inspecting main and rod bearings

[ktbtrucking]

Have a truck with cm870 with 1.2mil miles. The main and rod bearings were never changed. I bought a new set and studied a quickserve procedure with dissasembly and assembly but looks really difficult for me at this point. Maybe I will start with just inspecting them. Truck is at my lot and I have some time to work on it. Any suggestions regarding inspection? Also watched Rawze videos about overhaul.

[Brock]

I've never rolled my bearings myself, always paid a mechanic to do it but if your taking them off to inspect them.... isn't 75% of the job done? Don't you just use the one from the cap to tap out the upper bearing and slide/tap the new one in, put a new one on cap and reinstall?

[Rawze]

(10-25-2017 )ktbtrucking Wrote:  Have a truck with cm870 with 1.2mil miles. The main and rod bearings were never changed. I bought a new set and studied a quickserve procedure with dissasembly and assembly but looks really difficult for me at this point. Maybe I will start with just inspecting them. Truck is at my lot and I have some time to work on it. Any suggestions regarding inspection? Also watched Rawze videos about overhaul.

My suggestion,... have someone who knows what they are doing help you on it if there is any question. Also, your going to need a honkin' big air gun (a 3/4" air-cat comes to mind) on the main cap bolts. Those things area bout 450-500 ft-lbs when torqued properly. Follow torquing procedure in the book carefully and mark all bolts with arrows so that you know if they have been rotated correctly according to procedure.

[Nilao]

Yeah, they have to be rolled out, journals thoroughly cleaned and new bearings rolled in with assembly lube on the inner surfaces. You want no oil or assembly lube on the back sides as they have a small possibility to spin on first start up if there's lube on the backs.

[ktbtrucking]

thank you for all the replies, have a truck it is mine and I understand the engine is worn out with 1.2mil miles, do not have to drive it anywhere anmore and I am glad that it did not break down over the road so far, just have some time to assembly/dissasembly parts just for knowlegge how things work, have also started other thread http://rawze.com/forums/showthread.php?tid=2278,
dropped oil pan and dissasembled driver side of the engine to locate engine oil leak (just to kill some time with friends)
no work on bearings now( you need some good clearance under to do it with no stress I bet)

up to the point, put everything together with new oil , after start up blowby is really low , have not screwed rocker cover at all just covered, after around and hour of PTO idling have some really bad oil leak form rocker cover,
tightened rocker cover up and started an engine ( watched isx oil lubrication system on youtube to know how things work)

removed the oil fill cap and have some steady blowby there with some oil blowby from crankcase breather too ( if I compare to youtube videos it does not look bad with my engine) but looks like have some extensive pressure buildup under rocker cover because there is a lot of flow form oil drip channel located at the back driver side of an engine ( from a schematics it is oil drip channnel directly from head to oil pan) so i assume there is a lot of compression going from oil pan up to rockers area
Just would like to know how things work? Apologize for long post though .