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Adding a fan clutch?

Pizza_Man

Pizza_Man

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San Diego CA
I have my 71 Jimmy. And I wanted to add a fan clutch. Maybe I'm just in too much of a 'fix it' mood since I put the crossover in it.
But I have a 180 degree thermostat and a solid steel 4 blade fixed fan. I live in San Diego - it's July and where I'm at it finally hit 80 degrees outside. My temp is constantly really cold. Like 140. Even in heavy traffic it never really creeps up to 160. Back home in Fresno where it's 100-105 in the summer it sat around 180 and would creep up on 190 when it sat running. Never had a overheating problem. In fact I think it's running too cold. I went to the auto parts store and grabbed a '71 jimmy' fan clutch. Well there's not really a place for it. I'll toss in a picture if I can figure it out from my phone. My question is what do I have to do to put the clutch in? Do I need a different fan? I really don't want a flex fan. The junk yards around here suck, nothing for older gms (older than 91).
Thanks!

image.jpg
 
Well,GM started using 195 degree thermostats in 1968 or so...that's what I've always used,regardless of whether the truck is just a pleasure cruiser or towing..letting an engine run too cool can lead to sludge build up and it'll lower your fuel mileage..

You should be able to use a fan clutch & fan off some later GM vehicle with a V8..that spacer behind your "regular" fan has to be removed to fit the clutch fan in there...the rule of thumb you want the fan blades 2/3rd into the shroud and 1/3 sticking out towards the engine under ideal conditions..
I'm not so sure a clutch fan cools better though,the clutch can slip or fail and let the fan just freewheel..

I ran the "solid" fan on my 72 K5 for many years and never noticed much difference when I put a clutch fan on it..I did notice the clutch fan made a lot of fan noise on cold starts till it was warmed up some compared to the solid bladed fan..
 
So I can't re use my factory 4 blade? Is there a difference in power or load at all? I know the idea is less load on the motor, but is it noticeable? Like in any situation? I'm trying to figure out if it's worth doing or just going back to the factory temp thermostat
Thank you
 
Nope,the solid blade fan only fits directly to the water pump--clutch fans have much larger center hole and bolt spacing,and they bolt to the clutch,and the clutch has the hub that bolts to the water pump..

Basically clutch fans were made for vehicles with A/C and or were used for heavy loads like towing...seeing your complaint is it is running "too cool",then you'd likely only be aggravating the issue by putting a clutch fan on it..
If it in fact is running too cool,the thermostat is what keeps the engine at a certain "minimum" temprature..

I would go back to a 195 degree thermostat and see how it pans out--also I would use something other than the stock gauge to judge the actual temprature,like a heat sensing gun or a meat thermometer in the radiator,the dash gauges are noted for not being 100% accurate,especially when it is that old..
 
I have an aftermarket gauge, factory one went all buggy one day and I can't seem to trace the wire. So the new one is only around 6 months old and it seemed to be fairly accurate, at least when I put it in and it was 105 degrees outside. I hate to run a flex fan but would that help my 'too cool' situation? From my understanding they don't cool nearly as well as a stock fan but as backwards as it seems that's my goal. I never really had to mess with the cooling system before because it was always hot and for a while it had a slow leak and was running a little warm because of less coolant in the system.
In the mean time I'm sorting out my power steering return line. I kept having trouble with the local parts places either trying to get one or getting the wrong one or nothing would line up. So I tried to just use hardware with the right seat but it didn't go in right. Tomorrow at work I'm going to just machine something out of brass with the right threads and the right seat inside and a low profile side outlet and ditch the factory style half hardline thing. But that's a whole other deal
Thanks for the insight and help
 
The P/S return line hose has pretty low pressure in it and you can use rubber hose rated for P/S return or tranny cooler use with worm gear clamps..
I have even used regular rubber fuel line hose on the return line before with no issues,but the "right" hose is better..

Older steering boxes before 1980 or so had SAE flare fittings,ordinary brake line tubing (3/8") should fit the steering box ,you can also buy ready made barbed fittings for the box's return port from P/S hose suppliers like Edelman and Omega also,they are listed in the "illustrated" section of their catalogs..

I have just used 3/8" steel brake tubing with the flare fitting,once I even just sawed off the old factory return line that had a steel tube at the box end,and slid the rubber hose over it and clamped it..

I think the flex fans you could get years ago that had only 2 blades would change the blade pitch at higher rpms and it reduced the air flow when "not needed" at highway speeds..every time I tried using one on my Chevy's it wouldn't work,the blades would hit the V-belts,and if you added a spacer,it put it in the shroud too far...
 
Pizza_Man said:
I hate to run a flex fan but would that help my 'too cool' situation? From my understanding they don't cool nearly as well as a stock fan but as backwards as it seems that's my goal. I never really had to mess with the cooling system before because it was always hot and for a while it had a slow leak and was running a little warm because of less coolant in the system.
Click to expand...
It seems to me that a clutch fan is exactly what you want. Not sure why some of the guys are trying to talk you out of it. :dunno:

From my understanding, a clutch fan will just freewheel, basically doing nothing, until it gets hot enough to engage the clutch. At that point it'll work just as well as your current fan.
 
Yeah I read up and a clutch fan would be perfect. Problem is going to be getting a fan that fits the clutch. And no local junk yard has pre 91 GMs.
For the steering line I think I'll just run a brake line that's cut and double clamp it. That's how we did one of my buddies and his never failed

On the other end of the truck, for a k5 does anyone know or rather have a picture of the latches on the back hatch? My hardtop has everything except the latch part that bolts to the side of the top. I'm halfway through making one with some rough measurements but I don't want to be way off in design.

Thanks again to everyone
 
On the steering hose you can use a double flaring tool to put a "hump" on the end of the tube so the hose wont want to come off easily..

Getting a used clutch with a fan on it is the easiest way,but if no salvage yards around you have any,the fan blades for a clutch fan can be bought new from a parts store in Dorman and Hayden brand,among others...they run about 40 to 100 bucks...

I have two fan clutches with blades hanging on my garage wall,but I forget what they came off of now..but a lot of GM ones will work,I have even cut the bolt holes in one and made them slots,so it would bolt on my water pump ,which had a larger bolt pattern..
The clutch fan blade would have to be "close" to the right size to fit your shroud,you could measure the mechanical fan you have now and get one the same size..
 
Well new problem arised. Not about the fan. But rather my steering. Maybe someone can chef some light on it. I just switched to crossover and mechanically it's perfect. I got a reman 2wd box and I put the lines in. Leaking bad. So I replaced both the high and low side. And still leaking! Is there something I'm over looking? It feels like it's all right, and plus it's all brand new lines plus a reman box. I'm tempted to solder the fittings or switch to just using tapered pipe fittings. Might be sketchy but it wouldn't leak. It's not just a drip it's a full on stream out of the top of the nut the line runs through.
Any ideas?

Edit: found out my problem. Steering box is from an early 80s truck. Non metric fittings but uses the o ring type seal instead of flare. Looks like I gotta hunt down some adapters and fast. Im moving on Friday and the Jimmy is crucial in moving some small furniture - I don't think my bike is up for the task. Rumor on the Internet is that Napa carries such an adapter. But most of the posts I've seen are about the metric post 85 boxes
 
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Far as I know,GM steering boxes are either SAE flare or metric O-ring (after '80)...never seen one with flare connections and a SAE thread,but maybe there was such a thing..(I bet its 16MM metric,and a 3/8 flare fitting with 5/8"x18 threads just happens to screw in,but isn't the right fitting )..

There are these neat cone adapters you can drive into an O-ring style box to allow SAE flared hoses,but you'll need whatever the right nut fitting is that screws into the box too..

http://www.speedwaymotors.com/O-Ring-to-Inverted-Flare-Power-Steering-Adapter,24682.html
 
yup, I ran into the same issue awhile back. Honestly, what I found the easiest to do was to simply get an 80's power steering pump and hoses from the junk yard so that everything uses the same fittings with no adapters. The power steering pumps will bolt into your bracket without any issue.
 
Changing the pump side is simple,you just get a bung out of whatever year pump your hose matches up to,the bungs fit all the pumps--if you need an o-ring bung you can just get a used one from an 80 up GM pump and screw it in an older one,or vise-versa.....it's the box side that creates the issue most of the time..
 
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