Hi all.

Recently I have had two (2) overheating events on our D2 in the past couple of weeks.

On both occasions, it was in extended stop-and-go heavy traffic in 100F plus heat.

Both times got I it down from danger zone to 2/3 thirds mark by running the cabin heater as an additional radiator until I was able to get moving.

Once I got moving, it went back down to the halfway mark (I know, I know, the gauge is not terribly accurate).

I replaced the fan clutch as a preventative measure a couple of years and 15,000ish miles ago.

Could it have failed already?

How can I tell? What should resistance feel like when engine compartment is cold? hot?

 

In TX turn off the AC & it will make a 10F difference when you’re running hot. Make sure your efan for the HVAC is working.

 

I would replace the radiator and remove and discard the thermostat substituting it with direct hoses from block outlet to radiator inlet and radiator outlet to pump suction.
Before engine craps out on the next overheat. The thermostat is only for occupant comfort for 5 minutes at freezing ambient temperature. And to scratch your head wondering if it is working the rest of the time.

 

So no one's biting on it being the fan clutch?

Will check electric fan.

Replace radiator? It flushed pretty easily. Of course that was 2+ years ago.

Can you really run it without a thermostat? It has 170 degree one in it now.

 

Try reproducing the situation that lead to the overheating, stop and go, during 95° temps (maybe on a dirt road where you can control situation traffic wise). Then, when it does start to run warm...stop, turn engine off, pop hood and check resistance of fan...should be somewhat hard to turn. Cold, you should fell little resistance.

Also, if you can't reproduce the situation without having other vehicles involved...then maybe try staying back a little, from the vehicle in front of you during stop and go in the furture. This really restricts air flow, when you stay close.

And like mentioned, make sure your electric fan is in working order.

Brian.

 

Probably not the clutch.

What coolant are you using?

 

Since he's in TX I'm pretty certain it's either the AC condenser is adding heat to the rest of the cooling system or maybe a bad Efan which at slow speeds/traffic could certainly lead to a warm running engine. Try the same situation without the HVAC and I'll bet you anything you'll see a 10F difference. I've done enough testing in TX until I'm blue in the face. HD/Severe Fan Clutch, 620-112 Fan Blade or OEM 99-02, 180F thermostat (OEM Style either Britpart or LR Grey), green coolant, and in TX with the AC on in the summer it'll be 200-212F pretty easy.

 

Have you been monitoring the coolant level? Did you have to replace any? Are you saying you overheated without any coolant loss or overflow?

 

Working backwards:

No coolant loss at all.

Prestone(?) DEX coolant. Red stuff for aluminum blocks, 50:50 ratio.

Pretty new water pump (<15K miles ago, same time as I replaced the fan clutch, also a heavy duty version).

When I popped the hood and looked around during the latest overheat event, I did note through the translucent casing of my 180F from L8 (I think -- that was 4-5 years and 30K miles ago) what looked like a little air pocket (maybe 1/4-1/2 inch) at the top of the thermostat housing?

Frankly, I assumed the mechanical fan did all the cooling work and didn't even know my D2 had an electric condenser fan. Never had radiator out ever (even when my son and I pulled engine to rebuild it for a slipped sleeve we left the radiator in place). Haven't gone to RAV yet, but since I cannot see it, how do I check the efan operation?

FYI, before the overheating situation, I had been wrestling a bank 2 knock sensor and associated codes to the ground: it started as a broken (orange?) wire right at the connector, so got replacement connector pigtail from donor at my go-to recycler, mechanically spliced at the exposed two wire point (rather than further back at the coax splice), went back to recycler yesterday to get the other KS connector with a full coax pigtail, and they had crushed it :-( Super bummer.


BTW, thanks for all the replies so far. Where is Disco Mike? (off the grid in the Colorado mountains for the summer?)

 

Disco Mike is long gone, he hasn't been active in years. I highly recommend you get yourself an ultra gauge/scangauge II, or Bluetooth OBD2 device that can give you live/accurate temps. The stock gauge is pretty worthless besides cold/normal/overheat.

If it's been 4-5 years on the thermostat I'd certainly check it, and the green coolant works with aluminum blocks perfectly fine. You also really need to verify the Efan is working when the AC is on.