Stuck thermostat or something else?

[BoulderJeff]

Quick history...

The coolant hose that runs from the bottom of the throttle body burst. I'm having trouble finding a good diagram of it, but it could be the No. 2 Water Bypass Hose? Anyway, the engine overheated. I went to Napa and bought a 1/2" coolant hose and replaced the broken hose and filled the coolant back up. The check engine light was on at this point, so I disconnected the battery and it has stayed off since.

Since then, I have seen the following behavior:
-Engine heats up quickly to normal operating temperature
-Heat takes a long time (10-15 min) after engine warms up to come out of vents, but it does eventually
-Temp gauge will go from 3 o'clock up to almost touching red, then will drop back down to 3 o'clock

My question is, could this be a damaged thermostat that doesn't react correctly to engine temp or should I be looking at something else? The fact that the heater takes a long time to blow hot air makes me think it could be something else.

Thanks!

 

[ewillis]

T-stat replacement is quick and easy...wouldn't hurt to order a new one along with the O-ring, crack it open and give it a look. Did you remove the TB and replace the hose already?

 

[BoulderJeff]

I replaced the thermostat last year when I replaced the radiator. I did replace the hose already.
It was suggested that I may have air in the system still. I'm going to try to bleed the air out today and see if that fixes the issue.

 

[ajax1]

I'd check coolant level and do head gasket bubble test,

 

[BoulderJeff]

I opened the radiator cap and started pouring coolant in and it took a full gallon! I ran it with the heater on to see if the level dropped, but after about 10 min it was holding pretty steady. I put the cap on and the temp gauge is holding steady now. The heat also came on right away.

I was using the overflow tank to see if it needed more fluid, but I guess that's where I went wrong. The tank will stay full (at max line) even though the radiator is very low on fluid.

Thanks for the help!

 

[Reelitchy]

Air in the system...what's going on with the overflow bottle?

 

[chap79]

When adding coolant I raise the the front passenger side of the truck with a jack, rock, or piece of firewood so that the radiator cap is the high point. Helps get the air out of the system once the thermostat opens.

 

[BILT4ME]

Pull the front end up on a curb to get it up higher. Or drive it on top of a Prius. I found that helps the most. Get the radiator up higher than the rest, make sure the heater valve is on HOT, let it idle with the radiator cap OFF until it almost starts to overflow. Then replace the cap and take it for a drive with the heater on.

When you come back, park it on the curb (or Prius) and let it cool completely. Check it again and refill. Lather, Rinse, Repeat until it no longer requires more coolant in the RADIATOR. Then fill the overflow bottle to the correct level with 50/50 coolant and move on.