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D640 (G6200H) Rebuild Kit?


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#1 blacksmith1 OFFLINE  

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Posted November 27, 2013 - 11:48 AM

As I mentioned in: http://gardentractor...t-cut/?p=385772

 

I'm looking at a possible purchase of a DOA three cylinder Kubota that has come for sale and am interested in seeing if there is a difference in the deck's noise level. If I get it (and get it running) I will report.  I'd considered swapping the decks but read somewhere that the RC40 deck is almost too large for the two cylinder. I suspect the three cylinder has the RC44 or 48. 

 

 

 

I picked up the G6200 ($400/1000 hours) and while the 48" deck is in very good shape, the rest of the system looks its age; the hood has seen it share of bumps and bruises as this is typically the first casualty on a Kubota Mower. Hydro fan is mostly unscathed. Dog got the seat, seat pan has some holes. I power washed off 30 years of frame and component goo. 

 

The motor has less than 200lbs compression on any cylinder. Fuel flows, plugs glow, starter cranks - doesn't start. 

 

When I tear it down (my first motor rebuild ever!) I will asses what it needs and then order the parts individually. A kit would be cheaper but I can't seem to find a D640 kit. I've found "rebuild kits" for D600's to be plentiful but haven't found a one for a D640.  Still looking. 


Edited by blacksmith1, November 28, 2013 - 12:27 PM.

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#2 Cvans ONLINE  

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Posted November 27, 2013 - 12:02 PM

The first thing to do after you pull the head is to flip it over and check and see if the valves are closing all the way or if there is carbon under the valves. If you pour a little diesel fuel onto the valves it should set there for awhile and not just run away. The engine I just worked on had no compression and carbon was the problem. Starts and runs great now. 

Good luck.

 

http://www.joseph.co...ubota_flyer.pdf

First thing I ran into doing a search. D640 is listed. 


Edited by Cvans, November 27, 2013 - 12:09 PM.


#3 boyscout862 ONLINE  

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Posted November 27, 2013 - 12:34 PM

Take your time! Do not make this your first engine rebuild. Find an engine to practice on. You should be able to pick up a dead lawn mower for free. Try rebuilding or atleast over hauling one of these first. You should be able to pick up a useable ridge reamer, hone, piston grove cleaner, ring compression tool, and a valve lapper for under $50 for all. The old B&S Repairman Manual(in our Manuals Section) is excellant.

 

Before tearing that engine down, I would try starting it again after cleanning the fuel system. If you can get it running, put Marvel Mystery Oil in the fuel and run it a bunch. Marvel will clean the cylinder and free up valves. You might not need to do an overhaul. Good Luck, Rick



#4 Cvans ONLINE  

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Posted November 27, 2013 - 07:21 PM

A little more on Marvel. On the engine I mentioned I pulled the injectors and  put some Marvel in each cylinder and turned it over a few times. Later when when I pulled the head I was able to wipe (not scrape) the carbon off the piston head and upper cylinder. Most of the carbon came off the head the same way. This is the first time I've tried this and if I hadn't seen the results myself I wouldn't have believed it. Needless to say there is Marvel in the fuel and the engine is running better all the time.  :D


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#5 blacksmith1 OFFLINE  

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Posted November 27, 2013 - 09:50 PM

http://www.joseph.co...ubota_flyer.pdf
First thing I ran into doing a search. D640 is listed.

I saw that as well. The date on it is 6/2010 and it has no prices. Ii will give them a call though.

#6 blacksmith1 OFFLINE  

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Posted November 27, 2013 - 10:13 PM

Take your time! Do not make this your first engine rebuild. Find an engine to practice on. You should be able to pick up a dead lawn mower for free. Try rebuilding or atleast over hauling one of these first. You should be able to pick up a useable ridge reamer, hone, piston grove cleaner, ring compression tool, and a valve lapper for under $50 for all. The old B&S Repairman Manual(in our Manuals Section) is excellant.
 
Before tearing that engine down, I would try starting it again after cleanning the fuel system. If you can get it running, put Marvel Mystery Oil in the fuel and run it a bunch. Marvel will clean the cylinder and free up valves. You might not need to do an overhaul. Good Luck, Rick

Boyscout, good advice. I have machinist training/skills, just never had an engine I wanted to fix. I believe any fix on this beast will require it to come part.

I think a replacement D640 would cost $1500 to $2500. If I can find a price on a rebuild kit I'll have a framework from which to decide on tearing it down or replacing it. From what I have observed, the exhaustively complete kits can be as much as a remanufactured engine.

With just 1000 hours it should be something simple, but I have no idea how the previous owner treated the machine or if there has been any tampering with the hour meter.


Edited by blacksmith1, November 28, 2013 - 12:28 PM.


#7 blacksmith1 OFFLINE  

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Posted November 27, 2013 - 10:16 PM

Before tearing that engine down, I would try starting it again after cleanning the fuel system. If you can get it running, put Marvel Mystery Oil in the fuel and run it a bunch. Marvel will clean the cylinder and free up valves. You might not need to do an overhaul. Good Luck, Rick


Will a engine with 200lbs compression start?

#8 Cvans ONLINE  

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Posted November 28, 2013 - 01:13 AM

 

 

Will a engine with 200lbs compression start? 

 As I recall the compression on the Z430 is supposed to be 435 Lbs. One site says 285 to 350lbs. for minimus on a direct injection diesel.  Compression ratios run 16.4 to 18.6 and in excess of 22 to 1. 

Probably more information than you wanted but there it is. 

Are you sure that your compression tester is accurate and the fittings sealed correctly? A very small leak makes a very big difference. 


Edited by Cvans, November 28, 2013 - 01:14 AM.


#9 boyscout862 ONLINE  

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Posted November 28, 2013 - 07:09 AM

Will a engine with 200lbs compression start?

It may with diesel, but a tiny bit of starting fluid should get it to start. The Marvel can then work wonders. Good Luck, Rick 


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#10 blacksmith1 OFFLINE  

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Posted November 28, 2013 - 12:23 PM

Are you sure that your compression tester is accurate and the fittings sealed correctly? A very small leak makes a very big difference. 

 

I bought the Harborfreight kit, it specifically calls out "Kubota". The kit is supposed to work with the injector port, but does not fit, or at least I couldn't find an included adapter that fit the injector port; they look close but the vernier tells a different story. The glow plug adapter is a poor fit as the threads match up but the device bottoms out quickly. You can't cut it down because of the Schroeder valve inside. I wrapped it in a bit of teflon and made the test.  I looked on line for an adapter but they look exactly like the Harborfreight one. I've asked a Kubota parts dealer if they have the right one... still waiting. 



#11 blacksmith1 OFFLINE  

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Posted November 28, 2013 - 12:24 PM

It may with diesel, but a tiny bit of starting fluid should get it to start. The Marvel can then work wonders. Good Luck, Rick 

 

I've never tried Starter fluid, I'd always heard it was a hard on diesels. 



#12 Cvans ONLINE  

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Posted November 29, 2013 - 01:08 AM

Starting fluid is not good but if used sparingly you might get by. I have actually had a diesel engine stall the starter when giving it a whiff of the stuff.  If the engine kicks back at all quit using it. 



#13 boyscout862 ONLINE  

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Posted November 29, 2013 - 07:29 AM

When trying to do a compression test, after a low reading you should ad a teaspoonful of oil into the cylinder. The oil will "seal" the rings for a few turns. If the compression comes up, the rings are the problem. If the compression doesn't come up, the valves are most likely the problem. I use Marvel Mystery Oil when testing the rings.

 

I use just a small puff of staring fluid through the air cleanner housing in the winter. My old desiels will not start below 50* without it. My 55 AC HD6G even came with a built in starting fluid injector system. You should look at the injector timing while doing the compression testing. You probably don't need to tear that engine down. Take the time to figure it out first. Good Luck, Rick



#14 blacksmith1 OFFLINE  

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Posted December 02, 2013 - 01:09 PM

When trying to do a compression test, after a low reading you should ad a teaspoonful of oil into the cylinder. The oil will "seal" the rings for a few turns. If the compression comes up, the rings are the problem. If the compression doesn't come up, the valves are most likely the problem. I use Marvel Mystery Oil when testing the rings.

 

I didn't have quality time to do a proper test but I filled the cylinders up to the brim with Marvel. I assumed it would either disappear down the rabbit hole in a flash or dribble out over an hour or two. Either way it might actually touch something and do some good. 

 

Interestingly, though Marvel is not terribly thick/viscous, after 24 hours two cylinders were down about a quarter of an inch and the third was down about half an inch. 

 

Figuring it was surface tension holding it in the glow plug chamber I stuck a wire in each glow plug hole to break the fluid bubble and watch it disappear. Nope, it was really there. Still in disbelief, I determined to suck the fluid  (turning it over with full cylinders would have Marvel on the ceiling and everything else) out of the hole with a small manual pump. The Marvel was there, and in quantity.

 

I can only assume the valves are universally built up with Carbon or the timing is wrong. 



#15 Cvans ONLINE  

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Posted December 02, 2013 - 10:47 PM

This is interesting. I hope you will continue to post as you go along.

Although I don't recommend this, when I had mine apart it was reassembled with the old head gasket as I was just trying to find out if the engine was worth sticking any money into. I torqued the head to 5 ft. lbs.over specs. and the engine runs fine so it can be done. 






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