Just gave my 3.2 a real-world coolant system stress test...

150K, was planning to do water pump, hoses, radiator, oil & tranny cooler myself but got busy before a road trip. Towed a trailer in the Sierra Nevadas in 110 *F heat, I did use an OBDII guage to keep coolant temps mostly under 105* C, with short excursions to 110*C.

Made it to my vacation home (ten hour drive), but the PCV hose sprung a leak the next morning after cooling down over night. Got that and some hoses replaced at a good but expensive local shop (mountain town, few options). A couple days after that I had to go get another trailer and pull it up a mountain pass... then the radiator sprung a leak.

Ended up getting hoses, water pump, drive belt, idler/tensioner, radiator, oil & tranny coolers done since it seemed that the cooling system was at the end of it's line.

So 150K looks like the limit, probably should replace all that stuff at 120K if you're doing severe duty. I was using dexcool, but will now switch to a G13 spec.

At least it didn't strand me anywhere.


p_gill's high mileage thread on the Brit forum...

https://www.freel2.com/forum/post411194.html#411194

 

Faced with a similar situation, I think I would have rented a pickup truck with a hitch for the part where you pulled a trailer up a mountain hill.

 

I'd done it before many times, with a heavier trailer, but probably a few degrees cooler. So I think the issue was just age on the cooling parts.

I've also in the past got it hot enough to cause the coolant temp needle to rise off the middle, which happens at 113*C IIRC. Since I got the OBDII gauge, I never let it get that hot anymore, try to keep it under 105*C.