Help with Valve Adjustment on PT425

[SRB331]

Happy Holidays Everyone!
I'm looking for some guidance on how to rotate the crankshaft to tdc so I can adjust the valves. The manual tells me where to align the marks but on the 425 it seems you would have to lift the engine out to access the fly wheel. Any assistance is appreciated. Thanks in advance.

 

[MossRoad]

What engine do you have?

 

[SRB331]

It's a Robin EH72 with carb.

 

[MinnesotaEric]

Giant strap wrench on the harmonic balancer.

If you have an access plate, you can pop it off and rotate the engine with a flywheel turning tool as well. A shade tree could use a pry bar as well.

My flywheel turning tool says Mac Tools on it, meaning I overpaid for it by about a million dollars, but they all look and work the same.

Amazon.com: Powerbuilt 648455 Flywheel Turning Tool: Home Improvement

Amazon.com: OTC 7206 Multi-Purpose Strap Wrench: Home Improvement

 

[MossRoad]

I'd try pulling the spark plugs, then bump the starter.

 

[SRB331]

Thanks guys. I have no access point on the engine, not to mention the tub makes it pretty hard to get any kind of jacking tool in place. I'm going to go with bumping the starter. One of the members pointed out that if one valve is in the down position (open) the other will be clear of the cam and can then be adjusted. I'll just work my way through the valves.

Thanks for your help everyone!

 

[marrt]

See page 38 of the service manual on the Robin Subaru site. You have to line up the flywheel with a mark on the cylinder. This needs to be done accurately or you're wasting your time (and likely creating a worse problem). I don't look forward to this procedure and will probably pull the engine in order to conveniently access everything.

 

[MossRoad]

You can also use a drinking straw in the spark plug hole and rotate the crankshaft back and forth until you can tell where top dead center is. Just do that by hand, not with the starter.

I guess the issues with this setup is how to spin the crankshaft, since its hard to get to. Can't you see any part of the crankshaft, pump couplings, etc... that you can grab with a wrench and turn?

 

[Gravy]

I've done literally thousands of valve adjustments on a wide variety of engines, and about six on my EH72 before the engine swap. None of the conventional advice and methods apply to the EH72 in a PT. There is no practical way to turn it over by hand or to see any timing marks without removing the engine.

Fortunately, and contrary to popular opinion, you don't actually need to be very precise about being at TDC. The camshaft profile is extremely forgiving. The base circle is evidently close to 180 degrees of camshaft rotation. Just get the piston fairly close to the top of it's travel and it'll be OK.

Pull the plugs, use soda straws to determine approximate TDC, and bump it over with the starter. It will take patience because the starter doesn't like to bump in small increments, but keep at it. If you have to turn the adjustment screw more than a tiny bit to get clearance, you're probably not on the firing stroke. Bump some more and try again.

 

[SwampmanLA]

I know this is all wrong but it worked for me. I just bumped the starter till the valves were seated, slack in the lifters, and tightened the arm down till it was about to touch the valve. Worked great for me and my Robin is singing.

 

[ponytug]

I like SwampmanLA's practical suggestion.
I don't have a 425, so this may be totally off base, but...
I'm sure that I am missing something about the hydraulic setup, but couldn't you use the hydraulic pump to turn the engine? Hook up an attachment and turn it to pump PTO oil? Or lift a side of wheels, and turn one with the treadle down?
Educate me in the ways of the 425, and why this would never work... :mur:

Just for the record, I haven't tried this with my 1445, either, but the 1445 has access to the crankshaft.

All the best,

Peter

 

[MossRoad]

I like SwampmanLA's practical suggestion.
I don't have a 425, so this may be totally off base, but...
I'm sure that I am missing something about the hydraulic setup, but couldn't you use the hydraulic pump to turn the engine? Hook up an attachment and turn it to pump PTO oil? Or lift a side of wheels, and turn one with the treadle down?
Educate me in the ways of the 425, and why this would never work... :mur:

Just for the record, I haven't tried this with my 1445, either, but the 1445 has access to the crankshaft.

All the best,

Peter

Nope.

The tram pump will bypass before it will turn the engine over if you try to spin a wheel.

The main PTO just returns oil to the tank. You can't push the engine over, you'd have to suck the engine over, and, again, it won't work.

Believe me, I've thought about that many a time, too. :laughing:

 

[MossRoad]

Man, I just went and looked at several pictures of people's engine compartments... there just isn't any way to physically turn it from the pump side. What about the back side where the cooling fan is?

Or, just do the remove the plugs and bump the starter trick.

On my 2001 model with the kohler, there's a gap between the VVP and the engine. The VVP is mounted to the fan side of the engine as shown in this picture...

The PTO pumps are mounted to the "normal" output shaft behind the engine as shown in this picture...



I believe almost all of the units made since 2003 or so have all three pumps mounted to the output shaft side of the engine, with the VVP first, then the PTO pumps piggybacked onto the VVP. So there is NO gap on that mount from the output shaft to the VVP.

Take a look at the fan side and see if you can see anything in there. If the fan is plastic or flimsy, don't bother as you may damage it. But it you can stick a bar in there, with the plugs out, you may be able to spin it easily with a flat bladed screwdriver from the rear of the tractor.

 

[Kent]

A side benefit of splitting the shroud across the top of the engine flywheel fan is having access to the flywheel for turning/pushing.

I followed KMA's lead on my engine (http://www.tractorbynet.com/forums/p...ml#post3740605) and have taped mine back together with Gorilla Tape (I think a flexible "H" strip holding the edges together would be ideal, but couldn't track one down).

Interesting that Kohler sells an access panel kit, "Allows for cleaning debris from behind blower housing and also servicing of ignition modules. Kit includes instructions/template for cutting holes in blower housing, plus panels (one with pop-out plug and label for keyswitch), mounting clips and screws."

25 755 21-S - Genuine Kohler Access Panel Kit

But no equivalent for Subaru engine.