Whats a D640 Diesel from a 1782D worth?

[otep858]

ok I have a question that i would like to pick every ones brain on. What would a running Kubota 640 diesel from a 1782 (1994 model) with the reduction drive stater and glow plug upgrade already done. Complete with wire harness, radiator and everything needed to put it in any Super or regular garden tractor. What would it be worth. Also its had the head rebuilt on it with a valve job done last summer. Ok Go.

[dag1450]

What do u want it to b worth....r u buying or selling? Idk $1000. Very hard to say...the value is how many people want it. That's a tough one. Good luck

[otep858]

I have a 1782D that ive had for 5ish years. and i switched it over to a Kohler gas from a donor 1683. And im trying to figure out if i want to hold onto the D640 or sell it off. I was tired of the starting problems when its anything less then 60 degrees out.

[dag1450]

Wow...first time I heard that one....from diesel to gas. Yea if u don't need it sell it and let someone else enjoy the smoke and starter. Lol. U have really devalued your tractor as maybe u should have sold and bought a gas.....but if u like it and plan to keep for a while no harm. I said $1 k.....what do u think?

[otep858]

OK maybe i should elaborate some more here. its almost mowing season. and the diesel will run but it is a pain to get started and cant even get it started when its under 60 degrees. even with the glow plug upgrade. compression is between 200 to 230 on each cyl. cranking pressure. allowable limit shows 337 but normal is around 440 (i think without looking at the book) 700 hours on the machine. 2 years ago i thought that it might have been cracks in the head so i had the head rebuilt and a valve job done, so 200 bucks right there. There was some small cracks that got fixed.. But it didn't help, and it has blow by horrible bad. I'm trying to decide if its better to sell the diesel or if its worth the cost of a rebuild. love having a good running diesel. i can mow 3 times as long on a tank of fuel then with a gas motor. since its value is higher then i thought it would be then i will probably try and get it rebuilt instead of selling it off. Since a rebuild for these is expensive. If i do that i would put it back in the tractor. because i really would much rather have the diesel. but until its rebuilt im going to run the gas. Make a little more since now?

[dag1450]

That stinks! U should get four times those hours before needing to tear it down. I don't have any experience w those engines to say possible other problems. I'm not sure if we have many diesel guys here....but maybe start a new topic on this. U might see some replies. I can't believe u would need to rebuild at 700 hrs from wear...i could see something that broke ....but not wear!

[otep858]

I'm not sure is the PO ran it low on oil or over heated it or what. But it's been that way since I bought it. When I tore the head off to have it rebuilt the cyl looked like they were in good shape. Thought about just reringing it. But even rings are 95 per cyl.. The hour meter has worked as long as I've had it but maybe the PO had it unplugged for a long time
The shape of the rest of the tractor is consistent with many more hours then it shows as well. It wasn't taken care of real well. And there are a couple more problems with it that are driving me crazy on it as well. Like free wheeling and having hardly no power in reverse. Thinking about rebuilding the hydro because all the other usual fixes didn't help it Even shimming the damper and cam plates. Love the diesel and the super but it's been a real drain on the bank

[dag1450]

Paul u bring up a good point.... Hour meters r for honest people.

[drcjv]

I would not sell unless I gave full disclosure. With all the problems not worth much in my opinion. If it were me I would part it out. You would make more than selling whole. Some parts hard to find and valuable like the hood and fuel tank. Once all is sold go buy a nice diesel to replace it. They can be found.

[Tom Scott]

Paul - My thoughts...

Based on your knowledge of the low compression, that is obviously the reason for the poor starting. As Charles says, you need to be honest if you are going to sell it, so it isn't worth much cash. To an outsider, it is pretty much just a core to rebuild.

Based on your desire to having the tractor back as a diesel, I would consider checking the engine over. It might just need rings and a hone. You didn't say how it ran, but perhaps you got the timing a link off when working on it, that could potentially make for real low compression. Since it was this way before you tore it down, I doubt that's the problem. More likely to have overheated and cooked the rings.

As far as the hydro, you might just have the release valves leaking internally. If you swap the valves with a known good one (one at a time so you only have to buy one) that would tell you if it is internal to the hydro. Poor reverse performance in a Cyclops can also be that the early machines didn't have the control cam (703-0198A) drilled in the right place to provide enough reverse throw. The replacement number is drilled with overlapping holes, one for the 82 series, and one for the Cyclops that need more linkage throw. Finally, the trunion spring is a bit soft for these Supers with steep hills and heavy attachments. I have seen mention of using the "Help" brand of automotive parts, they have a spring that I believe was for exhaust mounting that is said to fit, Help #03107 is what I have written down.

Worst case scenario, if you need a new hydro, used ones in good shape go for around $300.

Is it worth it? Only you can answer that, but if you have serious mowing or tractor work to do, then a good replacement machine isn't cheap either. You may be able to repair this for much less money than a replacement machine, which will have its own problems if it is used. I would probably at least start by digging into the repair of the engine. The head work is already done, so at least find out what you have wrong. Even if you have to bore and hone for new pistons it might be cheaper and easier than divesting what you have and finding a replacement.

[dag1450]

Lots of good info Tom. First thing to do is probably build a run stand so u can work on and diagnos problems. I read somewhere after a low compression test u could pour some oil in the cylinders and see what the test is after that. If it goes up than its rings....no change than valves or timing. But to do this u will need a run stand. I would love to help cause that sounds like fun. I remember back in high school auto shop we had about four engines lined up on stands. Man...can u say hours of teenage fun!

[Tom Scott]

dag - That can be a clue with the oil, but building a stand can be a pain. Just need a leak-down tester. Don't need to run it. Leak-down test will tell you where it's all going.

[dag1450]

Look Mr Parts washer.....he needs a stand. Think how fun that wood b to have the diesel running in the shop on a stand. All the men could gather around and watch.....

[Tom Scott]

Listen Mr. All Talk, no-do, maybe you should spend a little time bolting that Magnum back together before you go expanding someone else's project!

[otep858]

Drcjv, I wasnt wanting to know the value to doop someone. i was trying to figure out if its worth rebuilding the diesel and put back in my tractor or selling it (just the diesel). The rest of the tractor im holding onto. not sure if i was going to rebuild the diesel or part the motor or sell as a whole off.

[otep858]

Tom Scott, Like i said wasn't looking for the value to try and pull one over on someone. Only to see it it was worth dumping money into. I'm hoping it only needs rings. and in the tear-down (as in having the head rebuilt) there was nothing that would have changed the timing at all. As far as the hydro Ive swapped the relief valves even with ones from another hydro that i picked up off a 1541. i would buy the not enough of a reverse notch in the cam if it didn't reverse fine when first running (until hydro fluid was warmed up) that's what has me stumped. Ive put new cam, springs, even shimmed the cam plate. everything except rebuilding the hydro. what makes me think it needs rebuilt is that it runs good in reverse until the fluid is hot. and yes before you ask Ive used cub hytan and filter. Ive got 3ish acers that i keep mowed so it gets somewhat of a workout. As for as the trunion springs what different springs are you talking about using in place of the ones from cub?

[otep858]

Dag1450, The put oil in and recheck the compression trick uped the compression about 30 to 40 psi per cyl. 30 to 40 over what i said earlier. so im assuming rings. as well. it had to have gotten hot at some point. just the design, the screen in front of the radiator fills up with grass pretty fast,. combine that with mowing when its 100 out and presto.

[otep858]

Tell you what guys. you come help with the stand and the leak down tester and ill buy all the beer you can drink. im good with that idea. lol

[dag1450]

Wow...Tom a deal we both like...u get your brew....and I get my stand. We will b over tonight Paul

[BigMike]

My .02?....rebuild the grease burner and put it back in and with some loving care it will live the rest of your days.

[otep858]

lets do this. lol