03 zr-2 over heating

[truckdude239]

hey guys friend of mine has a 03 s-10 zr-2 with the 4.3. started having issue overheating . It only over heats on the high way or pulling a trailer. rest of the time it is normal (for the most part) Heres the kicker parts replaced: rad, water pump, tstat, rad cap,fan clutch, flushed system, refilled antifreeze with peak life time coolant. and it still over heats. He took it to a shop, and they told him sorry cant figure it out. there is no water in the oil intake isn't leaking. so we are at a lost to figure it out. had another shop say transmission was probably on the way out and building to much heat and the rad can't over it all. i don't believe this one we changed the tranny fluid 10k ago and it still clear not smell of metal in it. soo any ideas where to look next?. was thinking maybe the lower rad hose sucking shut under load maybe?

any help is helpful

[gchemist]

I suggest two items. Add an external transmission cooler. Two upgrade the clutch fan to an Explorer 4.0. I upgrade my 4.3 fan. Add some Water Wetter to the system. Try running a larger % of water. Last, the switch could be failing.

[truckdude239]

antifreeze is a 50/50 mix, which switch are you talking about? we have verified the engine temp when it over heats and it is th same as the gage. will look into an external trans cooler

[Arad68]

I'd definitley check the lower hose to see if it is collapsing under higher rpms.

[gchemist]

What brand is the thermostat? I install only Modine. Thermostats can be bad, even new ones. In the summer, you can nearly run 100% water. 100% water is more efficient than a mix. Was it converted over from Dexcool?

[truckdude239]

the t-sat was a super stat from advance. the peak life time is their brand of extened lvie antifreeze but is compilable with any antifreeze

[68C15]

how hot is it getting number wise? does it stop at a point or does it keep climbing?

[truckdude239]

it will sit at 210 untill we hit the highway or anything over45 or we have a tailer on the back ( small trailer with a zero-turn lawnmower) it will hit 210 sit there then start to climb it got to 240 the other day and they cut it off and it ended up boiling over out the over flow tube

[68C15]

is the air coming from the radiator fan hot?(air pocket in coolant) decent air flow? (fan clutch) low coolant flow? (water pump impeller)

[truckdude239]

Well he took it to another shop and they did a test on the antifreeZe and said it had combustion gas in it sook looks like a brown head

[truckdude239]

it does have good air flow air was hot coming off the radiator and it has a new water pump heat was hot (running heater) did not help itfrom over heating) water was flowing the the rad pretty good

[truckdude239]

okay found out other shop was trying to take us the truck doesnot have blown head gaskets but we did find a leaking intake gasket. will this casue it to over ehat its seeping but not like full blown leaking deal

[truckdude239]

well after 2 years we finally found out what was going on had the intakes fixed but it turned out to be the aftermarket radiator we put in it, installed a dephi radiator and no more problems towed my 12ft tailer the other day with 24oo pounds on it and temps never got over 210!!!!