FYI for those people with overheating issues with their VX

[blacksambo]

The more I read the more I respect Isuzu OEM parts.

[rocket man]

Wow that is a bewildering dilemma you have VX Kat. That is a crazy maker.

I have a 89 Isuzu Amigo that I have also have had since new. Now in that one I had a two row (like yurs) Modine radiator put in years ago to cool down the little 4 cyl engine that just couldn’t handle pulling that trailer. After the install I could pull a bus up Pike’s Peak and it wouldn’t push the needle past the middle of the gauge.

That radiator of yours is the, “bomb” and should way way way over cool your engine. IMHO. But since it doesn’t….. from the description you describe I would take a real hard look at your thermostat. At 60-75 mph you should be getting plenty air through the radiator so that you really don’t need any fan at all. Personally I don’t think if you R&R the fan clutch and fan it will make any difference. Seems to me that your “inconsistent” engine temp variations are consistent with a thermostat that won’t fully open and restricting your coolant flow.. Another thing to me that points to a stuck thermostat is that you basically have same issue that you had with this new radiator that you had with old one… yet it has to be 25-50% more efficient. Yet you mentioned you noticed a little drop in the engine temperature when the heater was turned on… and that was only running through a teeny heater core with fan on. That water is running right out of the block through the heater core to make a noticeable difference in your temp gauge. If the “stat” is half closed or a quarter closed it amounts to a significant restriction that even a big "Mondo" radiator like you have can’t overcome. JMHO

It was 97 degrees in Santa Clarita today and I was chugging up down hills and it was nailed at just below midway on the gauge with the A/C on. And that’s with an “el cheapo” very thin non-oem cooler that I have no faith in for the long haul. I know from 1st hand experience it’s a pain the @#$ to change this part but I’d take a hard look it anyway. If you do end up swapping out the thermo be sure to order the little seals and “o” rings from Merlin once you get the plenum chamber off.

Good luck Kat

Oh yes and BTW thanks for all your links on your radiator... Im gonna get me one of those...
Thanx
John