RK55HC Air Conditioner Belt Tension and Mystery Fill Cap

g8erh8er · Jul 16, 2020

My A/C belt has started to squeal so I attempted to tighten it but realized when I got some components removed to make some space, I'm unable to get the lock nut loosened on the tensioner pulley. The flats are oriented such that it's impossible to get a wrench on them due to the limited clearance around that nut. I've got a set of crows foot adapters coming and I'm hoping that will do the trick.

Anyway, while looking at the tensioner assembly, I noticed a fill cap that is normally hidden by the muffler and air intake tube. Any idea what that's for? Obviously, it's not meant to be removed very often considering you can't get to it without taking a lot of stuff off.

In the pic below, the red arrow points to the tensioner lock nut, the green arrow to the fill cap. Second pic shows a better angle of the cap.

Qapla · Jul 16, 2020

Can't say for sure since I don't own an RK - but, it looks like a filler cap for the oil in the front differential

g8erh8er · Jul 17, 2020

Mystery solved, kinda. That's a filler cap on the bonnet assy of the cylinder head. It's #37 in the parts diagram below. Since it's not used for regular maintenance, I wonder what its purpose is. Maybe only used during a tear down.

ptsg · Jul 17, 2020

That cap is just to fill the engine with oil. What happens with these engines is that they are used under several applications. On some applications the top cap gets blocked like your tractor and you have to use the side cap to fill the engine. On other applications the top cap is not blocked and the side one may be blocked.

Most engines have two ways to fill it with oil, specially Yanmar and Kubota engines that are used in a lot of applications, like excavators, tractors, loaders, etc.

g8erh8er · Jul 17, 2020

ptsg said:
That cap is just to fill the engine with oil. What happens with these engines is that they are used under several applications. On some applications the top cap gets blocked like your tractor and you have to use the side cap to fill the engine. On other applications the top cap is not blocked and the side one may be blocked.

Most engines have two ways to fill it with oil, specially Yanmar and Kubota engines that are used in a lot of applications, like excavators, tractors, loaders, etc.

Ahhhh - that makes perfect sense. Thx for the insight PTSG!

g8erh8er · Jul 21, 2020

As a final update to this post, I strongly suggest those with the a cabbed RK55 tractor who intend to do their own maintenance invest in a claw foot wrench adapter set. My tractor is stored inside and exhibited zero corrosion on the A/C tensioner lock nut, but that dang nut was frozen and would not move.

After rounding some of the corners of the nut with the claw foot adapter and a wrench, I sprayed everything down with PB blaster and let it sit overnight. Tried again the following day and still no movement. I finally put just the adapter on the nut and banged the corner of the adapter with a hammer about 15-20 times. It finally let loose.

I replaced the nut with a new one. The stock nut is 10 x 1.5 mm and accepts a 14 mm wrench, making it lower profile than typical nuts you'll find at a hardware store. I got one anyway, and while the replacement nut accepts a 17 mm wrench, there's still enough room to be able to tighten/loosen it, with a claw foot adapter that is. I have no idea how you'd get it off without that.

Included some pics showing the claw foot set up with the direction you turn the nut to loosen it, the condition of the old nut once I got it loosened, and the replacement nut installed.

sengli · Aug 22, 2020

According to the manual, they said to adjust the AC belt tension, but moving the alternator. I dont have my tractor yet, but read that in the very vague owners manual.

g8erh8er · Aug 22, 2020

sengli said:
According to the manual, they said to adjust the AC belt tension, but moving the alternator. I dont have my tractor yet, but read that in the very vague owners manual.

You will find that information, like a lot of other parts of the manual, to be incorrect. The tractor has two belts. The A/C belt does not route around the alternator.

fried1765 · Aug 22, 2020

g8erh8er said:
As a final update to this post, I strongly suggest those with the a cabbed RK55 tractor who intend to do their own maintenance invest in a claw foot wrench adapter set. My tractor is stored inside and exhibited zero corrosion on the A/C tensioner lock nut, but that dang nut was frozen and would not move.

After rounding some of the corners of the nut with the claw foot adapter and a wrench, I sprayed everything down with PB blaster and let it sit overnight. Tried again the following day and still no movement. I finally put just the adapter on the nut and banged the corner of the adapter with a hammer about 15-20 times. It finally let loose.

I replaced the nut with a new one. The stock nut is 10 x 1.5 mm and accepts a 14 mm wrench, making it lower profile than typical nuts you'll find at a hardware store. I got one anyway, and while the replacement nut accepts a 17 mm wrench, there's still enough room to be able to tighten/loosen it, with a claw foot adapter that is. I have no idea how you'd get it off without that.

Included some pics showing the claw foot set up with the direction you turn the nut to loosen it, the condition of the old nut once I got it loosened, and the replacement nut installed.

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