wrist pin bushings.

[07cl733]

I'm not sure if I need to start a new topic for my etech project, but I have another question and can't find many answers for it in any search. How can I tell if the wrist pin bushings are bad? This is a high mileage truck, 1.8 million, and I don't have any history on it for the first 1.6 million. The bushings are copper colored. Is that normal, or does it suggest high wear? The manual says you need a special press and broach to change the bushings. Is it possible to change them without these very expensive tools? New rods are much cheaper than the tools, but still $400 a piece. 

[BottleHauler84]

53 minutes ago, 07cl733 said:

I'm not sure if I need to start a new topic for my etech project, but I have another question and can't find many answers for it in any search. How can I tell if the wrist pin bushings are bad? This is a high mileage truck, 1.8 million, and I don't have any history on it for the first 1.6 million. The bushings are copper colored. Is that normal, or does it suggest high wear? The manual says you need a special press and broach to change the bushings. Is it possible to change them without these very expensive tools? New rods are much cheaper than the tools, but still $400 a piece. 

I always take connecting rods to a good machine shop. Im not sure if you have one local to you, but when putting new bushings in the small end of the rod, they need to be machined and sized to fit for proper tolerance spec to the wrist pin. The wrist pin bushings are bronze and need to be pretty precise. 

[davehummell]

There are two types of machines for rod bushing the one is a Sunnen hone which is the type I own and use and another type that I have seen used but I can't remember the name of the machine I just did a set of spindles for a 47 Cadilac pressed in new bushings and fit them to new king pins 

[Joey Mack]

If remeber correctly,  the clearence is .0015".

Can you post pics of the bushings in their current state ?

[Freightrain]

Most all pin bushings are copper colored,unlike rod bearings which have a copper base and metal coating on top.

.0015 you should just feel it wiggle,barely.  Not real scientific way to measure it but with skill you can tell if "ok" or bad.  Taking to a machine shop is best.  Any one with a pin hone will have the proper bore gauge to check it.  

When I did my 300, I have a Mitutoyo bore gauge that was able to check mine.  It was good enough not to need redone.

[Joey Mack]

Freightrain, I bet we have the same bore gauge set. Mine is in a faded orange case.  

Yes to the feel.... if they rock back and forth, its worn. If it slides smooth back and forth, they are good. Yes to the copper color.   

[Freightrain]

Typical 511 series, 2"-6" bore.  We have same kits at work but can go down to .75 bore with smaller head.

Similar to this.

 

[Joey Mack]

Oh hell thats nice.. pricy too.. 

[Joey Mack]

here is my old junk..  I bought these almost 30 years ago along with some 2-4'' mic's.  for $75.00 at a yard sale at an Antique store in Scarborough Maine...  I think it was called Centervail Antiques...  

[07cl733]

Thanks for all the replies. I do not have a machine shop close by, but may need to find one. I don't have any type of bore gauge that will come close to .0015, so I probably should find someone that does. Do you think a feeler gauge between the pin and bushing would be a good enough indicator? I'm trying to upload pics, but not having any luck. 

Would you normally have the bushings replaced, if worn, or get new/reconditioned rods? 

[07cl733]

Here are some pics.

[Joey Mack]

Well, for almost 2 million miles, I will say the bushings look great.  Do you have a .002'' thickness gauge or a sliver of steel shim paper to cut a thickness gauge out and use it to check the fitment?  If it was mine and on a budget, I would wash my hands good and dip my finger in some oil and feel the bushings for any grooves and go from there... This may not sound professional, but Ive done it many times..  

[Geoff Weeks]

Be careful of perfection being the enemy of good enough. What are your plans for this build? Another 2M miles build? or a engine that can go another 1m miles?

 Yes, there are specs for new parts, often there are spec's for usable wear limit. 

having built many engine with success, I would use my "mechanic's feel" for things like pin bushings. I know that isn't what the "book" lists as the spec for new parts going together, however as long as it is within usable wear limits it will give satisfactory results. Even slightly outside usable wear limits it would give a fair lifespan.

So this comes back to what your plans are for the engine. If you are doing it for hire, and offering a guaranty, then spend the money for reconditioned parts or to have your parts reconditioned.

If, however you are building for yourself, can accept a little risk, and have the basic understanding of what it required and can make your own judgement, then "feel" is good enough.

I see Joey was writing about the same time as I was.

[Joey Mack]

G.W.   There is truth to just ''Knowing'' it's good to go..  You speak a truth..  

[Geoff Weeks]

What many people fail to understand, there are spec's for new parts fitting together and "usable wear limits" which are far greater. If within the "usable wear limit" the mfg is saying it is good enough to be re-used. Not as good as new parts but not determental to placed back in service.

You use the 1st when assembling new parts together and the other when reusing parts that are already in service.

[Geoff Weeks]

I recently repaired a D950 Kubota, the useable wear limit was .2mm on the crank bearings, the 1st undersize on the bearings was also .2mm! 

While I doubt that engine would have good oil pressure if all the crank bearing clearances were .2mm (~.008"), when assembling a used crank with new bearings it would be highly unlikely that you would be far off the new part range for bearing clearances.

In my case the clearances were within the spec's for new crank (re-ground) and new bearings.

[Joey Mack]

Yep, that is why I suggested .002'' thicknes gauge... If it doesnt fit then it's good...

[07cl733]

Thanks guys! I do need this truck to work, but the reality is it has almost 2 mil on the chassis and another 250k would be a pretty good ride in my line of trucking. Your words make good sense. I'm going to think on it a bit and weigh my options. This already turned out to be more involved and expensive than hoped and I do need to get back on the road. The motor ran good with good oil pressure before this, a blown head gasket started me down this rabbit hole. Low liners lead to new liners, bearings and pulling the camshaft, which turned out to be bad and I'm trying to get the right balance of getting a reliable truck and not going broke. 

[Joey Mack]

sounds like you are on  a good path..  I expect you to be pleased with the end result as long as you stay diligent..   

[Geoff Weeks]

Like Joey, I would oil the bushing and push the pin through without the piston then see how much if any "wiggle" the pin has.

I had a job that required me to "break all the rules" of engine building. I found that you can get years of good results with used parts, even those swapped from another used engine. Ideal, no, but it taught me that perfection can be a bad thing just as wear can.

I have pulled dry liners out of one block to be inserted into another. I have replaced broken valve springs caused by excessively worn valve guide, on a hot engine on the side of the road, to have it go a few more year before the head of the valve dropped. The repair was only supposed to last the "season" and the head was supposed to come off. Promises made but not kept by the owner.

[07cl733]

I think this motor is a testament to what you are saying Geoff. I found 3 different kinds of lifters and the connecting rods aren't all the same either. I've felt the rings have been sticking since I started running it and pulling a couple off has proved that true. I still feel its been a good motor that pulls strong and makes good fuel mileage. 

[Joey Mack]

I'm telling you  The mack engine is a tough S.O.B.   

[Geoff Weeks]

32 minutes ago, 07cl733 said:

I think this motor is a testament to what you are saying Geoff. I found 3 different kinds of lifters and the connecting rods aren't all the same either. I've felt the rings have been sticking since I started running it and pulling a couple off has proved that true. I still feel its been a good motor that pulls strong and makes good fuel mileage. 

So you are saying it has been apart before? Still that isn't all a bad thing. things replaced before they cause more damage.

[07cl733]

It has definitely been rebuilt somewhere in the past and I have put head gaskets in it once before, also. I didnt realize "in spec" wasn't necessarily good enough for the liner protrusion, so I just bolted it back together with new gaskets. I got over 200k more miles out of it for $500 and my labor. 

And I totally agree with Joey Mack, these things are tough! And I'd like to keep this old dog barking a while longer. If this truck were what you got when you bought a new one today, I'd be making payments. 

[Geoff Weeks]

I got 1.3m out of original build on an 855 Cummins. The rest is hard to say as they were all overhauled at some point before I got them. 

At 1.3m it had no problem running, just a problem keeping oil off the outside, it leaked from just about every gasket. I ended up doing an out of chassie overhaul on it. ($1500 in parts). AFAIK it is still running today.