PT422 Aux cooling

[Phils]

Great idea, Tim!

It seems that the stock fan (like you used) moves more air than the one I installed. I make that call after using my hand to accurately measure air flow from each. This weekend I was wondering if using a second stock PT fan might've been a better idea, if for no other reason than having a "spare" fan onboard. Better that it costs less too!

I did SOME PT work this weekend but not the extended three-hour-with-PTO days that caused vaporlock to present its ugly little self. For the longest continous period (maybe 1 hour) I ran the aux fan. The only thing I noticed was that the hydraulic fan never came on and it usually would have in that time with the work I was doing.

On whether to push or pull air, one consideration I had was that locating a plastic fan assembly above and near that hot muffler and exhaust could shorten the life of or even damage that fan. This could happen after you've shut the PT off because the hot muffler would continue to radiate heat. Your's is a smaller diameter tho, and my larger diameter fan would've mounted closer to that exhaust than what you should have been able to do.

I may consider rewiring mine provided it HAS solved my VL problem. Having it on whenever the ignition is on may be the best plan. That eliminates having to think about it. Now I turn the aux fan on when I anticipate longer and hotter.

This weekend I also gave thought to adding two automotive relays in a "latching" setup triggered by the hydraulic fan. That is... when the hydraulic fan turns on, the aux fan would too. But when the hyd fan turned off, the aux fan would remain running until the key was turned off.

So keep us posted Tim on your results.

Phil

 

[BobRip]

Great idea, Tim!


I did SOME PT work this weekend but not the extended three-hour-with-PTO days that caused vaporlock to present its ugly little self. For the longest continous period (maybe 1 hour) I ran the aux fan. The only thing I noticed was that the hydraulic fan never came on and it usually would have in that time with the work I was doing.


Phil

Phil, I would be a little concerned that the PT hydraulic fan did not come on. The air flow that you created is cooling the fan thermal switch, but it may not be cooling the hydraulic fluid as much. Can you check the fluid temperature and see how it is doing. You might want to have both fans come on from the fan switch if that does not overload that switch. Of course I am not sure this is a problem, just one of my usual paranoid concerns. You could also wrap some insulation around the fan thermal switch so that it more closely thermally couples to the hydraulic fluid. I think this is a better idea.

 

[Phils]

BobRip,

Good idea on wrapping the hydraulic oil thermal switch. Possibly I hadn't worked the PT long and hard enough, possibly the extra cooling air actually contributed some to hydraulic cooling, and possibly the thermal readings are skewed from the extra cooling air.

I will be monitoring closely. I don't imagine "too cool" is a problem normal to PT.

Phil

 

[Marks481]

the top fan works off of a thermoswitch that is just clamped onto the outside of the hydraulic piping. It is believable that if you are not using the PTO, that the engine compartment temperature rather then the hydraulic oil temperature is triggering the thermal switch.

The downside of the 7.5 amp fan is that it is noisy (although probably not noticeable with PT at full throttle). I will keep you all informed if the exhaust starts melting the plastic shroud.

The PT422 temperature just makes me nervous; after extended PTO ops I generally get a backfire and a bit of "dieseling" after I shut down... anything that drops the overall temperature should help. Strangely enough, I have not had any problems with vapor lock.

Temperature monitoring would be nice; I bough two 2" oil temp gauges to mount on the vertical section of the center tunnel.

Any suggestions on where/how to mount the sending units? Eventually, I will mount one in the hydraulic tank, but that will have to wait until the first drain interval when the tank is empty. Until then, I will probably clamp the sending unit to the side of a metal hydraulic fitting and wrap it in insulation.

Location for the engine oil temp sender is the harder choice.

Of interest, Spal makes a PWM fan controller, which will ramp one fans speed from 50% to 100% based upon user selected temperature, and control another fan with a relay. Not cheap, but it woul be an option which would not be much more expensive then putting in a relay. My theory is that the PT runs hot enough that pulling air across the exhuast manifold is a good idea regardless of engine temp.
JayCorp Technologies - SPAL Programmable Fan Controller

 

[Phils]

the top fan works off of a thermoswitch that is just clamped onto the outside of the hydraulic piping. It is believable that if you are not using the PTO, that the engine compartment temperature rather then the hydraulic oil temperature is triggering the thermal switch.

The downside of the 7.5 amp fan is that it is noisy (although probably not noticeable with PT at full throttle). I will keep you all informed if the exhaust starts melting the plastic shroud.

The PT422 temperature just makes me nervous; after extended PTO ops I generally get a backfire and a bit of "dieseling" after I shut down... anything that drops the overall temperature should help. Strangely enough, I have not had any problems with vapor lock.

Temperature monitoring would be nice; I bough two 2" oil temp gauges to mount on the vertical section of the center tunnel.

Any suggestions on where/how to mount the sending units? Eventually, I will mount one in the hydraulic tank, but that will have to wait until the first drain interval when the tank is empty. Until then, I will probably clamp the sending unit to the side of a metal hydraulic fitting and wrap it in insulation.

Location for the engine oil temp sender is the harder choice.

Of interest, Spal makes a PWM fan controller, which will ramp one fans speed from 50% to 100% based upon user selected temperature, and control another fan with a relay. Not cheap, but it woul be an option which would not be much more expensive then putting in a relay. My theory is that the PT runs hot enough that pulling air across the exhuast manifold is a good idea regardless of engine temp.
JayCorp Technologies - SPAL Programmable Fan Controller

That controller would be a good answer. Just leaving it on like your's is probably better though, because of the KISS philosophy. And keeping it simple is what will probably stop me from installing those relays.

The dieseling and backfire result from running hot. As the engine heat increases, the gas starts to turn to vapor but not so much that it kills the engine. But it makes the engine run lean, which causes the engine to run hotter. Which makes the gas vaporize more, which makes the engine run leaner, which makes it run hotter, which will cause dieseling and backfires at shutdown. Rather a vicious spiral.

Also contributing to the backfire "pop" is IMO the exhaust "manifold".... that is, some sections of square tubing welded to a couple of pieces of round tubing, and feeding a box with baffles. Hot spots develop in the "manifold" when the engine is running hot, then at shutdown those hotspots ignite the air/fuel mixture that's present in the exhaust stream because the spark plugs were turned 'off'.

It all relates to heat and I am confident that you and I won't be having the problem anymore!

Putting oil temp gauges where you describe is a good idea. Aren't there some unused bungs in the hydraulic tank? When the oil is cool, it'd be easy enough (I'm imagining here) to install a sender in the tank by pulling the plug and putting the sender in quickly, thereby letting very little oil out? Or am I imagining the extra bungs?

Phil

 

[Gravy]

I also thought the backfiring was due to the funky square exhaust system. I was really disappointed when my adaptation of the Robin side-mount exhaust system with the round tubing manifold made no difference. Oh well, at least it's not quite as obnoxiously noisy.

Gravy

 

[ponytug]

Um... I'm a rank amateur here, but I'm with Phil on this one. When you shut off the ignition, all you shutoff is the sparkplugs. If you have a hot spot in the engine (the plug itself, a valve, a bit of carbon), you always get run on from a carburetor equipped engine. Fuel injection engines are a different story (no fuel). As Phil points out, what one wants to do here is get the engine cool enough before you turn it off. That way there won't be any internal part of the engine hot enough to diesel on. Besides, if the engine is cooler, the oil and the engine will last longer, but that's a whole 'nother thread.

Of course, you could get fancy and have the engine, and the headers sent off for coating to insulate/conduct the heat. But it does seem like overkill in a tractor engine.

As far as mounting the senders, getting a good thermal bonding is all you need; just use a pipe clamp around the metal nut on a non-swivel hydraulic hose, and put a wrap or two of neoprene pipe tape on top. It will read the oil temperature accurately, just with a slight lag. Don't tighten the pipe clamp too hard or you'll break the sender.

For those of you that didn't buy the sender, you can get a cheap electric BBQ thermomenter and pipe clamp it to a metal fitting. You have to replace the AAA periodically, but most come with alarms- assuming that you can hear it over the engine. The price is right; you can often find them on sale for less than $20.

All the best,

Peter

I also thought the backfiring was due to the funky square exhaust system. I was really disappointed when my adaptation of the Robin side-mount exhaust system with the round tubing manifold made no difference. Oh well, at least it's not quite as obnoxiously noisy.

Gravy

 

[kmaz]

I also thought the backfiring was due to the funky square exhaust system. I was really disappointed when my adaptation of the Robin side-mount exhaust system with the round tubing manifold made no difference. Oh well, at least it's not quite as obnoxiously noisy.

Gravy

Hey Gravy, I too was interested in the robin side mount exaust. Sorry to hear you weren't happy with it. You dont happen to have any picteres of that do you?
Kris

 

[Gravy]

I do have photos. I'll try to post some soon.

Gravy

 

[MossRoad]

I do have photos. I'll try to post some soon.

Gravy

Woo Hoooo!!! We love photos!