Help me add a manual fan override switch to my 5ton

[RobertoGatos]

I'd like to add a manual fan override switch to my 5ton for various reasons. Prefer to not add any electrical systems for simplicity's sake, so I've been thinking about mechanical options. Take a look at my napkin sketch:



What I'd like to know, is if there is a valve made that would accommodate the functions of "valve 1" and "valve 2" into a single unit? Additionally, is there any way to avoid conditions 3 and 4 with said valve? I'd prefer to foolproof the system if possible.

Been digging through Mcmastercarr, and would like to find just the right valve. Someones got to make it?

 

[Swamp Donkey]

Search "3 way ball valve". No need for 2 valves, and conditions 3 and 4 become irrelevant.

One side is plumbed for the shutterstat to operate normally. The other side bypasses the shutterstat. These valves don't have a closed position.

If you plumb things in where the fittings go into the shutterstat and/or fan clutch, you can do everything you're wanting in 1/8" NPT. You don't even need to come all the way from the tank. You just need to add a T on either side of the shutterstat so a bypass loop can be added, then the valve controls the direction of air flow.

You'll also have redundancy if your shutterstat starts leaking. Open the valve to the bypass side to run the fan and the air will be shut off to the shutterstat. Then you won't even have to use the lock up bolts, and the shutterstat stops leaking.

I've worked it all out but haven't gotten around to putting it in place yet.

You going to put it in the cab or under the hood?

 

[73m819]

I would use a deuce/939 front wheel drive air switch, two one way valves and a tee, the one way valves on each input to the tee to prevent back feed, the air switch as your manual air feed, VERY SIMPLE.

 

[porky69]

Put a 3way ball valve in the supply line to the shutterstat and a "T" on the output of the shutterstat and connect the second outlet on the 3way to the "T".

In position 1 everything operates as normal automatic mode and the second outlet is blocked prevent the control line from leaking back, flip the valve to position 2 and the shutterstat is bypassed manually activating the fan.

 

[Wildchild467]

I like this idea. However you do it, make sure there the fan can always come on when the temp switch calls for it, regardless of how you have your valves set or have it plumbed. Not saying you are stupid or anything like that, its just nice making it so you never have to worry about "did i turn the fan back on?". I did a similar modification but it was to my street rod with an electric fan. The thermal switch on the intake grounds out the fan relay when it calls for the fan to be on. I just ran another switch under my dash to ground out the relay if I wanted the fan on as well. So no matter what, if the temp got hot enough, the fan would come on no matter what. the switch under the dash was essentially "Automatic (fan switch) or ON". It has worked great for me. I agree not having anything electrical is the way to go. I like 73M819's idea about the front axle switch but I would have to see how they are plumbed. On my deuce, they only supply air or dump the pressure. maybe there is a variant out there that will act like a 3 way ball valve and do what you are looking for? Interesting project for sure. I like your ideas.

 

[RobertoGatos]

Here's what I'm thinking based on Swamp Donkey / Porky's input.



Position 1: truck functions as normal

Position 2: manual fan override

Position 3: truck overheat

Here's the valve I'm considering



I'm unclear if these valves can also allow for position 3. If so, I need to come up with something else. Also, are the positions relatively discrete, or is there the chance of partially open / closed positions? What do you think of the valve I'm looking at? Right track?

 

[Swamp Donkey]

If you use the valve you have pictured then it apparently has a closed position due to the valve orientation to the handle. If you get a valve where all 3 outlets are horizontal (or parallel if you want to look at it like that) to the handle, then there are only 2 positions, one way or the other. This would eleminate your position 3 in the diagram. You can also get them with handle locks so it can't change. All of them can be left between directions which is why I would suggest one with a handle lock.

Give me a bit and I'll post one I was talking about.

 

[RobertoGatos]

Thanks! Would like to see what your thinking.

 

[RobertoGatos]

Also worth mentioning: this is for an a2 truck, but I would image a1 variants and earlier use a shutterstat that is also normally closed (not supplying air to the fan until heated.)

 

[Swamp Donkey]

The shutterstat for the 8.3 is the same as the NHC250, just with different activation temperatures. I don't know where they're located on the 8.3 but I'd bet you have more room to work with. They're in a tight spot on the NHC250.

I'm having trouble locating one of the valves I'm talking about. I know they exist because I just replaced one last month at work. We use them to adjust flow between 2 outputs for blending. There is no closed position, only open either way and anything between. There is a mechanical lock at each end to lock it full open one way or the other. I'll get with my parts guy at work and see where we're getting them from. It'll be Monday though.

 

[RobertoGatos]

Sent 74m32a2 a pm for some clarification on what he was describing. The front axle switch as I understand it it a 3 way valve with two positions. On and off / vent, as previously mentioned.

I know I need a 3 way "diverting" valve, but this looks interesting also:

Think it might work?



Also tossing around the idea of using a tractor protection valve, or parking brake valve? Need to play with one to see if it might work.

 

[RobertoGatos]

OK, think I've got this figured out. Its called a "spool valve". It looks like the 6wd engagement lever would also work if it has a controlled vent line, and does not just vent out of the body. Will find out tomorrow. From what I can tell, there would be no issue with air moving both directions between the A and A Exhaust ports right?

 

[Swamp Donkey]

The parts guy happened to stop by this morning and said that the valve was specific to that piece of equipment. I could get one for the mere price of $183.xx...plus shipping. Just looks like a regular brass ball valve to me, but I digress...

Since we couldn't find a cross or a cheaper price, it looks like I'm following y'alls lead now. I have a couple of those switches somewhere around here so I'll wait to see how y'all work it out. I was wanting to add this in at the shutterstat but since my switches are plastic I guess they won't like it under the hood.

 

[Csm Davis]

Okay here's my swing at making it idiot proof, take two axle engagement switch valves and flip their bodies in opposite directions then weld or screw the handles together so when one is on the other is off, so no chance of numbers 3 or 4 happening.

 

[rosco]

All this has been worked out in intimate detail in OTR trucks. Any valve you can imagine, is available at the heavy truck shop, at modest prices. Some valves are controlled electrically, and they work flawlessly for hundreds of thousands of miles. I had an "ON/OFF" switch on the dash, because the fan would fly a Super Cub, but if I super-cooled the engine on the approach to Atigan (when I went to the Beach), and it didn't turn on at the switchback, I could pull the hill, one gear higher.

May I suggest cultivating a relationship at the heavy truck shop? The Guys that work there, are "Gear Heads" too, many of which are suffering from the lack of exposure to MV's.

 

[WillWagner]

Isn't the idea of adding a fan switch to be able to control the fan when you want to instead of relying on the auto switch? All the ball valves and monkey motion isn't needed. Ever heard of KISS. What you want to do can be done with 2 small check valves, a tee, an air shift axle switch and maybe 5 feet of DOT 1/4 inch air line and, it can be controlled from the seat

Pull the air to supply the axle switch from under the dash, run out of the switch to the outlet side of the thremo switch on the engine. install a Tee with check valves on the inlet ports to prevent back flow if the manual switch is in use or the thermo switch is in control and run the outlet to the fan. Simple, over the counter parts, the switch will match what is in your truck now.

Parker and FastRite offer check fittings. I have a Parker catalog at work that shows more than the attached. If I can remember, Monday I will bring it home and scan the pages.

http://www.fast-rite.com/wp-content/uploads/2011/10/FastRite2012_FittingsCatalog.pdf

 

[RobertoGatos]

Isn't the idea of adding a fan switch to be able to control the fan when you want to instead of relying on the auto switch? All the ball valves and monkey motion isn't needed. Ever heard of KISS. What you want to do can be done with 2 small check valves, a tee, an air shift axle switch and maybe 5 feet of DOT 1/4 inch air line and, it can be controlled from the seat

Pull the air to supply the axle switch from under the dash, run out of the switch to the outlet side of the thremo switch on the engine. install a Tee with check valves on the inlet ports to prevent back flow if the manual switch is in use or the thermo switch is in control and run the outlet to the fan. Simple, over the counter parts, the switch will match what is in your truck now.

Parker and FastRite offer check fittings. I have a Parker catalog at work that shows more than the attached. If I can remember, Monday I will bring it home and scan the pages.

http://www.fast-rite.com/wp-content/uploads/2011/10/FastRite2012_FittingsCatalog.pdf

Looks interesting, but in your drawing the shutterstat cannot vent pressure to turn the fan off when it returns to the normally closed position as coolant temp drops. It would be stuck on. Same problem with the manual switch in the cab.

I will be mounting the switch in the cab.

OTR truck shop is a good idea, I've got a good one here.

 

[RobertoGatos]

Okay here's my swing at making it idiot proof, take two axle engagement switch valves and flip their bodies in opposite directions then weld or screw the handles together so when one is on the other is off, so no chance of numbers 3 or 4 happening.

That would work. Like a single pole, double throw. Hah.

 

[Jason O]

How about pressurizing the VENT port of the shutter-stat with air when you want the fan to be forced ON,using an axle engagement switch. In the OFF (auto) position, the shutter-stat switch vents through the axle engagement switch, and cycles the fan as needed.

 

[74M35A2]

This is really easy to do, and would look most at home using a front axle engagement switch. The shutter-stat has a very small air bleed hole in it so it can relieve air pressure when off to release the fan. But, I like stuff automated and to work like it is supposed to. I want to ask why you want the fan to come on earlier than 200F, but I do things nobody agrees with either. I was going to do this same mod when adding A/C, but still have it automated via a 24v air control solenoid tied into the A/C clutch actuation signal. Instead, I bought a cab roof unit with the condenser and 24v fan built into it, because I want to add the full size front mount charge air cooler.

Today's OTR trucks are now actually the opposite of how they were a short while ago. Today, big rigs fans are run as "fail-safe", meaning their air actuated fan clutch is in the locked/engaged position with no air pressure, and they require air pressure to disengage. So, loss of air in fan cooling circuit = fan on. They will rotate with the engine at first start if the vehicle has no air pressure.

So, use a front axle engagement switch/valve on your dash, with an air check valve in line with the hose which routes to a "T" you install after the shutter-stat and before the fan clutch. This is so the normal 200F engagement of air through the shutter-stat does not bleed off through the new front axle engagement switch you added, since I believe that added mechanical switch/valve has an air dump drain on the output line when in the off position (the hiss you hear when disengaging the front axle). When you pipe air into the newly added "T", you will have a small amount of air bleed going through the shutter-stat bleed hole due to it's designed in function. That hole has to be there in order to release the clutch when either switch has activated it, otherwise pressure would stay on the clutch and it would not disengage.

I can put together a care pack of what you would need with a bar napkin drawing if you want, and send it your way. Probably only a few dollars in parts. I could even fund it for the delay in shipping starters which FINALLY went out. Your tracking number will show progress by the end of the day Monday, it takes Fed-Ex almost a day to update.