New PT, New Problems

[Redfisher]

<font color=blue>Well, I finally pulled the trigger and bought a new PT. I’ve had the tractor about a week and, overall, I’m very impressed. However, with a grand total of 3 hours on the tractor, I’ve had a few problems</font color=blue>

I have to ask, Marrt Was it worth the Risk? /w3tcompact/icons/smile.gif

(No disrespect to the PT looks like a nice little machine)

oops I guess I should have read your other post first Don't want to get into that again( By the way our jinma has 50 hrs on it now and the tack has been the only problem,coverd by warranty) Anywho have fun.

 

[PTRich]

Went to NAPA and got: spark plugs, air filter and gas filter. Worked like a charm, runs great.

 

[deadstick]

I did 3hrs tonight spreading 36yrds of topsoil... Felt the battery after use and I could keep my hand on it as long as I wanted. It was hot but not hot enough for me to remove my hand. Now the muffler on the other hand WAS too hot to touch /w3tcompact/icons/shocked.gif.....

 

[duane]

I did the same with my unit. The battery was hot, but I could keep my hand on it. Same with the rear of the tractor. How much of the heat off of the muffler is pulled up through the hydraulic cooler?

 

[marrt]

To be a little more specific, only the corner right under the muffler on my battery was “too hot to touch.” On my new battery, the positive post happens to be in that spot, right under the muffler. Since Lead has a much higher thermal mass than the plastic case of the battery, I suspect this is why that one spot was so hot. The rest of the battery was very hot…but certainly not too hot to touch. I’m going to buy a digital meat thermometer and mount the probe in that spot to get an accurate reading.

I called PT and they are researching the problem on a test unit they have.

BTW, they have been using this new muffler for only a few months. Deadstick, do you have the “new” muffler?

 

[deadstick]

Yes I believe I do.... Mine looks exactly as your picture depicts. I purchase the PT425 about a month ago. It's rectangular in shape with the exhaust going out the right side and the left side has the intake hole (or whatever it is)...

I felt the battery right under the muffler and I could keep my hand there. Now I did accidentally touch the muffler and boy was that hot /w3tcompact/icons/grin.gif...

 

[MossRoad]

I mowed the lawn tonight. Outside temperature was around 70. After 35 minutes of mowing I stuck a meat thermometer under the negative battery terminal through the rear grill and it got to about 125. Warm to the touch but definately not hot.

Cleaned the thermometer off and stuck it in the hydraulic reservoir. 135 degrees.

Stuck it on the hydraulic cooler with the fan running and it dropped way down below the scale to (my guess) around 80 degrees.

I'll repeat the experiment on a 90 degree day sometime and see what it hits.

 

[marrt]

MR, thanks for posting. I bought a meat thermometer yesterday for this purpose. I will be able to mount this particular thermometer in the engine compartment and leave it there. I was looking for a digital thermometer and found one for about $20. However, since the cord for the probe was only 3 feet, I wouldn’t have been able to mount it on the dash without reworking the probe wire, which, for all I know, may have affected the accuracy. Anyway, I found another thermometer for less than $5 that I can just leave in the engine compartment for a while. I probably won’t be able to test anything until this weekend though.

I wonder if 125 degrees is a problem. As I mentioned earlier, I read that the life of a battery is cut in half for every 15 degrees over 77 degrees. However, its not clear to me what this means. Is this an average temperature over the battery’s life? If so, then it definitely wouldn’t be a problem. My guess is that 125 degrees isn’t a problem.

I’m betting mine was higher than 125 but it certainly wasn’t up to the boiling point (does anyone know what temperature sulfuric acid boils? /w3tcompact/icons/smile.gif). I think the problem with batteries “boiling over” when being overcharged is that they produce too much hydrogen gas too quickly and the pressure builds to the point where a release is necessary. I don’t know how much the battery’s temperature, by itself, has to do with it.

 

[MossRoad]

327 degrees C, but that is pure, not diluted in water like a battery.

 

[GarretV]

"I wonder if 125 degrees is a problem. As I mentioned earlier, I read that the life of a battery is cut in half for every 15 degrees over 77 degrees. However, its not clear to me what this means. Is this an average temperature over the battery’s life? If so, then it definitely wouldn’t be a problem. My guess is that 125 degrees isn’t a problem. "

I kind of wonder about that too. I mean, doesn't the engine compartment of every one of the millions of cars & trucks on the road regularly see 125 degrees?

Garret

 

[marrt]

OK. The verdict is in. I finally had a chance to mow today and the temperature around the battery hit almost 225 degrees after one hour! And that’s with an ambient air temp of about 75 degrees. By the time I grabbed my camera, the temp had already dropped to about 212 degrees on the thermometer. The thermometer, as you can see in the attached pic, basically measures the air temperature around the battery, and therefore falls fast when the engine is idling. I have no idea what the actual battery temperature was but can guess it will get really high if bathed in 225 degree air for several hours.

I leave this thermometer in all the time now and will continue to measure as the summer gets hot. One thing’s for sure…I think 225 degrees is too hot for a battery.

 

[MossRoad]

I'm not doubting you that it is HOT in there, however, isn't that type of thermometer supposed to be vertical only? I used a metal cased meat thermometer in mine, and as I reported earlier, it didn't hit anything near that in about the same air temperature.

You definately have a heating problem there. Water boils at 212, and I don't know how potent your acid is, but I'll bet you were right in your thinking that the sucker just boiled to death after several hours of cooking back there.

I'd call Power Trac and ask them for help. That is too hot!

 

[Charlie_Iliff]

Marrt: For some years, Chevy trucks had starter problems because of heat radiated from the exhaust. They cured it with a with a simple shield, which also became available after market. It was two thin metal sheets with asbestos or other fabric sandwiched. It eliminated the radiant heat completely. I recall seeing pads to protect counter tops in kitchens for cheap that would probably work great. They still around?

 

[Schultz]

I agree a radiant barrier could prevent a lot of energy from heating your battery, especially since batteries are usually black, black being very absorbent of radiant energy. I think this is your biggest source of heat transfer to your battery. Your thermometer may have been heated mostly by the radiant energy from the muffler rather than the air. I say this because air has very little mass to transfer energy, compared to your massive battery. A simple experiment would be to put a sheet of shinny metal (aluminum, Stainless Steel) or just wrap aluminum foil around the battery area with the thermometer behind the foil. The reflector should not touch any heat source (muffler, engine, etc) otherwise conduction will rapidly heat your reflector and then it will begin radiating heat.
Tim

 

[marrt]

MR, regarding the question of the thermometer needing to be vertical…I don’t think that’s required. I think this thermometer works by having a sealed enclosure under a known pressure. As the temperature increases, the liquid (used to be mercury…think it’s alcohol these days) expands at a know rate based on the initial internal pressure. If true, I think it may even work upside-down.

Schultz, I agree that a big component of the heat problem is radiant heat. I think I may be able to solve both the air and radiant issues with some type of shield. I sure wish I knew how to use a smoke wrench as this would be a perfect project. I’ll have to think about what I can come up with to address the problem.

 

[davesisk]

Another thought here. Harbor Freight (can you tell I love that place?) also sells a 115V resistance welder (ie. a spot welder, you know, the type with clamps that are used for autobody repair work) for about $200 that'll weld sheet metal and small parts up to 1/8" total thickness. You can weld most metals except aluminum (even galvanized stuff without releasing toxic gases, to my understanding). I don't have one (yet /w3tcompact/icons/smile.gif) but I understand that it's neat, clean, and easy to use, and you probably don't have to worry about blowing anything up around flammables.

The FCAW makes a really crusty weld that you have to spend quite a bit of time grinding. Of course, you could just get an inexpensive "stick welder" (ie. arc welder that uses clamped electrodes). I understand that makes a pretty neat and strong weld, but is fairly difficult to master "striking" an arc. The spot welder doesn't need an arc (welds through resistance) and the FCAW makes it's own arc (the current melts the wire, which then creates and maintains the arc).

If you've got lots of money to spend, send some of it to me first, then go buy yourself a TIG welder. /w3tcompact/icons/tongue.gif That's supposed to be the neatest and cleanest welding approach available (although about $1000+ for the welder).

One more thought: pick up a copy of "The Welder's Handbook" from Lowes/Home Depot, or order it from Amazon. Great book for learning this trade as a hobby!

I suppose I have some rather odd hobbies when you think about it, eh?

HTH!
Dave

 

[MossRoad]

Before going through modifications, what did Power Trac say about the heat problem? I'd ask them if maybe there is a real problem with this muffler design and see if they can repair it or give you a different style muffler.

Anyway, if you look at my muffler, there is a heat shield on the back of it to protect the engine from heat. I've attached a picture, in case you're interested. It might give you some ideas towards modifying yours.

 

[MossRoad]

And here's another picture, from the other side(the side with the battery). Hope they help.

 

[marrt]

Dave,

Thanks for the reply. I am looking for that book now. Is the author Richard Finch by chance? I’ve been wanted to experiment with welding for quite a while now. Your excellent summary is the most education I have received on the topic. Seems like there are a lot of choices. I know that I will want to weld up some home made attachments and that means using metal up to ¼ inch. That may limit my choices.

I like Harbor Freight too. Although some of their stuff is “cheap” (and I mean quality in addition to price), often I find it’s “good enough” for the home owner. I bought a bunch of sockets from them and am impressed. Also bought a 3HP router. It’s not that well made but it gets the job done and was very inexpensive compared to “branded” product. Some of the deals they have on the front and back covers (i.e., the “loss leaders”) are incredible.