Help! JD 770 Dead!

[kennyd]

I think the clue here is he unhooked the hydro lines off the remotes and the ENGINE labored. He then shut if off and when he tried to restart he heard the pop!

If you read his post, he restarted after connecting the backhoe lines:

when I dissconnected the hoses the tractor labored a little and when I heard that I immediately shut it down. I connected the backhoe hoses to the tractor in preperation to adjust the subframe and when I turned the key........POW!

 

[kenstrac]

.......and when I put the negative side of the tester on the selenoid and the positive at the lead......shows voltage which means something is closed? if it were open it would not register voltage.[/QUOTE]

Explain better where where you are putting test leads almost sounds like you have a poor ground.or a poor connection on the hot side
Put yor lines back as if there is no bh on it with key off in high gear rock tractor back and forth listen if you hear starter snap back.

 

[Diamondpilot]

If you read his post, he restarted after connecting the backhoe lines:

I dont think it started after he shut it down. It went POW when he tried to restart. Either way he has big problems.

Chris

 

[Whitey]

OK.....I spoke with the JD service manager this morning.....I explained the situation completely to him. He said that I should not have hurt the hydro pump.....it would have taken a very high idle and some time to burn out. He also said that he felt that the hookup to the BH was a coincidence

Any way he said that I should start with the battery (just as AKfish said) and trace through the starter and selenoid. Can someone please explain wher I am to remove the starter at.....there is a large plate at the base where it bolts to the body or there are two long bolts that look to hold the starter and I think those are the ones to go for.......can anyone confirm??

 

[kenstrac]

I would not take the starter off yet not till you trouble shoot the problem.I would put the meter on the wire that comes from the battry that is on the starter and other test lead to ground on the starter and turn lights on and see if the voltage drops.

 

[Cocre]

I would replace the battery. Take a good unit out of another vehicle and try it. Do not jumper one to the other. A dead short in the battery would prevent a jump off from working.

 

[crashz]

Whitey,

I'm also thinking that its electrical. So no dash lights, no headlights when key is on, and fuses OK, hot lead from ignition to the starter solenoid send juice, and hot lead from battery is live? I'm thinking its the starter solenoid or the connection at the hot lead(s) at the starter are corroded and are not giving you power correctly. Corrosion will do funny things.

I think the pop was electrical, but I have another question for you. Did you have the headlights or anything drawing electrical current on while operating the tractor at idle? Its possible that the battery was drawn down enough to reduce voltage and increase current draw enough to "pop" something. What condition is the battery in now? Can you try another battery just for kicks? Have you checked and cleaned the grounds gound to the body and the engine?

 

[irwin]

I would not take the starter off yet not till you trouble shoot the problem.I would put the meter on the wire that comes from the battry that is on the starter and other test lead to ground on the starter and turn lights on and see if the voltage drops.

I would replace the battery. Take a good unit out of another vehicle and try it. Do not jumper one to the other. A dead short in the battery would prevent a jump off from working.

Both these are good advice, put a known good battery in it......if it doesn't fix the tractor.. then do a trace for open or short (component and connection check)

BTW a loud POW noise is an issue that should be answered..get a look at the pigtail side of the ignition switch (where you said the noise came from) you might see a sign of heat damage somewhere...

The starter is removed by unbolting the whole starter from the block (2 bolts) it's on the left side.

 

[dqdave1]

You have gotten a lot of good advise so far. To recap;
1. Remove battery and have it checked at an auto parts store.
2. Inspect the positive and negative battery cables; clean ALL ends. If possible; check continuity of both cables while wiggling them. Make sure gound wire at frame is clean and tight.
3. Check starter switch closely; can you remove it?; does it smell llike it burnt? Using a tester; bench test all poles for correct operation.

4. Check primary wire from start switch to starter for continuity. ( you may have an internal break in a wire from surge that is not noticable to eye.) Wiggle wires while watching omh meter.

5. Check the fuse link again.

6. IMHO; sounds like a grounding issue or battery issue.

GOOD LUCK

 

[banjodunn]

G'day Whitey i think you are heading in the right direction with checking the battery for starters but when you do don't overlook the obvious dirty battery terminals they can give you a reading with your meter but as soon as the load of the starter comes on zilch also check all your connections are clean and tight if you find all good and you are getting 12v down at the starter on both the main and the trigger wire you have probably got a starter at fault, to remove this do not undo the two long bolts as these are the tie bolts that hold the starter together you need to undo the larger bolts where the starter mounts to the gearbox bellhousing also chris i think what you are referring to is called hydraulic lock when water fills the cylinder i.e a blown head gasket it cannot be achieved by a hyd pump blowing and dumping its guts into the sump, to achieve hyd lock you have to fill the cyl with a liquid not possible i believe unless the engine has had a long time to sit and the engine is overflowing with hyd oil

 

[Whitey]

OK.........thanks guys! I up to the task.....I will print these replys off today at work and proceed with surgery......I was really down in the dumps.....but you know sometimes you can't learn without a little turmoil or hardship in your life. In this case I probally did something stupid and now I must learn from my mistake. I just hope it's too expensive of a mistake.

PS.........my good friend that lives about a mile away has a battery tester and is pretty good with diesels and he has offered to help me with this one.

 

[Diamondpilot]

OK.........thanks guys! I up to the task.....I will print these replys off today at work and proceed with surgery......I was really down in the dumps.....but you know sometimes you can't learn without a little turmoil or hardship in your life. In this case I probally did something stupid and now I must learn from my mistake. I just hope it's too expensive of a mistake.

PS.........my good friend that lives about a mile away has a battery tester and is pretty good with diesels and he has offered to help me with this one.

That was my next suggestion, phone a friend. Many times I look at a problem and can not figure it out then a buddy comes over and says hey whats this or that hanging off. It is something I had totally overlooked. Many times we get tunnel vision and will step over a dollar to pick up a nickle if you know what I mean.

Chris

 

[wcpeabody]

I also have a 770 so I am curious if you were able to resolve your problem?

Thanks,
Bill

 

[Whitey]

OK let me first say how thankful I am to all whom gave their advice. I really mean that for I do not know what I would do without this web site. I am not very knowledgeable at all when it comes to equipment but you guys have given me the desire and capabilities to try to repair things on my own. With that said the tractor is fixed! I started out by borrowing my friends battery tester (slick gotta find one or keep his) and tested the battery. Upon doing that I noted the battery cable clamp on the positive side a little loose. Upon trying to tighten I noticed it would not. Closer inspection revealed a crack in the clamp itself. Trip to town.....replaced clamp and tightened......tried the lights....and they worked!!!! Wow!.....stood there with the dash in one hand and the key in another and.......turned the key and over she went and started as she did the day I bought her! WOW!! Now I cannot tell you what made that pow sound behind the key the day she died.....and I am not asking questions but I buttoned her back up and she has had no signs of any problems. I hooked the backhoe up and off we went. So here I sit with my tail between my legs telling you this and I must say it pays to start at the very beginning of the power source and check from there in and when all seems right......sometimes it is not. I should pay closer attention to what I preach.

 

[Diamondpilot]

Really glad you got it fixed and that it was fairly cheap. I am still curious what made the engine labor when you disconnected the BH? Either way its up and running. Good luck.

Chris

 

[zzvyb6]

Sometimes the cracked battery cable will spark and ignite hydrogen gas given off by the battery ventting during high current discharge. That means explode. In fact when this thread started I was reminded of the exact same situation on my tractor. From this I learned its also a good idea to have safety glasses on when looking at battery and cable issues. Just connecting up jumper cables can flash the gas and a sulphuric acid splash in you eyes will ruin your day.

Originally, I thought the pop might be the fuel shutoff relay noise, but a memory of my own starting problem came back from the past.

 

[RobS]

Good to hear you're back in the saddle!

 

[dqdave1]

I would suggest when you have time; replace the battery cable with a molded one. It seems the cables that are redone do not hold up well and the diesel needs all the current it can get. Just measure it and pick up aa new one. Make sure you get same guage one or heavier.

 

[kennyd]

I am still curious what made the engine labor when you disconnected the BH? Chris

Simple, the BH is connected to the Power Beyond loop that has constant flow through it, so when he un-coupled the QD's it sent the hydraulic system into relief because the flow was stopped.