Ryobi RBC430SBD

[KE4AVB]

There is one major problem those engines. They use a non pressurized oil system via a dipper type system. If the trimmers are ran on their side there is no oiling occuring. Most that I worked on that oil dripping out the air filter box are trashed piston and cylinder wise. It is the reason Ryobi only offers a short block for these engines. BTW even to replace the timing belt requires you disassemble the crankshaft. It is the reason I will not even take these 4 cycler in for repairs. The only two OEMs that I have repaired that work well sideways are the Stihl 4 mix and the Shindaiwa 4 cycler trimmers.

[Stoner]

Hi, Skywatcher
The engine was not turned upside down. The valves are installed in the same way as yours. The oil should not have been overfilled when refuelling. By the way, when filling up the oil, should the engine have been tilted back a bit because of the Grass Deflector Assembly (figure 11)?

[Stoner]

There is one major problem those engines. They use a non pressurized oil system via a dipper type system. If the trimmers are ran on their side there is no oiling occuring. Most that I worked on that oil dripping out the air filter box are trashed piston and cylinder wise. It is the reason Ryobi only offers a short block for these engines. BTW even to replace the timing belt requires you disassemble the crankshaft. It is the reason I will not even take these 4 cycler in for repairs. The only two OEMs that I have repaired that work well sideways are the Stihl 4 mix and the Shindaiwa 4 cycler trimmers.

So when using a trimmer, is it better not to tilt it sideways? How is the crankshaft disassembled?

[KE4AVB]

There is one major problem those engines. They use a non pressurized oil system via a dipper type system. If the trimmers are ran on their side there is no oiling occuring. Most that I worked on that oil dripping out the air filter box are trashed piston and cylinder wise. It is the reason Ryobi only offers a short block for these engines. BTW even to replace the timing belt requires you disassemble the crankshaft. It is the reason I will not even take these 4 cycler in for repairs. The only two OEMs that I have repaired that work well sideways are the Stihl 4 mix and the Shindaiwa 4 cycler trimmers.

So when using a trimmer, is it better not to tilt it sideways? How is the crankshaft disassembled?

Right they are designed for upright operation only.

It takes a hydraulic press and it not a job for a non experienced tech. This is because the crankshaft maybe splined assemble one that must correctly re-align exactly as was prior to disassembly. If had D shaped setup than it is a lot easier. It is not recommended for anyone to do this.

Personally I don't try repair this crappy four cycle handhelds. The first and only two I ever disassemble because of struck rings only lasted four hours after I got repaired before it failed again. The manufacture does not provide parts to anything inside the short block. They simply do not want anyone repairing these units.

[Stoner]

Can you show us an example of a hydraulic press?

[KE4AVB]

Can you show us an example of a hydraulic press?

Well it is much easier for you to just to Google "hydraulic press" and then you need to learn to use it and which arbors that would work pressing the parts apart. You already use a version of hydraulic press every time you stop your vehicle. These presses produces from hundreds of pounds of pressure to many tons to separate items apart or to press items together. I just over the weekend pressed apart a shaft assembly for my machinist that is modifying a metal lathe. Finally getting to pay him back for all the custom tools he has made for me.

I even have a hydraulic crimper here to can produce so pressure that the stranded copper wire are fused into a solid mass; although, I try not to go to that level of crimping..

[Skywatcher]

Hi Stoner

It sounds to me like you are just getting started in trying to repair machines like this. Unless you want to use this unit as a learning experience just to see how it comes to pieces and if you can get it back together again, I think you'd be much further ahead to simply buy a replacement trimmer for next year. If you were wanting to get this unit going again, a complete short block (P/N 309962012) is available through Partstree.com for under $60.00 which is not much more than an hour's shop rate for most small engine repair shops in the US. Shop rates tend to be higher up here in Canada as the dollar is worth less and parts are more expensive.

The manual for this unit says to use SAE-20w50 engine oil and oil level should be checked with engine sitting perfectly level, that is with crankshaft horizontal and cylinder vertical. The other thing you'll find with these small 4-cycle engines is the smaller the engine, the more fussy they are about fuel quality. I have taken to using 100 octane aviation gasoline in any engine under 50cc unless it has a catalytic converter, then I use the Aspen-4 93 octane fuel. Aspen is more expensive than aviation gasoline but won't wreck a catalytic converter. As I tell my customers, the cheapest fuel is seldom the most economical fuel. All the best,

Sky

[KE4AVB]

Sky that what I was getting at. I got forty years of experience of taken apart just to see how they work. And the last 11+ yrs of that has working on handhelds. When I first started things were a lot easier to get apart and then MTD and Ryobi started coming with these setups where the only way to the timing belt off or piston out was to disassemble the half crank shaft assembly. While it you risk damaging the oil seals and bearings. And most shops are like mine just the labor time far exceeds the cost of the replacement trimmer. Even charging just for the parts and one hour of labor cost nearly as much as new trimmer. That heck of a lost of time when it takes several hours to do this that I can be working on a much profitable mower repair.

The only handheld I even repair now is the commercial ones.

[Stoner]

Does the plug need to be screwed in to check the oil level?

[KE4AVB]

Does the plug need to be screwed in to check the oil level?

Ever thought about downloading the owners manual and reading it. I posted a link to them in the very first reply.

<These the instructions extracted from the owners manual>

To check engine lubricant level:
 Set unit on a flat surface.
 Wipe dipstick clean and re-seat in hole; do not rethread. (to clarify "Do not screw it in")
 Remove dipstick again and check lubricant level. Lubricant level should fall within the hatched area on the dipstick.
 If level is low, add engine lubricant until the fluid level rises to the upper portion of the hatched area on the dipstick.
 Replace and secure the oil cap/dipstick.