I’m just here eating popcorn....
Hoping you find a cool way to fix the problem!
Hoping you find a cool way to fix the problem!
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.
'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
I'm not sure that trimming the shroud will help. I suspect the problem is based on the fan intruding into the main part of the shroud, the more rectangular area that covers the radiator.
What I read said the problem with the fan being too far into the shroud was that it creates turbulence in the air flow. From Flex-a-lite:
This is the starting point. The blades are about 1/2" off the bench.
The severe duty clutch I've been running is at the top and the low profile clutch is at the bottom. I can see on the new one where it would be easy to make changes to the thermal coil. The other clutch looks like it has some sort of sealant holding the end of the coil.
Here you can see the height difference. You can also see the difference between severe and heavy duty clutches. The severe duty has larger cooling fins which is supposed to help them last longer.
A tape measure to quantify the difference in fan location.
I played around with how much I could space the fan from the clutch. The most I could do was 4 washers. Any more than that and I could not get a nut into the gap to mount the clutch to the pump. In the second picture there's a piece of 1/4" aluminum under the mounting flange. I would say I probably gained 3/4" to 13/16".
As I was installing the fan clutch I realized I very nearly had another issue with my attempts to draw the fan back. The fasteners only clear each other by maybe 1/16".
I would have liked to get more fan out of the shroud, but this is the best I can do.
I didn't test it for 2 reasons. It was only 85F yesterday and I would like it to be in the 90s to get a better test. The second reason is an installation error. I was going thru the box the clutch was in and found a bronze bushing. I did some checking and realized the pilot diameter on the clutch is 3/4" and the pilot on my water pump is 5/8". The bronze sleeve is included so you can make the 3/4" hole fit the 5/8" pilot.
@nvrenuf shipped me his 7-blade fan that will be here Wednesday. Wednesday is also supposed to be the hottest day next week, so I'll pull the clutch to install the "new" fan and put the pilot bushing in. It will be quicker this time because I figured out I can get the fan clutch off without removing the shroud. Plus I know the trick to getting the clutch bolted to the pump.
What I read said the problem with the fan being too far into the shroud was that it creates turbulence in the air flow. From Flex-a-lite:
This is the starting point. The blades are about 1/2" off the bench.
The severe duty clutch I've been running is at the top and the low profile clutch is at the bottom. I can see on the new one where it would be easy to make changes to the thermal coil. The other clutch looks like it has some sort of sealant holding the end of the coil.
Here you can see the height difference. You can also see the difference between severe and heavy duty clutches. The severe duty has larger cooling fins which is supposed to help them last longer.
A tape measure to quantify the difference in fan location.
I played around with how much I could space the fan from the clutch. The most I could do was 4 washers. Any more than that and I could not get a nut into the gap to mount the clutch to the pump. In the second picture there's a piece of 1/4" aluminum under the mounting flange. I would say I probably gained 3/4" to 13/16".
As I was installing the fan clutch I realized I very nearly had another issue with my attempts to draw the fan back. The fasteners only clear each other by maybe 1/16".
I would have liked to get more fan out of the shroud, but this is the best I can do.
I didn't test it for 2 reasons. It was only 85F yesterday and I would like it to be in the 90s to get a better test. The second reason is an installation error. I was going thru the box the clutch was in and found a bronze bushing. I did some checking and realized the pilot diameter on the clutch is 3/4" and the pilot on my water pump is 5/8". The bronze sleeve is included so you can make the 3/4" hole fit the 5/8" pilot.
@nvrenuf shipped me his 7-blade fan that will be here Wednesday. Wednesday is also supposed to be the hottest day next week, so I'll pull the clutch to install the "new" fan and put the pilot bushing in. It will be quicker this time because I figured out I can get the fan clutch off without removing the shroud. Plus I know the trick to getting the clutch bolted to the pump.
The sealant on the coil is typically just silicone. Easy to reapply.
I’m glad you’ll get it all together before BB. Hopefully all of this will make the difference you need so you won’t have to watch the gauge as much or more than where you’re going.
Where did you find the lower profile clutch? Just looking at the physical dims in a catalog or was there something about the application? I don’t have any temp issues but my fan is placed deep in the shroud similarly to yours so I’m sure moving it wouldn’t hurt. My hitch will be that it’s reverse rotation.
Where did you find the lower profile clutch? Just looking at the physical dims in a catalog or was there something about the application? I don’t have any temp issues but my fan is placed deep in the shroud similarly to yours so I’m sure moving it wouldn’t hurt. My hitch will be that it’s reverse rotation.
When you pull it back out to do the bushing, you could replace the bolts holding the fan to the clutch with some allen socket bolts. That would give you more clearance from the other bolts it looks like.
Button head allen also.
That specific one came from Carquest. It only comes up under 350 applications. I first found it on RockAuto, Hayden 2947. Hayden lists it as being for more of a hot rod application where a thicker radiator core has been installed and you need more clearance between clutch and radiator. This one from Carquest I suspect is the same as Hayden because based on pictures it's the exact same thing.
Napa also lists one but it's a lot more expensive. The Carquest clutch was priced between Napa and RockAuto, but I wanted it sooner than I could get it from RockAuto without expedited shipping.
Not a bad idea. It's close enough I was thinking I may only clear because I got lucky with the flats of the hex lining up just right.
button head allen head for even more room .
Beat you to it.
But they also have a larger head diameter than a standard allen head bolt. But standard allen head can be drilled or purchased with holes to run safety wire. So pros and cons to everything.
That position of your fan in relation to the shroud looks good to me.
Received the fan from @nvrenuf !
It is definitely different. The big block fan from @nvrenuf has a more blade; it's on the right in the picture below.
About an inch deeper draw. They are the same diameter.
I was able to lose the spacers and the fan is sticking out the same from the shroud. I debated some about adding some spacers but some guidance I found on Derale's website said to keep 3/4" clearance around the fan. That's how far I am now from the alternator.
Hope to do a test drive in about 30 minutes if I can get away from the office.
It is definitely different. The big block fan from @nvrenuf has a more blade; it's on the right in the picture below.
About an inch deeper draw. They are the same diameter.
I was able to lose the spacers and the fan is sticking out the same from the shroud. I debated some about adding some spacers but some guidance I found on Derale's website said to keep 3/4" clearance around the fan. That's how far I am now from the alternator.
Hope to do a test drive in about 30 minutes if I can get away from the office.
Last edited:
That's good to see/know, hopefully that'll make a noticeable difference in cooling.
If I remember correctly from when I worked on big rigs that one should be lots more aggressive and pull way more air I bet.
Wider blades, more of them, more is better. Other than the prop plane on takeoff roll sound you'll have with the clutch on, it should do the trick I bet.
I see the differences in the blade width, but I must be older than I think. I have counted the blades too many times, and I come up with the same number on each. Where is the extra blade?
Seems to be an improvement. Internet says it's 88 which isn't as hot as I was hoping for but still at least as hot as it was on our last trail run.
Driving around never got above 180. I notice the fan doesn't seem to roar as much, and I think this may be due to more air flow moving at the lower temps so that when the fan really needs to kick in, it doesn't need to do as much for as long. I also observed the RPM doesn't have to be as high to get the temperatures dropping. I didn't experiment too much for definitely 1300rpm was sufficient versus 1500rpm before.
I let it idle for over 15 minutes. It climbed 2 degrees in the first half, but then held there. I did the towel experiment at idle.
In fairness, I never tried that with the other fan/clutch setup but I did this time because I could feel the air moving at the grill. I'm just not sure the other setup was doing that.
I may still add the pusher fan. While I'm not freaking out that the fan is inadequate, I still like the idea of being able to cool things off when parked.
Myth: Big block fan pulls more than small block heavy duty cooling fan.
Verdict:
Driving around never got above 180. I notice the fan doesn't seem to roar as much, and I think this may be due to more air flow moving at the lower temps so that when the fan really needs to kick in, it doesn't need to do as much for as long. I also observed the RPM doesn't have to be as high to get the temperatures dropping. I didn't experiment too much for definitely 1300rpm was sufficient versus 1500rpm before.
I let it idle for over 15 minutes. It climbed 2 degrees in the first half, but then held there. I did the towel experiment at idle.
In fairness, I never tried that with the other fan/clutch setup but I did this time because I could feel the air moving at the grill. I'm just not sure the other setup was doing that.
I may still add the pusher fan. While I'm not freaking out that the fan is inadequate, I still like the idea of being able to cool things off when parked.
Myth: Big block fan pulls more than small block heavy duty cooling fan.
Verdict:
HmmmI see the differences in the blade width, but I must be older than I think. I have counted the blades too many times, and I come up with the same number on each. Where is the extra blade?
Cheese and rice! You're right! The fan from the C10 was 7 blades. I must be getting a case of the Wades!I see the differences in the blade width, but I must be older than I think. I have counted the blades too many times, and I come up with the same number on each. Where is the extra blade?
It's the Wades; they're going around....
I was also confused about the blade count. I'm assuming the new fan is the one with the much steeper blade pitch?
