Just replaced the plenum and now it is running at 220-240. Before it used to run at 210-215.

I replaced the thermostat (195), gasket, and temp sensor when I did the plenum. I'm gonna try to put the old thermostat and temp sensor to see if that does anything.

 

Flush your cooling system, and use a descaler as well. Sounds like things are just kinda clogged up.

 

replacing t-stat is the right move. hate to say this but make sure its not in upside down. sensor down.

i like to test t-stat's in a pot of water on the stove with a cooking thermometer. it should crack open at the beginning of all the little bubbles, well before it boils at 212. i've only found 1 bad new one over the years, but i still always do it, just because i like to know and i'm that kind of **** person.

 

I dont have time to mess with the truck today but when I did the plenum I flushed the coolant but did not use descaler. I was thinking maybe something got clogged up or the tstat is not opening. The hose connecting the tstat and the upper rad is very very hot and the hose at the bottom is barely warm. I'm 98% sure I put the tstat in correctly, but you never know! I was working on it at 7 am in the morning right when I woke up.

I'm thinking of getting a 180* stat. Should I?

 

most people are able to run a 180 tstat without a problem. occasionally someone gets stuck with a cel code ? engine too cold for too long. i think they just have a combination of slightly off tstat's and coolant temp sensors. your mpg might drop a smidgen but its an insignificant amount. i think lower temps are better than higher temps, and when you climb that big hill while towing the boat it reduces the temp rise slightly.

 

i would probally use a 180 if u can stand to lose some heat in the winter

 

I'm thinking maybe my water pump is going bad. The week before i did the plenum I noticed my temp was reading 220-225. Which was higher than normal. Now it is reading 230-240

 

from a coolant moving perspective, water pumps seldom go bad. its an aluminum impeller, so unless it just rotted away, or started slipping on the shaft, there's nothing to go bad. wp problems are almost always the seal or bearing.

 

Well here is the deal... I put the old thermostat in and it still wants to run at 240-245.

Do I have a clog in the system? When I put the new tstat in there was a bunch of stuff on it. Like rust colored all over the tstat. It seems like the coolant isnt moving beause the lower rad hose is cold. I'm lost?

 

did you drain the block yet using the block drains behind the engine mounts ? that might release some of the heavier deposits. edit - caution, they can be difficult to remove. i had to use vise grips to get ahold of them and prevent roundoff.

the rust color is normal. the inside of the block is all cast iron, so it'll be rusty as hell.

try this - remove the t-stat completely. what happens? it should run very cool, like around 150'ish. if not, disconnect top rad hose and see if you have strong flow coming out of the engine. careful - things are hot.