ISX cm871 in frame overhaul nightmare

[Rawze]

Now, with that out of the way...

FIRST AND FOREMOST... If the head is removed from an ISX .. IF THE COUNTER-BORES ARE NOT CUT AND THE LINER HEIGHT RAISED TO AT LEAST 0.015", up form 0.010", then YOU HAVE DONE ABSOLUTELY NOTHING TO EXTEND THE ENGINE'S ACTUAL LIFE-SPAN AT ALL to ready it for its next million miles of expected use after the inframe!... YOU HAVE GAINED PRETTY MUCH NOTHING! towards extending the engine's life. Does not matter what condition the mid-stops were in.

- This also means REPLACING ANY HEAD THAT IS MORE THAN 435K MILES OLD (wear, age, and compression loss due to valve seat wear, etc has now started setting in) .. OR IF THE HEAD GASKET FAILS ON ONE!!!... This is because first and foremost,.. the head gasket will never fail unless it was defective (and it failed very early in the engines life from the factory or it is an aftermarket garbage gasket) ... unless a liner moved... PERIOD!. There is no exception to this.. it has never been seen!. Many shops that replace only head gaskets are just not trained enough to spot fretting wear properly and all they do is a simply check of liner height like complete fools and let it go. this is because liner height check alone is not nearly reliable enough to show the the actual cause of failure in many cases. Like dumrarsses! they change only head gasket and even worse,.... try to re-use the head, ... because they never bother to check for the 0.001" to 0.002"+ fretting wear that occurs on the bottom of it where the liner was sitting. This is much harder to spot, but can be checked for. -- Like I said... complete lack of proper training and lack of education towards the precision these engines need to be done properly!.

And since a liner moves to cause the head gasket to fail.. it ALWAYS FRETS A FEW THOUSANDTHS OF AN INCH UP INTO THE BOTTOM OF THE HEAD!!! ... the the holding/clamping force for that cylinder will be a couple thousandths shy in that area,.... might as well have the wrong liner height.. this is what it is the equivalent to. - here is an example...
http://rawze.com/forums/showthread.php?t...48#pid7648

and it also DOES NO GOOD to replace the cylinder liners, pistons, etc.. on an ISX whatsoever during an inframe IF THE BLOCK IS NOT COUNTER-BORED!.. it does not matter if the liner height is up to cummins spec., or of it does not look like it has ever fretted... NOT COUNTER-BORING IT WILL NOT EXTEND THE ENGINES LIFESPAN -- so.. THIS MEANS THAT WITHOUT COUNTER-BORING AND RAISING LINERS, THE ENTIRE OVERHAUL-- only stopped any oil consumption issues and nothing more!. IT DID NOT EXTEND THE ENGINE LIFE ONE DAMNED IOTA AND IT WILL STILL HAVE TO COME APART IN HALF ITS EXPECTED TIME FRAME because no one counter-bored it AND THE MID-STOP FINALLY WORE IN ENOUGH DUE TO AGE AND USE WITHOUT BEING RE-MACHINED AND RAISED.

I see shops do this like mad, then the truck owner is wondering 3 or 4 years later why his engine has to be inframed yet again!, blaming the engine instead of the lack of proper workmanship by the place that could have made that difference towards building it into another million mile engine.

- A minimum liner height if 0.014" - 0.015" should be used/set with counter-boring every time an engine comes apart and it has more than 400k miles of run time on on it already. This is a MUST if you want it to last a full million miles the next time around without fail, and especially now that they all have brass shims and anti-carbon rings now . You loose 0.001" - 0.0015" just in the brass shim crush alone when he head to torqued. ... Anything less, and your just wasting someone's time and money!. - People spend upwards of $20,000 dollars because they EXPECT A POSITIVE RETURN ON THAT INVESTMENT into their equipment,,. and they can't get that if in 3 or so years, they have to spend this much all over again. I blame the shops and their serious lack of understanding on these engines for this and it can totally be prevented by using better procedures and standards.


- NEXT::: Is the fact that most shops any more will not let the head gasket crush properly on the ISX... I guess the ways of proper engine rebuilding have been thrown out the window these days. -- WHEN the head is installed... and then torqued to 300 ft-lbs.. IT NEEDS TO THEN SIT OVER NIGHT FOR THE HEAD GASKET TO CRUSH!... THEN THE NEXT DAY, THE 300-FT.LBS DONE A SECOND TIME... BEFORE MOVING THE BOLTS TO THE +90 DEGREE POINT!. MOST OF THE TIME, THE BOLTS WILL TURN A BIT MORE THAT NEXT DAY BECAUSE THE HEAD GASKET SETTLED AND CRUSHED PROPERLY!.. Most shops are in too much of a goddamn hurry to do this any more and don't bother.. then wonder why the engine has issues again.

And lastly.. ON ALL HIGH COMPRESSION ENGINE MODELS-- Cm2250, 2350, X15, etc... after 400k miles of run time,.. if the pistons have to come out for any reason.. THE BRASS WRIST PIN BUSHINGS IN THE RODS NEED TO BE REPLACED!!! PERIOD!.. THE higher compression ISX engines have already been seen to have accelerated wrist pin bushing wear, so if this is not done, it will be a ticking time bomb waiting to send a piston thru the block about 600 - 800k after the in-frame and ruin someone's day unexpectedly.