Started cleaning the heads prior to disassembly. First cleaned the exterior of the head being careful to direct the stream away from the internals (I wanted to reduce the potential for grit getting in). Then proceeded to scrub the combustion chamber using a heavy duty green Scotch Brite pad which quickly removed the deposits. The interior surfaces of the head are all heavily varnished and it does not dissolve with the Dyna 143 but will scrub away via the Scotch Brite with some effort; I may try brake cleaner to see if that takes it off easier as there are too many crevices to scour by hand.

I plan on removing the rocker shafts to replace the broken rocker shaft spacer springs as well as to permit further disassembly to replace the valve stem seals.

 

Weather cooperated yesterday, so I rolled the engine block out to hone the cylinders and clean the oil passages.

Flex Hone recommends 600-900 rpm for bores from 2" to less than 3.75" which includes the 6G74's bore of 93mm (3.66"). The 1/2" Craftsman drill is rated at 600 rpm, so I used what have.

Flex Hone recommends 60-120 strokes/min (1-2 strokes/sec) which I interpreted as down and back. They also recommend 20-45 seconds per cylinder. With this information, I simply counted "one thousand one, one thousand two, etc" to pace myself for 45 seconds.

Pictures of honing showing before, during, and after. I took a video of the honing process but it is too large to post.

 

After all of the bores where honed, I proceeded to clean the engine block.

I used Dawn Soap and extremely hot water. Scrubbed the oil lines from the pump to the galley, from the galley to the mains, from the galley to the heads. Scrubbed the oil drain back holes from the heads, and scrubbed the cylinder bores several times.

After scrubbing, the block was flushed with extremely hot water (hose connected to full hot of laundry tub). After hot water flushing, I used an electric leaf blower to blow out all of the passages and to dry the bores and machined surfaces so as to prevent flash rust. Lastly, I applied WD40 liberally to the bores, machined surfaces, and oil passages to protect them from rusting.

These photos show the benefit of removing the oil galley plugs so that it can be brushed clean end to end. The 3rd oil galley plug associated with the pump feed is visible in the pictures but you can see that the flexible brush can get in and clean to the galley without need to remove the plug.

 

The oil galley plugs are part number MD040338 and have an 8 mm hex. I took one to a hardware store to try to determine the thread size in hopes of getting a cleanup tap. It appears to be 16mm but it would neither thread into the course or the fine gauges. I also checked it against the SAE thread gauges without success.

Fortunately, the new plugs thread into the block fine despite the damage sustained during removal. I will install them with Loctite 271 (red) and liberally seal the threads.

 

Cleaned all of the main bearings and mating surfaces in the block and girdle with lint free cloths and brake clean. Also cleaned the remanufactured crank and scrubbed the oil cross feeds with brush and flushed the feeds. The oil path to the rod throws is via drilled feeds to the main cross feeds; these are peened shut with what looks like a ball bearing so the feeds to the rods could only be flushed.

 

Checked main bearing clearance with plasti-gage. Plasti-gage on journal surface, torqued bolts to spec in 3 passes, removed bolts, use 2x to pry girdle off, and checked the net clearance.

Manual specifies 0.02 − 0.04 mm (0.0008 − 0.0015 inches). Close enough.

 

After checking bearing clearance, disassembled girdle bolts, and removed crank.

Cleaned bearings and journals with brake clean and lint free cloth. Then applied Lubriplate 105 to the main bearings and thrust bearings. Repeated assembly with torque again in 3 passes.

Spins nicely! Finally headed in the right direction!

 

Anyone had any luck cleaning the valve lash adjusters (VLA's)? Manual shows a 3 part diesel fuel bath process to segregate cleaning stages. Is each bath for all adjusters or one bath per each? The later uses more diesel and more soaking cups.

Or do folks just replace them? The engine has had a slight lifter tick since at least 40k and am now at 152k with this rebuild.

If you replace them,what brands have been good and which to avoid?

Edit 7/10/16 - mileage at failure was actually 173,875 not 152k

 

The 3 stage diesel fuel bath is for all lifters. This is done so that you progressively flush each lifter with cleaner solution by the time you are done with it. I'm sure some folks will disagree with me, but my personal philosophy is to clean and re-use the lifters unless they are collapsed and not working. If you are going through the 3 stage cleaning, at the end there is a specification how much lifter should compress. If it does not hold to that spec, then replace the one that is bad.

 

Thanks Hunter. I will try the VLA cleaning method when I get to that stage.