About 4 weeks ago I replaced the leaky heater core, everything seemed fine other than a stretched out heater hose in the engine bay that I made a mental note to replace the following Monday when I could get a new hose - I forgot. So a few days ago Jr overheats on the way home and its the heater hose leaking that I had forgot about, replaced it and two days later it blows a small hole in the upper radiator hose. So I replace it and now I have been checking each time Jr gets home, the coolant overflow is hard as a rock and completely full of coolant (its one of the clear plastic ones) and the upper rad hose is hard and engine is starting to run hot. Truck sounds great, no white smoke, nice clean looking oil. I did the head gaskets about three months ago. My fear is that this last overheating event caused a leak that is forcing exhaust into the coolant system and pressurizing the system? Anybody have any thoughts on 1. if that is possible or 2. ????


Thanks, Mike

 

no need to guess

 

Thanks Dusty - I had forgotten that I have one of those test kits, nothing but blue fluid (I checked the fluid with the breath test and it did turn yellowish) so I don't think there is exhaust gas in the cooling system. Could there be another way for excess pressure to be introduced into the system, or is the cap exposed to vent excess pressure before it gets to high, could I just be fighting a case of air in the system. I burbed it pretty well I thought with the front end up high and the plug out of the top of the rad until there were no more bubbles.


Suggestions?

 

"I checked the fluid with the breath test and it did turn yellowish" doesn't that mean you have HC in the coolant?
perhaps it was faint, has to do with the heater core being replaced
did you replace the coolant? so were you test pretty much new coolant
it is also possible this has been going on for a while, and the pressure was escaping from the heater core leak.

 

"the breath test" is just a method described on the bottle of test fluid for verifying that the fluid is working correctly.


Yes - I replaced the coolant after replacing the heater core

 

What we know: If all is circulating properly, not getting hot and you are not adding gas to the system, you would not be over pressurizing.
Ruled out gas. So..
Have you confirmed that the stat is opening properly?
What kind of temps is it holding?

 

Took out the thermostat and boiled it last night and it stayed firmly shut as the water temp went past 200, so that's part of the problem. Jr drove it to school and back today with no over heating but it still had extra pressure in it when he got home (hard hose). So it seems to me the only way to get extra pressure in the system is through and exhaust leak into it or by making steam. So I am going to flush radiator new stat and see where that gets me. Since I missed the obvious step of checking the thermostat first (thanks Dusty), does anyone I have any other suggestions.

 

exhaust gas isn't the only way to build pressure. you could just be running on the hot side. I am assuming that you are not taking real temp reads of the system......I would advise it ,on this. if you are heating it up too much........pressure.
if you don't have a way to read the real time temps, you can check it with one of those cheap ir guns.

 

yes its probably time to buy an ultra gauge - any recomendations

 

Installed ultra gauge, runs at 200+/- for about 1o mins driving around 35-55 mph then starts to climb and hits 220 when I pull back into the drive. Upper rad hose is pretty hard at this point. It does this with and with out stat installed - just hotter without stat. The way the temp changes so suddenly doesn't make sense to me, the coolant is just moving through there with no event to change the situation, but something is making it suddenly make steam.


Can a water pump have intermittent failure?


Thoughts?