782 KT17 Noise

[Tyler Rabuck]

Hello all,

I have a 782 with a Series II engine and when warm, there is an audible ticking noise, almost like injector noise in a modern engine. I'm not sure if this is just a normal sound, valve noise or if the carb needs adjusted. I can't tell if the sound is coming from either cylinder as it sounds loudest near the middle by the air cleaner. This engine has plenty of power and runs well, no smoke or anything. Hope someone can shed some light. Thanks!

 

[Rbertalotto]

Could be a simple air leak......Maybe points are loose or arching?

 

[kmcconaughey]

I don't have any experience with the KT17 but I believe that the mechanical diaphragm fuel pump is mounted in the center of the engine like on the Onan twin used in the 982 and others. Perhaps it's loose or is having some issue. Might be worth a look.

 

[mgonitzke]

Check valve lash. Also recently had a blown head gasket make that noise on my 782.

 

[Tyler Rabuck]

Thanks for the replies and suggestions. I finally had the chance to get around to it tonight. I tried using my mechanics stethoscope to better locate the source but sound travels everywhere on these small engines. I inspected the valve clearance and found that the intake valve clearance was about twice (0.012) more than the max spec called for in the service manual on the cylinder on the left hand side, operators position. I'm guessing this is the source of the tapping sound I hear.

Now my question is, what are the short and long term effects of this and what would be my best course of action, should it be a problem?

For now, since this tractor runs perfectly other than the slight tapping noise, I'm going to continue to use it as my main lawn mowing and snow removal machine; but I do have 2 other capable Cubs to use in the meantime should happen go wrong.

Thanks again!

 

[mfrade]

I am not familiar with this motor but is it not adjustable?

 

[mgonitzke]

The KT and Magnum twins do not have adjustable lifters, so you have to grind the valve stems. Once the clearance becomes too much, the only way to reduce it again it to replace the valve.

I don't think I'd get too excited about 0.012" clearance on the intake valve. In my opinion, that's not going to hurt anything. These engines seem to have valve noise even when everything is set up right anyway.

 

[rfunk]

The KT and Magnum twins do not have adjustable lifters, so you have to grind the valve stems. Once the clearance becomes too much, the only way to reduce it again it to replace the valve.

Have never had either a KT or Magnum, I've only seen that design in the manual for the smaller K-series (mine, CC149 with K321) Any chance that the tappets/lifters from a K321/etc. would interchange? I would have thought that these engines, being later-developed than the K-series would have had the "latest improvements"!

 

[mgonitzke]

The lifters on the KT/Magnum are tiny compared to a K-series single. No way would they interchange. Completely different engine.

 

[rfunk]

The lifters on the KT/Magnum are tiny compared to a K-series single. No way would they interchange. Completely different engine.

Ahh.
That's why I mentioned that I don't have either, so lack of knowledge of the situation. Too bad. And, of course, the finish and tolerance requirements for a tappet make DIY'ing an adjustable system impossible without the ability to create such finishes. Much cheaper to go with the factory system, even if frustrating.