Main and Rod Bearings CM870

[Rawze]

I have always gotten the bolts to go to 180 on the main caps. I use a 3/4" air-cat with a single heavy-duty 15/26" (because its slightly tighter than a 24-mm) deep impact socket 6-points only (no extensions or adapters) with about 180-PSI on the air compressor.

The socket is face-ground nice and flat on its end each time its used, to grind out the wear from the last time it was abused by that much torque. The bolt is marked + socket itself is marked so that I can see the rotation.

The bolt itself is dampened with tiny bit of ultra-slick on the bottom side of the head and threads also slightly dampened with engine oil (but not soaked in it), so that it does not bind or gall.

- It could be that your torque wrench is not accurate and that you over-torqued the bolts initially?. Something seems off in your statement about how tight they really are ... because they are usually about the 485-520 ft.lbs range or so by the time they get to 180-deg. Granted that is a lot of torque, but not really much more than a set of lug-nuts on the truck would be.

Just for reference ... my 3/4" air-cat advertises it is 1600-ft.lbs.. but it struggles (and will not quite make it) to get them all the way to 90-degrees unless I bump the air compressor to above 175-180 PSI + use a 1/2" line with NO QUICK-CONNECTS between the tank and the gun. Then it will get them there.

- SO much for the advertised 1,600+ ft.lbs eh?... but that is typical advertising for ya.
I have this one: https://amzn.to/3H2fLRV

I use truck glad-hands on the gun instead of quick-connects to prevent air-line restrictions... and even if the hose is really long (more than about 30 feet), then it will get weak.

so .. it could also be your air-line setup. - Long hoses and ANY quick-connects .. even a single 1/2" quick-connects in the line will cause far less torque.. even in that 1" gun that you mentioned there. i see a lot of shops with quick-connects at the wall pipe ... + another one at the gun sometimes ... and then wonder why they can't get things as tight as they should be when verifying with a torque-wrench.

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About the pre-lube...

I use an electric oil pump. I remove the check-valve at port #2 in that pic you posted and yes.. I turn key on and watch gauge in the dash for about 20 psi or so. - I have pan draining into a clean pail to recirculate the oil several times thru. Oil pump has an inline oil filter on it to keep the oil clean (because I use port#2 to get good flow and this bypasses the engine oil filter) .. and pump runs and circulates the oil several times thru .. all while someone bars the engine over by hand during the pre-lube phase.

- We watch the top-end for proper oil flow (valve cover off), and when it starts oiling really good in the top-end and there is about 15-20 psi on the oil gauge + feels good by hand turning the engine .. then we start buttoning it all up + re-install the updated check valve at port#2 .. fill the engine with the oil, and then crank engine with fuel/timing solenoids (or injector harness on common rails) unplugged so that if will not fire up .. until we see a few psi on the oil gauge in the dash just from cranking it.

After that, we finish priming the fuel system and start the engine for the first time.


When I build an ISX with someone here at the house, I get all the air out of the fuel/oil systems which takes about 10 mins or so of low rpm idle,. feathering it, etc.. , I make damn sure there is no air left in the oil/fuel system and that its all good pressures, no leaks, etc.etc. --> Once we are satisfied that everything is right with it ... I then slam the accel pedal all the way to the floor, let it rev all the way,.. then back it off only very so slightly so the rpm is only about 5-10 or so rpm less than its governed max. I leave it there, not moving the fuel pedal at all (big wrench in hand, between fuel pedal and the floor to help keep me from moving the pedal again) - for about 8 - 10 minutes solid. Me also though, being very cautious about it, listening and feeling for anything that might not be 100% perfect, and checking for anything that might be causing any buildup of internal resistance. Scares the hell out of the truck owner. lol

While holding the rpm by hand at a just a hare under its max, not moving the fuel pedal at all, ... if the engine starts slowing down at all then I know there is excess friction in it, and that it needs to be shut down because something is wrong internally. -- If it holds steady just under max rpm (just shy of the speed governor) without moving the pedal at all, then there is nothing to fear.

After that, I drive the piss out of it around the neighborhood for a bit, then straight to somewhere to change the oil again a second time after about 30 miles or so of horsing around with it. then ., Back home, then re-run the valve adjustment a second time after it cools back down.

That is how I do it anyways,,. call me crazy .. but I do everything by hand + use a damn torque wrench on everything.. and am super-anal about every single part, gasket, component, screw, etc.. on how it goes together. I leave nothing to question or chance. If something is going to fail, I want it to show up right now, and not 3 days or 3 weeks from now.

I also re-use the old engine oil that came out of the engine initially (before the tear-down) when priming it, unless something is wrong with that oil. That or I use some really cheap-o farm tractor oil. Remember .. Its going to get contaminated with assembly lube, spray residues, and all kinds of bad stuffs .. so it needs to be dumped in about 30 miles or so. There is no sense in putting brand new, ex$$pensive quality oil into the engine if it is simply getting dumped an hour or 2 after it is put in. Saving the old engine oil (and keeping it clean) if it is still in good shape is perfect for this unless it got contaminated.