Liner Height

[Mr Hagg]

Ok so I have a 2009 ISX CM871 that punched a hole in the side of the block (looked like possible piston cooling nozzle clogging from the truck owner using a Non-fleetguard brand of oil filters. cylinder ran dry of oil). The customer was on a budget. With his core being no good I had to build him up an engine as he didn’t want a used one. So I thought I would just buy a new Cummins short block and a brand new (not reman) OEM head.

So we got the block and it looked new and it was very pretty. When I open it up, I saw what appeared to be the writing or what may have been the liner height. It was (12)(11)(11)(10)(11)(12) I didn’t like what I saw so I pulled the liners down and checked it my self. Boy was I shocked. Both sides I checked as follows (11/11) (11/10)(10/10)(10/12)(11/10)(12/12)…

So I called Cummins and asked about it. The first question I got was “ And may I ask why you were checking?” Well hello I'm building a $20K engine and I don’t want any warranty issues. I could tell this was going nowhere and was told it was within spec…….

Next step was to call Rawze……He said he didn’t doubt it and advised me he would help us out and cut/machine the block for us for free to help the guy out. So We took that NEW short block and dismantled it. Another shock came when I saw the rings come out and the gaps were only 1 ½ inches apart instead of 180 facing away from each other. This thing would have burned oil for sure.

Well I ordered new shims and Rawze came over and checked out this mess. He then said the block was a bit off when they machined the top deck. Well he spent about 8 hours on it honing it and re-cutting counter-bores. I was busy so I did not get to put the liners in to check it and make sure it was like he wanted as far as height goes. So tonight I checked them…

All you guys know how annul he is. I now know firsthand…..Well I checked and the picture speaks for it self… ALL six are now setting at .014 dead nutz. So insane precise you could not even see any variance in the needle of the indicator from one side to the other, nor from hole#1 all way to Hole#6 across the entire deck. To think he did all of it by hand too.

Some people do not know Rawze or may say he is an arse sometimes but when it comes to perfection hands down this guy is it…..

Thanks Rawze for helping this guy out and giving us a hand in fixing this engine……..

[Hammerhead]

Hey Rawze when it's time to inframe mine, instead of spending the money on the counterbore cutter and stuff, can I just hire you and fly you and your tool up to do mine instead?

[Rawze]

(01-25-2017 )Hammerhead Wrote:  Hey Rawze when it's time to inframe mine, instead of spending the money on the counterbore cutter and stuff, can I just hire you and fly you and your tool up to do mine instead?

I had traveling jobs almost my whole life and have been all over the world...

I stay at home now.

[Hammerhead]

(01-26-2017 )Rawze Wrote:  I had traveling jobs almost my whole life and have been all over the world...

I stay at home now.

Did I mention; I don't work hard, I don't work fast, I have beer, whiskey, rum, vodka, and Canadian Ice Wine...and love to take breaks and sit around talking theory?

[un_yun]

Does raising line hieght help because of a tighter seal on the combustion chamber or because it lowers the compression ratio slightly, thus lowering cylinder pressure? Was thinking about this the other morning @ 3 am. In theory it would lower compression a bit wouldn't it? Which would reduce stress on the internal's and make the engine last longer and able to handle more power.

[Rawze]

(01-26-2017 )un_yun Wrote:  Does raising line hieght help because of a tighter seal on the combustion chamber or because it lowers the compression ratio slightly, thus lowering cylinder pressure? Was thinking about this the other morning @ 3 am. In theory it would lower compression a bit wouldn't it? Which would reduce stress on the internal's and make the engine last longer and able to handle more power.

It does neither...

What it does, is when the head is installed, it increases the holding pressure between the bottom of the head and the mid-stop in the engine block. This makes the liner significantly "tighter" in its seat so that it is less prone to vibration, fretting, and outer cylinder wall cavitation from the coolant ...






I know this video is about cavitation.. but it also shows the cylinder in motion quite well too ...
Watch the video at 24 seconds into it. You can see that when the piston fires, it tends to press not only downward, but in the opposite direction of the connecting rod, making it press harder to one side. In an ISX, this is the exhaust side. That is why liner fretting always starts on the exhaust side of the liner.

[un_yun]

Thanks!

[Running rough]

Anyone know if cummins is incorporating 'offset bores' on the piston pins, I know Most new Deere engines use offset bores and they claim a lot less piston slap and liner side loading and vibration on the powerstroke, it is just a slight offset

[Hammerhead]

(01-26-2017 )Running rough Wrote:  Anyone know if cummins is incorporating 'offset bores' on the piston pins, I know Most new Deere engines use offset bores and they claim a lot less piston slap and liner side loading and vibration on the powerstroke, it is just a slight offset

I haven't had anything to do with farm equipment in quite a few years, so forgive me if I'm mistaken, but are Deere's big tractors not powered with QSX's?

I am quite interested in the offset bores, can you please, or do you know where to get more info on this?