Cooling system, please check my police work...

Yes, yet another coolant thread. I can't find a thread with my specific combination of problems and I don't know if they are related or not. I would truly appreciate some experienced opinions.

System specs:
All components less than two years old, most less than 12 months

Runs in the 195* to 208* degree range on highway, hard pulls, city driving, it's consistent at these temps.

CSF 3 row installed six months ago
e fans installed this weekend
new pump
new tstat two months ago (195*)
new tstat housing
Good flush
new hoses last year
rad cap last year (16#)
Running Rotella ELC
Heater core has been flushed repeatedly and flows well when flushed.




Two problems:

First, the heat doesnt work. It gets luke warm (90* at the vent) at best. Slightly warmer on hard pull. Blender door is functioning properly and blend door motor has been removed cleaned and greased and works fine.
Upper radiator hose gets nice and hot, the temp switch for the fans kicks on and off as it should (it's mounted in the upper heater hose). Checked via torque II app from the ECM.

Lower hose does not get as hot, not nearly as hot. Talyn suggested checking that the hard line is not blocked and it is not.

Is it possible the heater core can have plates or tubes blocked but still flows well? As in the coolant, or water in a flush, simply follows a different path around the blockage? I am admitting I am truly ignorant as to how a heater core is designed and how coolant flows through it.


I have NO idea WTF is going on with this. HELP it's cold!!!



Next problem:

Some coolant loss of about an overflow jug about every 6000 miles. I live at the top of a 7 or 8% grade. When I stop the Jeep at the top I can hear some bubbling and smell coolant however I cannot see any signs of a leak. Just before I installed the CSF I had a new stock radiator and it did the same thing.


Yes, it's a 0331 head, no there is no overheating, no milky oil, no residue under the oil cap and my oil analysis comes back fine. I am not stupid enough to dismiss the possibility of a cracked head BUT there are no signs of it so far.

I'm thinking replace the radiator cap before I go and buy a coolant pressure system tester.

C'mon guys, I know you love a challenge. What do you think? What would you check next?

You can rent a coolant pressure tester for free at most parts stores. It will test the cap as well. IIRC there is a spot near the T-stat housing, front drivers side head bolt (that should have sealer on the threads????) and the exhaust manifold where a small leak can disappear to fast to spot. If it is a hairline crack in the cylinder head it may not be detectable yet except for a missfire when it gets worse.

On the heater core, it may be the outside air damper door is not closing to recirculate air, letting cold air in instead. That could be an electric or vacuum operated damper door controller issue.

If it is the heater core, then it has some scale on the tube walls, and running some diluted (with Distilled water) and CLR through the heater core (need a small pump and 5 gallon bucket and some hoses and adapters) or vinegar to dissolve the calcium scale that is insulating the tubes.
Or there is trash in the block still coming loose and replugging the heater core tubes.

Also, make sure the heater core is not leaking!!!!!!!

The air door underneath the glove box works fine. Is there another one that I need to find?

Ok--had to look in your profile for the year, 2001--although the 0331 head was a good clue.

Your cooling system is an "open" system. The radiator cap has TWO vents--one to allow expanded coolant out of the cooling system into the coolant reservoir, and another vent that allows coolant to flow back from the reservoir as the cooling system cools down and the contracting coolant creates a vacuum that draws from the reservoir.

Now, is your radiator cap less than two years old and of a high quality? If it is leaking you may be loosing coolant to the environment and it may be allowing outside air to enter the cooling system instead of pulling coolant from the reservoir.

As stated, rent a pressure tester or just replace the radiator cap--NOT with GARBAGE--with a quality made one. Renting the pressure tester will allow you to KNOW if there is a leak somewhere.

Stant 16lb about 20 months. Might as well replace it...

Doesn't my sig say I have an 01'? I thought I added that to it. Can't tell from Tapatalk.

LYKOS said:

Stant 16lb about 20 months. Might as well replace it...

Doesn't my sig say I have an 01'? I thought I added that to it. Can't tell from Tapatalk.

Click to expand...

Must be in the "More later..." part

I would say that if the heater return hose is staying cool then you've found the problem--no flow through the heater core. Based on what you've written so far, the most probable explanation is the sensor tap restricting the flow. Another possibility is bad pump creating insufficient pressure, although I would expect other problems to manifest from that.

ps--your sig says '01 but it would be easier to understand if it was spelled out. Joe thinks you're talking about the 1800s

ehall said:

I would say that if the heater return hose is staying cool then you've found the problem--no flow through the heater core. Based on what you've written so far, the most probable explanation is the sensor tap restricting the flow. Another possibility is bad pump creating insufficient pressure, although I would expect other problems to manifest from that.

ps--your sig says '01 but it would be easier to understand if it was spelled out. Joe thinks you're talking about the 1800s

Click to expand...

ROTFLMAO!

I thought his lift was one foot, three inches!

Actually, I missed the 01--multiple times. Back to basic reading comprehension class for me!

Re: Re: Cooling system, please check my police work...

ehall said:

I would say that if the heater return hose is staying cool then you've found the problem--no flow through the heater core. Based on what you've written so far, the most probable explanation is the sensor tap restricting the flow.

Click to expand...

I'll check the sensor tap. Thanks!

Re: Re: Cooling system, please check my police work...

ehall said:

ps--your sig says '01 but it would be easier to understand if it was spelled out. Joe thinks you're talking about the 1800s

Click to expand...

After I check the sensor tapI'm going to change that over to Roman numerals.

Concur with pressure-testing the system.

Also, know that scale can built up on the inside of the heater core tubes that will impede heat transfer, but can (and often do) form nice, flat layers that don't impede flow. I know you said you flushed it "several times," but what flush did you use and how did you use it?

I used CLR and a garden hose.

I'm going to use vinegar and compressed air on Saturday to see if that helps.

Any suggestions on removing that scale? I'm trying my best to not have to replace the core.



The sensor tap doesn't seemto be occluding the heater hose.

Will pressure test this weekend as well.

Re: Re: Cooling system, please check my police work...

joe_peters said:

I thought his lift was one foot, three inches!

Click to expand...

That would be AWESOME on 31's.


That's 31 inch tire not 31 foot tires BTW.

Try this: http://www.youtube.com/watch?v=dcL_0TWeZJY

I've not done it with air. Will get that Saturday.

Pressure check your 20 month old cap, too. I've gotten 2 from Napa, both Stants, that were faulty right out of the box. I ended up "adjusting" the ears to get the
cap to seat fully.