B5100E Oil pressure and charging issues

[twostep]

Background: I recently picked up an old B5100E. It doesn't have an hour meter so I have no idea how many it has. It blows a puff of black smoke on start up but none after that. The oil was BLACK when I got it and I have no idea how many hours were on that oil and filter so I changed it. I had planned to run it for about 6 hours and change it out again.... Mowed last week for about 3 hours with no problem, then yesterday I was mowing and was about 2 hours in when I noticed the oil pressure light came on. I shut her down and checked the oil level, it was fine. I started it back up and got it to the garage and went ahead and changed the oil and put some fresh Rotella in. checked coolant and everything seemed to be okay so I went back to mowing. Mowed for another 1/2 hour and the light never came back, shut the tractor down and went in to get a drink of water and to move some things so I could finish mowing... went to fire it back up and the battery was dead. It turned the engine over once and stopped. I jumped it off of my truck and finished mowing for about another 1/2 hour. Shut it down and the battery was dead again. This time I pulled the batter out to put it on the charger in the garage. I jumped the tractor again and glanced the battery terminals against each other and there was a spark so I know the dyno is charging just not sure how much. When I hooked the battery up to my charger it immediately said it was 75% charged and this morning when I went out it showed complete so I guess I'll give it another try.

Questions:
1) why would the oil pressure light would come on after running a few hours and then go off after the oil change?
2) any idea how/where to add an oil pressure gauge? I would prefer to monitor rather than rely on a dummy light.
3) will a dyno slowly die and stop charging enough to keep the battery up or do they just go dead?
4) anyone on here have experience with adding an alternator?

 

[ipz2222]

Search "low oil pressure" in the archives. Lots of good info there.

 

[twostep]

Search "low oil pressure" in the archives. Lots of good info there.

Thanks for the reply. One question though, could you kindly show me to the "archives" section? Are these "archives" dedicated to the B5100 tractor and/or the Z500 engine? The reason I ask is because I searched the normal SR&M section and got tons of results with none of them actually pertaining to my application... well at least none of the 500 results that I glanced at.

 

[birddogger]

1) I don't know if your model is prone to the "camshaft plug" falling out. That could explain the oil light "on" when hot, but "off" with a cold charge of new oil.
2)You put the pressure gauge into the same hole the electric oil sender is in.
3)Dynamos usually just stop putting out.
4)There have been a few. Someone added a 60 amp/single wire alternator designed/used for race cars; small & light-weight.

Maybe you'll have better luck with the search function than I had, but the camshaft plug, oil pressure gauge and replacement alternator are all in the messages somewhere.

Oh, clean (wire-brush) all 4 ends of the 2 battery cables and the battery posts before condemning the battery or dynamo. It can be also corrosion has crept under the insulating sheathing on the cables and turned a 6 gauge wire into a 16 gauge wire. Any of those conditions restrict the charging of the battery and it then delivering the charge to the starter.

 

[twostep]

Great reply! Thanks for the help. I will research the camshaft plug you speak of. I did see where someone added a T at the pressure switch and installed a guage... I'll look into that also.

I put the battery on the charger and will inspect/clean the wires and terminals when I put it back in.

 

[motorhead]

Before I started digging into the engine, I would put a temporary oil pressure gauge on it. Get a GOOD gauge. You could just have a bad sending unit. Put the gauge in place of the oil pressure switch.

I had a B5100D and the regulator quit. Usually from owners running the tractor with a bad battery. I substituted the expensive Kubota regulator with 3 wire regulator of a Chinese 12hp diesel engine.
Check your dynamo with a AC volt meter. with the engine running. put the meter across the 2 leads. Running at speed, the dynamo puts out about 35 volts as I remember. The regulator regulated it down to 13.5 volts and converts the AC current to DC.

 

[Kytim]

The oil senders used on these small diesels seem to fail after a little age. A gauge is a good idea, just know its a metric thread not NPT. There are ways around this for both temporary testing and permanent installation.

Let us know results, then we can help more.

 

[twostep]

I put the battery back in and nothing... so I put jumper cables from my truck to the bota's battery terminals (with the battery out) and it fired right up, I'm sure the battery is dead. Motorhead, thanks for the info. I actually did meter the tractors bat leads and I got about 12 at idle and 14.5 at full throttle.

Thanks Tim, I'll keep that in mind.

 

[motorhead]

I put the battery back in and nothing... so I put jumper cables from my truck to the bota's battery terminals (with the battery out) and it fired right up, I'm sure the battery is dead. Motorhead, thanks for the info. I actually did meter the tractors bat leads and I got about 12 at idle and 14.5 at full throttle.

Thanks Tim, I'll keep that in mind.

If you get 14.5 volts then you are charging. Was that with a good battery in the circuit? They don't charge at a very high amperage.....8-10 amps as I remember.

 

[twostep]

No, no battery just touched the multimeter leads to the battery cables. I didn't get a chance to check the dyno... I did have the battery checked and it's junk. Now I just need to find a replacement. Hard to find that small of a battery with top posts.

 

[twostep]

Finally found a battery that will fit (BARELY!!) but it is 540cca So this evening I pulled the old cables off and found what could have been the problem... The cables are older than I am... If you look at the middle pic that has the bat term you can see there was a huge gouge in the insulation on the pos side, I clipped it and the third pic is what I found. Neg side was pretty clean but I'm upgrading to a larger wire with much finner strand for both. I work in design engineering for a company that makes automotive wire harnesses so I've got a decent supply of primo cable.

 

[twostep]

The oil senders used on these small diesels seem to fail after a little age. A gauge is a good idea, just know its a metric thread not NPT. There are ways around this for both temporary testing and permanent installation.

Let us know results, then we can help more.

Tim,
Do you know what size that metric thread is? Mowed yesterday and again, right before I finished the light came. Looks like I need to put a gauge on it.

 

[asbug]

I havent measured, but the senders in these tractors look a whole lot like the units that are in an old Aircooled VW (through 1979). they are set to go off at 10 psi.
I put an autometer electric oil pressure sender in the VW so as not to have 12 ' of little copper hose to nick and leak, electric oil pressure gauges can be had at any FLAPS now a days.
KC

 

[Kytim]

I don't remember, there was another thread about the size and adding a gauge something ago. About the first part of the summer I think. New replacement senders are about $15 bucks at a dealer. I have heard if guys putting grease in the hole and tapping it to a NPT. I'm not that brave. My luck I wouldnt get all the grease and chips and cuttings out.

 

[T and S]

I just went through the "oil pressure" thing on my L185. The plug had fell out of the end of the cam shaft. I had no oil pressure at idle and 2 or 3 pounds at 1800 rpm. I bought a oil pr. gauge and mounted it on my dash and went from there. As stated you will need a metric adapter for your block to install your fitting. good Luck!

 

[twostep]

What is strange is that when my light has come on, it is full on with the throttle up at mowing speed. When I idle it down the light just flickers real dimly like the psi is boarder line low.

Anyway, I still haven't torn the engine down but the last three weeks I've only mowed with it for right at an hour and the light has not come on at all. Seem like it has to run over an hour before it happens... Considering the engine is up to operating temp way before then it just doesn't make sense.

 

[asbug]

What is strange is that when my light has come on, it is full on with the throttle up at mowing speed. When I idle it down the light just flickers real dimly like the psi is boarder line low.

Anyway, I still haven't torn the engine down but the last three weeks I've only mowed with it for right at an hour and the light has not come on at all. Seem like it has to run over an hour before it happens... Considering the engine is up to operating temp way before then it just doesn't make sense.

My B7001 did this once and it was a combination of too much oil in the crank case and high rev's and the tractor mowing on along a steep incline, not enough to roll over, but pretty steep.
I have used this tractor allot since then and I have not been able to repeat the problem.
I plan on installing a pressure guage (electric) on mine as well.
I do not have an hour meter, so this will be a good use for the hole in the dash.
KC

 

[twostep]

Thanks for the reply.
I guess there could be a possibility that there might be a little too much oil, I'll double check. My yard is pretty much flat so it shouldn't be a sump issue.

 

[bruceatlam]

I believe that the oil pressure sensor is 1/8" BSPT --- British pipe thread. If you buy that fitting --- should work. The 1/8" NPT fitting that you get with most all oil pressure gauges will also work --- just wrap it well with tread tape but, ---- it will cross thread so I wouldn't plan to go back to the stock fitting.

 

[Don in NY]

If it is the camshaft plug issue, you can expect about 15 PSI cold and 5 PSI warm. My B7100 runs about 50 PSI since I did the repair. My Kubota dealer refused to sell me the OEM aluminum plugs, made me a pair of steel ones by cutting a section out of a metric bolt (I think it's 8mm, but don't quote me) then roughed them up a little on a grinder, and used red Locktite on them. If you need to do this repair, be sure to replace BOTH plugs, one on each end of the camshaft. This is all for the B7100, assuming that the B5100 is similar.