Throttle/Choke cables insulation

MossRoad · Feb 16, 2022

My PT425 has insulation tubing around the throttle and choke cables where it passes by the engine and exhaust. After 21 years, it disintegrated and the outer rubber shield on the cable melted away, and the cables became hard to operate. I removed the cables and got them working again, and replaced the melted rubber areas with several layers of heat shrink tubing and I'm satisfied with that part of the repair.

I now need to find a source for some insulation for the cables. I think I'd like to put two layers if possible. Anyone have any suggestions? I know several of you have insulated your fuel lines to deal with vapor lock. Which product did you use? I've found several on-line. I'd like to find something locally, but no luck so far.

ruffdog · Feb 16, 2022

Those cables will normally have a nylon layer between the cable and the steel winding. If it gets hot and melts, it is tough to get that freed up. You might find more options for heat shield for wires:

Wiring Heat Shield | Buy a Wire Heat Shield Wrap & Heat Wrap for Wires - JEGS High Performance

ponytug · Feb 16, 2022

I have used aluminized glass fiber tubes like these;

https://www.amazon.com/Design-Engineering-010403-Heat-Sheath/dp/B000E267M4/

or the JEGS version;

JEGS Thermal Heat Sleeving - JEGS High Performance

JEGS thermal heat sleeving is designed to protect fuel lines, A/C lines, oil lines, heater hoses and electrical wiring from exhaust heat. Stable to 500°F. Features non-permeable heavy silicone jacketed fiberglass, highly flexible for tight radius curves and cuts cleanly with scissors. Resists...

www.jegs.com

I agree with @ruffdog that once the outer nylon melts a throttle cable, I have never had them ever work well again.

All the best,

Peter

MossRoad · Feb 16, 2022

Well, that might explain why, after the tractor cooled down, the choke cable wouldn't move. Once I got the tractor started sans choke (no easy task) and I mowed the lawn, I'd shut the tractor down and the choke cable would move easily. Then next time I tried to start the machine days later, the cable was stuck again. I would have blamed ice, but it was in the 50s last fall when this started happening. So I'm gonna guess there was a pretty good chance that inner coating was melting, letting the cable move eventually, then hardening after the tractor cooled.

The one was tough to get to move. I put one end in a vice and was able to break the sheathing free and get it sliding freely again. I bought a jig to inject lubricant down the cable. It didn't work. So I made a funnel on the end of the cable, hung it from my basement ceiling, and filled the funnel with lube, and let gravity work for a couple weeks. Kept filling it every day until it finally started coming out the other end.

It's OK now, and functions correctly. I just want to put the shielding on it so it doesn't melt itself stuck again. If it does, I'll have to buy new cables again. They were pretty reasonably priced from PT several years ago.

They are loooooooong cables. About 100". The first time I took them out, it was a bear, because they were tie-wrapped to the hose bundle going through the center tunnel. I was able to wiggle a mirror in there and see the tie wraps and cut them with some long tool (can't remember now). I put a pull cord on the engine end and pulled them out from the control end. They went back in pretty easy. That was a few years ago. I remembered the procedure this time and it's really only a 15 minute job to remove or install now.

Any ideas where someone could get that kind of insulation locally? I can't think of a place off-hand. I guess I'll just order from Amazon if I can't find anything tomorrow.

MossRoad · Feb 16, 2022

Oh, one more tip in case anyone has to remove the choke cable on a PT425. There are spacers under the dash between the cable lever bracket and the bottom of the dash. I didn't know why until I put it back together and then your fingers can get pinched between the choke lever and the steering wheel. The spacers lower the choke cable lever about half an inch, which lets your fingers clear the underside of the steering wheel, which is lower in the center than it is at the outer edges.

CalG · Feb 16, 2022

Header wrap would work, and would not require the disassembly that a sleeve might.

MossRoad · Feb 16, 2022

CalG said:
Header wrap would work, and would not require the disassembly that a sleeve might.

Hmm. They have some in stock at the local autozone. I'll give it a try. Thanks,.

ponytug · Feb 17, 2022

Personally, I have had better luck with the aluminized glass fiber tubes than header wrap. I find header wrap works best at trapping heat in, rather than keeping it out. Or put differently, I haven't found header wrap to be all that insulating for anything that isn't already hot. YMMV. I may not have bought good ones.

@MossRoad: zip ties! I bet that I would have been yanking on that choke cable for ages before I would have though to look for zip ties inside the tunnel. I would try auto one or Napa, if you need it soon. Even loosely wrapped and lightly crushed aluminum foil is worth a fair bit. Just make sure that it can't come loose with an over wrap.(e.g. safety wire.)

All the best,

Peter

MossRoad · Feb 17, 2022

Wire ties, zip ties, are a love-hate kinda thing with me. I've pulled hundreds of miles of wire in my past job at the newspaper. Networking, telecom, AC power, low voltage control wire, all kinds of stuff. The first year I was there, I worked with an electrician re-wiring the entire printing press for a unit-by-unit upgrade. We laid out a diagram on the floor of a large room and built harnesses. We stopped counting at, as I recall, 57 miles of wire. I've never used so many zip ties in my life!

But if you have to remove something, or try and troubleshoot the location of an open or short, in a wire bundle that's zip tied, forget it. Just run a new wire if you can to quickly eliminate the guestimation.

And those IT guys that want to wire tie CAT5 cables that are already laying in a cable tray above a suspended ceiling... I ask WHY??? It isn't going anywhere. It can't go anywhere. The tray is there to support it. Just don't do it. Pleeeeeeease.

I can see why PT would want to zip tie stuff in the tunnel to prevent rubbing and chafing. It's just a pain to locate and cut, especially since the tunnel can grab so much debris. At first pull, I'm thinking WHY? isn't this moving. Then I noticed the hoses moving as I pulled the cables. AH HA! They're one unit. That's what got me looking.

cqaigy2 · Feb 18, 2022

Haha, on the zip tied network cables, and have the sharp edge nick your finger. We'd have cable professionally run and one of our goofs would happen by and think, this just needs some zip ties to make it a better install.

MossRoad · Feb 18, 2022

Well, I slipped the cable back in last night, got it all hooked up and wrapped some of that header tape around it(that's all I could source locally). I was more impressed that I got the throttle and choke cables back in the right places. It started right up!

After moving snow for about 20 minutes, I was done, so I checked the wrap. It was warm. I'm thinking a metal shield between the cables and hot exhaust components would do a much better job, so I'll look into that over time.

MossRoad · Feb 18, 2022

A guy showed me a trick for reducing sharp cable tie cut ends. Instead of clipping the tag end, grab the tag end as close to the zipper block with a pair of pliers and spin it around a few times. That softens the plastic and it then breaks off leaving a very small, soft to the touch nub VS that razor sharp cut. Basically, you're twisting it off VS cutting it off.

ruffdog · Feb 18, 2022

A good zip tie tool will tighten and snip the tie flush.

Hellerman Tyton Steel Cable Tie Gun

MossRoad · Feb 18, 2022

ruffdog said:
A good zip tie tool will tighten and snip the tie flush.

Hellerman Tyton Steel Cable Tie Gun

$821.00?????

ponytug · Feb 19, 2022

That's my problem with specialized tools. If you use them all day long, it is wonderful. For rank amateurs like me, the cost/benefit ratio is a bit skewed.

I just use flush cut wire cutters, and watch how I do it, but I like @MossRoad's twisty idea.

All the best,

Peter