41DegreesSouth Build Thread

[Dieselwrencher]

I can't remember, was there any particular reason you went with electric fans over a mechanical with a clutch and a shroud? One way to test the air trapping issue in that hose would be this. Build a pipe out of steel with the ends and use a hose on either end to hook to the engine and radiator. Put a drain valve in the top of the highest point of the pipe. Crack the drain after filling it and see if air comes out. I know it wil be more work and a pain now that the truck is driving. I've had air get trapped in some builds and it can be a pain actually figuring out why it was there and why it wouldn't work it's way out.

[El Dorado Jim]

I use an old trick that my father-in-law showed me, I drill a small 1/8" hole in the thermostat, then when you are filling the radiator/block with water/anti-freeze, the air will come out of the block, seems to work, I drill every thermostat I install....

[Billhilly]

Originally Posted by Dieselwrencher

I can't remember, was there any particular reason you went with electric fans over a mechanical with a clutch and a shroud? One way to test the air trapping issue in that hose would be this. Build a pipe out of steel with the ends and use a hose on either end to hook to the engine and radiator. Put a drain valve in the top of the highest point of the pipe. Crack the drain after filling it and see if air comes out. I know it wil be more work and a pain now that the truck is driving. I've had air get trapped in some builds and it can be a pain actually figuring out why it was there and why it wouldn't work it's way out.

There wasn't any particular reason I went electric. I thought that's what the cool kids did Better with aircon, couple more horsepowers out of my tired 400... Like your steel pipe idea. I have ordered a steel pipe bend and if I get convinced I'll replace the middle section of that lower hose and put a bleed in.

Originally Posted by El Dorado Jim

I use an old trick that my father-in-law showed me, I drill a small 1/8" hole in the thermostat, then when you are filling the radiator/block with water/anti-freeze, the air will come out of the block, seems to work, I drill every thermostat I install....

Good idea. Did a rush driveway change to the 180* thermostat in Taupo. Would be worth getting a hole in it when I drain it next.


I talked to the local engine rebuilder yesterday. He wondered about the shroud being restrictive. One easy check is remove the electric fan shroud, chuck on a stock fan, and see what happens. A relatively easy check so I'll start there. If I can find the original fan I took off nine years ago! I also want to do a block flush as well. Anyone done a rust/scale flush before? What chemical did you use?

[sharpmark]

haven't been on here for awhile an just caught up with your progress. looks most excellent and congratulations on your first big trip. good luck with the fan problem - I used a stock fan and shroud and have never had any issues. we were down your way last weekend for the cruise martinbourough deal an also went to the wheels with attitude car show at dannevirke.
keep up the good work
mark

[Billhilly]

Thanks Mark! Certainly nice to be driving it after all this time! I didn't make it down to Cruise Martinborough. Not sure a redneck in a 4X4 was their target vehicle Might have to reconsider for next year.

Meanwhile, at OCD Engineering, I wanted to do something about these fans/surging motor temps. Couldn't find the original fan so swaping back to that wasn't an option. Ended up ringing SPAL to discuss my set up. Biased or not, they said for my vehicle/motor combo they would recommend a minimum 3000cfm, and the two 12's that I had were topped out round 2200cfm. They do a 13 1/2" fan with a increased blade pitch and uprated motor that would give me around 4500cfm for the pair. Much as I wasn't spending any more money (!) I bought a pair of motors/fans and shipped them down. Time was of the essence because I had another trip planned. I wanted to open it up as much as possible so drew up a sguare to round shroud pattern, and had it laser cut.
Laser is so cool, they even etched the fold lines for me! Not up to CO standards but ok for my first square/round attempt. Top and bottom sloped 5mm 'back', sides vertical, and fan center is slightly left/right of opening center because combined blade diameter is more than radiator width (pic 4-5).

[swamp rat]

That is just plane ole Awesome!

[Billhilly]

Thanks Swamp!

Yes, I should have TIGed it! But like I said, time was against me, and it took long enough anyways!
So I went from two 12" diameter holes, to a 14" X 28" opening, with the fans further back from the radiator face, and potentially doubled fan capacity. It seems to have taken at least 15* out of the running temps. We left for another 600 mile trip the day after I got them installed, and the hottest I saw was around 195*-200*. Still haven't had a load/trailer on, but I'm heading in the right direction. There is a space below the fans about 3 1/2" X 28" that i could open up and put rubber flaps on so that would be the final step I guess. I still need to 'finish' the shroud anyway, I just rattle canned the top face and chucked it in! Still need to tidy up the welds and paint it properly...
Apparently I didn't take any shot's of the fans installed before I put it in the truck. Sorry for the rubbish shots.

[1985-GMC]

Awesome, THAT is how you build a fan shroud! Great work!

How far are the fans sticking out or the shroud? You could try shimming them out so they're half in/ half out and just to see if that helps any.

[7dee2]

Please put your tray in the upright position, buckle up and prepare for take off! That's some serious cooling right there!

[Billhilly]

Originally Posted by 1985-GMC

Awesome, THAT is how you build a fan shroud! Great work!

How far are the fans sticking out or the shroud? You could try shimming them out so they're half in/ half out and just to see if that helps any.

Thanks! Hope it does the trick. I talked to the tech guys at SPAL and they recommended nearly 3/8" clearance between blade tip and shroud ring, and the fan set back 3/8" into the shroud, and sticking out the back 3/8". I'm kinda close to those specs, but need to show them the pictures and see what they think.

Originally Posted by 7dee2

Please put your tray in the upright position, buckle up and prepare for take off! That's some serious cooling right there!

! Should do the trick huh?!

[Billhilly]

Following on with the OCD theme.... I haven't posted any pictures of another little project that sucked far to much time as I was trying to get the truck going in December.
I wanted a sun visor shelf, but hadn't seen anything like I wanted commercially available. So me and Princess made a hardboard pattern, transferred it to sheet steel, then made final tweaks to the pattern. We then cut a final copy. I ended up using 3/64" plate in case anyone's head ends up making contact with it, but I think 1/16" would be better. Either way I put a small brace in the middle and it's more than stable/strong enough. Got some Heep sun visors that mounted on a 'flat' plane (but still need further mods!) Had a friend come and glue some vinyl onto it and I'm really happy with how it came out. It's pop riveted on around the top of the window frame, just inside the window rubber, a small bracket left and right side, and the already mentioned middle brace.

[Billhilly]

It's tucked up nice and high, level with the top edge of the window frame/door opening. Bit of extra storage space, and provision for gauges as well. On that front I had drilled a small hole top and bottom of the A pillar to make it easier to run wires. I hacked up a 'custom' gauge cluster (did you know that 2" medium NB pipe has just the right ID for gauges?!) that hold a clock and my O2 sensor gauge.

[Billhilly]

Looks the part huh? Overall I'm pretty happy. It's out of the way, I didn't want gauges under the dash, and the sunglasses and wallet etc are easy to grab.

Scratch that twitch!!

[7dee2]

We had a 73 GMC motorhome that had a overhead shelf just like that very handy! Very impressive build sir glad to see some bugs on the windshield.

[Dieselwrencher]

I personally think your shroud turned out awesome! I have people tell me all the time that a fan should be half in/half out of a shroud or the fan won't pull air correctly. Some semi's have the fan buried in the shroud and they cool great. On my wife's excursion it's like that and it's never even thought of getting to the top of normal let a lone hot. Either way, it definitely sounds like you're making good progress as your temps did drop. That head liner visor is nice! I had one in a 89 F250 but the design was crap. I can't remember who produced it, but it had to have stiffeners installed to keep it from vibrating it's self off the roof. I like your gauge provisions too. Great job!

[Billhilly]

Originally Posted by 7dee2

We had a 73 GMC motorhome that had a overhead shelf just like that very handy! Very impressive build sir glad to see some bugs on the windshield.

Hey Brett, the 73 must have been quite the beast. It was certainly worth the bother to make the shelf up. Thank you for the compliment! Your chassis/axle build up is looking really sharp! And yeah, bugs everywhere = it's finally driving!

Originally Posted by Dieselwrencher

I personally think your shroud turned out awesome! I have people tell me all the time that a fan should be half in/half out of a shroud or the fan won't pull air correctly. Some semi's have the fan buried in the shroud and they cool great. On my wife's excursion it's like that and it's never even thought of getting to the top of normal let a lone hot. Either way, it definitely sounds like you're making good progress as your temps did drop. That head liner visor is nice! I had one in a 89 F250 but the design was crap. I can't remember who produced it, but it had to have stiffeners installed to keep it from vibrating it's self off the roof. I like your gauge provisions too. Great job!

Thanks Ryan! As I said, my first foray into square to round. Not perfect, but when I get time I'll dress the welds up and get a proper coat of paint onto it. When the fans are running it doesn't feel anything like twice the airflow I had, but who knows.
A lot of time into that shelf, I told Princess we were going to sell them to the Ameerrican's!

[7dee2]

Originally Posted by Billhilly

A lot of time into that shelf, I told Princess we were going to sell them to the Ameerrican's!

You could retire in style!