SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: Ralph Brunt on July 30, 2011, 09:27:09 AM
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i had a bad oil leak in my liberty and i noticed it most when the boat was on the trailer. so i pulled the motor to find it and what i found was that the milodon pan was cracked rite where the suction end of the pick up was..
so i had a dooley pan that i got from nordie that i was going to put on it. well, when i inspected it it was cracked it the same spot :o. i find this really weird since i have two different pans from two different manufactures, from tow different motor and two different boats that have cracks in the same area. no the pickups were NOT hitting the pans and the pans did NOT hit the bottom of the boats....
any ideas?
here are some pics
milodon pan first
[attachimg=1]
[attachimg=2]
now the dooley, the hole in the pan is from me pushing a screwdiver through it
[attachimg=3]
[attachimg=4]
[attachimg=5]
the milodon had a standard straight pick up while the dooley had a c/j pick up.
im stumped
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Could the pans be fatigued from years of the oil pump pulling the pan up and leting it back down.
Don't know much, but I think i'll check my pans the next time the motors are out.
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well to give my 2 cents, years of heating and cooling.
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Ralph,
I gotta be honest, the only time I have ever seen that was on a motor that sat on the floor in the shop on the oil pan, never before on a running engine....
That's simply weird... :screwy:
GT
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Could the pans be fatigued from years of the oil pump pulling the pan up and leting it back down.
Don't know much, but I think i'll check my pans the next time the motors are out.
that would be one hell of a vacume, so i went out to see if i could flex the pans on the boattom and could not :(
well to give my 2 cents, years of heating and cooling.
i only have one problem with that, these pans see very minimal use heat cycle wise as opposed to a care at 100k miles..
Ralph,
I gotta be honest, the only time I have ever seen that was on a motor that sat on the floor in the shop on the oil pan, never before on a running engine....
That's simply weird... :screwy:
GT
i dont know about the past of these pans as i got them both used but, since i have had the milodon it's never sat on the floor, always in the boat, cherry picker or engine stand...
i went out and sat the dooley on the floor and where it is cracked doesn't even touch the ground, as it has a slight rise in the back to compensate for the 4* install angle of the engine.
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Talked to the old man....... 8)
He has seen this before, guess what caused it?
Running too much oil in the pan and the reverberation from the windage makes bad with the sheet metal... :thumbdown:
Ralph, it was probably broken/weakened before your time brother.... :-\
I remember now I had a windage tray break in about six places on one of the race boat small blacks after a weekend of abuse, we did a test afterwards and found that we had three too many quarts of oil in the pan..... :sly:
I guess the same could hold true for a pan. ???
GT
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Just going to throw this out there and see what you guys think. I have seen oil pumps and pick up tubes break and not from vibration, but from harmonics! from many reasons like .....gear drives, engine balance issues and even gerator drive of the oil pump it self. Now regarding the pan, the only thing I can think of.....(and this is a guess) Is that a harmonic from some where is transmitting threw the oil in the pick up tube and "focusing" it directly at the pan underneath the pick up screen. (think about the old Memorex commercial, where the sound wave at the right frequency, causes the wine glass to break!)
On a possible fix, you might be able to tig weld a small, lets say 3 or 4 inch square piece of 14 gauge sheet metal on the bottom of the pan at the spot under the pick up. This solve 2 problems, #1 repair your old pans #2 changes the thickness and the resonate frequency of the pan and hopefully it does not happen again.
Then again........I could totaly talking out of my ass! :screwy:
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Can the heat from the oil and cool water have something to do with the metal being cooled too quickly by cool lake water?
Sent from my Samsung Galaxy S 4G
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The only problem I have with the harmonics idea is this. One pan is ribbed, one is dimpled. One pan is a straight bottom and the other has and angled section. It would be VERY difficult to get two pieces of sheet metal to have the same harmonic issue when they are different sizes (damage on the Dooley is on the smaller angled section) and have different surface shapes (ribbed/dimpled).
How about this for an idea sense this happened to both pans right below the pickup. When the motors are shut down, very hot oil is draining back through the pickup into the pans creating a hot spot right below the pickup. Is that even possible ??
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Somebody call Mythbusters or get those "Searching for Bigfoot" guys to do something worthwhile.....Saw that for the first time the other day....don't watch much TV....but what a bunch of idiots running around doing nothin'..... :screwy:
The harmonics thing? maybe. Combination somewhat of both? Who knows?
The fact that BOTH happened directly under the pickup, almost completely different designs and manufacturing technique, I think is very important. And I can honestly beleive that suction/vacuum created by a HV oil pump through the pickup tube theory could honestly cause enough flex do this over a relatively short period of time. And probably your answer, completely feasible.
Back in HS, yes I know, back when Dinosaurs roamed the earth and Girls actually said "no", my Physics teacher showed us how vacuum worked by hooking up one of those little compressors (Older version and probably not as efficent) that everyone uses nowadays to inflate water toys or beds to a 55 gallon drum through a T fitting. Took about a half an hour before the first loud noise of something cringing from the strain, but in the end, about 2 hours, the thing looked like a smashed and squashed beer can. Those pumps only put out about, what, 10 PSI??? I couldn't get the side of an oil drum to flex without a LOT of effort either. Any cavitation, however unlikely, would cause extreme flex both ways if that theory proves true.
I would repair VERY carefully or replace the pans. Welding on them in this high stress area that apparantly showed it's ugly head doesn't seem like a very good idea to me. I would also make sure, next time, that the pickup is maybe a bit higher off the bottom than we would normally do. I think 3/8" is pretty much as close as any of us go, but I think after seeing this, I may just go to 1/2 inch or more on those types of pans.
Just thinking out loud.
Ray
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some really good answers here and i love this kind of tech talk :thumbup: i am going to call both manufactures (sp?) tomorrow.
i dont think they would be too bad to fix as long as they went to a good welder and had about a 4x4 peice replaced. hence the cheap price coming soon ;)
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Long-term fatigue and nothing more. Find the ends of the fissures (ZyGlo, etc), drill a hole at both ends of the hairline cracks, prep and weld the pans, go boating. 8)
LO