Replace viscous clutchh, if it freewheels almost a full turn then it is barely hanging in there. Radiator is at the limit for sludge build up. Time to think about radiator rod out.

 

what temps should the OBD scanner be picking up on the coolant? When is it too hot and I should shut it down? Are there any coolant sensors that might be in need of replacing, giving me inaccurate readings on my dash gauge? I'm ordering a new main fan today. the radiator was repaired, cleaned, flushed and pressure tested back in July but was not rodded out.

Thank you,

 

1. Temp would depend on thermostat installed. IMHO the D1 should be capable of 50 mph speed in 90 F ambient with coolant temp at or within 5 degrees of opening point for thermostat. So yesterday I drove to Tractor Supply, in the 80's, AC on. 178-183F, I run a 180F stat. If you are running 15+ degrees above start to open point, then why? If you are pulling a trailer, headed up a mountain, stuck in traffic in the high 90's, then yep, it will be higher. But not all the time. IMHO the purpose of a thermostat is to control the low temperature the system runs at once warmed up, and to increase/decrease water time in the radiator to regulate temperature. When you get to wide open temp and stay above it, the thermostat is just an orifice.

2. When it is to hot, let's say 219, you should attempt to reduce heat load on system, but keep running. This can be done by turning on heat (cools the heater core), turning off AC (drops the hot air flow from condenser straight into radiator), maintain some vehicle movement, but slower (drop down from 80 to 55). Of course if you have an ice chest in the back you can stack ice on the radiator to chill it down a little. Don't open the coolant jug unless you like scalding hot 230 degree water and steam blasting in your face and those around you. I once saw an idiot wheel into the gas station, throw up the hood, ****** off the radiator cap. The water shot all the way to the roof of the pump island. He is still wearing the scars.

3. The OBDII coolant sensor in a D1 is separate but near the gauge sensor. PIx shows one with square top, that drives OBDII via ECU. One with single wire drives gauge. Worth cleaning connections. They poke down thru the roof of the intake manifold. When coolant is low, or has a serious air bubble, they don't touch the liquid, they just touch the steamy gas. If low enough, the coolant won't flow steady thru heater core, and you have greatly reduced heat (a bad sign). If installing a stat, don't buy "fail safe". Just get one with a jiggle device, or drill your own small hole (1/8 inch) in the flange. Orient the hole or jiggle device at 12:00 position, so it can pass gas and not allow a steam pocket to build up behind the stat.

Most likely you don't need a fan, just the clutch it mounts to. There is a basic one that crosses over; Chevy 2000 Express van, 4.3 liter, without AC. It is same thread, same 6 inch diameter, same rotation. You will have to enlarge mount holes in fan slightly and use the larger bolts.

Keep in mind if you have a weak clutch, and install a new firm one; the old water pump has been waltzing with that old girl for millions of spins. A new Brazilian body builder beach babe is gonna wear him out in short order.

 

well over lunch hour today I sat in the truck for 30min. with the AC on and the temp guage did not raise past it's normal position. The viscous fan did only spin less than a half rotation after running the truck for that period. It seems like it's all good but just can't handle a traffic jam with the heat above the mid 90's with the AC on HIGH. I guess I should feel lucky, especially since mine is a daily driver, compared to the headaches that some people are having with their Land Rover's.

 

Does sound like your rad is ready for rod out. Both electric fans blow strong?

 

Yes both electric fans blow strong and in the right direction. I will look into having the radiator rodded out but for now as long as I don't run it with the AC on high there are no issues with the truck. Thank you for your input.

 

hmmm..

So it does not overheat if AC is on and inside fan is selected for something less than max? Maybe a loose ground. Or something weird like electric fans cut off.

Any difference on the temp sent to the OBDII scanner? The scanner sees a different sender than the gauge does.