Ugh - trans fluid in coolant, one radiator hose cold

[Mike1991Explorer]

You guys like a mystery? Below is a quick overview. My questions are at the bottom.

Problem: overheating. Symptoms: radiator cap cold, lower radtr hose cold; also there had been a squeaking noise for a while.

I installed a new thermostat and a new water pump and flushed the radtr.
But it is still overheating and the radtr lower hose is still cold. I disconnected the lower hose from the radtr and found that water runs freely from heater hose through water pump and out the lower hose: no blockage.
I pulled the radiator to test it with a hose. Water runs freely through the radiator from the cap and top inlet, out the bottom outlet. No blockage.

New issue: After flushing the radtr I found globblets of reddish trans fluid floating in the radtr and in the top radtr hose. Earlier those lines fittings had been leaking so I put sealer on the threads and re-tighted where the trans lines enter the radtr.

I think there might be a couple of things going on. MY questions:
1. IS it possible that I broke the trans cooler so it now leaks into the radtr?
2. Why is the lower radtr hose still cold and the engine still overheating?
3. Could these two problems be caused by one bad radiator?

Many thanks, Mike

 

[Anime]

Even if the trans cooler is leaking all over the radiator, the lines are seperate from the ones that carry coolant so there's no way for them to mix without there being a leak in both lines. It's not impossible but it's unlikely. If you have any doubt about the shape the radiator is in, just get a new one. They are rather inexpensive, especially online.

If the lower hose is cold then the coolant isn't circulating in the system. This is usually caused by one of two things, either a bad thermostat that isn't opening, or air trapped in the system that creates an air bubble in front of the thermostat, preventing the hot coolant from getting to it and making it open.

The fix is a thermostat that works (just because a thermostat is new doesn't mean it works, though) and to follow the factory coolant refill procedure to "burp" the air out of the system when putting coolant in. If you just fill it and put the cap on and drive, the trapped air will stay in there and cause it to overheat.

Also note that overheating ruins a thermostat, so even if you just put a brand new one in, if you overheat it, it's ruined and must be replaced.

It IS possible for a radiator to be clogged as well, even if it flows water poured through it slowly, it might not flow fast enough to cool an engine if it's partly clogged. If the engine temp climbs really fast after the gauge needle gets to the middle, usually it's the thermostat and no coolant is circulating. If the temp gauge needle creeps up past the middle, then it might be a clogged radiator that has some coolant going through it but not enough.

I'd guess thermostat/air bubble from not burping the system correctly, since the lower hose would still get warm if even some coolant was getting through.

 

[Roadrunner777]

Did you use some kind of chemical to flush the system with? If so, then that explains the trans fluid in the coolant... you need a new radiator. The trans uses the radiator for cooling, you should see the lines on the driver's side tank.
Everything else is circulation, which screams thermostat.

 

[Mike1991Explorer]

Thanks guys. I replaced the radiator: no more trans fluid. When I tightened the fittings I must have punched through into what looks like a coolant tube right behind the nut. So, that's solved.

Since I've replaced everything, it must be the thermo and/or bubble. I'll give it a try.
thanks.

 

[Mike1991Explorer]

Merging two posts:
see my update at: "Replaced everything - still overheats"