Chapter two, heat pistons or not, yesterday's happening

[texasgeezer]

Early yesterday I took my piston assemblies to the machine shop that was touted 'to heat pistons' to insert pins.

They seemed to not have heard about heating pistons. Also said their good machinist was retired & came in only when needed.

So I then went to the machine shop used by the other Kubota dealer. This dealer & the machine shop said the pistons were 'press fit' & did not need heating.

My assessment yesterday morning,

- long time in business
- build & ship engines all over the U.S.
- have many, many, repeat customers
- have always done 'good' work for me in the past
- used by local Kubota dealer
- really, really, a nice owner to talk with

Because of this I asked him to:
- pull the pins, check for anything that should be replaced with new,
& put in new bushings (properly fit)

A couple of hours later I picked up the assemblies & didn't think about looking at the work at that time. Later that evening I was looking at one assembly & noticed that the rod bushing was exposed on one side but not the other. Looked at the other two & they were the same way. Edges of new bushings show edge damage.

My concern is the bushings are not centered & would not center the load properly & 'might' have reduced the oil hole opening by the offset amount (can't tell because it is at the top of the rod).

The new piston appears to have two cracks in the bosses, one on each side. They catch my fingernail if I scratch them. Might not be cracked but visually appear so. If they are cracks then this is probably because it wasn't heated. The picture does show the cracks but not at first glance.

Also looked at the old bushings. Looks like one was removed with the aid of a chisel. That's ok as long as the rod wasn't damaged.

Talked this morning with Country Sales & Service - Ohio". They are a Kubota dealer & also rebuild engines. The service manager told me they would look at the three assemblies, check for damage, round the rods, replace anything that 'needed' it, center the bushings, & they routinely heat the pistons if it is called for.

Will be packing them later today.

Pictures are included.

 

[lsmurphy]

 

[texasgeezer]

I'm having an 'oldtimers' moment, what does the smiley mean? How does it relate to my post? Are you being 'off topic' again?

 

[lsmurphy]

I'm having an 'oldtimers' moment, what does the smiley mean? How does it relate to my post? Are you being 'off topic' again?

In your original thread............

Two mechanics and myself told you to heat the pistons. I suggested oil, the others use water but outcome would have been the same.


NOW you are complaining again about what some shop has done or not done........now you are complaining about stress cracks due to forcing the pins into the pistons.

NOW it may cost you for new pistons anyway.



You do it your way.


The smiley is a roll eyes..........as in .........I told you so.


But hey

 

[texasgeezer]

Also, the local 'larger' Kubota dealer told me the pistons were press in & did not need to be heated.

Their newer shop manual, for my tractor, did not have the wording in to heat the pistons.

Others said the pistons were press in.

An aftermarket piston supplier said the pistons were 'press in' & not to be heated.

--------------

I do not consider your information to be trust worthy "because of your added abusive comments & smiley faces". It seems you have not much else to do except sit around waiting to 'pounce' on someone, inflict your damage & then go back into hiding again.

Some people get big grins when they are being abusive & hateful.

A smiley face conveys multiple meanings & you have just verified what I thought. I'll bet that sometimes when you're standing behind an animal you think you are looking into a mirror.

I believe the following describes both of us:

"people targeted by verbal abuse explain why what they’ve just heard is not true or not okay. They explain themselves because they believe the perpetrator is rational and can hear them and the relationship will then get better. Then they usually hear more verbal abuse, for instance, “You’re too sensitive.” At that point they don’t usually realize that they have just been defined, and, therefore, verbally abused again.

If you truly think you are a good guy go to this link:

http://netforbeginners.about.com/od/weirdwebculture/f/what-is-an-internet-troll.htm

Hopefully you will learn something. I did & will ignore you in the future.

Maybe the moderators have time to research your many posts & remove you from the forum.

 

[texasgeezer]

Also, the local 'larger' Kubota dealer told me the pistons were press in & did not need to be heated.

Their newer shop manual, for my tractor, did not have the wording in to heat the pistons.

Others said the pistons were press in.

An aftermarket piston supplier said the pistons were 'press in' & not to be heated.

 

[hodge]

Also, the local 'larger' Kubota dealer told me the pistons were press in & did not need to be heated.

Their newer shop manual, for my tractor, did not have the wording in to heat the pistons.

Others said the pistons were press in.

An aftermarket piston supplier said the pistons were 'press in' & not to be heated.

--------------

I do not consider your information to be trust worthy "because of your added abusive comments & smiley faces". It seems you have not much else to do except sit around waiting to 'pounce' on someone, inflict your damage & then go back into hiding again.

Some people get big grins when they are being abusive & hateful.

A smiley face conveys multiple meanings & you have just verified what I thought. I'll bet that sometimes when you're standing behind an animal you think you are looking into a mirror.

I believe the following describes both of us:

"people targeted by verbal abuse explain why what they’ve just heard is not true or not okay. They explain themselves because they believe the perpetrator is rational and can hear them and the relationship will then get better. Then they usually hear more verbal abuse, for instance, “You’re too sensitive.” At that point they don’t usually realize that they have just been defined, and, therefore, verbally abused again.

If you truly think you are a good guy go to this link:

http://netforbeginners.about.com/od/weirdwebculture/f/what-is-an-internet-troll.htm

Hopefully you will learn something. I did & will ignore you in the future.

Maybe the moderators have time to research your many posts & remove you from the forum.

Texasgeezer, you are new here, and have your feathers ruffled up. I can see where you are irritated, but don't miss the forest for the trees; lsmurphy is a wealth of knowledge and experience, and usually has good wisdom to offer. You might not like his delivery, but don't waste the opportunity to pick something up good.
I doubt if you will hurt anything heating the pistons up- certainly an oven won't get them as hot as combustion will. Why not try heating the pistons and cooling the pins, instead of throwing money away?

As far as your ire and desire for the moderators to "remove him from the forum", you are being just as bad as what you are irritated at. I doubt the moderators will even look twice at your ranting and venom- research posts by lsmurphy yourself, and see what he brings to the table. You will find that you two are rubbing each other wrong at this particular point, but this usually isn't the case.
At the least, private message him with your distaste, instead of doing it on a public post.

 

[North Idaho Wolfman]

Lets cut to the chase!

It looks and sounds like the pistons are now damaged and if the are cracked then they are worthless. Pressing a bushing or rod into a hole that is too small will ruin it every time. I would make the shop that improperly assembled and ruined them replace them. They should have checked tolerance before just pressing them in. I really worry about the competency of the shop that would use a punch or chisel to remove a bushing!

I personally would get new pistons, bushings, and maybe even rods (if they were damaged too, and have a qualified shop put them together for you.

We can only give our best advice... If you don't use it and things go bad... we will probably give you a little sympathy and a few rib jabs telling you "I told you so"!

 

[Kubota Newbie]

Well... Being one of probably very few folks here that has actually ever installed and re-sized rod bushings or had to do a "touch-up" hone on a piston pin bore here's what I think.
If the bushings are off center, they were just being sloppy and often that carries over to the rest of the job. That being said, the bushings are always press fit into a smaller hole in the rod than what the OD of the bushing is (some really old antique stuff does use a cinch bolt). The interference fit is what holds the bushing in place. After the bushings are pressed in they usually must be honed with a rod hone machine to bring them to the correct size as the pressing in of the bushing usually distorts it some and the ID of all the rods won't be exactly the same due to manufacturing tolerances. The most common problem that occurs here is that an inexperienced or careless operator can hone the hole at a slight angle which causes the piston to be cocked sideways in the cyl. bore (you check the squareness of the pin and journal bore against each other when you're doing the honing. You can also check for axial twist, but this is less a problem than having the bores out of square to one another.
Regarding the pistons & possible cracks - The pistons in the photo are not "press fit" pistons. They are a full floating design. You can not "press fit" a pin into a piston that does not have even/square outer bosses. Further, you don't need retaining clips to keep a pin in something that is press fit. Your "cracks" may very well be scratches, which again is often a sign of carelessness and can also cause stress risers that could (not likely in this application, but could) lead to a pin boss crack later. I also think that the piston would be seriously deformed somewhere if enough pressure was applied to crack the pin boss.
The heating issue has nothing to do with a "press fit" in this application since the specs list a "clearance" tolerance. Rather it has to do with ease of installation. Where a fairly tight clearance spec is quoted it can often be difficult to slide the pins in the pistons. The extra heat increases the clearance just enough that the pins install more easily.
Too bad you had the bad luck of using a shop that may not have been real careful with your stuff. You had no way of knowing aside from possible references and previous experience. Most people would've put it back together without noticing things weren't quite right, and probably, everything would have been ok. BUT....
I'd be talking to the shop owner about setting things straight no matter where you take them next.

 

[jkebxjunke]

my 2 cents... now.. it seems the guy was going by what the DEALER said... and the same shop the dealer used... now are not the dealers supposed to be TRAINED by Kubota? It sounds like it could be a bad dealer.... and the dealer is is just guaranteeing himself more repair business due to shoddy repairs and advice. correct me if I am wrong.. but isn't the dealer not following Kubota's service instructions frowned upon?

 

[efharg]

I learned a long time ago that if I wanted something done right, I usually had to do it myself.

If it were my engine, I would buy a new piston and a new rod. I would then put the new piston in a pan of hot (200 degree) water for about 10 minutes.

chill the pin in the fridge, slide them together, put the engine back together, and put my little tractor back to work.

 

[Kubota Newbie]

j'junke, you would probably be right except that there are few if any dealer shops out there that do anything that resembles automotive machine work, and pressing a pin or re-bushing a rod usually falls into that category. They almost always farm that type of stuff out. Now if the dealer was actually doing the rebuild, then they'd be responsible, or should be, for someone else screwing something up as part of that job.
I tend to fall into the same category as efharg. But I have access to a full automotive machine shop, most people don't. Then too there's the fact that the older I get, the less interested I seem to be in having to do things myself.

 

[hodge]

j'junke, you would probably be right except that there are few if any dealer shops out there that do anything that resembles automotive machine work, and pressing a pin or re-bushing a rod usually falls into that category. They almost always farm that type of stuff out. Now if the dealer was actually doing the rebuild, then they'd be responsible, or should be, for someone else screwing something up as part of that job.
I tend to fall into the same category as efharg. But I have access to a full automotive machine shop, most people don't. Then too there's the fact that the older I get, the less interested I seem to be in having to do things myself.

Not all dealerships are full service shops. Some sell tractors, but do little else. My local dealership has a decent shop, for instance, but I don't think they have the technical expertise to work on the construction equipment (track loader and track hoe).
Just because the dealership says so doesn't mean much, in light of written instructions. If the parts were mine, I would heat them to assemble. It certainly won't hurt anything.

 

[jkebxjunke]

j'junke, you would probably be right except that there are few if any dealer shops out there that do anything that resembles automotive machine work, and pressing a pin or re-bushing a rod usually falls into that category. They almost always farm that type of stuff out. Now if the dealer was actually doing the rebuild, then they'd be responsible, or should be, for someone else screwing something up as part of that job.
I tend to fall into the same category as efharg. But I have access to a full automotive machine shop, most people don't. Then too there's the fact that the older I get, the less interested I seem to be in having to do things myself.

guess I am spoiled with our dealer also being a full service shop...but then my local dealer has 3 dealerships... and shops in each one.. but it depends on which shop you go to... one did not want to put a creep gear in a M6800 by saying that they dont last and do not hold up and the other shop in the same company said they do it all the time and they do last. guess it just goes to show which mechanic wants to work.