No cabin heat and overheating

So it was -9 when I left work this morning. I have had a no cabin heat issue for the past few days when it got below zero here. I had the same issue before a few years back when It got very cold before. Temps would got up to 190 and stay there but the air of any vents had no hint of heat at all. This morning the change along with the no heat was once I got above 40 mph the temps would just creep up and hit 260. I would pull over and let it idle and the temps went back to 190. Coolant stays full in the tank. I took side streets home and the temps remained normal until almost home when they creeped into the lower 200s. This has the feel of a water pump impeller failure how ever I did change the belt and pump maybe 60k ago and am fairly certain a steel impeller pump went on. Do these fail the same? It did notice to the lower hose was ice cold after the first time I stopped when the needles pegged out. however once I got home it was normal. I’m going to try and get some more troubleshooting done tomorrow after work.

Thermostat.

MoparMarv said:

So it was -9 when I left work this morning. I have had a no cabin heat issue for the past few days when it got below zero here. I had the same issue before a few years back when It got very cold before. Temps would got up to 190 and stay there but the air of any vents had no hint of heat at all. This morning the change along with the no heat was once I got above 40 mph the temps would just creep up and hit 260. I would pull over and let it idle and the temps went back to 190. Coolant stays full in the tank. I took side streets home and the temps remained normal until almost home when they creeped into the lower 200s. This has the feel of a water pump impeller failure how ever I did change the belt and pump maybe 60k ago and am fairly certain a steel impeller pump went on. Do these fail the same? It did notice to the lower hose was ice cold after the first time I stopped when the needles pegged out. however once I got home it was normal. I’m going to try and get some more troubleshooting done tomorrow after work.

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It does sound like it could be the water pump impeller slipping.
If it was mine I would consider removing the thermostat and doing the boil in a pot test. And while the thermostat is out you can reach your fingers in to the pump impeller to see if it turns/slips.

It kinda sounds like two problems. One is the thermostat isn't opening or the water pump isn't pumping. That would explain why the temperature climbs and why the lower radiator hose is cold. If no coolant is circulating, the coolant in the engine never cools and if no coolant is circulating, the bottom hose would not get warm.

The no cabin heat, I'm not sure because I haven't made the time to study the coolant flow and whatnot on these. Maxcow has it right with pulling the stat and checking the water pump. If the pump is spinning on it's shaft, you know it's time for that, but since the stat is out, check it to see if it opens and closes properly, then install a new OEM stat.

Do you see antifreeze returning to the bottle from the small hose?
If no it could be the water pump impeller.
Do you have enough antifreeze that it did not freeze up?

I'm with wonneber... did you check the return line to the tank? If there is water coming out of the return line hose, then generally speaking your water pump is working. As far as T-stats go they are inexpensive and easy to replace.

Well once I got it in the garage I found a leak on the back left side of the engine collectiing on top of the trans. The temp sending unit came dislodged and it now crooked in its seat. I preemptively ordered a timing belt kit, Tstat and that sensor. I’ll try and figure out a picture of it.

I bet something froze up.....

Thermostat tests good. Starts to crack at about 190-195 and fully open at 205. The water pump looks and feels solid and Nothing appears broken. I’m leaning toward a leak at that sending unit causing some air to getting into the system and or the sending unit possibly going bad.
There is flow at the bottle but it seems low to me compared to the rabbits I had in the past. Yesterday I had the car running while moving stuff around and I did get heat while it was sitting on an slight upward incline.
The coolant does seems a little light to me so I also agree with the coolant freezing possibility or not being good for -10. I’m wondering if that return line or something got Iced up in the system. I’m going to poke around a little bit more and take car of a few things since it’s inside.

....or there may gas being introduced into the cooling system from a leaking head gasket....is your coolant reservoir clean or dirty inside?

Leaking EGR cooler perhaps. I'm wondering if the thermostat fits in its housing backwards. Not that anyone would do something like that.

Maybe try using recirculate mode to see if the heat is better?

That just moves blend doors around. He's got a more serious issue.

sisyphus said:

That just moves blend doors around. He's got a more serious issue.

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Correct, less cold air coming in maybe?

MoparMarv said:

Well once I got it in the garage I found a leak on the back left side of the engine collectiing on top of the trans. The temp sending unit came dislodged and it now crooked in its seat. I preemptively ordered a timing belt kit, Tstat and that sensor. I’ll try and figure out a picture of it.

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+1 on the freezing theory.
Did you get a new clip for the coolant temp sensor? If freezing caused that to be pushed out of place then the clip is probably ruined (or gone).

Can lack of pressure in the cooling system be a likely cause allowing air intake? I recently replaced my blue reservoir cap because it failed to hold pressure. My temperature was hotter than normal, even with a new, oem t-stat. I have yet to test the reservoir itself; just waiting for warmer weather which is on the way.

This is starting to sound like poor circulation.
After the car runs for 1 minute (still cold engine and running) if you loosen the reservoir cap do you get pressure release?
Did you check if antifreeze is returning to the bottle from the small hose?

I just buttoned up the cooling system and let it run for a few minutes. I ended up breaking off the return line nipple in the reservoir so I picked up a new one. There is a good stream returning the coolant reservoir so the pump checks out good unless is something really odd. I’m leaning very heavy toward the coolant being frozen. The coolant in the pan tested to -22 and that’s with maybe 2 quarts of straight coolant added trying to limp home from work. So it’s very possible I did have ice causing issues with the long stretch of sub zero weather. The clip broke when taking it off but a new one came with the new sensor. And top that off with the low coolant level. I have a few other things to finished before I get it out on the road. It should be a lot warmer in the next few days so it will be harder to hide an overheating issue if that problem remains. I’ll report back in a few days.

wonneber said:

This is starting to sound like poor circulation.
After the car runs for 1 minute (still cold engine and running) if you loosen the reservoir cap do you get pressure release?
Did you check if antifreeze is returning to the bottle from the small hose?

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I will check this the next time I run it. It almost felt like suction on the cap when I was having issues. Which if that return was say frozen closed you would have that issue?

MoparMarv said:

I will check this the next time I run it. It almost felt like suction on the cap when I was having issues. Which if that return was say frozen closed you would have that issue?

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If the return line was frozen nothing would go through it.
It's warmer here, almost 30F today, any change there?

MoparMarv said:

I will check this the next time I run it. It almost felt like suction on the cap when I was having issues. Which if that return was say frozen closed you would have that issue?

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Any update since things warmed up?

Update

So I have been driving it since Thursday. Outside Temps have ranged from 40f to about 0f. The gauge gets up to to 190 and stays right there. So my conclusion in the end was a low coolant level and or coolant in poor condition for the extended subzero cold snap we had here. I would guess my coolant was good for right around zero to -10. The new coolant shows -40. Another wild card is my low coolant level sensor may have went bad covering up the low coolant condition. I broken the fitting off of the reservoir so put a new resevior in. I may try to test the old one to see if that’s the case. The cap has no pressure when taking it off or so it feels so I’m not sure if that’s normal? I reused the old thermostat after it tested good. If I were in these shoes again the steps I would do.
1. look for flow back to the coolant tank at the small hose.
2. Check the coolant condition
3. Check the coolant level and see if there is air in the system as the heater core does appear to be the highest point. Try parking uphill and see if that changes anything.
4. Hook up the vagcom and see what it shows the tempature is since sending units do go bad.
5. Test thermostat while it’s out take a peek at the water pump for any thing that odd as these symptoms also point to a failed water pump.
6. I did not have the means but would to have like to flush out the heater core and radiator and system for that matter so to get as much fresh coolant in as possible and make sure nothing was plugged.

Did you replace the cap?