As I mentioned, my engine is a horizontal and like the block you show, that opening was not used nor was a block off plate shown in the parts book. I could not figure out what it did either. I did not block it b/c as you decided, you would loose ALL your oil pressure is it were meant to be blocked.
I set the pressure regulator on my air compressor for 50 and with an adapter (I forget what) I blew against the relief valve and found it opened below 50 so I turned it in till it opened at 55.
Checking the clearance with plastigauge is definitely on my list. I intended to do that last night but I couldn't find the plastigauge left over for my last project. I'll pick some up tomorrow.
Be advised at16 knots the boat will get squirrely. I think it's called "chine walk" where it will go from side to side It is unavoidable, it's what the boat does. Feels like it is going to flip over but it won't.
I haven't got a smoking gun yet, there is way too slop in the thrust bearing, the crank may have self clearanced itself against a main bearing cap, I don't see any shiny or full spots from wear. I have cracked all but the first main cap loose, I have only pulled main cap #7 so far, it showed more wear than the connecting rod bearings.
I really don't know for sure, my best estimate is between 4500-5000 hours. The hour meter was at 750 when I purchased in 2021, it had clearly been changed. A survey from 2010 (or so, I forget the date) reported the hours to be 3500 at the time.
Sounds similar to our story. We too have gotten plenty of use while saving the maintenance chores for winter layup.
I have considered white, and now would be the time to switch it. It is currently a mix of Ford blue and crusader blue which is pretty close to Perkins blue. I think it will be light enough to allow for good inspection. Once I get the bilge painted and some lighting down there, I should be much improved.
I haven’t ordered it yet but will be replacing it. I have a growing list of additional parts to order, most will be through TAD. I am not looking forward to the expense but I need to order new engine mounts as well. That will be around $600 or so. Overall it is a relatively cheap project for the benefit it should provide. Just time consuming.
Be careful grinding a crankshaft. I know of 2 Perkins cranks that broke within a short time after being ground. It has to do with grinding into the heat affected zone on the journals.
Thank you for pointing this out. The nitrated crankshafts have limitations on being re-ground. Based on the stamped numbers on the crank, I believe mine was induction hardened and not subject to the same limitations. Fortunately I have the shop manual thanks to this forum which includes the casting numbers and treatment of the various cranks used.
Turns out that I don't know what I am looking at. I dropped the crank off to the machinist this morning who assured me it was a nitrited crank in spite of it not having a casting number that shows up on the workshop manual. He is going to magniflux it for cracks first and believes that 20 thousands will do the be adequate for the damaged main journals. Surprisingly, the thrust surfaces which were riding against the copper base of the thrust bearing looked fine and measured out in specs
The #4 main journal was close to 10 under due to the wear. There was shavings in the oil pan from the crank scraping on something.
