watch those pre-cups!

[parts man]

We bought a B275 diesel for parts. We knew it was tired, and they said it had a bad head gasket. Oil in the coolant, coolant in the oil,, you know the drill. I was stripping it out today, and this is what I found.

http://www.chowntractorparts.com/posts/imgp0436.jpg

Notice the ugly hole on #3 piston, it goes clear down to the top ring! :00000060: (Here's a little closer shot)

http://www.chowntractorparts.com/posts/imgp0437.jpg

And this is the culprit.

http://www.chowntractorparts.com/posts/imgp0440.jpg

It was obvious that the head had been off before, because one of the grade 8 flat washers had been replaced with a lock washer! :banghead3 I'm guessing that someone didn't take care to see that the precup was properly seated, and possibly wasn't even straight for the bore in the head! Once it was able to move even a fraction the piston would hit it, and very soon both the precup and head wear so that it can bounce up an down like a strippers tassels! :hide:

[jodyand]

Ouch thats not good. Hope the of the tractor is in better shape.

[Archdean]

watch those pre-cups (http://www.mytractorforum.com/showthread.php?threadid=2410)

When I first saw the headline I thought you guys were talking about a Training Bra!!
Great pictures BTW I wish more members would post pictures like that afterall most small tractor owners have never seen anything like that!!

"so that it can bounce up an down like a strippers tassels!" "
Thanks for clearing that up!!ROF ROF

[Ingersoll444]

Are the other chambers cracked, or are they suposed to look that way? I assume thats where the fuel is injected in? Where are the glow plugs located in that motor? Sorry for the dumb Q's, but dont know a ton about oil burners.

[simple_john]

When I first saw the headline I thought you guys were talking about a Training Bra!!
most small tractor owners have never seen anything like that!!


guilty as charged.... sadly, i must admit.... even after the photos.. and the post info.. the only thing i got out of it was the 'strippers tassles'ROF


i see the big hole in the close-up.. but from the last picture... it looks like the other 2 things (piston holes? pre-cups?) have holes in them too....


is the motor toast?

ps: great pics.. that probably the closest ive gotten to the inside of a motor...

[Argee]

guilty as charged.... sadly, i must admit.... even after the photos.. and the post info.. the only thing i got out of it was the 'strippers tassles'ROF


i see the big hole in the close-up.. but from the last picture... it looks like the other 2 things (piston holes? pre-cups?) have holes in them too....

That's a pretty good indication of where your mind is ROF

[chipmaker]

I am still lost......just what are you referring to when you say pre-cup?
Which I would have thought would have been a T shirt.

[DYT4000]

"Pre-cup information" (http://www.myfirstbra.us/)

[parts man]

DYT,, nice link! ROF

I took some pictures to show what the precup is supposed to look like, and where it fits into the mix. I guess the proper term is pre-combustion chamber, but the shop forman at the local dealer always calls them precups, so I got into the habit.

This is what they are supposed to look like. (when out of the head)
http://www.chowntractorparts.com/posts/precup1.jpg

This is the order they fit together. (Injector on the left, then injector seat, and precup)
http://www.chowntractorparts.com/posts/precup2.jpg

Fitted together.
http://www.chowntractorparts.com/posts/precup3.jpg

I'll try to remember to get a picture of the piston once it's removed from the block.(It'll be a few days, we're finally getting the weather to do our bit of seeding.) The engine is toast, but the cank, hopefully, will be useable, and a few other parts, the head and pistons are done, and the block has been welded so it's scrap, but the cam and rockers and push rods should be OK, and I think the oil pan isn't bent up too bad either. It had been slipping out of a couple of gears, so the tranny is a question mark so far. I'll try ot get some pictures of that too if it's worth taking apart. (Made a puller for one particular piece, so I'll be able to show that off too. LOL)

BTW,, glad you liked the "tassles" line, I like a mental picture, and I know it created a strong image for me. :D

[chipmaker]

Ahhhhhhh, now I know what your talking about......heard them called squish chambers, hyperbolic chamber and a few other names, never a precup.....

The militarys multifueled engines have the "precup" built into the piston top, as do some other diesels I have seen.

[parts man]

Chipmaker, these engines are an older design, and are an "indirect" injection setup. The newer diesels injectors tips go directly into the combustion chamber and don't use a precup.

BTW, the glow plugs go into the hole in the side of the precup evident in the last picture.