Parts cannon loaded and fired, still having issues.
Symptoms are:
- car will eventually boil over idling, with the coolant gauge showing a little over half.
- Air coming through the radiator is cool, so no flow there.
- Air coming out of the heater is cool, so no flow there, either.
- You can't see the interior of the radiator with the cap off due to the radiator design.
Background is:
- Coolant temperature sensor recently replaced and had been functioning normally.
- Thermostat replaced and had been functioning normally. Thermostat has been stove tested and appears functional.
- Coolant all flushed, old coolant reasonably clean before coming out.
- Radiator hoses are new.
- A turkey baster can pull coolant from the overflow.
- New radiator cap, appears to be holding pressure and properly pulling fluid from the reservoir.
I had done the above work, and everything was running fine. Then we started overheating. The new radiator cap was not pulling fluid from the reservoir, so I replaced that. I also thought, "hey, stupid, you replaced everything but the water pump." So I replaced the water pump and serpentine. The water pump actually looked good, no wobble, pump head appears tight on the shaft. I replaced it anyway with a Beck/Arnley that also has no wobble and a pump head that appears tight on the shaft.
The pump spins freely and the shaft is spinning with the pulley. The serpentine belt is routed correctly (can't really get that wrong).
What else do I check?
My first guess is an air lock from service. How did you bleed it?
Air lift vacuum bleeders are worth the money
P3PPY
SuperDork
10/1/23 12:39 p.m.
Can you have routed the water pump belt to where it will spin it backward?
Run_Away said:
My first guess is an air lock from service. How did you bleed it?
Air lift vacuum bleeders are worth the money
There is an air bleed at the thermostat housing that makes sure the water pump is fully submerged. I burped a couple times. I suppose there could still be air in there so checking again will never hurt.
Do any of the flaps rent vacuum bleeders? I will put that on my list if things to check.
Purple Frog (Forum Supporter) said:
Blown head gasket?
I don't seem to get constant bubbles, just the expansion if it gets too hot? Perhaps a leakdown test is on order.
Also, even with a blowing headgasket, unless actively and obviously puking, would still let the heater work, yes?
P3PPY said:
Can you have routed the water pump belt to where it will spin it backward?
I did not take a picture, but the routing matches memory, online routing pictures, and the sepentine has so little extra length (only slides over the non-ribbed water pump pulley) that I don't think you can actually route it wrong and get it on. Current routing matches the correct rotation for the old pump on my floor. I think the new pump rotates in the same direction as the old, the housings are certainly the same.
Do you have heat from the heater? If so, coolant is circulating.
I had a Dodge pickup with terribly blocked radiator tubes. Do you have hot and cool segments of the rad?
Put the thermostat in right side up?
In reply to Streetwiseguy :
No heat from the heater, and dual zone heat, so no heat from either controlled zone.
Thermostat is integrated into the housing, so there is no way to install it backwards. Even if the thermostat was a total failure, I would have heat out of the heater as the heater is on the engine side of the thermostat, yes?
Any chance you clamped the heater hoses while doing the work, or something similar? We have all left the rotor out and spent an hour wondering what went wrong.....
If it was fine before the repairs, gotta be something simple.
I use the magic funnel and have the front end up on ramps (and the heat on full blast) when I'm burping coolant and that seems to help get most of the air bubbles out. I idle the car for a while, and then also run it around 1500 RPM, as well.
Steve_Jones said:
Any chance you clamped the heater hoses while doing the work, or something similar? We have all left the rotor out and spent an hour wondering what went wrong.....
If it was fine before the repairs, gotta be something simple.
So it stopped working before the repairs, but could have just been a bad radiator cap. Radiator inlet and outlet, transmission outlet all come off for the waterpump. I drained enough to remove the waterpump, so no clamped hoses.
I agree, it should be something stupid simple. It is not a complex system, it had no sludge, and everything is clean.
dj06482 (Forum Supporter) said:
I use the magic funnel and have the front end up on ramps (and the heat on full blast) when I'm burping coolant and that seems to help get most of the air bubbles out. I idle the car for a while, and then also run it around 1500 RPM, as well.
I have to have the radiator cap on to get the thermostat to work. It will let hotspots cause boiling with the cap open and no flow. Front end is jacked up, I will give it a little RPM and give it another burp.
Gotta be air in the system, or blocked heater core at this point. You've done the rest. Any way to bypass the heater core just to see?
Pretty easy to rule out a clogged heater core. Put your hand on the hoses when it's good and warmed up. Are they hot or cold ? If you have a couple of cold hoses, you got a water supply issue.
3000 rpm got a half qt bubble out, so I topped up and went for 4000. I am only running 20 seconds or so to keep temp below 1/4. I still have to let ut sit 10 minutes before I can open it.
I have another quart in it since this afternoon and I am starting to get heat from the heater, so some RPM may be all I was missing. I will keep burping it and see how that goes.
When you open the bleeder screw on the thermostat housing, do it with the engine off.
Fill the radiator to the top. If it is low enough then it cannot pull from the overflow, so ignore what the overflow is doing.
Open the bleeder screw again.
Fill the radiator again. If you can't see the level, it isn't full enough.
Put the cap on, run engine at moderate speed until it gets heat.
The fun part: The air from the heater core gets introduced fairly low in the engine. It then circulates through the engine instead going up and out.
So after you start to get heat, shut it off, wait a little bit, then open the bleeder again. If there is no pressure in the system, do the add/bleed cha-cha again. If it is under pressure, satisfy yourself with just bleeding the air for now.
Repeat run/check heat/shut off/bleed until you are satisfied.
Heat from the heater, but not the radiator. I will keep burping and if that doesn't fix it, I will pull the thermostat for the data point.
How hot are you letting the engine get? IIRC opening point is right on up there, quite a bit over 200F.
Chrysler does not set a P0128 until something crazy low like 160. Thermostat failure on the 3.6 is really common, as is people bringing their car back because the temp gauge is going a lot higher than it ever did. Then a tactful conversation has to happen explaining that is because it is working properly for the first time since they bought it.
Feeling the upper radiator hose is a better metric for thermostat opening than feeling the radiator, in case that is tripping you up.
Air lock or the radiator is plugged because of the HOAT coolant. IR temp gun the radiator. I bet it's ice cold outside a few places.
Radiator and hoses have been largely cold. Radiator has seemed pretty clean, just looking inside the lower hose nipple. I will see what I can get for hose and radiator temps.
203 degree thermostat. The needle is usually in the middle. It was getting to 3/4 to top and jumping when it was boiling past the failing radiator cap. That was before the new water pump.
Wanted to check to make sure we were on the same page re: hot. I helped diag an "overheating" LS that turned out the guy was used to small block Chevys and was freaking out that the engine was going over 210. Chevy does not even turn the fan on low speed until 220 
Definitely sounds like air. It is kind of silly how Chrysler returns the heater core coolant to the water pump, so any air in the heater goes straight to the pump and ends up going right back in to the heater cores. I have had problems getting all of the air out even after using an Airlift to pull the system down to 28 inches of mercury before adding coolant.
Pete. (l33t FS) said:
When you open the bleeder screw on the thermostat housing, do it with the engine off.
Fill the radiator to the top. If it is low enough then it cannot pull from the overflow, so ignore what the overflow is doing.
Open the bleeder screw again.
Fill the radiator again. If you can't see the level, it isn't full enough.
Put the cap on, run engine at moderate speed until it gets heat.
The fun part: The air from the heater core gets introduced fairly low in the engine. It then circulates through the engine instead going up and out.
So after you start to get heat, shut it off, wait a little bit, then open the bleeder again. If there is no pressure in the system, do the add/bleed cha-cha again. If it is under pressure, satisfy yourself with just bleeding the air for now.
Repeat run/check heat/shut off/bleed until you are satisfied.
That is exactly my procedure. With the needle barely over half, it is taking the overflow from max to overflowing with the radiator fan kicking on and the radiator hoses cold. Heater core hoses are hot.
Thermostat is coming out. If that "fixes" I will look at sourcing a 185 thermostat.
In reply to Pete. (l33t FS) :
I missed your "definitely sounds like air." I guess I can keep trying to burp it. I worry that if things are slightly less than perfect, the radiator does nothing. That gives me "middle of nowhere reliability concerns." If, on the other hand, fixing it this time leaves me good for another 9 years and 130k, I can live with it.
Does all the air end up going through the heater core? If I make an air trap and bleed for the heater return line does the problem go away? It really doesn't seem like enough of a bubble can be at the thermostat to keep it from working, but I certainly can't see in there when it is all together.
You keep saying "burp it". I just want to make sure you are using the bleeder screw and not burping it through the thermostat itself like an old school muscle car. I am also assuming it's the 3.6?
