No Heat, Erratic Engine Coolant Temperature

[gfresh]

Brrrr... . I need some help and I'm thinking I have a thermostat problem. Here are the particulars...



I have no heat coming from my heater vents. It's not ice cold, but it's nowhere near warm - this is day 2 or 3 of this. This morning, my 25 mile commute looked like this...

1. Outside temperature was 34 degrees to start, roads were dry.
   
2. During initial acceleration to hwy speed up a slight hill (after driving a mile through town), my engine coolant temp (ECT) rose from 110 to 200 in about 3/4 of mile. Such a quick rise is unusual for my truck.
   
3. Depending on the load (down or up moderate and short hills) the ECT fluctuated from between mid 180's to 202.
   
4. On flat ground, at 55 mph, the temperature stayed steady at mid 190's initially. As the outside temp rose to 38 degrees, the ECT rose to 200 on flat ground.
   
5. Temperature changes were rapid depending on the load factor
   

If it turns out to be a thermostat, is this easy to change and where do I find it on a 2006, 2500?

Do I need to or should I replace the coolant at this time too (I think it's original)? Wondering if this is a handy time to do that.



Thanks.

 

[LNaugle]

Did u check your coolant level?

 

[rscurtis]

I agree. A thermostat that won't open will give you excellent heat. The quick warm-up is a tip-off to low coolant. My signature truck requires 12-14 miles of driving before the thermostat opens.

 

[gfresh]

Turns out I had a loose cap and yes, low coolant levels. So simple yet I would never have figured this out. TDR saves the day and saves me a dollar yet again. Thanks to both of you for taking the time to read this and reply. (I'm assuming that topping up will correct my problem, if I don't add to this post by tomorrow AM, it worked).

 

[gfresh]

Ok, so here's the final update. I went to my local auto parts store, bought a gallon (3. 78 litres in Canada) of premix, diesel coolant and proceeded to "top up". Well, I had to go back in for another gallon. I ended up using them both! How I didn't harm my engine is beyond me, but I had managed to lose almost 30% of my coolant by having a loose cap. And I never noticed a thing until I had no heat. There was no smell, no code, no engine anomalies, no indications that I had noticed. I'm not sure I would have even noticed anything under the hood if I had checked the oil the last time I filled up. You can see in the first photo above that the air cleaner housing has some muddy looking fluid on it, but I think I would have just scratched my head and forgotten about it if I saw that (the bottom of the housing is open to the ground - puddle?). The engine compartment was dry and though a little dirtier than normal, not alarming. I still have no idea how the cap got loose because I haven't done anything to the coolant system in a very long time... or ever. So, I guess the lesson here is - check your cap once in awhile and keep an eye on your gauges. Thanks again TDR, rscurtis and LNaugle. Now it's time for an oil change and an inspection of all other caps, belts, seals etc. etc. Might throw a coolant flush in there too...

 

[Tractorat]

When my truck was new, I took it to a dealer for an oil change. When I got home, just for the heck of it, I opened the hood. The radiator cap was just laying there. Why it didnt bounce off and down into the engine compartment (and or to the street) Ill never know. Now I watch for that kind of thing all the time.

 

[AH64ID]

Are you still running the OEM coolant? The OEM coolant is HOAT, not your normal diesel coolant, and it is known to not play nice with other coolants (even those that say they are compatible, it takes 2 compatible coolants to mix).

If the coolant is OEM and you added non-HOAT you need to do a complete flush! The OEM coolant is also only rated for 5 years/100K miles so it's probably due for a flush anyhow.

https://www.turbodieselregister.com/forums/showthread.php?218402-Coolant-flush-on-a-3rd-Gen/page3

 

[LNaugle]

Well good deal, your are welcome.