Tatra 912-2, Still stumped for extra airflow/cooling

Long time since I posted but lotsa things have been keeping me busy

Does anyone possibly know where I can find a temperature switch or thermocouple of sorts for air temperatures?

I am still trying to rig some electric cooling fans to help evacuate the engine compartment of hot air and I'm tired of the toggle switch.
http://www.steelsoldiers.com/mechanical-upgrades/25228-tatra-912-2-upgrades.html

The other day I needed to pick up a load of 3" pipe and some wood for some farm stuff and instead of hitching a trailer to my truck and picking it up I hopped in the Lizzard, dumped the cannon turret behind my shop, and headed to the scrap yard and Home Depot.
The in cab temperature is OK if you leave the engine bay doors open while driving but once I hit the interstate I have to close it up so stuff wont rattle around and man it gets hot

I've got two fans up in the nose to push the air on each side of the engine back and they work OK but then they're so quiet I sometimes forget to turn them off. I'd like to find some sort of temperature switch that will cycle them automatically like a modern vehicle.

Anyone have a clue?????

If you want - need real Tatra parts, I can look here in teh Czech Republic, but is would cost you shipping though.

If the upgrades are special gadgets, not manifactured by or occasionally appearing on Czech or at least European Tatra's, I cannot help.

There is plenty of temperature controlled electronics available. How many amps do the fans require when running under stress? You either need a heavy duty switch or some sensitive electronics with a relay. A quick search for temperature controlled switches brought up plenty results.

Can even go crazy and use one of them temperature sensitive resistors, so the hotter it gets the more power is supplied to the fans.

Lastly, I recently poked about in the engine bay of an old tatra car, they use a temperature sensitive membrane to open the engine compartment cooling ducts. No electronics required

Thanks for the offer Robo, I may take you up on it in the future. My Jesterka has very few KM on it and everything is new but I have been replacing the old paper gaskets with new synthetic compound ones.

Duncan, that actually crossed my mind too. Something like the magnesium strip in an automatic choke for a carburetor. Problem is I wouldn't know where to start with it. I want the engine to reach operating temp but I dont want the heat to build up that it's so stifling.
On this 6cyl the air is sucked in by the turbine and the hot air gets dumped right in front of me (drivers side). On a regular PV3S there is an ample sized air intake on the front of the truck and the firewall is done in such a way as to deflect heat. Also the driver sits up higher. With me I'm down **** near sitting beside the engine and that hot air is hitting the firewall directly in front of me. The firewall is also quite large and flat and doesn't allow the heat to go down and out nor do the armor skirts on the sides either. The only spot that doesn't heat up is the angled part by my feet that is part of the fender well and is designed to deflect the blast from a landmine should that wheel hit one.

If it were possible I'd like to fab a heat sheild that comes off that angled part but then if I did that the next path of least resistance is up through the transmission tunnel and it gets hot enough as is. Fans are my salvation here I think. If I leave the engine doors open its a world of difference because the heat can freely rise.

Well it's very easy, you just buy one of the temperature sensors that bolt into the radiator hose... errrrr.... wait

Seriously though, you just set the sensor to operating temperature, so the fan switches on when on temperature. Easiest place to start might be to simply walk into an electronics specialist store and ask there.

Most everything here is for liquid applications. The only air stuff is for aircraft and it's not the type I need. Next place was an AC place and they found what I need for $500 and there's no way I'm spending that on a switch.

Somewhere there is something that would work and be inexpensive. I'm just hoping someone will think of it.

Being you have the V-12, how does your cab feel temperature wise? Does each bank of 6 dump air directly down or off at an angle like mine?

Well its a v12 and the temperature is almost as bad as the noise There is one fan to the front, with a fluid coupling to control the speed. The cilinders are covered with ducts to control airflow, and from there it dumps out to the bottom. Most of the heat stays in the doghouse though.

Found some temperature controlled circuits for under $20, or maybe build the circuit as in the images:

• R1 = 1 kΩ
• R2 = 1 kΩ NTC
• R3 = 10 kΩ
• R4 = 220 Ω
• P1 = 10 kΩ
• D1 = LED
• D2 = 1N4148
• T1, T2 = BC 547B

Click to expand...

Replace LED and R4 with a relay.

Ah, also found some results for complete kits here: http://www.apogeekits.com/ just search for thermostat.

And since we're on it: http://www.lmimg.com/Thermostatically_controlled_outlets.asp. Not sure if that work with the voltages though.

OK, I'm gonna check this out, thanks so much bud!

Hey, I notice your fan is open in this pic? Don't you have a deflector/shroud that clips down in between your intake manifolds and also a skirt on each side of the block?

Here's some videos of mine, look under the intake manifoild and you can see where it bolts in then meets up and encircles the fan. If not that might be why your cab is getting so hot.

[media]http://smg.photobucket.com/albums/v425/EZFEED/Videos/?action=view&current=Picture001-3.flv[/media]

[media]http://smg.photobucket.com/albums/v425/EZFEED/Videos/?action=view&current=Picture002-2.flv[/media]

EZ, reading your post above, it looks like you need to work on a duct of sorts to dump the hot air to the outside more effectively...

EZFEED said:

Hey, I notice your fan is open in this pic? Don't you have a deflector/shroud that clips down in between your intake manifolds and also a skirt on each side of the block?

Click to expand...

Well... yeah It was removed because I was working on the fan and fuel pump

cranetruck said:

EZ, reading your post above, it looks like you need to work on a duct of sorts to dump the hot air to the outside more effectively...

Click to expand...

If I could get it under the drivers side fenderwell that'd be awesome but the skirts come down so far it's kinda difficult. If you look how the nose is shaped, the downward angled panels in front of the doors continue all the way down below the frame so if the wheel hits a mine the blast gets thrown out. It's pretty tough stuff too, 10mm compressed chrome moly armor plate. I don't guess I would mind cutting it out but it's a job just to keep it hot with the little torch I have.

Do you mean fabbing a sheetmetal duct Bjorn?

Oh and to add, the two electric fans I shoved up there work pretty decent for this purpose. It's just I'd like to find some automated temperature switch that I can hook to the 12V side of the system that would keep them running till a decent temp drop just like todays modern cars.

duncan said:

Well... yeah It was removed because I was working on the fan and fuel pump

Click to expand...

LOL! OOPS sorry! The fuzzy dice are awesome!

Anyone?
Could a liquid temperature switch be modified to work?

can you find an appliance parts house or try johnstone supply. your clothes dryers use thermostats for heat control some are adjustable low temp are usually 130* air temp

I would try the switch that controls an attic fan. They have a manual on and an adjustable thermostat. I have one in the peak of my shop roof. Switches don't know the difference between ac and dc power.

Depending on the amps of the fan, the 120/240vac switches may not have a high enough rating (often different amp ratings for ac, 12vdc, and 24vdc). Not as big an issue if you are using a relay.

You can use a switch meant for liquid, the response will just be slower because they have the mass of the waterproof tube around the actual thermal sensor. Air ones just have a lot less (or no) shielding, often just some plastic shrink tube over the thermocouple junction or sensor.

Here is one place that sells fans and accessories, never used them, I had them bookmarked because they sell 24vdc stuff-
Thermal Fan Switch - The Fan Man

Most auto parts places used to sell a generic add on 12vdc fan switch with a real thin sensor tube that is designed to slip into a radiator hose under a clamp, the better ones are adjustable. I've used a bunch of them on Triumphs, always with a relay, (the stock mechanical fans just can't keep up here !), but not recently enough to have a part number on hand. You can adjust them cool enough to trigger the fan by holding the probe in your hand. (I've also seen them slipped in between the radiator fins.)
This isn't quite the same as I've used (but its been ~10 years since I bought one !), but would probably work, and includes the relay-
Derale Cooling Products 16759 - Derale Performance Deluxe Adjustable Fan Controllers with Radiator Probes - Overview - SummitRacing.com

You could also mount the probe up against one of the hot metal pieces, maybe with a little thermal grease, if the air flow heat transfer alone is too slow.

AWESOME! THANKS SO MUCH!!!!!!!! These are fantastic ideas!!!!!

And voltage-wise.......everything is 12VDC on my truck with the exception of the starter and weapons which are 24VDC.
I can tie into either the 12V or 24V bank so there is some flexibility here with that.

For temperature switching, try "Klixon" on ebay. These little thermostat switches come in all temps and opens on increasing or decreasing temps, read the spec sheets.
Usually rated 5 or 10 amps, they can be used in conjunction with a relay to power any load.

As far as duct work, yeah, I was thinking that some kind of ducting could be fabbed up, but then again, I'm not familiar with your truck. A heat shield in front of the firewall could help keep it (the firewall) cool also.
Check out tank engine cooling systems.