6640 starter very sluggish

whitcarroll24 · Mar 1, 2018

Have a 6640 that has a new battery, new starter, and new alternator.
Also am pretty certain that it has good ground as the ground
connections have been removed and thoroughly cleaned, even
added a ground wire from battery directly to back of starter as there
was a grounding terminal there. With the battery fully charged the
starter will bog down, it will turn the engine over but it is very slowly
and it drains the battery quickly. My question is what else could cause
this? I have been told that there could be some sort of hydraulic load
that is causing this, but I do not know how to check for this since I am
not very familiar with the hydraulics on the tractor. This seems
plausible because this used to happen intermittently, but now is a
constant problem. Any help would be appreciated.

el6147 · Mar 1, 2018

I am not familiar with that model tractor, I would bet that you have covered all the electrical problem possibilities.

Hydraulic load is very possible, I worked on a Case backhoe sometime back that had the same starting issues as yours and the problem was a load on the hydraulics.

Hopefully someone here will help you troubleshoot the problem.

showcrop · Mar 1, 2018

Your problem is usually caused by clean cable connections or perfect cables. Check each cable end for heat.

Bern · Mar 1, 2018

Sounds like you've covered most of your bases on the electrical side, however don't overlook voltage drop across the starter solenoid contacts.

If the problem is caused by a hydraulic load, typically the engine will roll over normally the first few revolutions before slowing down as the hydraulic pump builds pressure. Since you mention that the battery drains quickly, this lends credence to the hydraulic load theory. Check your remote valves to be sure they're all in neutral.

whitcarroll24 · Mar 1, 2018

Thank you, I have not checked voltage drop across the solenoid contacts. I hope that it is some kind of electrical connection problem, but I have not been able to find it. The engine does start out faster and then gets slower and within probably10 seconds won?t turn over at all until I turn the key back and try again in a few seconds. It doesn?t start out as fast as it should though. Like I said I am very unfamiliar with the hydraulics, how do I check to see if the remote valves are in neutral?

whitcarroll24 · Mar 1, 2018

(quoted from post at 17:20:52 03/01/18)
Your problem is usually caused by clean cable connections or perfect cables. Check each cable end for heat.

I have cleaned all connections and the cables seem fine visually, I may just replace them anyway. I will check them for heat.

Destroked 450 · Mar 1, 2018

6640 remotes are cable operated, you could have a sticking cable no letting the spool center up.
Work the remote levers and make sure they are centered.

Bern · Mar 1, 2018

Each remote valve should have 4 distinct positions: raise-neutral-lower-float. Float is all the way forward, and raise is all the way back. Make sure you can find and feel each of the 4 positions, and make sure it ends up in neutral. If you're unsure, push it all the way forward into float, and that will give you the same effect as neutral for the purposes of starting.

sotxbill · Mar 2, 2018

My 6640 is the same.. if I jump around the ground cable, it spins faster,, so I need to clean/replace where it bolts to the transmission housing but have not got around to it as that tractor is located way way off site. Its a very large bolt on the side of the tranny that grounds it.

Bern · Mar 2, 2018

Would likely be far easier and better to simply route a #2 cable from the ground stud to the starter mounting bolt.

whitcarroll24 · Mar 2, 2018

(quoted from post at 07:56:07 03/02/18) My 6640 is the same.. if I jump around the ground cable, it spins faster,, so I need to clean/replace where it bolts to the transmission housing but have not got around to it as that tractor is located way way off site. Its a very large bolt on the side of the tranny that grounds it.

What exactly do you mean jump around the ground cable?....Yes, it is a 3/4" bolt that goes to the housing. I was just going to go to a local heavy duty parts place and get them to make me a new cable which normally wouldn't be a problem, but no on has a ring terminal that is 3/4". So instead I cleaned all the connections and sanded down to clean metal on the housing. I also ran a jumper straight from the negative battery terminal to the grounding stud on the back of the starter, however this did not help which is making me question if this is a grounding issue. This is very frustrating

whitcarroll24 · Mar 2, 2018

I had considered a gear reduction starter to see if it would spin it any faster. Any thoughts on whether that might work or not?

whitcarroll24 · Mar 2, 2018

(quoted from post at 09:12:31 03/02/18) Would likely be far easier and better to simply route a #2 cable from the ground stud to the starter mounting bolt.

This may be a stupid question, but I ran a cable from the negative battery terminal to a stud on the back of the housing which I assumed was for grounding. Would this work the same as running it to the mounting bolt?

whitcarroll24 · Mar 2, 2018

(quoted from post at 09:12:31 03/02/18) Would likely be far easier and better to simply route a #2 cable from the ground stud to the starter mounting bolt.

This may be a stupid question, but I ran a cable from the negative battery terminal to a stud on the back of the housing which I assumed was for grounding. Would this work the same as running it to the mounting bolt?

showcrop · Mar 2, 2018

(quoted from post at 10:22:03 03/02/18) I had considered a gear reduction starter to see if it would spin it any faster. Any thoughts on whether that might work or not?

Yes, my thought would be that it would work better but I would first want to get the primary problem out of the way.

Bern · Mar 3, 2018

If the stud you're talking about is on the back of the starter, then yes, it would be just as good as attaching it to the mounting bolt.

6640 starter very sluggish

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