My truck does the same thing in Moab, with the heavy duty fan clutch I can roll 10 feet and have it drop 10 degrees... Eventually I want to swap to the Tejas electric fan setup.
CK5
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'89 R3500 Crew Cab 2wd to 4wd conversion & beyond
- Thread starter mrk5
- Start date
Started out with 2wd TBI350 with SM465 to current 4wd with 454, 700r4, NP241
My truck does the same thing in Moab, with the heavy duty fan clutch I can roll 10 feet and have it drop 10 degrees... Eventually I want to swap to the Tejas electric fan setup.
That fan just roared all day. People probably thought a big trash truck was coming down the trail. I need to put a louder exhaust on the truck now.
I guess these are just the struggles when you're trying to use 1 truck for multiple roles. The electric fans are great for the trail. The mechanical fan is great for towing (in theory I guess since I haven't road tested it yet). That's why I'm thinking I just need to do both fans.
I joke and say it's my supercharger cause the exhaust was so quiet.That fan just roared all day. People probably thought a big trash truck was coming down the trail. I need to put a louder exhaust on the truck now.
I guess these are just the struggles when you're trying to use 1 truck for multiple roles. The electric fans are great for the trail. The mechanical fan is great for towing (in theory I guess since I haven't road tested it yet). That's why I'm thinking I just need to do both fans.
Decades ago I bought a 70 2wd 1 ton with a 10 foot camper from a mechanic friend of the family. New the history and low miles drive train. He had built the 454 that was in it. Ran good but would heat up pulling hills while towing. I mentioned it to him one day. He gave me the "wet kit" that he had on it. 10 gallon water bag attached to the bumper with a 12v pump and 2 nozzles that clipped to the grill. Misted the radiator. I laughed. He was serious.
Yep. Thatbis why the front bumper had a 4 wire plug with 2 wires. And a switch under the dash. Turn it on when pulling hills only. Temp would stay at 190 with my foot buried.
Way before electric fans were common.
Yep. Thatbis why the front bumper had a 4 wire plug with 2 wires. And a switch under the dash. Turn it on when pulling hills only. Temp would stay at 190 with my foot buried.
Way before electric fans were common.
That's what I've thought about doing, but for the passenger compartment! I was thinking I could get a little fan and a squirt bottle to cool myself off.
I remember there was a member on CK5 that lived in Texas and he had a mister system set up on his roll cage to keep the passengers cool.
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Workhorse did use a couple of pusher fans on the cooling stack with 8.1's. They still had the big mechanical fan on the water pump. The electric fans were mainly for the ac system.
I'm not saying you are wrong wanting to add a pusher fan as you seen it's been done that way at the factory. If you are having to put it in a specific gear to keep the revs up for cooling it's not moving enough air at the lowers speed. Could be the clutch isn't as aggressive as ours our. Could be the fan is not deep enough in the shroud or it's too deep. I know you are using stock parts here so it should be right. But typically you want the blade half in the shroud.
I did have that probably initially with my big radiator and the 5.3. since it was so much smaller and sits back further the fan was completely outside of the shroud and did not draw well. I ended up making an extension of the shroud with landscape edging. System cooled perfectly after that.
Not every setup is the same so what's worked on me and Larry's might not 100% translate to yours. The part for ours is reverse rotation. If the electric fan is the last bit you need for the low speed cooling then go for it.
I'm not saying you are wrong wanting to add a pusher fan as you seen it's been done that way at the factory. If you are having to put it in a specific gear to keep the revs up for cooling it's not moving enough air at the lowers speed. Could be the clutch isn't as aggressive as ours our. Could be the fan is not deep enough in the shroud or it's too deep. I know you are using stock parts here so it should be right. But typically you want the blade half in the shroud.
I did have that probably initially with my big radiator and the 5.3. since it was so much smaller and sits back further the fan was completely outside of the shroud and did not draw well. I ended up making an extension of the shroud with landscape edging. System cooled perfectly after that.
Not every setup is the same so what's worked on me and Larry's might not 100% translate to yours. The part for ours is reverse rotation. If the electric fan is the last bit you need for the low speed cooling then go for it.
I'm pro mechanical fan but there's no denying GM put electric pusher fans on some trucks in the mid 80's although I don't know what dictated the extra fan. These were on the passenger side if I remember correctly, you might be able to find a direct bolt up fan.
I'm pro mechanical fan but there's no denying GM put electric pusher fans on some trucks in the mid 80's although I don't know what dictated the extra fan. These were on the passenger side if I remember correctly, you might be able to find a direct bolt up fan.
That sounds like it would have just led to a lot of plugged up radiators.
Just sprayed out when the truck was washed. I used it for 2 years like that, then sold it to a friend and he ran it until it was t-boned in an intersection. Camper looked like a grenade went off in it.
That’s a good point!
But like Wade said they washised it out.
Amazing how much water a wet rad will hold in the fins! Dusty conditions would clog it for sure!
We have reverser fans on some of our tractors... they blow a ton of dust out when the cycle!
I do think the fan might be in the shroud more than it should be. I figured I'm stuck with it tho. Even though I'm using factory parts, they are a mix. 6.2L shroud with a 454 mounted fan. If you look in this pic the fan is fully shrouded.
I was thinking it seams like the fan doesn't spin enough at low RPM. I idle at 650. But I don't think the idle number matters because I know from experimenting, the engine needs to be at least 1500RPM to start cooling the motor down. The clutch I bought new last year for the 73. It's an AC Delco HD unit.
I wonder if a 6.2L clutch would be any different. While I bought the clutch for the 350 in the 73, it's the same part number for a 454. The 6.2L does have a different part number clutch even though all the physical dimensions are the same as the 350/454 clutch.
No, salt stained white.So what color is your hat going to be? Pink too?
just asking..
I do think the fan might be in the shroud more than it should be. I figured I'm stuck with it tho. Even though I'm using factory parts, they are a mix. 6.2L shroud with a 454 mounted fan. If you look in this pic the fan is fully shrouded.
View attachment 350705
I was thinking it seams like the fan doesn't spin enough at low RPM. I idle at 650. But I don't think the idle number matters because I know from experimenting, the engine needs to be at least 1500RPM to start cooling the motor down. The clutch I bought new last year for the 73. It's an AC Delco HD unit.
I wonder if a 6.2L clutch would be any different. While I bought the clutch for the 350 in the 73, it's the same part number for a 454. The 6.2L does have a different part number clutch even though all the physical dimensions are the same as the 350/454 clutch.
No, salt stained white.
With the mix of parts you are close. Fussing to move it back slightly isn't going to make a huge difference.
A diesel clutch might be more aggressive, but I have no way to prove that. I looked at Napa prolink yesterday and found they list the same clutch part number for big block or small block. Even the same number for a P-chassis rv with 454.
Looks to me like you need to move the engine, transmission, Magnum and transfer case back 1 inch before Blazer Bash.
Yeah, that's exactly what I need to do!
The best place I know to look is Rock Auto. So this is what I find there.
1985 K30 w/454 (donor truck for the motor I have)
- Four Seasons 36704 "severe duty"
- AC Delco 154949 Fits CODE FD or Trans. code SM465/M20; HEAVY DUTY RADIATOR(V01); CODE DM,GZ; 4 speed Manual trans.
1985 K30 w/6.2L diesel
- Four Seasons 36996 "severe duty"
- AC Delco 154950 Fits3 speed trans.; HEAVY DUTY RADIATOR & TRANS OIL COOLER(V02); STAMPED DT; 3 speed Automatic trans. or Trans. code SM465/M20; CODE AW; 4 speed Manual trans. or 3 speed trans.; Except Air Conditioning - Manual Temperature Controls (C60), Heavy Duty Radiator & Trans Oil Cooler (V02); Stamped AW; 3 speed Automatic trans.
1985 K30 w/350 same as 454 but with a couple options for different fan clutch height
- HAYDEN 2947 Thermal; Heavy Duty; Low Profile Info FitsStandard Rotation; Optional; w/ Fan Clutch Height Less Than 3"; w/ 3.73 Or Higher Rear Axle Ratio orStandard Rotation; w/ Fan Clutch Height Less Than 3"; w/ 3.42 Or Lower Rear Axle Ratio ****Distance from mounting flange to clutch is about 5/8" closer than AC Delco 15949
1973 C10 350 and 454 are the same as above.
Difference between standard, heavy duty, and severe duty fan clutches:
- Standard: turn fan 60-70% of the shaft speed, fan pitch under 2.5"
- Heavy Duty: 70-90%, fan pitch over 2.5"
- Severe Duty: 70-90%, fan pitch over 2.5", Larger working area, 65 sq-in versus 47 sq-in for HD. The larger working area is supposed to increase the life.
I know the fan I'm using from the 73 has a pitch over 2.5" because the first clutch I bought was standard duty and did not work. Figured out I needed HD when I checked the fan pitch. I have a fan from a 6.2L and it has the same 2.5" pitch, but only 5 blades.
I currently have the Four Seasons 36996 severe duty clutch. Normally I might be tempted to try the AC Delco 154949 but it's $118! That's too much to spend just to see if a different clutch changes anything. The low profile clutch is tempting but I don't know if 5/8" is enough of a difference to matter. I do wonder about the difference with the diesel clutch, but I would guess it has to do with the gas version being able to handle higher RPMs.
Driving the truck Sunday in the 90+ temps in stop and go traffic, I'm confident the mechanical fan will do at least as well as the electric fans when it comes to towing. It's just the idle cooling I'm having an issue with. I can only think of 2 solutions for this, 1) a mechanical fan with more blades and/or larger diameter or 2) auxiliary electric fan.
