I pulled the pan of my mystery 302 (1971 block, mileage unknown) to deal with an oil leak. It had a 4 piece gasket with lots of blue silicone, and a definite leak at the rear where the squished out silicone made a giant shelf to hold outbound oil. So, my questions are more related to what should be typical to find inside the pan, and what should I take note of while it is down? I have found: The small valley next to the drain plug was full of mud. At the bottom of it next to the pan surface were small, sand sized grains of steel? seemed like round granules. What I have noticed: timing chain looks like stock type, about 3/8" of slack......rods and caps are numbered according to cylinders, cylinder walls do not have obvious cross hatch looking up at the ones I can see. Generally, it looks dirty, but no build up. sides of the oil pan are just oily. 1. does anyone care to guess how many miles create 3/8" slack in the chain? 2. If it has been converted to a one piece rear main seal, and I pull the cap hoping to put in a new 2 piece in there, what have I created for myself? I dont think it leaks....but can you tell if the pin that holds the rope seal has been removed without pulling off the main cap? If It is possible to tell the pin is gone, I will assume I dont have rope at least.
If it currently has a rubber type rear main seal...The pin is gone... 1971 vintage block is not a one piece seal. Rods/caps are numbered...Someone has already been through that engine once. Check bore diameter. You really don't want to go more than 40 over on the cyl bores. 3/8" slack in chain...its stretched yeah... Type of use is as much a factor in chain wear as miles so... on the miles....Muck in the bottom of the pan is not unusual on engines that have been around the block for 20 yrs or so. Granular metal bits in the pan though...Could be from a wiped cam lobe or three, stick a magnet in em and see what sticks.
The metal looked like small chips (about .040 x .060) and chards...in the bottom of that thick mud, so I am guessing they have been in there awhile. But, if they are in the filter too, then it is ongoing? So I will investigate that tomorrow.
after consulting the internet for filter dismantling instructions, I removed the paper core and found lots of debri in the bottom of the can. it turned out to be non magnetic mostly, but metal filings were on the formerly clean magnet. I didnt bother going through the paper much, as I figured what I saw in the can was a good sample? carbon chips?
It used to be common to find bits of white plastic(nylon) from timing gear & black chunks that were disintegrated valve stem seals. Not uncommon for the stem seals to lock up oil pump. I don't remember anything but a little sludge in pan of my old 302, apparently off sometime prior. Chain was sloppy and gear badly worn, but had full steel timing gear(guessing orig), heads were 1978.
How many miles to that amount of slack ? With the stock type chain ? Not many. You can't convert a two piece rear main to one piece
Baddad457 is correct. By removing the pin from the cap, if you can, it will allow you to use a 2 piece rubber seal instead of the old rope seal. You need a newer roller type block to use a 1 piece rear seal.
One piece seals began in those dark days of the DOAE blocks in the early 80's a couple years before the 85 roller block.
