Tuesday, June 3, 2014
'Basics boy, Basics'- Part 2
The inspection had thus begun in the mystery of the smokey diesel.
Here comes part 2.
After dismantling the valve assembly, the first thing I noticed was heat damage on the intake side rocker arm assembly- discoloration of the metal and ground-down sharp edges on the rocker arm and the thrust washer that holds it on the shaft and no oily feel to the parts at all. Eek, the rocker arm and its associated parts had not gotten any lube- not good.
Right, so no oil to the intake side valve assembly- that sucks. I see small holes drilled into the top of the oil galley in the casting of the valve cover that are intended to spray oil at the rockers and valves, so I inspect further.
Screwed into the top of the valve cover oil galley is a plunger attached to a red indicator that, when pressurized by the oil pump, rises up about 3/4” (19mm) and out into a clear plastic bubble for visual verification of oil pressure. Well, the oil spray holes would only be exposed to oil pressure once oil pressure had pushed that plunger up out of the way.
After some measuring, I realized the plunger could not move out of the way of the top-most hole even pushed all the way to its mechanical limits. The top hole was the one that was almost- but not quite- aimed at the intake rocker arm bushing.
The intake valve assembly had never seen correct oiling and the rocker arm had destroyed its own bushing because of it! Sheesh! I find myself amazed at the hundred or so hours the engine has run already without proper lube to the valve-train.
Finding no major damage beyond the bushing and the thrust washer, I decided that I could replace the bushings, find a new washer and clean things up with a file and some emery cloth to take off the burrs and ridges, and create tooth to carry and hold oil.
Knowing that the bushings were getting no oil, just replacing the bushings and putting things back the way the manufacturer built it, that 'fix' would only have lasted a little while again. I smell a corrective hack coming on here...
First, primary cause of failure: lack of oil to lube the rocker arms. Since the alignment of the spray nozzle holes was not even close to optimal for oil spray to lube both ends and the center bushings of the rocker arms, I filled those holes with epoxy after a repeated and thorough solvent cleaning and scrub off the area with a brass brush.
Next I drilled two 3/16” (4.8 mm) holes aimed toward the top of the rocker arms and epoxied a copper 3/16” tube into each of those holes to direct oil to the top of each rocker arm. Anticipating gravity will function predictably, oil will run down the rocker arm, getting some caught along the way to lube the center bushing, and drippings to lube the bottom end where the ball end of the push-rod engages the rocker arm.
Then, using a sharp file, I carved oil catch grooves in the rocker holder to help guide oil into the center bushings more effectively.
Next, I found, to my amazement, that Amazon.com has bushings of very high quality. Good bronze bushings. Nice. Got them the next day (thanks Prime) and began the install. I cut the bushings diagonally end-to-end with my Dremel and a cutting disc as an oiling groove. I then used a propane torch and plumbing soldering techniques to solidly anchor the bushings into the center of the rocker arms.
Since I didn't like the silly oil pressure indicator setup anyway and I'd rather a gauge for accuracy and/or switch for alarms or shutdown. So in order to evaluate options, I checked fittings and found, to my great astonishment, the threads the Chinese manufacturer chose are NPT compatible!!
So I removed the cheezy plunger/ indicator system and used standard brass and steel parts from the local hardware store to plumb in a pressure gauge and switch for safety and better accuracy. This hack also accomplished the additional goal of removing the plunger so the oil sprays immediately and directly onto the valve-train components unimpeded instead of having to wait for oil pressure to push the plunger out of the way.
I fully expect epoxy, soldering, and cleaning process I used to survive the environment inside the engine, so I have no doubt all will be well for years to come. The new system will get a few hours to run and a re-inspection before I post success for the repairs and upgrades.
The moral of the story is that sometimes the engineers and builders screw up. Sometimes a good hack is the only way to keep things going. Sometimes, the worst thing you can do is put things back the way they were by just replacing parts that failed. Finding the root cause of the failure is the only way to assure an actual fix and long term reliability again.
Cheers, and til next time... MW out!
UPDATE: Yep, all is well. After about 30 or so hours of running, and one adjustment to tighten valve clearances, the rocker arms are both covered in oil every time I open the cover, and everything is still tight and operating perfectly.