# jd 790 diesel fluid in oil



## Michael Ritzel (Aug 5, 2020)

Have a jd 790. was working doing little things around farm. tractor stopped running. had fuel in tank. Bought a fuel pump fuel Aasy. I had not checked when tractor stopped. bought the Assy and replaced the one that was on there. Had a friend say it was the fuel not getting through the pump assy. Now have diesel fluid in the oil. Has anyone rebuilt a pump Assy. A guy that works on John Deere tractors says it is the seal on the pump.. Need some help and information if possible. The picture is of one just like mine.


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## jd110 (Nov 23, 2015)

Are you saying that the tractor quit running, then you replaced the injection pump, and now you have fuel in the oil? Is tractor now running? Was it a new pump? If it was new and it is leaking, then I would return it and get another one. If it was used, thenI would try replacing the fuel transfer pump that is bolted to the side of the injection pump. There is a rubber diaphragm inside that can rupture and leak fuel into the crankcase. If it is a bad driveshaft seal, I am not familiar with how hard it is to replace that. The seal is not supplied from Deere, you would need to get it from a fuel injection service facility. The transfer pump is #25 in the diagram


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## Michael Ritzel (Aug 5, 2020)

The tractor had been running ok for a couple of years, One day it just stopped running. the tractor is not running now. The pump was a used pump from on line. I will check to see if it is the transfer pump. Have the one off the old injection pump.


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## thepumpguysc (Jan 25, 2015)

U can CHECK the supply pump by removing it & blocking the "outlet" & applying air to the inlet & dunk it.. look for bubbles..


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## Michael Ritzel (Aug 5, 2020)

thepumpguysc said:


> U can CHECK the supply pump by removing it & blocking the "outlet" & applying air to the inlet & dunk it.. look for bubbles..


put the other fuel pump on, don't seem like there is not going into the oil but tractor still does not run. tractor runs using a gas rag over the air intake. Even with it running with gas rag there is pressure going up to the injection pump { but nothing going up into the injection pump,


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## Michael Ritzel (Aug 5, 2020)

Hope you can understand what I am saying, fluid is pumping from fuel pump to injection pump


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## bmaverick (Feb 20, 2014)

Your JD790 is really a Yanmar painted JD green.  

With that said, there should be plenty of info for the diesel fuel pumps here in the manual section here on the forums.


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## thepumpguysc (Jan 25, 2015)

U can remove the side cover & put your fingers on the control rack & try to move it left & right..BUT & it’s a BIG BUT.. u have to use a hand impact driver & hammer w the proper Phillips bit.. Those tiny screws are in there EXTREMELY TIGHT.!! U WILL strip them if u don’t use a hammer n impact..


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## Michael Ritzel (Aug 5, 2020)

bmaverick said:


> Your JD790 is really a Yanmar painted JD green.
> 
> With that said, there should be plenty of info for the diesel fuel pumps here in the manual section here on the forums.


Yanmar was bought out by John Deere some years ago, had 2 Yanmars over the last few years. Have manual, fluid up to the injection pump and it stops. Loosen nut on line coming from filter and it is pumping diesel out at line.


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## thepumpguysc (Jan 25, 2015)

Have u been reading my replies.??


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## Michael Ritzel (Aug 5, 2020)

thepumpguysc said:


> U can CHECK the supply pump by removing it & blocking the "outlet" & applying air to the inlet & dunk it.. look for bubbles..


Yes I have, the problem I have is not getting fuel pumping from the pump {loosen it up and fluid sperts out when turning it over. But nothing is getting into injection pump


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## Michael Ritzel (Aug 5, 2020)

bmaverick said:


> Your JD790 is really a Yanmar painted JD green.
> 
> With that said, there should be plenty of info for the diesel fuel pumps here in the manual section here on the forums.


I had looked it up and it was made john deere with a yanmar engine made in Japan in 2000 and I think 2005


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## Michael Ritzel (Aug 5, 2020)

Found out that the pump I bought was seized up on the inside. The guy has a shop and repairs all kinds of hydrolics. Thank ever one everyone for ther input


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## bmaverick (Feb 20, 2014)

Michael Ritzel said:


> I had looked it up and it was made john deere with a yanmar engine made in Japan in 2000 and I think 2005


Per the database, It's 100% Yanmar made with green paint made in Japan.
http://www.tractordata.com/farm-tractors/001/2/2/1227-john-deere-790.html 

John Deere is only listed as a distributor. 

Here's a photo of the Yanmar owned facility.


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## 7mmtcu (Sep 18, 2019)

John Deere does not own Yanmar.


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## DairyAyre83 (Oct 13, 2017)

They try there best by deceptive marketing. But the castings and everything are Yanmar. They just put the wheels on here and call it American made. There hasn’t been an American made tractor under 60 hp since the 1960’s.


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## bmaverick (Feb 20, 2014)

DairyAyre83 said:


> They try there best by deceptive marketing. But the castings and everything are Yanmar. They just put the wheels on here and call it American made. There hasn’t been an American made tractor under 60 hp since the 1960’s.


Actually, today, Yanmar is located in Adairville-GA and John Deere has an 'assembly' plant in Augusta-GA. guess what. Yanmar makes much of the tractor just north of Augusta and ships the rest to the JD assembly plant. 

You are very right, JD adds the wheels, the English stickers, the JD electronics, the JD weights, and a few other small items. Then off it goes by flatbed or rail across the country. 

Now, with that said, Yanmar first opened the Adairville plant as a joint venture with MTD to make Compact tractors for Cub Cadet. But, it seems, MTD had ran into a small money crunch and Yanmar acquired the entire facility. This was around 2011. Now, Yanmar makes all kinds of stuff for other tractor makers or rebrands with their name on it. 

The real question isn't if it's a John Deere or Yanmar, but how reliable and bullet proof the machine is. And for the most part, both of these brands are just that. 

I was a former JD850 owner. Then a chump of a bad diesel mechanic messed up the engine. Bent the governor shaft and swapped injector lines of 2 & 3. Well after a few hours, yes the engine blew. Could not for the life of me find another available engine till I discovered Fredricks with ample amount of these engines. But, to swap engines was a mere few hundred less than a totally restored YM2500 or YM2610. The JD850 3T80 by Yanmar was in all of these tractors. I opted for the legal gray market tractor by Fredricks. It's the ONLY Yanmar approved gray market importer in all of North America thru the UTDA.


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