same day so I think thats unlikely but possible.
 
Well it will run strong the way you have it. Does your fan clutch have a bimetal coil on the front that locks it up at temp? If you are concerned about MPG, the 195* tstat will likely help, but you can adjust that fan clutch coil so the fan kicks in at like 210-220F temp if it gets that warm under load.
 
I'm not too worried about the gas mileage if its a mile or so difference. As long as it will run strong then I'll be ok. I think I read at a couple places that the 6.2 originally had a 180* stat then they switched to 195* later for emissions control.

I did hear from someone that the 6.5 stat is actually different from others because it has an extra tab or something that covers the hole that goes to the water pump on the crossover piece. If so do you know if there's one for the 6.2 also because I think they have the same style thermostat crossover piece.
 
Your body style has better airflow and less chance of overheating. My 1988 NA 6.2 ran best with a higher T-Stat in it - less rattle. The temperature gauge and sensor including wiring is suspect in a rig this old. Worse is the gauge gets hypersensitive and for example will show a 10 degree movement for 2 degrees. Corroded wires or connectors makes a big difference on this low voltage circuit.

Your 180 T-stat is full open at 190 degrees. Idle produces little heat and the heater bypass alone can keep you at 160. A long downhill grade where the fuel gets shut off can cool your engine way down.

I would use a 2nd source to confirm the gauge readings if you like. The above readings you have appear to be "normal".
 
That's kind of what I was wondering about it being "normal". So I'm fine with that...haha.

The tamp gauge is under a year old. I thought about it being suspect but it read 205 one morning then when I put the 180 stat in it read lower, so I figured it was ok.

I have noticed now with the new stat that it takes a long time to warm up. I hope I didnt buy a faulty one and it's just stuck open. I looked at it before I put it in and it was closed. May be nothing though, I get so damn paranoid since it's my only means to get back and forth from work.
 
Does anyone know if the truck won't warm up over 150* on a day thats about 50*, does that mean the stats not opening? ( I drove about 45 mins on the highway to work and then another 45 home) Sorry if I'm being a worry wort, this is just new to me. My truck has never ran under 190* so when it won't even get there I get a little curious.

Also I noticed today when the truck wouldn't warm up that it was a bit shakey, might be a separate issue though.
 
The truck should run at 180-200 at -40 let alone 50f. T-stats are notorious for being bad when new. Like 1 in 3 is bad or worse. I would return it if it were me. You can get a candy thermometer and put it in a pot of boiling water with the new t-stat to see when it opens and closes. That way you don`t install a junk t-stat.
 
So I must be the most dumbest "do-it-yourself" mechanic.

The cooling system started leaking afew days ago right between the thermostat housing and crossover. I took off the housing today to see if the crossover piece was cracked (last one did that to me) and when I got it off I saw the problem clear as day. When I installed the thermostat I didnt realize there was a lip on the crossover it sat in, I just used gasket maker and the gasket to hold it in place. But that didnt work, the thermostat dropped about a quarter to half an inch down. So the truck wasnt warming up because the water was constantly flowing and the housing was leaking because the thermostat dropped enough to where it was actually flush with the bottom bolt hole so there wasnt a good seal.

I drove the truck around the neighborhood and it sat pretty firm at 190*.
 
you can't be the dumbest DIYer. you figured out what was wrong and fixed it. We all have the D'oh:rolleyes5: moments from time to time.
 
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