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Trying to repower a 20G

10K views 47 replies 8 participants last post by  TexasT 
#1 ·
Hello all,

I have a 20G purchased new in 2000 with an Robin Subaru EH64 power plant. I dropped a cylinder last fall and recently ordered a replacement engine. There was some confusion in ordering over the phone. They kept asking me the diameter and length of the shaft. After some back about seal location we finally agreed on an 1 1/8" diameter and 4" length. When I received the engine I opened the box and new right away it wasn't going to work. It was an 1 1/8" all the way to the block. My old engine's crank shaft bumps up to about 1 3/8" before it goes in the block. When I called BrandNewEngines they said they had never seen a crank shaft like that. At that point I felt I was in a corner. They said Robin Subaru's are no longer available and that they had some in stock but none with that type of crankshaft. They also recommended machine work to make the new engine work. I just don't know where to turn next. Any thoughts??

k
 
#2 ·
I believe you are overthinking this.

Use the new engine. When you put the adapter plate on, it will work just fine. Just use some oil resistant form-a-gasket between the adapter plate and the block. I have done that with 3 engines so far. No issues.
 
#3 ·
Maybe post pictures of each. I have an EH64 on mine, which basically the same engine.

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#4 ·
EH65 sorry. Stupid autocorrect.

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#14 ·
Yes, you have the same problem I am referring to, no way to seal the adapter because of the mounting boss design of the engine. no continuous ring to seal the engine to the adapter. So without the correct crank configuration, the shaft seal in the adapter will not work.

But the crank shaft length is not a problem. As long as you have reasonable engagement of the crank and the gear, the crank need, and should not extend out to the snap ring in the gear, as mentioned before there needs to be space there to allow the gear to truly ride on the thrust bearings, not on the end of the crank.

Sheldon
 
#18 ·
I'd probably locate a good used M20, have it rebuilt if you feel it needs it, and put it on a shelf until needed. But you are probably 600 hours away from any problems with the M18, given good maintenence.

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#20 ·
Are we talking damaged cooling fin (ie, head) or flywheel?

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#19 ·
Unfortunately, it seems you didn't search the forum for threads on Robin repowers.

I've included a link to the post with the Gravely/Robin-Subaru part # for the Gravely spec'd engine.
http://www.mytractorforum.com/8617857-post7.html

I had a Kohler KT17 Series II and was able to come up with the Robin adapter plate through another one of our members. I was able to get most of the other parts I needed from Gravely. I've got plenty of pics in the thread -- hopefully that will help. All I can say is -- with the Robin adapter plate (which you have) and the right engine, everything bolts right up as it should with no fooling around. I've got quite a few details in this thread that might help you out.
 
#23 ·
Yes, unfortunately I didn't find this site until after I had purchased the replacement Robin/Subaru and found my problem. It's looking more like I'm going to have to remove the crank shaft from the old engine (and hope that it's not damaged) and swap it into the new Robin/Subaru.

k
 
#24 ·
#25 ·
Certain parts for the Magnums are very expensive. Price out replacement pistons or cranskshafts.
 
#26 ·
I see that your new crankshaft has a step in it for a larger seal. You have to run a deal on the Robin Subaru because the engine mounting surface is just raised mounting bosses and no way to seal that with a gasket or sealant. I would find a seal that fits the crankshaft and have the adapter plate machined/bored out to fit the new seal. Also the length of the new crankshaft will need to be short enough to allow the input gear room for the snap ring. The snapring is not needed with a half moon key but is required for a square key to keep the key from sliding out the end of the gear and falling into the trans.

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#28 ·
Update: Another dead end! No real good way to seal the key slot on the crankshaft as it goes the full length of the crankshaft outside the block. Without a proper seal, the transmission oil will have a direct path out.

I called a local small engine shop and he says "what you have is something you can't get a replacement engine for. You'll have to machine something".

I sent the Robin Subaru back and I'm now looking for other alternatives.

k
 
#33 ·
There is really no nice way to say this -- my post on page 2 to my thread gave all the information you needed to get the right replacement engine:
I did some more digging on my own re the Robin-Subaru engine that was on the 20G for the last 4 years of its production.

The part # Gravely lists is 08256000 -- and digging further, this is Robin-Subaru engine EH650DB7510. I have found the EH65 on several websites for sale but have not dug any further as to the difference in model/specs.

It also appears, from what I can tell, that the Gravely designed muffler for the Robin-Subaru engine (Gravely part #04901500) is still available (although at a healthy cost of $262).

I know for a fact that Subaru Industrial Power, located in Lake Zurich, IL has at least 3 engines with the Gravely spec in stock. I actually called them, they referred me to a dealer who sold me the Gravely-spec engine. I picked it up since they are about 20 min away from me.

It's frustrating to read your post and realize you must not have dug any further. You can buy a drop-in replacement Robin-Subaru engine made for the Gravely -- that will bolt up to what you currently have. Why in the world would you be confused if you are looking for a drop-in replacement?

Now, if you want to do a re-power with something else (an Onan, a Kohler, a Honda) you certainly can. But you will have to collect a bunch of parts or figure out a way to get things machined to fit. You have one of the best solutions right in front of you since that Gravely-spec engine is still available. With a 5 yr warranty no less!

Seems as if you're making things really difficult for yourself.
I had to come up with a bunch of parts to make things work on my conversion from an old Kohler twin to the Robin-Subaru (from engine adapter, muffler, wiring, throttle and choke cables, etc). In your case, the Gravely-spec engine will bolt right up and I would guess had I had your situation, could have been up-and-running in a few hours.
 
#29 · (Edited)
In your case, since you have the Robins adapter, I would be looking for other vendors who might have the correct crankshaft version Robins engine to fit a GRAVELY - they do exist.

A Kohler or Briggs Vangard will work if you can find a Vangard adapter plate or are willing to have one custom made. But you "average" GRAVELY adapter was designed for engines with a large diameter mounting surface "ring" and they will not work with any of these modern engines.

Most of the GRAVELY tractors that came with Kohler Magnum twins had a special version of the engine where the adapter is a custom part KOHLER made. It is the rear closure plate of the engine and the GRAVELY adapter all in one piece - of no use on other engines.

Sheldon
 
#30 ·
I believe those P220 engines are starting to look pretty good right about now.
 
#31 ·
If the larger seal was back on the smooth stepped up portion of the crankshaft it should be sealed. But even if the seal had to ride on the keyway you can use a seal saver sleeve to cover the keyway.

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#32 ·
There are many ways to take care of the keyway slot. Speedy-Sleeve with JB weld is one.
 
#35 ·
If you want to PM me, I can dig up the contact info for you at Subaru Industrial Power. I guarantee that guy didn't know what he was talking about. They found the part number in their system and have a few Gravely spec'd engines IN STOCK. If you haven't moved down this path yet by carving up your Robin adapter, it would be worth a phone call to the RIGHT person at Subaru.

Direct drop-in replacement.
Honestly, don't know what kind of bad info people will supply these days.
Other than a few specific Gravely modifications that Subaru built into the spec'd engine, these are stock units.
Parts are NOT hard to come by -- and there is also a specific parts list (most are the same as bone stock EH64-EH65) for the spec'd engine.

Offer is open. I can't believe you'd want to go down the path of redoing a bunch of stuff and not drop in the right engine!
 
#36 ·
And if you do decide to switch to s different engine. They are a free people that would be interested in your old Robin Subaru and adapter plate. I for one would be interested.

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#37 ·
This thread prompted me to pull my blower housing on the EH65 to inspect flywheel cooling fins and do some general cleaning. Turns out I had an old mouse nest near the left cylinder head that dated to the previous owner. I am in the market for a new blower housing, as mine was cracked and patched by the PO.

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#38 ·
A new blower housing is $75-85 might find one on eBay for half that.

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#44 ·
That is a good question that no one seems to know the answer to.

The Briggs adapters are rare, just as rare as Robins adapters. Small Engine Warehouse sells a Briggs engine with an adapter that they custom made. They do not sell it separately. GRAVELY has no more of the the Briggs adapter they made in the late 90's.

No one seem to know if any of these will work with the newer Kohler Command Pro engines - I might have bought one by now if I could figure out for sure the adapter question.

Bruce G has the Honda solution, I would have to pull up an old thread to remember the details, but I'm not interested in a Honda.

The issue with all of them is sealing the transmission at the crankshaft, or, sealing the back of the engine to the adapter so that the trans is sealed that way.

Sheldon
 
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