Can debri fall thru crankshaft flywheel bolt holes into oil sump?

robthechemist

Member
Mar 30, 2019
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5
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Los Angeles, CA
I had to helicoil one of the flywheel bolt holes in my crankshaft. In the process there was some metal shavings that I cleaned out best I could. I am curious if its even possible for them to get into the oil and cause damage? Or is the tiny area behind the back of the crank separated from the internal engine? It is a 1966 mustang with a 302 from a 1974 Maverick. So 74' 302. Please advise. I do not want to start her up before being certain about this. :) Thanks in advance!
 
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stormsedge

Active Member
Jun 17, 2018
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E. TN
To reassure yourself, take a Google at a '74 302 crankshaft photo. Note that the flywheel flange is outside/aft of the rear main seal, so no metal filings could enter your engine (unless you had the oil pan and rear main cap off at the time, then maybe). I've encountered many crankshafts (that doesn't sound right :( ) while working in auto parts and service and cannot picture one that had the potential to cause the issue you describe. Even the unflanged crankshafts that one might think would be an issue (no outside flange, just the round crank end almost flush with the rear main) are not, as the ones I have seen all had blind bolt holes. Not to say there isn't something out there drilled through to the crankcase, but your 302 isn't one of them.
 

Billm

Member
Apr 16, 2014
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Interesting question. I have had oil seep past flywheel bolts if they are nor coated with sealer before tightening. I also have had a 289 tip over and pour oil out of the crankshaft bolt holes. I learned the hard way about transporting an engine with oil in the pan and no flywheel bolts installed. The engine was resting on a wood n box in my van and strapped down. Had to make a panic stop and the engine tipped and oil poured out of the flywheel bolt holes. Could you run a small magnet in the bolt whole and see if you gat any shavings? Maybe put a magnetic drain plug in. Flush the bolt hole out by sealing up the other holes with bolts and sealer on the threads. Then spin the oil pump as if you were priming the motor and flush the bolt hole with oil?
 

robthechemist

Member
Mar 30, 2019
12
5
13
32
Los Angeles, CA
To reassure yourself, take a Google at a '74 302 crankshaft photo. Note that the flywheel flange is outside/aft of the rear main seal, so no metal filings could enter your engine (unless you had the oil pan and rear main cap off at the time, then maybe). I've encountered many crankshafts (that doesn't sound right :( ) while working in auto parts and service and cannot picture one that had the potential to cause the issue you describe. Even the unflanged crankshafts that one might think would be an issue (no outside flange, just the round crank end almost flush with the rear main) are not, as the ones I have seen all had blind bolt holes. Not to say there isn't something out there drilled through to the crankcase, but your 302 isn't one of them.
Excellent point. This is exactly what I did actually. I looked up pictures/ videos and I came to the same conclusion. However my crankshaft bolt holes DO drill all the way through. However, they still seem to be outside of the rear main seal. Careful with those crankshaft encounters... sounds like a new craigslist category! ahahhahahaha :)
 

robthechemist

Member
Mar 30, 2019
12
5
13
32
Los Angeles, CA
Interesting question. I have had oil seep past flywheel bolts if they are nor coated with sealer before tightening. I also have had a 289 tip over and pour oil out of the crankshaft bolt holes. I learned the hard way about transporting an engine with oil in the pan and no flywheel bolts installed. The engine was resting on a wood n box in my van and strapped down. Had to make a panic stop and the engine tipped and oil poured out of the flywheel bolt holes. Could you run a small magnet in the bolt whole and see if you gat any shavings? Maybe put a magnetic drain plug in. Flush the bolt hole out by sealing up the other holes with bolts and sealer on the threads. Then spin the oil pump as if you were priming the motor and flush the bolt hole with oil?
The magnet is a really good idea. Before I bolted the flywheel up I ran a magnetically tipped screwdriver in there several times to collect tiny pieces and then I just blew it out with compressed air. The magnet is a very good idea. Perhaps ill drag one along under the crank and pull the pieces (if there are any) toward the drain and just do an oil change. Flushing the bolt hole is a good idea as well, but I already bolted her up... and the moment that helicoil held 75 ft/ lbs I nearly screamed with joy so there is no way I'm about to risk taking her apart :doh: ha.
 
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