sv730 throttle cable seizes

[Castleford]

This engine runs in an MTD Gold lawn tractor about 12 years old.
The cable from the throttle lever to the carb linkage is solid 'piano wire ' running in a spiral wound steel sheath
like a bikes brake cable with plastic coating on the outside.
I replaced it when it began to jam and it was ok at first but now is jamming again.
I think most of the problem is when the cable begins it's final approach to the carb it has to run closely over one
of the exhaust tubes, this has melted the plastic sheathing away.
A month after freeing it up with penetrating oil and brake cleaner it seized again.
It looks like the heat and moisture while running the snowblower cooks it really well and it locks up.
I tried sheathing it with aluminum tape used on heating ducts but no go.....
It's getting old dismantling this every 4-5 weeks....
Anyone have any solutions? (Short of putting a .410 slug in this machine that is...)

 

[Castleford]

I had a thought, maybe wrap aluminum foil around the cable where the plastic sheath
has melted away with a good layer of high temp disc brake caliper grease first?

 

[Castleford]

I just had a better thought, why not use higher quality lined brake cable casing like is used on bicycles?
Still may have to install a heat shield but this is still "a good thing" as Martha Stewart used to say....

Amazon.ca

 

[StarTech]

Use some fiberglass sleeving. Doesn't conduct heat like aluminum does. Might take a couple layers or so depending on the amount of heat involved.

Something like these from Grainger.

 

[Castleford]

Use some fiberglass sleeving. Doesn't conduct heat like aluminum does. Might take a couple layers or so depending on the amount of heat involved.

Something like these from Grainger.
View attachment 63315

Good idea, thanks! I may even have some of the correct size from my diesel tuneup days!

 

[Castleford]

I've ordered some high(er) quality brake cable casing lined with nylon I presume; and some 1/16" music wire. I'll keep everyone apprised as to my progress, good or bad.

 

[Castleford]

So far so good..
The wire arrived, interesting job taking the curve/bend out of the length needed.

Then I noticed that there was a mirror so to speak for the carb linkage not only
allows for a left hand approach but also raises the pushrod/cable housing a couple of inches
off of the nasty old exhaust pipe.The white arrow at lower right shows the cable's position as presented to me when I bought it back in '18.....it was barely a 1/2" clear of the exhaust pipe.
I doubt if the new linkage would have had much more of a chance even with the heat sleeve.

I still installed the fiberglass heat shield since I had it.....

And there was much rejoicing while dancing around the fire.....

✂️ Fire!

18 seconds · Clipped by strawboss59 · Original video "Cast Away (3/8) Movie CLIP - I Have Made Fire! (2000) HD" by Movieclips

youtube.com

 

[bertsmobile1]

Very important
DO NOT USE WD40 or similar product to lube the cable.
Water despersants will soften the nylon causing the cable to jam
The best stuff is a dry teflon lubricant that is used for lubing push bike cables

 

[Castleford]

Thanks for the heads up, I used graphite spray lube.It was on hand.
It uses a very thin solvent carrier that evaporates in seconds, it didn't occur to me to check for compatibility....

 

[bertsmobile1]

Honda are about the only push mower company I know of that uses nylon lined cable and it is a regular fix
The cable gets sticky so they pour the WD 40 down it and a week latter it is frozen solid .