Revieving b7100 after several years sitting

Roadsiderick

New member

Equipment
Tractor possibly b7100
Jul 9, 2022
8
4
3
06712
Hello . I know very little about tractors . So im here I might have a b7100 it has 3 cylinders it cranks but nothing else it doesn't seem the glow plugs work they only put out 6 volts . It has sit for maybe 10 years it was my grandfather's and my grandmother doesn't want it anymore so if I could work it could help me on my property I have no idea what I'm doing though see pictures to help me even apriciated thanks
 

Attachments

  • Like
Reactions: 1 user

85Hokie

Well-known member
Lifetime Member

Equipment
BX-25D ,PTB. Under Armor, '90&'92-B7100HST's, '06 BX1850 FEL
Jul 13, 2013
9,114
1,153
113
Bedford - VA
Rick,

Welcome to the forum - lots of help here, just wait for it!

If you are at all mechanically handy - you will get her running again!

First thing .......how do you know the glow plugs work? How did you measure 6 volts?

When it cranks ...... does it crank at a speed that a riding lawn mower typically would - or does it crank very slowly?

DID any smoke come out at all? White? Black?

That battery has to need a little help - assuming that it is a least 10 years old and not charged lately.

You either need a jump or new battery to spin that diesel to get it to spin faster to start.


IF you have not do so - drain the fuel tank and add fresh fuel, no need to fill the tank - a gallon will be fine for right now.



There is a bleed screw at the injector pump - see picture:
1657407440528.png



open this screw - no need to remove it, just loosen it. Turn engine over until NO BUBBLES come out of that bleed screw. It may take several attempts to get this to happen. Then engine may even try to start, but I do not think it will. Once you get a solid dribble of fuel then tighten the screw back down snug.

Glow the plugs by turning the key backwards ............CCw ....... hold for about 10 seconds or more, THEN turn it CW to turn engine over.

Many will tell you to get a WSM .........

here that is : https://kubotabooks.com/AutoIndex/index.php?dir=Tractor%20Owners%20Manuals/&file=B7100HST_WSM_complete.pdf

There is so much more info to give you - but first things first.

Do what I said - and see if any of that gets you going.

IF not - more to come

(look at the front wheels - are they 4 bolt lugs or 6?)
 
  • Like
Reactions: 1 users

torch

Well-known member

Equipment
B7100HSD, B2789, B2550, B4672, RC54-71B, 48" cultivator, homemade FEL and Cab
Jun 10, 2016
2,259
512
113
Muskoka, Ont.
Looks like that's a gear drive, so probably one of the older ones (ie: 4 bolt front rims). The manual that 85Hokie linked is actually for the hydrostatic drive version, but much else is the same between the two. Most of the gear drive stuff can be gleaned from the I&T manual, available in 3 parts from Kubotabooks.com:
Part 1
Part 2
Part 3
Also, you will want a copy of the owner's manual as well:
Owner's Manual
 
  • Like
Reactions: 1 user

GreensvilleJay

Well-known member

Equipment
BX23-S
Apr 2, 2019
4,919
1,629
113
Greensville,Ontario,Canada
OK, I'll say the obvious...
put air into the tires BEFORE you try moving it !
i know the urge is to 'get er going'... but... while the batteries being charged up,toss some air in the tires...makes it a LOT easier to roll
also check oil level and the rad for coolant ! hate it to be low,engine starts, you walk away... and oopsy..... :(
 
  • Like
Reactions: 1 user

woodman55

Active member

Equipment
L6060HSTC, RTV 1100
May 15, 2022
250
135
43
canada
That could be a great old tractor. The great thing about those old rough and tough rigs is, you don't need to worry about the paint or another dent when using them. Do what these guys said, their dead on for what to do.

I would also "crack" open all the drain plugs and see if there is any water in the bottom of the cases. But that might be a bit much for a novice, so if your not comfortable doing that don't worry, you can change all fluids and filters later.

But do check all your fluid levels.
 

Roadsiderick

New member

Equipment
Tractor possibly b7100
Jul 9, 2022
8
4
3
06712
Rick,

Welcome to the forum - lots of help here, just wait for it!

If you are at all mechanically handy - you will get her running again!

First thing .......how do you know the glow plugs work? How did you measure 6 volts?

When it cranks ...... does it crank at a speed that a riding lawn mower typically would - or does it crank very slowly?

DID any smoke come out at all? White? Black?

That battery has to need a little help - assuming that it is a least 10 years old and not charged lately.

You either need a jump or new battery to spin that diesel to get it to spin faster to start.


IF you have not do so - drain the fuel tank and add fresh fuel, no need to fill the tank - a gallon will be fine for right now.



There is a bleed screw at the injector pump - see picture:
View attachment 83308


open this screw - no need to remove it, just loosen it. Turn engine over until NO BUBBLES come out of that bleed screw. It may take several attempts to get this to happen. Then engine may even try to start, but I do not think it will. Once you get a solid dribble of fuel then tighten the screw back down snug.

Glow the plugs by turning the key backwards ............CCw ....... hold for about 10 seconds or more, THEN turn it CW to turn engine over.

Many will tell you to get a WSM .........

here that is : https://kubotabooks.com/AutoIndex/index.php?dir=Tractor%20Owners%20Manuals/&file=B7100HST_WSM_complete.pdf

There is so much more info to give you - but first things first.

Do what I said - and see if any of that gets you going.

IF not - more to come

(look at the front wheels - are they 4 bolt lugs or 6?)
4 lugs . White smoke comes out ot the exaust . Has a strong crank new battery fresh diesel . I bled the screw as it had no air . I put a multimeter on the glow plug wires while the key was in glow plug and it reads 6 volts along all the plugs . It shows 0 volts at the glow plug controller wires so maybe thats somthing to look into . Thank you for your help
 

torch

Well-known member

Equipment
B7100HSD, B2789, B2550, B4672, RC54-71B, 48" cultivator, homemade FEL and Cab
Jun 10, 2016
2,259
512
113
Muskoka, Ont.
White smoke usually indicates unburned diesel going out the exhaust pipe. quite possibly related to your glow plug issues. Read over the manuals and if you have any questions about testing and repair we're here to help.
 

85Hokie

Well-known member
Lifetime Member

Equipment
BX-25D ,PTB. Under Armor, '90&'92-B7100HST's, '06 BX1850 FEL
Jul 13, 2013
9,114
1,153
113
Bedford - VA
White smoke is a good step in the right direction! - you can test each glow plug without removing them by unhooking the lead at the top and taking a very good ohm meter to the top and ground - you should have a reading very close to ONE ohm.......

HOW long did you glow the plugs? Try a long period of time, like 30 seconds - even a minute and see if anything changes.
 

Roadsiderick

New member

Equipment
Tractor possibly b7100
Jul 9, 2022
8
4
3
06712
White smoke is a good step in the right direction! - you can test each glow plug without removing them by unhooking the lead at the top and taking a very good ohm meter to the top and ground - you should have a reading very close to ONE ohm.......

HOW long did you glow the plugs? Try a long period of time, like 30 seconds - even a minute and see if anything changes.
I put it on for several minutes still did nothing . Measuring all three of them they dont respond . Guess that means they need replacing. Looks like the intake is in the way . I'm just letting them soak in some penetrating oil . Any tips to take them out
 

GreensvilleJay

Well-known member

Equipment
BX23-S
Apr 2, 2019
4,919
1,629
113
Greensville,Ontario,Canada
Don't mean this to come out wrong but maybe kinda obvious , use the CORRECT metric socket on them ? Don't use a monkey wrench ,a 'close but kinda loose' Imperial socket or an adjustable !

If you remove the power 'strap' between them, each should measure about one ohm. The WSM should say the 'nominal' value.... most are close to one ohm though.
 
  • Like
Reactions: 1 user

Kenonf

New member

Equipment
B7100 hst, l4200dt,b2920
Oct 22, 2019
20
1
3
Florida
From your picture, you are missing the indicator coil for the glow plugs on your dash board. The hole on the right side of the dash, with the two ring terminals hanging out in it. there was originally a resistance coil there that would glow to indicate the glow plugs were active. Since it is gone you might need to fasten the two wires together to get the plugs to glow. They were all wired in series, so they all saw about 9v DC when you turned the key to the left. Ohm them and see if they are good as previously suggested. Try not to use starting fluid, even if you see a can laying around there. Better to spend a little time, figuring the system out, and asking questions, and fixing it right.
Looking back at picture the ring terminals might even have grounded out on the dash. There are fuses on the back of the dash, might want to check them also.
 

Russell King

Well-known member

Equipment
L185F, Modern Ag Competitor 4’ shredder, Rhino tiller, rear dirt scoop
Jun 17, 2012
3,192
417
83
Austin, Texas
I put it on for several minutes still did nothing . Measuring all three of them they dont respond . Guess that means they need replacing. Looks like the intake is in the way . I'm just letting them soak in some penetrating oil . Any tips to take them out
You will need a deep socket to get the glow plugs out and back in. You may even have to grind the outside of the socket but I don’t think that I had to.

You can probably get an open end wrench on one of them to figure out the size.

The wiring is easy to figure out... from switch glow position to indicator then to the first glow plug then there is a heavy wire connector going from one glow plug to the next. In the switch crank position the indicator is bypassed but the glow plugs are still powered while cranking.
 
Last edited:

D2Cat

Well-known member
Lifetime Member

Equipment
L305DT, B7100HST, TG1860, TG1860D, L4240
Mar 27, 2014
10,829
1,994
113
40 miles south of Kansas City
Do you have an infrared temperature gun? The can easily tell you if GP's are heating up. You can get them fairly inexpensive these days, even Harbor Freight.
 

torch

Well-known member

Equipment
B7100HSD, B2789, B2550, B4672, RC54-71B, 48" cultivator, homemade FEL and Cab
Jun 10, 2016
2,259
512
113
Muskoka, Ont.
I put a multimeter on the glow plug wires while the key was in glow plug and it reads 6 volts along all the plugs . It shows 0 volts at the glow plug controller wires so maybe thats somthing to look into .
When measuring voltage, one should specify from where to where -- ie: what each meter wire is connected to during the measurement.

If you measured the voltage as 0 volts between each glow plug, that's a good thing; it means there is little resistance along the series of wires. If you read 0 volts between each glow plug and the negative (-) terminal of the battery, that's a bad thing; it means no power is reaching the plugs.

Look at the wiring diagram from any of the above-linked manuals. I'll reference the Kubota WSM " B7100HST_WSM_complete.pdf ", because page 320 (of 355) gives a clear picture of what happens inside the ignition switch -- the electrics are pretty much the same across the entire series.

Power goes from battery + to the starter motor. From there, the red wire carries it to the key switch terminal 30. When the key is turned left to glow to start, power is sent to terminal 19 and from there to the glow plug indicator via the black wire with white stripe, through the glow plug indicator and back to key switch terminal 17 via a black wire with red stripe. A second black wire with red stripe carries power to the top of each glow plug. Finally, the circuit is completed by grounding the plugs through the engine block which is connected to battery - terminal.

The glow plug indicator is critical to the circuit. As noted by Kenonf, if it is not in the circuit, the glow plugs do not receive any power during pre-heat. If it is by-passed (eg terminal 17 connected directly to terminal 19) the glow plugs will receive too much power and burn out.

When the engine is cranked over, the huge draw of the starter motor brings down the battery voltage, so the key switch sends battery power direct to the glow plugs, bypassing the indicator.

So, three tests:

1. Voltage between top of any glow plug and battery - terminal should be around 8-10 volts in the glow position and the glow indicator should start to glow dull red in 10 or 15 seconds (depending on temperature). 0 volts means no power reaching the plugs. 12 volts means the indicator was bypassed. 6 volts suggests one or more plugs are drawing current, but one or more connections are corroded and need cleaning.

2. Repeat above while turning the key all the way right to activate the starter motor. Again, voltage should be up around the 8 - 10 volts range. Maybe a touch higher than the previous test depending on battery and starter motor condition, etc. The glow indicator should stop glowing while cranking -- this is normal, it no longer receives power in the crank position.

3. Disconnect all glow plugs from power (there may be a stiff metal bus bar delivering power to the top of all 3). Set your meter to the lowest Resistance (ohms). If your meter is auto-ranging, manually force it to the lowest ohms range available. Touch the two meter leads together and note the value displayed (eg: "3 ohms". Deduct that value from subsequent measurements. Measure the resistance of each plug from the top of the plug to the battery negative (-) terminal. You should see a (corrected) value of around 1 ohm. Higher means it is burnt out, lower means it is shorted.

Pro tip: when posting questions and results, please be as detailed as possible. Assume we can't see exactly what you did and saw because, well, we can't.
 
  • Love
Reactions: 1 user

Roadsiderick

New member

Equipment
Tractor possibly b7100
Jul 9, 2022
8
4
3
06712
I have ordered a new glow plug regulator and glow plugs they looked to be bad . Wiring might be bad somewhere else cause the book says the oil light should come on when the key is in start and it doesn't. Is my ignition missing a wire . And what are these loose wires here . Thanks for all your help so far .
 

Attachments

Roadsiderick

New member

Equipment
Tractor possibly b7100
Jul 9, 2022
8
4
3
06712
When measuring voltage, one should specify from where to where -- ie: what each meter wire is connected to during the measurement.

If you measured the voltage as 0 volts between each glow plug, that's a good thing; it means there is little resistance along the series of wires. If you read 0 volts between each glow plug and the negative (-) terminal of the battery, that's a bad thing; it means no power is reaching the plugs.

Look at the wiring diagram from any of the above-linked manuals. I'll reference the Kubota WSM " B7100HST_WSM_complete.pdf ", because page 320 (of 355) gives a clear picture of what happens inside the ignition switch -- the electrics are pretty much the same across the entire series.

Power goes from battery + to the starter motor. From there, the red wire carries it to the key switch terminal 30. When the key is turned left to glow to start, power is sent to terminal 19 and from there to the glow plug indicator via the black wire with white stripe, through the glow plug indicator and back to key switch terminal 17 via a black wire with red stripe. A second black wire with red stripe carries power to the top of each glow plug. Finally, the circuit is completed by grounding the plugs through the engine block which is connected to battery - terminal.

The glow plug indicator is critical to the circuit. As noted by Kenonf, if it is not in the circuit, the glow plugs do not receive any power during pre-heat. If it is by-passed (eg terminal 17 connected directly to terminal 19) the glow plugs will receive too much power and burn out.

When the engine is cranked over, the huge draw of the starter motor brings down the battery voltage, so the key switch sends battery power direct to the glow plugs, bypassing the indicator.

So, three tests:

1. Voltage between top of any glow plug and battery - terminal should be around 8-10 volts in the glow position and the glow indicator should start to glow dull red in 10 or 15 seconds (depending on temperature). 0 volts means no power reaching the plugs. 12 volts means the indicator was bypassed. 6 volts suggests one or more plugs are drawing current, but one or more connections are corroded and need cleaning.

2. Repeat above while turning the key all the way right to activate the starter motor. Again, voltage should be up around the 8 - 10 volts range. Maybe a touch higher than the previous test depending on battery and starter motor condition, etc. The glow indicator should stop glowing while cranking -- this is normal, it no longer receives power in the crank position.

3. Disconnect all glow plugs from power (there may be a stiff metal bus bar delivering power to the top of all 3). Set your meter to the lowest Resistance (ohms). If your meter is auto-ranging, manually force it to the lowest ohms range available. Touch the two meter leads together and note the value displayed (eg: "3 ohms". Deduct that value from subsequent measurements. Measure the resistance of each plug from the top of the plug to the battery negative (-) terminal. You should see a (corrected) value of around 1 ohm. Higher means it is burnt out, lower means it is shorted.

Pro tip: when posting questions and results, please be as detailed as possible. Assume we can't see exactly what you did and saw because, well, we can't.
I got 6 volts in both positions but see no corrosion. Don't think that's enough volts to power them which it doesn't seem they have any reaction to my resistance test the meter just stayed at 1 . I am using the free harbor freight multimeter but it did react when I tested a random fuse . So im guessing the glow plugs are bad . I dont have a glow plug indicator it is missing so my voltage might be even lower if I did. oil pressure lamp doesnt come on in start position. And maybe missing some wiring to ignition switch . I'm thinking to give the glow plugs another shot if I can pull them out and test them that way . Not to good when I found a mouse house under the battery .
 

Attachments

torch

Well-known member

Equipment
B7100HSD, B2789, B2550, B4672, RC54-71B, 48" cultivator, homemade FEL and Cab
Jun 10, 2016
2,259
512
113
Muskoka, Ont.
I'm not sure that's the right ignition switch. It should have 5 terminals, that one looks to have 4?
 

Roadsiderick

New member

Equipment
Tractor possibly b7100
Jul 9, 2022
8
4
3
06712
I'm not sure that's the right ignition switch. It should have 5 terminals, that one looks to have 4?
You are right I'm gonna order a new ignition as well . Wonder if it ever worked with 4 ? Man someone screwed this tractor up .
 

ve9aa

Well-known member

Equipment
tg1860, bx2380
Apr 11, 2021
466
256
63
NB, Canada
PLEASE go back and reread torches very well thought out and detailed post. Multiple times if you have to.

I've been working in and around all things electrical for a very long time and couldn't find a single fault in his text. Very well done !