"False" Overheats in an '07 Eddie Bauer?

[mcgee1895]

Hey guys! I just bought an '07 Eddie Bauer with the 4.0L V6. It has 133K on it and is a beautiful car, encountering two weird issues with it though.

First: There is no heat. I'm thinking this is the blower actuator which I've read about on here already but I'm wondering if it ties more into issue #2

Second: "False" overheats. Now what I mean by this is the dashboard says the temperature is reaching too hot- a buried needle on the H- but only for a few seconds and never actually impeding driving ability nor causing any physical sign of an overheat(no coolant leak, no abnormally hot engine temp)- the only sign of an "overheat" would be that the defroster actually blows slightly warm air for a few second afterwards. This first happened going up a hill where it felt like transmission was running sloppy and whole engine got loud, then the needle shot to H for around two seconds, I pulled over and then it went to normal instantly. I did not even get time to shut the truck off before it returned to normal. I think the "loudness" was the fans kicking on as I've read that on here.

It's hard to replicate the issue but it happens consistently so far, the only thing that happens before seems to be the fans kicking on and a slight "stutter" like if you had a bad coil or it needed a fuel filter, but only for a few seconds. Then sometimes it will get the overheat needle bury but it goes away without me even pulling over or turning truck off. I don't leak coolant(and have not, at all)- Oil is at normal level and clean.

I pulled these codes from Autozone:

P0304: Cylinder 4 misfire detected
P0300: random misfire
**P0117:** Engine Coolant Temperature Circuit Low Input------- This is what I'm guessing problem is, I bought a replacement and will be trying to swap out tomorrow
P0305: Cylinder 5 misfire
P0446: Evaporative Emission System Vent Control Circuit

Also pulled a U2023-20: ABS warning

I did not pull a single code related to the transmission so I don't think it is that.

Does anybody have any ideas on what this could be? I'm at a bit of a loss and was hoping someone recognized this behavior.

Any help greatly appreciated!

 

[Bazz270]

Did you replaced the spark plugs and ignition coils (misfires 99% cause)?

 

[mcgee1895]

Did you replaced the spark plugs and ignition coils (misfires 99% cause)?

Did not get a chance to do that yet- is that a likely culprit?

 

[Bazz270]

Could be the ignition coils ,but the spark plugs should be replaced first

U codes usually refer to Can bus communication issues (bad wiring)

 

[mcgee1895]

Could be the ignition coils ,but the spark plugs should be replaced first

U codes usually refer to Can bus communication issues (bad wiring)

How hard(or expensive) is a fix for bad wiring? How would I check for that?

 

[Bazz270]

If you have the ability to read vehicle electronic drawings,you can find the issue's related circuits for physical / visual inspection (bad insulation,high resistance etc).

No idea about shop pricing.

 

[mcgee1895]

If you have the ability to read vehicle electronic drawings,you can find the issue's related circuits for physical / visual inspection (bad insulation,high resistance etc).

No idea about shop pricing.

Hi!

Just a quick update- I swapped the sensor out. Did not solve the issue. I'm thinking there may be air in coolant because engine keeps reading as overheating- but no coolant is leaking and engine does not actively reach an extremely hot temp(have checked with hood open).

Any ideas? My guy will hopefully do spark plugs soon

 

[Bazz270]

what is the actual coolant temperature ?
read coolant PID

do you see any bubbles at the radiator cap hole when running on high rpm?

if no leaks detected (even the whole tonnes of coolant lines checked includes the aux heater and the front dashboard heat exchanger) head gasket to be suspected

 

[Mbrooks420]

If you’re low on coolant you can overheat the motor without any of the things you’ve associated with overheating. Fill the coolant and try and clear any air bubbles. YouTube will likely have a video with your engine and year range.

 

[Fix4Dirt]

will say the 07 X ive heard has wiring deterioration issue, nor sure if thats the cause of the u code

 

[mcgee1895]

what is the actual coolant temperature ?
read coolant PID

do you see any bubbles at the radiator cap hole when running on high rpm?

if no leaks detected (even the whole tonnes of coolant lines checked includes the aux heater and the front dashboard heat exchanger) head gasket to be suspected

I do see bubbles in there at idling and I saw a little brown in the coolant, has to be a head gasket. What should my next step be?

 

[Fix4Dirt]

I do see bubbles in there at idling and I saw a little brown in the coolant, has to be a head gasket. What should my next step be?

replace head gasjet and check head for leaks.

 

[mcgee1895]

replace head gasjet and check head for leaks.

I'm not very mechanically inclined- should I be sure it's a head gasket?

On one hand there is a little bit of brown in the coolant but on the other hand what kind of overheat goes from buried HOT to operating in 4-5 seconds?

 

[Mbrooks420]

One where your coolant temp sensor is hanging out in an empty passage and then hot coolant actually hits it and it functions. Fist step is to actually fill the coolant and see if the heat returns.

 

[94Eddie]

I'm not very mechanically inclined- should I be sure it's a head gasket?

You can buy a test kit to determine if there is combustion gases in the coolant from about any auto parts store. This will definitively tell you if there is a head gasket leak into the cooling system. The test kits aren't that expensive.

 

[mcgee1895]

One where your coolant temp sensor is hanging out in an empty passage and then hot coolant actually hits it and it functions. Fist step is to actually fill the coolant and see if the heat returns.

sorry should have mentioned this- my coolant is topped off. Overfilled if anything. Still no heat, but coolant reservoir is completely filled, I do not lose coolant and have not.

So here is something interesting, too. My mechanic friend took a look at it for about 2 minutes before he had to go(we factetimed) and he floated the idea that previous owner used stop-leak and now it's clogging thermostat, hence the sporadic "overheating" and the brown(but not very oil-like) stuff in coolant. Any thoughts on this? I tried using a youtube video to clear out air bubbles in the coolant system but the two techniques I saw didn't work for me, tho admittedly the one said to rev engine to 3500 RPMs(!) and that seemed super high/dangerous so I did it at 2,500 and it did not work.

 

[Bazz270]

brown colored coolant means old, deteriorated coolant (people forgot of the coolant change somehow).dont really have to be the head gasket.

no A/C heat mean anything from clogged heat exchanger thru stuck thermostat to low manifold vacuum or broken A/C controls actuator latch.
try the very simple coolant/exhaust gas check as mentioned first (buy the kit and follow the kit instructions).

 

[Trainmaster]

I had a small coolant leak in the rear heater hose behind the fuel tank. The coolant level would drop and the overflow tank would empty perhaps every three months. From time to time this would create an air pocket that would affect the heat too. Sometimes it would also put the temperature sensor out of the water and the car would think it was overheating. This would lock up the electric cooling fan clutch, which would sound exactly as if the transmission wasn't shifting out of second gear.

I think that is your problem. Solve your coolant leak, stabilize the coolant level and your "transmission problem" will go away.

 

[Lee's Automotive]

will say the 07 X ive heard has wiring deterioration issue, nor sure if thats the cause of the u code

Yep, I've heard and seen the same

 

[mcgee1895]

I had a small coolant leak in the rear heater hose behind the fuel tank. The coolant level would drop and the overflow tank would empty perhaps every three months. From time to time this would create an air pocket that would affect the heat too. Sometimes it would also put the temperature sensor out of the water and the car would think it was overheating. This would lock up the electric cooling fan clutch, which would sound exactly as if the transmission wasn't shifting out of second gear.

I think that is your problem. Solve your coolant leak, stabilize the coolant level and your "transmission problem" will go away.

Hmmm, this is very interesting. The only problem is I'm not leaking coolant. Level is solid, though down perhaps slightly(i think from sloshing around) but no coolant on ground. How did you find your leak?