Frutratated Frank has a question for you mechanical types. I have developed an oil leak where my alternator mates to my assy. case. I overhauled the alternator back in the fall, and reinstalled the alternator and had no leak problems. Now all of a sudden it starts leaking a lot more than is acceptable. I pulled the alternator & tach drive, cleaned the surfaces, put on a thin coating of Tite Seal and a new gasket. I also put a thin coating of Tite Seal on the tach housing and alternator before reinstalling. Tighten up everthing and did an engine run. The %#(!+$ is still leaking Appears not to be leaking at the old leak place, but is leaking on the opposite side. What to do. Maybe there is a secret to this procedure I am missing. I have R&R'd my alternator several times in the past without this problem so now I am approaching my wits end. With out any alternatives I am going to give it one more try next weekend by pulling the alternator and applying more Tite Seal to the outer edges of the gasket to see if that might possibly solve the problem. I know not to get too aggressive with the Tite Seal as it can get into to oil system and cause problems. Should I be using something else other than Tite Seal or what suggestions are there other than having my AI come take a look at it?
Frank, I suspect the leak is WITHIN the alternator. There is a "garlock" type oil-seal on the armature-shaft of the alternator that is likely the source of your leak. You'll be ahead of the game to replace that seal, or send your alternator off to the shop for rebuild/reseal.
Then you can re-do the mounting gasket (and don't forget the oil seal within that tach-drive housing.)
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention. An originality nut (mostly) for the right reasons.
Thanks George. Since I had the alternator overhauled last fall, wouldn't you think the oil seal would have been replaced? I am not in town so I can't ck the parts list on that overhaul. Another thought, since the oil I am seeing is coming from the outer circumference of the mating area between the alternator and the accessory case would't that indicate a leak there rather than either of the two possible places you suggest? I am just guessing, but I would have thought if the seal on the alternator shaft was leaking it would probably leak out internally from the alternator case itself . Just trying to look at all possibilities. Gotta get this thing fixed before the 12th!
The oil seal, if replaced at overhaul, can still fail at midlife, etc.
If it leaks, it'll allow oil to leave the sump and leak out anywhere else it comes into contact with. (But I would be surprised if none were found inside the alternator itself.)
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention. An originality nut (mostly) for the right reasons.
That would be my guess too, sounds like you've done all that is necesary to fix a gasket leak, and I'm sure that gaskets have played a big role in your life(<: Hot oil leaking in a pressure cowl environment can wind up in strange places upon post fight inspection...WHERE IN THE%@*^ING HELL IS IT COMING FROM??? armature shaft seal... and you'll owe me a beer.
Hey! I said it first! I get that beer!
Frank, a common mistake of some rebuilders is to install the seal backwards. It LOOKS better that way when viewing the alternator/generator on the bench...but it's wrong.
The open-end of the seal should face the engine ... (to keep the oil IN. Facing it backwards towards the alt/gen will do exactly as you might have experienced...it'll work for a little while then fail.)
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention. An originality nut (mostly) for the right reasons.
Same type. Different size/part number I suspect. Depends on which alternator you have.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention. An originality nut (mostly) for the right reasons.
Thanks to all who offered suggestions/ideas/possible solutions to my leak. Fortunately, as it turns out, it was neither the tach drive oil seal or the alternator oil seal that was leaking. It was just doing so at the alternator flange where it mates to the accessory case. A local AI told me that if the repair manual didn't call for any type of sealant (Permatex, Tite Seal, et al) that he never used any. His thought was the new gasket should prevent any leaks if both surfaces were clean and not distorted. I had installed the alternator in the fall without any such sealants and never had a problem until 6-8 weeks ago when all of a sudden it started. I used a new gasket and put Tite Seal on both surfaces, but alas, it still leaked, although not as much. The last time I used a bit more Tite Seal and it now appears to have stopped the leak, at least with ground runs. Tomorrow I will put Ole Pokey in the air and see how it does. Gotta get it ready for Kelowna! Thanks again folks. This is just ONE good reason to belong to this great organization.
O'L pokey,
I was thinking with every one else, It was the seal (you can never think a new product in infalliable. But Tight seal is a wonderfull product (along with antiseze, silicone, and a large hammer) Tight seal could hide other problems, be carefull of slapping a lot of tightseal on any thing (it is supose to be used spairingly) just a thought
brad
Brad, thanks for you input. I'm aware that too much Tite Seal, etc. can get into the engine oil and cause problems. Unfortunately after putting about an hour on the engine yesterday (Sat) I still have the same problem and after washing the engine down and running it for 2-3 minutes it is evident the oil is leaking between the alternator flange & accessory case. I am attempting to contact my mechanic to see if he wants to take a shot at solving the problem.
Frank, have you tried washing the engine down and using ZyGlo developer or baby powder/flour as a method of confirming the actual leak site?
Magnetos have a bad habit of leaking and allowing the oil to get down onto that seam and make it appear to be the alt/gen gasket. Look at your mag gaskets and VENTs carefully to make certain that they aren't leaking. (Oily vents are a sign of internal mag leaks due to bad oil seal.)
Also, check your starter drive, as another opportunity for this sort of problem.
Finally, I've experienced a nasty oil leak that occured after a cylinder change,... it turned out to be a thru-bolt at the rear cyls. The fix was to remove the nuts, clean the area, Permatex the exit point of the bolt, replace the washer and nut, and apply proper torque and let the Permatex dry. It fixed it pretty well.
The oil leaks mentioned can be misleading and make it appear to be coming elsewhere. The purpose of the developer/powder/flour solution is to catch the evidence early in operation to pinpoint the source.
PS-BTW, while the overhaul manual does not specifically address gen/alt installation, it does discuss mating surfaces using gaskets in the "Final Assembly" discussion. It recommends Permatex Aviation #3 for gasketed case/half assy's, etc. I personally prefer #2, because it's more widely found and is only slightly more tacky.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention. An originality nut (mostly) for the right reasons.
Frank, I am haveing the same problem with my 0300D engine. I have changed every gasket on that accessory case. Including the tach drive garlock seal. My alt has been o/h and i know for a fact that the seal was replaced. As far as correctly i will find out. I even went as far as installing Red Seal Push Rod Kit on all cylinders. But still get about a dozen or more splaters after a 30 minute test flight. I even sprayed that whole engine down with spray on foot powder because it sticks to the surface. lookig for a leak. All i can say is good luck in finding yours because i'm not.... Just for grins my wasn't leaking but your's might be, plug up your oil quick drain you could be getting some leakage from that..
For what it is worthy I was told by more than one I/A AND A/P's that you will never fix a oil lek on a 0300 engine. They say it builds up to much interenal pressure. You fix one leak another will develop somewhere else. all you can doe is fix the major ones and don't sweat the small ones. ALL I KNOW IS I HATE A FRICKIN OIL LEAK...
I had an oil leak that drove me crazy. I had new gasket installed on generator. So I thought it must be the tach drive unit. I used Tite Seal on Tach drive unit and found that it would not seal in the area of heat. Also, installed more than one seal, still leaked, finally sent to G&N and bought a new Tach Drive housing, then new seal, then used a contact cement with a new gasket. no more leak. C-145 engine.
The generator/alternator oil leak on the O300, and other similar rear case engines, may be do to a leaky or often times missing little o-ring. This small o-ring goes on the alternator/generator shaft before the drive assembly is slid on the shaft. The "lip type" seal, seals between the foreward housing and the drive assembly. An o-ring is required to seal between this same drive assembly and the armature or alternator rotor shaft. I may have missed this being mentioned in a previous post, by going thru the posts too rapidly. At this age every moment is precious and should be used having fun fixing and flying airplanes.
has a question for you mechanical types. I have developed an oil leak where my alternator mates to my assy. case. I overhauled the alternator back in the fall, and reinstalled the alternator and had no leak problems. Now all of a sudden it starts leaking a lot more than is acceptable. I pulled the alternator & tach drive, cleaned the surfaces, put on a thin coating of Tite Seal and a new gasket. I also put a thin coating of Tite Seal on the tach housing and alternator before reinstalling. Tighten up everthing and did an engine run. The %#(!+$ is still leaking 
Tight seal could hide other problems, be carefull of slapping a lot of tightseal on any thing (it is supose to be used spairingly) just a thought