Cracked oil tank

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jesse

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Jesse
I've had an oil leak that's been getting exponentially worse on the Flybaby that I finally decided needed to be fixed. A little cleanup, some uv dye, and a blacklight and it was quickly located. The attached pictures were taken after 20 minutes of idling.

Once I figure out how to get it removed (looks like not-fun to do) I'll probably try and find a local welder to repair. I'd really rather not do this again anytime soon so if anyone has any recommendations for a welder that'll do it right..let me know.

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You knew this already but for those who don't, don't zip tie stuff to it and it won't crack.
 
As part of the series of things I'm working on, phasing out the majority of the zip ties, is in progress.
 
Lycomings are typically plastic and my guess is that it wouldn't be a progressive leak but a BIG suprise when it lets go :yikes:
 
This appears to be a weld that's just not done with good heat penetration. Pretty common that the surrounding plate area will break loose with vibration and heat and age.

I would grind all the existing weld out, maybe cut down the neck piece slightly to get a good piece of metal to start with, and see what the tank will provide after the existing weld is gone. If there's a gap between the neck and the tank circumference, it's best to use a fill in there without distorting the tank metal. The fill piece should be of the same material or very close as the tank and neck.

The other option is that the neck piece could go to the muffler shop and have them put a slight flange on it to expand the neck piece. This has both benefits and a caution cause the neck metal gets deformed and made a bit thinner as it's flanged. I think I would avoid this even though it would provide a better welding surface for the two pieces.

This is also an area where I would gas weld. Gas welding heats the sheetmetals more uniformly and provides less porosity except for the best TIG welders. A very good TIG guy could do it of course, but I don't have TIG and I"m better with the torch anyway.

Pressure test with some soap bubbles afterward or you'll be right back here again.
 
What dye did you use? I have a persistent leak as well, but haven't really been able to track a solid source. At this point I'm wondering if its residual.
 
You'll pay hell welding that old oil tank, after it has been soaked in oil for many years. It is a black iron sheet of unknown alloy, and very thin.

I'd soak in a strip tank for a couple days, wash it really good, then very carefully braze it.

They are very common in the salvage yards, and probably cheaper than a visit to a good welder.
 
JLowe said:
What dye did you use? I have a persistent leak as well, but haven't really been able to track a solid source. At this point I'm wondering if its residual.
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This is what I did..made finding it super simple:
1.) Went to harbor freight. spent $10 on a pump garden sprayer
2.) went to home depot and bought a gallon of mineral spirits
3.) sprayed engine with mineral spirits
4.) picked up uv dye from autozone that was labeled as being for oil
5.) drained 1 qt of oil from engine. mixed appropriate amount of dye in new qt and added it
6.) let engine idle for 20 minutes
7.) look with black light
 
Tom-D said:
You'll pay hell welding that old oil tank, after it has been soaked in oil for many years. It is a black iron sheet of unknown alloy, and very thin.

I'd soak in a strip tank for a couple days, wash it really good, then very carefully braze it.

They are very common in the salvage yards, and probably cheaper than a visit to a good welder.
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I called Pacific Oil Cooler and they said they could fix it up right for me for about $300 in 5 business days....
 
Tom-D said:
You'll pay hell welding that old oil tank, after it has been soaked in oil for many years. It is a black iron sheet of unknown alloy, and very thin.

I'd soak in a strip tank for a couple days, wash it really good, then very carefully braze it.

They are very common in the salvage yards, and probably cheaper than a visit to a good welder.
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Yeah, I was thinking of brazing too. Sand the edges down real well, and clean it super good then brazing might be better than gas weld or trying to TIG.
 
FWIW that joint is right at the static 'full' level of the tank meaning it's above the oil level when it's running. So, although messy it's not something that could cause you to lose all your oil in flight. Just pointing out that it's not a crisis situation.
 
Oil tank removed, crack pretty damn obvious:
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Mercy.

Very glad you found that.

UV dye... who'da thunk it? :D
 
Yep, that there looks like a crack.
 
I couldn't swallow the cost and time delay of sending it to Pacific for repair. I dropped it off at a local shop today that said it shouldn't be a big deal and said they will just tig weld it. Bit of a gamble we shall see. Should be done on Monday.
 
jesse said:
I couldn't swallow the cost and time delay of sending it to Pacific for repair. I dropped it off at a local shop today that said it shouldn't be a big deal and said they will just tig weld it. Bit of a gamble we shall see. Should be done on Monday.
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I hate sending stuff to the coasts... My Zulu 1 left for Oregon Tuesday :mad2:
 
jesse said:
I couldn't swallow the cost and time delay of sending it to Pacific for repair. I dropped it off at a local shop today that said it shouldn't be a big deal and said they will just tig weld it. Bit of a gamble we shall see. Should be done on Monday.
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The previous weld may be undercut which may have caused the failure. Undercutting reduces material thickness and increases stress.

Easy enough for a good welder to see the problem and correct it if they are paying attention. If not, it'll crack again in the same portion (at the root) of the weld.

If ya post pictures of the repaired part all of us internet experts can guess about the quality of the repairs!:rolleyes::D
 
Clark1961 said:
The previous weld may be undercut which may have caused the failure. Undercutting reduces material thickness and increases stress.

Easy enough for a good welder to see the problem and correct it if they are paying attention. If not, it'll crack again in the same portion (at the root) of the weld.

If ya post pictures of the repaired part all of us internet experts can guess about the quality of the repairs!:rolleyes::D
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It probably only made it about 60 years before failing. I'll post a picture so that the experts can explain how they would have done a better job.
 
jesse said:
It probably only made it about 60 years before failing. I'll post a picture so that the experts can explain how they would have done a better job.
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I can tell you already. I would have used JB Weld.
 
Ted DuPuis said:
I can tell you already. I would have used JB Weld.
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While JB Weld is the accepted solution of experts everywhere my uncle's cousin's brother had it fail on his son's wife's daughter's Pinto and therefore I won't use it!
 
Ted DuPuis said:
I can tell you already. I would have used JB Weld.
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Like I said before this isn't a situation that would lead to the loss of concernable quantities of oil. Believe it or not JB Weld would probably work. I know it's an airplane and all but seriously - think about it....

The only time you are leaking oil is when you are completely full - a temporary condition.
 
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Silvaire said:
Like I said before this isn't a situation that would lead to the loss of concernable quantities of oil. Believe it or not JB Weld would probably work. I know it's an airplane and all but seriously - think about it....

The only time you are leaking oil is when you are completely full - a temporary condition.
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Of course the jb weld fix might stop the leak for now but probably won't stop the crack from progressing until it finally progresses enough to split the whole damn tank in half resulting in a catastrophic loss of oil followed by engine.

Uh, no thanks.

Maybe on my lawn mower but sure the hell not on my airplane.
 
jesse said:
Of course the jb weld fix might stop the leak for now but probably won't stop the crack from progressing until it finally progresses enough to split the whole damn tank in half resulting in a catastrophic loss of oil followed by engine.

Uh, no thanks.

Maybe on my lawn mower but sure the hell not on my airplane.
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Stop drill the crack first, heck I would have as part of a real welded repair.
 
jesse said:
Of course the jb weld fix might stop the leak for now but probably won't stop the crack from progressing until it finally progresses enough to split the whole damn tank in half resulting in a catastrophic loss of oil followed by engine.

Uh, no thanks.

Maybe on my lawn mower but sure the hell not on my airplane.
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If it were me I'd be doing the same as you and fixing it right. I'm just pointing out the nature of what you have here, it's the filler neck joint that is cracked and it's not ever going to cause the whole tank to split in two. But I'm not seriously advocating the use of JB-Weld as a fix.

Furthermore there is a reason it's cracked that you should address or it's just going to do it again. There should be an additional bead along the aft radius of the neck that joins it to the tank seam and a support bracket half way up that bolts to the lower engine mount boss. Also, as pointed out earlier, don't use the filler neck to support any wire harnesses, hoses or tubes - especially anything that connects to the firewall.
 
Picked up the oil tank from the local welder today, total charge for repair: $20, turned around in two days.

A little cheaper than the quoted $300 from the aviation oil cooler shop with a 5 day turnaround and another 6 days or so in the mail.
 
BTW: I was joking about the JB Weld, even though I agree it could work. After all, MT props are repaired with 5 minute epoxy.

Let us know how it works, Jesse.
 
Yahbut that fix is only guaranteed for car oil. Your fancy super-slick airplane oil will run right through it. That's the reason I never used Ford alternators with the same part number as the Cessna-provided part on my 210 . . . on my 210 . . . on my 210. ;)

jesse said:
Picked up the oil tank from the local welder today, total charge for repair: $20, turned around in two days.

A little cheaper than the quoted $300 from the aviation oil cooler shop with a 5 day turnaround and another 6 days or so in the mail.
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wabower said:
Yahbut that fix is only guaranteed for car oil. Your fancy super-slick airplane oil will run right through it. That's the reason I never used Ford alternators with the same part number as the Cessna-provided part on my 210 . . . on my 210 . . . on my 210. ;)
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Did you also never buy alternator belts from Advance Aviation Parts?
 
The little foil Cessna sticker that was pasted over the Ford sticker would peel off, which made it easier to get the unit repaired at the auto shop without answering a bunch of irrelevant questions. The car part and the "plane" part were identical.

SCCutler said:
No way Wayne would do that.

He used NAPA Aviation! :D
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wabower said:
The little foil Cessna sticker that was pasted over the Ford sticker would peel off, which made it easier to get the unit repaired at the auto shop without answering a bunch of irrelevant questions. The car part and the "plane" part were identical.
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No, no, no!

It was coated with Distillate of Unobtanium prior to application of the Magic Cessna Sticker. :D
 
jesse said:
I called Pacific Oil Cooler and they said they could fix it up right for me for about $300 in 5 business days....
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It looks tempting to just put some JB weld around it or spray the outside of it with that $15 per can instant poly-urea roofing rubber and call it good.:)
 
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