B7100 Not Starting

boseephus

New member
Apr 3, 2012
18
0
0
GA
Removed engine and went to work. What I found were all three pistons were busted in between rings. The ring "ridges" I call it were completely destroyed so now for polishing liners and put back together and see what we got.
 

Stumpy

New member

Equipment
L175
Dec 1, 2011
848
3
0
NE Ohio
If the rings were able to move around those liners are trash. They're almost certainly ovaled and out of spec if there aren't any deep gouges. I don't think polishing isn't going to get you anywhere. You may be able to have a shop bore them out but I don't think you'll find oversize pistons and rings available. A new set of liners, pistons, and rings is what you need.

What are you intending to do?

I don't see a pack available on ebay for that tractor so you'll have to get them from the dealer or someplace on the internet. Messicks will have them.
 

boseephus

New member
Apr 3, 2012
18
0
0
GA
can I reuse my new head gasket? all i done was put it on and wasnt the problem so I pulled motor. Not like it was ever run. Just wondering. thanks.
 

Stumpy

New member

Equipment
L175
Dec 1, 2011
848
3
0
NE Ohio
Should be fine as long as it's not torn it'll live.

Can you describe the damage, what you've done, and what you're planning on doing more clearly? It sounds like you pulled the pistons and replaced them along rings and them honed the cylinders lightly and reinstalled with new parts. If you think the liners are saveable that may be the case, you can see it and I can't, but if the lands on the piston were damaged those rings were able to move and I'd be giving those liners the hairy eyeball.
 

boseephus

New member
Apr 3, 2012
18
0
0
GA
Yes, I am replacing pistons and rings. Then polishing cylinders. The landings on the piston were busted, but I did not fall apart when I removed pistons. They were in there pretty snug. The cylinder walls look good. I dont think the landings and rings were able to move around because they were kind of jammed in place even though landings were cracked. I know this doesnt make any sense. I will post pics later tonight. Sorry I havent responded in a while. Thanks to everyones help. It is appreciated more than you know. ;)
 

Stumpy

New member

Equipment
L175
Dec 1, 2011
848
3
0
NE Ohio
Wow look at those! Definitely preignition damage. Either ether or pump timing was way too early (the money is on ether as Kytim suggested). I'd still be worried about those rings having been able to roll slightly and their very sharp edge scraping away liner material but if you think it looks clean it couldn't hurt to try. A bore gauge isn't something you find in most garage shops :) If it doesn't work you're only out time and a new set of rings. Go for it!

Oh and a couple of people suggested a ball hone as the way to go for surface finish on a liner. I did some reading and it grinds away the surface irregularities leaving a clean cut instead of just smashing them over like a traditional bore hone does. It's one of the reasons cars engines don't having much of a break in period compared to 30-40 years ago. The break in period was mostly removing those microscopic bit of smashed over metal without overheating the rings. Make sure you get a nice 45° crosshatch.
 

Kytim

New member

Equipment
B6000DT, B7100DT,Snowplow, RM360, Scoop, Cultivator, Carryall,Disk, plow
Aug 14, 2009
848
11
0
Western Ky
When you do run that ball hone, use a heavy duty drill. Just because it'll chuck in a light 1/2" drill doesn't make it the right tool. A heavy drill won't bog down and also helps with your fatigue too. I alway like to use one with an accessory handle on the opposite side, using like your lifting a barbell. Easier to keep centered in the bore. Making a complete crosshatch without eroding any of the liner material.

Others mileage may vary
 

B7100

New member

Equipment
B7100,B7100 with Backhoe and FEL, Goldoni Quad 20
Feb 11, 2010
422
2
0
Wales
Just an observation,the stones on a conventional hone,because they have straight solid sides could give a better indication of how uneven the bore has worn if they are inspected after a few passes up and down?
Dave
 

boseephus

New member
Apr 3, 2012
18
0
0
GA
Well, Well, Parts finally came Friday. I had already honed cylinders and had head done waiting for pistons, rings and bearings. Got it all put together saturday and when I was priming the injector pump (without heating glowplugs) just turning motor over. Violia, That baby started. It starts and runs awesome now. I kinda walked around with chest poked out all weekend.:cool: Would like to thank everyone for their input and help. Thanks alot.
 

Apogee

Member

Equipment
B6100, B7100, B8200, B9200, G4200, L175, L35
Jan 22, 2012
518
0
16
Tacoma, WA
Nice work! :)

Out of curiosity, what did the engine rebuild end up costing by the time you were done?

What did you do to it? Did you replace bearings while you were at it?

I'm asking because I have a couple of them to do and it would be nice to have an idea of how much they're going to cost.

Again, congrats on a job well done!

Thanks,

Steve
 

boseephus

New member
Apr 3, 2012
18
0
0
GA
Nice work! :)

Out of curiosity, what did the engine rebuild end up costing by the time you were done?

What did you do to it? Did you replace bearings while you were at it?

I'm asking because I have a couple of them to do and it would be nice to have an idea of how much they're going to cost.

Again, congrats on a job well done!

Thanks,

Steve

I dont know an exact number but I would say @700 bucks. The pistons are very expensive and you have to kind of shop them around. Replaced bearings while I was in there also. Didnt cost me a penny for work done on head. I have awesome friends.
 

Apogee

Member

Equipment
B6100, B7100, B8200, B9200, G4200, L175, L35
Jan 22, 2012
518
0
16
Tacoma, WA
Boseephus,

$700 seems very reasonable.

Did you pull the block out of the tractor to do the work, or were you able to do everything "in frame"? If you did in in-frame, would you do it again that way or would you split the tractor and remove the whole engine if you had to do it again?

Also, did you buy the pistons from Kubota or did you find them aftermarket? Would you mind sharing where you found them for a good price?

Thanks for the info!

Steve
 
Last edited:

Apogee

Member

Equipment
B6100, B7100, B8200, B9200, G4200, L175, L35
Jan 22, 2012
518
0
16
Tacoma, WA
Figured I'd bump this up again in hopes Boseephus might see it and answer my questions.

Thx,

Steve