Overheating and no heat - help me diagnose?

psmitty2 · **Joined:** Wed Jul 10, 2013 2:27 pm **Posts:** 20

Hi all -

I've told you about how my 05 CRD has overheated in the past. (Three years ago August, Eisenhower Pass headed East, 90+ outside). Today, it came awfully close.

42 degrees outside, the heat worked until the Tstat (replaced in July) held steady a tick below straight up. Then I noticed that the hot air was not coming out hot, even though the dial was all the way to the right. It wasn't cold, but it was cool, coming out of the vents. Temp guage was solid.

I went up I-70 toward Evergreen, a steep and steady incline. (This past summer I went up there with CC locked at 65 MPH, and when the temp guage started past straight, I'd turn on heater and it would relax back down; this issue would not present itself on 7 to Estes, also a steep and steady incline but about 45 MPH). It started past straight. I switched the heater from foot and cabin to just foot. Still no heat. The temp guage continued on to 3/4. Then past. Then I pulled over before it could get to the redline. Cranked the heat to 4, but still no hot air coming out. I went outside to check; the fan was engaged, there was coolant in the well. It slowly cooled down.

Luckily, this was not a mission critical trip, so I just cancelled it, and turned around. On the way back down, the temp guage slid to 1/4, and hot air came out. The Tstat closed, and the temp guage went back to a tick shy of straight, and the heat cut out again.

I think that was the viscous heater re-engaging.

I had the oil changed 500 miles ago last month, and the oil filter, antifreeze/coolant swapped same time.

Any ideas what's happening?

PS: Merry Christmas, Hannukah, Kwanzaa, etc. Happy New Year!

flman · **Posted:** Sun Dec 21, 2014 4:23 pm

Sounds like a blown head gasket or warped head considering it was overheated, especially if you have no heat under heavy acceleration, and better heat with slow cruising and coasting.
Pull the rad cap in the AM after the Jeep cools down. Should be no pressure. If it is like the video it is bad.

https://www.youtube.com/watch?v=4Go4FC0riQs

WWDiesel · **Posted:** Sun Dec 21, 2014 4:34 pm

Did you see any loss of coolant or level in tank???
Sounds to me like it maybe got air bound and the pump was not moving the coolant as it should since you had no heat coming out of the heater.
If you have a head gasket leak, it should have loss some coolant or boiled over if the temperature went off the scale as you stated...
very strange indeed!!!!

gmctd · **Posted:** Sun Dec 21, 2014 4:36 pm

One function of the viscous fan-clutch is to disengage at higher rpms, where vehicle forward speed guarantees high-volume air-flow thru the radiator - as vehicle slows the bi-metal activated gate allows viscous fluid to re-engage as air-flow becomes hot - if hi-speed air-flow temp exceeds bi-metal calibration at high rpm, clutch will re-engage until air-flow temps are reduced (one very good reason not to replace with after-market versions, which are usually viscous-only)

Could be deteriorated ECT sensor - would also affect viscous cabin heater function

Could be deteriorating T-stat

Could be low coolant - check radiator level (not reservoir level) when cold, then reservoir level

Could be deteriorated fan clutch operation

Also blown head gasket, as flman indicates - pull coolant-pressure cap when engine is cold, crank it up and watch for bubbles popping out of coolant, indicating blown headgasket

psmitty2 · **Joined:** Wed Jul 10, 2013 2:27 pm **Posts:** 20

Thanks for the quick replies.

Will check the head gasket asap, but that won't be a few days, given the time of year, etc.

racertracer · **Posted:** Sun Dec 21, 2014 6:31 pm

I also experienced loss of heat after replacing the thermostat back in 2009...... it was due to air pockets which never purged out and possibly frying the head, or expediting the event.

John3:17 · **Posted:** Sun Dec 21, 2014 7:39 pm

Check for leaks around the water pump. Just had a Cherokee with same symptoms - water pump wasn't circulating the coolant.

thermorex · **Posted:** Sun Dec 21, 2014 11:06 pm

How old is the thermostat? A partially opened thermostat would cause exactly what you describe.

flman · **Posted:** Mon Dec 22, 2014 8:57 am

psmitty2 wrote:

Thanks for the quick replies.

Will check the head gasket asap, but that won't be a few days, given the time of year, etc.

Only takes a second to pull the rad cap on a cold engine, and if it has no pressure, take a sigh of relief.

papaindigo · **Posted:** Mon Dec 22, 2014 9:49 am

Don't have the link or the solution but there has been an episode of this symptom that you might look for.

That said consider the route of coolant flow on the CRD. Coolant enters the thermostat housing directly from the head. Assuming the OEM tstat is working properly then 1) on a cold engine coolant mostly flows thru the lower tstat aluminum/bypass port to the water pump housing with some flow to the radiator (top big port) and viscous heater (large plastic port) and 2) as the engine warms up and the tstat opens the tstat closes the bypass port directing progressively more coolant flow to the radiator and the viscous heater with the right angle plastic port serving to bleed excess coolant as it expands from heat and any air in the coolant to the tank on the firewall. There is no in-line valve controlling coolant flow to the heater core; what controls heat in the cabin are the blend doors in the HVAC housing. Hence if coolant is flowing normally the heater core in/out flow lines should both be hot and essentially the same temperature. If they are both coldish when engine temp is hot something is blocking that flow.

psmitty2 · **Joined:** Wed Jul 10, 2013 2:27 pm **Posts:** 20

Thanks to all who replied.

I did check for coolant pressure, but it had sat a few days, and then I went out of town, and then it was super hectic at work because a new year and nobody did anything in the second half of December.

Thank God this is our second car!

So I checked it out after it sat three weeks, and the coolant appeared low. I took it a few miles, and boom, started overheating. Also no heat from vents, even on high.

Let it sit another few hours, and again, no pressure. So sigh of relief.

flman · **Posted:** Fri Jan 09, 2015 7:15 pm

psmitty2 wrote:

Thanks to all who replied.

I did check for coolant pressure, but it had sat a few days, and then I went out of town, and then it was super hectic at work because a new year and nobody did anything in the second half of December.

Thank God this is our second car!

So I checked it out after it sat three weeks, and the coolant appeared low. I took it a few miles, and boom, started overheating. Also no heat from vents, even on high.

Let it sit another few hours, and again, no pressure. So sigh of relief.

3 weeks may be too long, but mine would have the temp gauge go up and no heat with a blown head gasket. Unless the impeller on the water pump is slipping? It can only be poor circulation, or combustion gases causing this kind of problem.

geordi · **Posted:** Fri Jan 09, 2015 10:30 pm

Failed thermostat.

The key is the lack of heat in the cabin, where there should ALWAYS ALWAYS ALWAYS be heat available if there is water.

Because this is a dual-function thermostat, when it opens the port to the radiator, it is supposed to close off the bypass loop that allows water to the heater core and the viscous heater and back into the engine / water pump inlet.

When the temperature came down, the thermostat "closed" the main port, but it opened the bypass, which is why you got heat in the cabin again. When the temperature came up (because the main port was closed) then the bypass closed again, BUT the main port is either not open fully, or some blockage exists in the system that is preventing the coolant loop from working normally. It is only that this engine normally runs so cold, why you could get away with still being able to drive it without any effective cooling methods.

First, get yourself a 3 gallon bucket and drain the radiator from the nipple on the passenger side at the bottom. Some tubing will prevent making a mess, and the valve opens with regular pliers, you shouldn't need to use a socket.
Then, pull the thermostat and test it in a pan of water on the stove - check for operation as it should be, and report back. I'd bet money that it isn't functioning properly. It would be the first time I've heard of one of these failing closed, but that isn't an unheard of failure method in other designs.

If what comes into the bucket has chunks or sludge of any type - the system wasn't refilled properly. If it looks OK, store it and you can refill it later.

WolverineFW · **Posted:** Fri Jan 09, 2015 11:34 pm

psmitty2 wrote:

Thanks to all who replied.

I did check for coolant pressure, but it had sat a few days, and then I went out of town, and then it was super hectic at work because a new year and nobody did anything in the second half of December.

Thank God this is our second car!

So I checked it out after it sat three weeks, and the coolant appeared low. I took it a few miles, and boom, started overheating. Also no heat from vents, even on high.

Let it sit another few hours, and again, no pressure. So sigh of relief.

I can attest that checking for pressure under the cap on a cool motor is not a surefire way to diagnose. I had a blown head gasket and would not have pressure under the cap on a cold motor. I started to notice heating issues as in the heat would cut out under load and cycle on and off.

geordi · **Posted:** Sat Jan 10, 2015 12:14 am

Were you also losing water? I've never heard of a head gasket failure that didn't involve some form of water migration or loss... Usually loss.

65Corvair · **Posted:** Sat Jan 10, 2015 12:09 pm

I had a issue like this, bleeding the air out of the radiator helped a lot. I would bleed it every time before I drove the vehicle. But ultimately, I had a leaking head gasket.

Link to my thread.
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=78100

flman · **Posted:** Sat Jan 10, 2015 4:28 pm

65Corvair wrote:

I had a issue like this, bleeding the air out of the radiator helped a lot. I would bleed it every time before I drove the vehicle. But ultimately, I had a leaking head gasket.

Link to my thread.
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=78100

I agree leaking head gasket same symptoms, but for the sake of the OP we can only hope Geordi is right. With an old leaky radiator cap, you may not get pressure, especially after 3 weeks.

geordi · **Posted:** Sat Jan 10, 2015 6:52 pm

In thinking about the thermostat, I'm not as certain that it is the primary problem anymore - here's why:

The lack of heat in the cabin doesn't make any sense, as that loop should always be receiving water, no matter what the position of the thermostat. Something doesn't compute here, and if the water level isn't changing (I'm ignoring the pressure questions for the moment) then what is happening to block the heater core's water flow when the engine is hot? There seems to me to be a temperature-based blockage, which normally would be the thermostat... But not closing when it is hot!

If there was a head gasket problem, you should be losing water or gaining pressure - Or both. If neither is happening, then the head gasket is not the problem.

Papaindigo had a good suggestion to feel the heater core hoses and see if they are both equally hot, but to me, that would only indicate an air blend door problem. I don't think you are having a blending issue, this seems to be entirely in the water system.

Is the water system stock? Have you removed / altered the EGR and the outflow from the intake side of the head, over to that Y pipe? Do you have an in-hose thermostat, or just the stock unit? I'm really scratching my head here. You've found a unique problem, that is for sure. In an ordinary car, I would suggest bypassing the known problem of the thermostat and see if the blockage goes away. On this, that isn't an option unfortunately. I also don't have one of those laying around to look at and see if there is some way that the wax motor could be pushing the valves to both close.

In absence of any other problems though, the water pump has been the reason occasionally, I think RacerTracer had one where the plastic vanes of the pump impeller had somehow been worn down to just little nubs, and he had overheating b/c of lack of water flow. I've never seen that before or since, and I highly doubt it is even possible with the brass impeller of the Graf pumps. Do you have a Graf pump or the original?

joelukex4 · **Joined:** Thu Sep 29, 2011 4:54 pm **Posts:** 386

Check to see if the heater core is blocked. I had two out of three Cherokees that needed the heater core back flushed because they were clogged. You would get intermittent heat. I don't know if the Liberty has the same issue but it may be worth a look. It may be a combined issue with a bad thermostat.

WolverineFW · **Posted:** Sun Jan 11, 2015 4:53 pm

psmitty2 wrote:

On the way back down, the temp guage slid to 1/4, and hot air came out. The Tstat closed, and the temp guage went back to a tick shy of straight, and the heat cut out again.

This is the same thing mine would do when my head gasket was leaking. My coolant loss was obvious though as it was going out the relief on the overflow tank and evaportating off the heat sheild and downpipe.

psmitty2 wrote:

So I checked it out after it sat three weeks, and the coolant appeared low.

So was it low or not? Have you being having to add coolant?

I would suggest you get a combustion gas test kit for diesel motors and check your coolant with the kit.

Overheating and no heat - help me diagnose?

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