Overheating and no heat

[Larryjb]

I believe that is the problem. I just re-pressure tested and noticed a pretty good leak (much worse when touched) from a tee-connector just behind the trans fluid dipstick. Would it make sense for that to be my only problem causing the overheating? Truck has 220k miles.

I suspect this leak has caused an air lock in your system. You can try bleeding it. You should also be able to use the pressure tester to test your rad cap.
Larry

 

[Jeremiah Parks]

If you're overheating but not getting any heat in the cabin I would check your heater core. I had a stoppage in my s10 that caused it to overheat but not blow hot air because no coolant could enter the heater core, and no coolant in the heater core meant no circulation, meaning the truck overheated and died. It sounds like you caught yours before that last part, and I never did fix it cause you know, 35 year old truck, who cares, so I have no clue what would cause it, but that's where I'd start

 

[Scharper]

So I replaced the leaking tee connector and it still leaks from the same spot on the new connector... Is it possible the metal tube is bad and not capable of sealing? Or did I just get another bad tee connector? Is that little O-ring really all it takes to seal properly? Seems like there should be a rubber sleeve or something that goes in the connector to seal up against the metal better. To clarify, its not leaking at the heater core, its leaking at the T that branches off to send coolant to the rear heater core.

 

[retiredsparky]

Yes it is likely that corrosion has damaged the metal piece. It is fair to say that these type of connections on a vehicle of any brand are not the most reliable. Fuel lines with o-rings are famous for leaking liquid on the pressure side, and allowing air to be sucked in if the fuel pump is external to the fuel tank. You are not the first, nor the last to have leaking o-rings.

 

[Scharper]

I got the tee connectors to stop by replacing just the o-rings. Anyway, its not leaking anymore but the temperature will still rise past 210 and the heat doesn't work. I've been looking around for a good how-to on bleeding air out of the system but what I find for this truck says it doesn't require it. It doesn't seem to have a radiator cap either, just the reservoir cap.

If air in the system isn't the issue, would the thermostat being stuck closed prevent coolant from circulating through the heater core?

 

[ISU-152]

Yes

 

[Scharper]

New thermostat, same problem. Engine gets up to 240 before I shut it down. In that time the coolant hoses never feel even a little warm or feel pressurized at all. It seems to me it has to be the water pump at this point, not pumping any coolant. I don't see any leaks around it though. Thermostat was tested and does open properly.

 

[bottomline2000]

bad water pump..if the lower hose isn't getting hot the coolant isn't being pumped back into the radiator. This could be a bad thermostat, but you've replaced this. If the hoses leading to the heater core aren't getting hot you have a bad water pump more than likely. the blades wear down over time and it ceases to pump fluid.

 

[Scharper]

Update: I figured the coolant system might not be full of coolant, besides the reservoir, and that perhaps the water pump needs to be primed before it can draw coolant from the reservoir. I'm kind of learning/figuring out as I go here. Anyway I disconnected the return line to the reservoir and plugged the port on the reservoir then used the pressure tester to force coolant into the system. After a few times forcing it through, refilling the reservoir, eventually when I would run the truck I was getting heat so coolant was going through the heater core. I then drove the truck 1/2 hour away and it held perfectly steady at just under 210 (before it would rise past 240 within minutes). The only thing was I got a low coolant warning on the way back and I checked and indeed the rservoir appeared empty although I made it home without overheating. It had been at full-cold when I initially left. Once cooled the level showed at about half. I'm hoping that was just the system continuing to circulate throughout the entire system. I'll top off again and see what happens.

I'm thinking my whole problem to begin with was allowing the coolant to get too low (hopefully only because of those leaking tee-connectors) and it drew in air and overheated and really just needed to be bled.