I worked all this week on the Catalyst, continuing the big winter project.
I started out by measuring the crankshaft to figure out whether or not the journals are egg-shaped (which could, if you remember last week’s entry, be one reason that the bearings are cracked up). I took a lot of initial measurements and found that it’s out-of-round about three thousandths of an inch at most in a few places. I’ll polish it and then check it again, but it’s not totally out-of-round. Number six journal is the most round, so it was probably machined “recently” – which means probably more than 25 years ago, since Dan and I know all the owners since then and none of them had it done.
I went up to Everett Engineering to talk about the rod bearings and borrow a tool (more on that later). It turns out that they’re too swamped to re-pour all of the rod bearings on our time-frame, but they know of a shop in Utah (Utah Babbitt Bearing Specialists Inc) that can do it pronto. After they’re poured, the bearings will go back to Everett Engineering for machining. They’ll touch up the spares at the same time.
I picked up the pistons and brought them to the shop to for cleaning, then on Wednesday I started measuring radiuses. The tool I borrowed from Everett Engineering is a radius gauge, which I used to measure the fillet radiuses on the edge of each journal. Everett needs to know exactly how big they are so that they can cut the fillet radiuses into the bearing babbitt. Cylinders one through five have five-sixteenths-inch radiuses, but number six has a three-eighths-inch radius with a 45-degree flat bevel on it, which is weird (see Week 36).
Then I started cleaning parts. I had the valve cages and valves in my shop, and I ran them all through the hot tank (which is filled with hot lye) in batches. I then sandblasted them, then ran them through the solvent tank to get all the sand out, then sprayed them down with brake cleaner to get all the solvent out, and then put them on Dan’s desk so that he could do the grinding (it’s his machine, and he likes grinding valves). I also wire-brushed the stems to clean them without taking off too much material.
While I was cleaning them, I noticed that three of the main valve nuts on the top of each valve were different sizes from the rest, so I hired Grant to make three new ones the same size as the rest. Valves should be rotated every so often, but Catalyst‘s haven’t been very often since it’s so hard to get a wrench in there. I’m going to make a fancy wrench so that the engineer can get in there and rotate all the valves regularly, but all the nuts need to be the same size so that one wrench will fit all of them.
I went back up to Everett on Thursday to return the radius gauge and talk more about the bearings, then I went back to the shop to start cleaning cylinder heads. I used a chisel and a scraper to get all the big chunks of carbon off, then I 3M pads and a flapper wheel to get the rest off. There was a lot of black carbon (soot) that needed to come off, as well as white chunky stuff that I’m assuming is sulfur. The heads were really dirty, since they haven’t been cleaned in a while and the engine runs a lot.
On Friday, we started looking at the main bearings. We used plastigauge to measure how much clearance the main bearings have, which is a thin little wire of plastic that goes between the crankshaft and the top half of the main bearing shell. We bolted the bearing down tight around the plastigauge, then unbolted it and pulled the top half of the shell off, and measured how much the plastic squished.
We then compared the measurements against what’s specified in the Washington owner’s manual to make sure that the bearing clearances were within the right range. Too little clearance and the bearing can get damaged from the heat of friction, while too much clearance can mean low oil pressure, since oil will flow through a gap and drip down into the crankshaft rather than staying on the bearings (this can also mean that less oil goes up to the rod bearings and wrist pin bearings, but this doesn’t seem to be happening on Catalyst). Having the right amount of clearance means that the crankshaft is perfectly balanced and can run for a long time without any issues. Since one of the problems we’re trying to solve during this repair period is low oil pressure, we wanted to make sure that the main bearing clearance was fine.
Sure enough, we found a lot of extra clearance (about 13 thousandths of an inch, when it should be around four thousandths), which is a likely cause of the low oil pressure. This is pretty typical, since over time the bottom half of the bearing wears down and the crankshaft sinks down into it, making a gap between the crankshaft and the top half of the bearing. The reason the gap is so big is probably because the main bearings haven’t been looked at in a long long time. Main bearings are hard to look at and the process is kind of scary, so it’s easy to put off. I should clarify that we have been strain gauge the crankshaft every year to make sure that the bearings are wearing evenly, which is the most important part, but it’s important that they’re tight enough to hold oil, too.
After checking the clearances, Dan came down and we started rolling the bottom half of the main bearings out to inspect them. These are a curved piece of forged steel with babbitt in the concave side, which fit into the bed plate between cylinder bays. Each main bearing has a cap that sits on the top; when you take the cap off there’s an oil hole underneath on in the crankshaft. You can put a bolt into this hole and then rotate the crankshaft around by hand, which will rotate the bearing all the way out so that you can lift it right off:
This lets you really look at the babbitt, measure its thickness for wear, and make sure that the crankshaft is riding smoothly and evenly between each bearing.
The first main bearing we rolled out was number five. Its surface was wavy, sort of like the surface of the moon. Yikes! We rolled out another one, and found that it was okay. Whew! We’ll roll the rest out next week, and hopefully find most of them okay. Any wavy ones will need to be re-done.
A brief note on election night
All of us at Old Tacoma Marine are glad the election is finally over and we will enthusiastically participate in changing what it means to be an American for the better under our new inspirational leader.