To verify that the fan is good or bad, you can cut the wires and apply 12 vdc to the wires and see if fan works or not, that will rule out rest of circuit.

 

If you do the radiator replacement yourself you are going to need the 4 o-rings that seal the cooler lines.

 

Thanks for the head's up Spike.

I'm picking up the chevy clutch fan today from Napa (had to order it). They quoted me $55 and I usually get 10% off from that...much better than $200 for the OEM part!

Will the old allen head bolts work with the new piece?

 

No, the new piece will have a different thread, and the bolt pattern is a good match, but you'll need to enlarge the holes in the stock fan to use the larger bolts. Surprised that clutch was not a stock item, fits a lot of chevys, you want the NON-AC version, it will be six inch diameter. The AC version is 7 inch.

Chevy unit will look like this.

 

I was surprised too. I researched the part numbers from the sticky and took several of the #'s with me to the store. They all cross-referenced each other but still didn't match what they had in stock. Our special-order parts come from Spokane and we can usually get anything by the next AM. It's there waiting for me now.

Hopefully I can match up the threads while I'm there and get the bolts.

 

Maybe non stock due to non-AC version. I also snagged various Chevy / GM from junk yard and they fit as well. Ones with bigger fins are "HD" rated and povide more cooling when engaged, less fuel economy, you want ones with metal mounting area. Again, this is for either experimentation, or broke down in Oklahoma with nothing but a junk yard available, or just broke. About $20 for fan and clutch at yards near me.

I mention that not all owners have plastic in their wallets that the numbers have not been worn off this time of year, and sometimes even a well-heeled owner needs an available option, even when folding money is not the issue.

 

Installed new clutch fan. Pretty straight-forward after opening the holes up slightly. It's not an extremely beefy thing but certainly works. At idle it's pulling enough air to get both elect fans to turn.

Unfortunately it's not enough to keep the beast cool however. Idle was fine. I ran it for a good 20 min with the temp gauge at 9:00. I bought an IR thermometer today and consistantly shot the t-stat housing at about 145 to 165 (without t-stat installed).

So I decided to take it for a spin. I didn't even make it to the end of the street before the needle started climbing. It was in the scary zone in less than three blocks. I turned around and took it home. Ran it at idle (now the elect fan is also running) for a while longer and shot the hoses and t-stat housing some more. Saw 200-210 mostly. Again this is with the t-stat removed and OAT 30 deg F. By now the temp gauge was buried way above hot but it never got above 210 according to the gun and didn't boil over at all.

I removed the temp gauge sender wire and the gauge immed dropped to cold. I think the little sending unit might be bad although what is there to fail on it? Also, obviously my rad isn't up to the task.

Oh, and just for good measure, when I started it up I noticed one of the oil cooler lines leaking badly. I mean like one drop every 2-3 seconds. Oddly it slowed and eventually stopped as the eng warmed. It's leaking above where the hose turns into the metal fitting portion. Must have a pinhole there and maybe it swells up when the eng get hot.

Attached are some pics of the new clutch fan.

 

A few more pictures...

 

Thats part of your problem, with no t-stat the engine will actually run hotter because the coolant is not staying in the radiator long enough to be cooled off.
Put a t-stat back in.
192*F is OEM, I use a 195*F.

 

I have a 180 deg t-stat to put in. I tested it in a pot of water and it starts opening at 190 ish and is fully open around 200-210 (there's some lag). I think that puts me in the OEM range. I guess I try that next.

It's hard to shoot the rad with the IR because of the fan. I cn't get a good reading but it seems to loose about 10 deg of temp each panel over from driver's side to pass. I can't really tell if there are any dead zones.