Am I missing something? I installed a rebuilt generator. I got it from Aerotech, so I know the seal is good. It continues to leak around the edge of the generator. I redid the installation being very careful. Removed all of the old gasket, New gasket, new bottle of gasket cement, let it get tacky, new tach drive seal. I am starting to think that the case is cracked or something. How about that hole between the tach drive and the generator? Could it be too large, and oil under pressure is sneaking out from the pump? I am running out of ideas.
Dave
Oil Leak at Generator
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
First, are you absolutely sure that's where the oil is coming from and not blowing in from somewhere else?
Second, what kind of gasket seal are you using? The old aviation peanut butter works below the oil level like the generator, but there is a newer sealant that is supposedely better - can get you the name later when I am at the hangar.
Be careful not to apply too much sealant that would be squeezed into the inside of the engine. And, too much wrench tightening can crack your accessory case fairly easily.
My generator leaked when I assembled it dry. Came back with another new gasket and peanut butter and it does not leak. But, found out about the new sealant and wished that I would have known about it before, it's not as thick as peanut butter(can't remember the real name) and is not as likely to squeeze out and get inside the engine.
Second, what kind of gasket seal are you using? The old aviation peanut butter works below the oil level like the generator, but there is a newer sealant that is supposedely better - can get you the name later when I am at the hangar.
Be careful not to apply too much sealant that would be squeezed into the inside of the engine. And, too much wrench tightening can crack your accessory case fairly easily.
My generator leaked when I assembled it dry. Came back with another new gasket and peanut butter and it does not leak. But, found out about the new sealant and wished that I would have known about it before, it's not as thick as peanut butter(can't remember the real name) and is not as likely to squeeze out and get inside the engine.
Joe
51 C170A
Grand Prairie, TX
51 C170A
Grand Prairie, TX
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N73087
The first time was with permatex non hardening from a tube. Currently is is leaking past permatex from the little jar with the brush. New gasket each time.
After the first attempt, I cleaned the oil off the case, dusted it with talcum powder, and took it aroung the patch. It is definitely oozing around the generator from the top.
Is that new sealant called something like "Hypalon?" I was tempted to try that when I saw it, but opted for the tried and true fifty year old method to match the airplane.
After the first attempt, I cleaned the oil off the case, dusted it with talcum powder, and took it aroung the patch. It is definitely oozing around the generator from the top.
Is that new sealant called something like "Hypalon?" I was tempted to try that when I saw it, but opted for the tried and true fifty year old method to match the airplane.
Permatex No. 2 (non-hardening) is excellent stuff and is good for this job.
If the oil is coming from above the generator as you say, then you should look in that area for the problem. (The magnetos come to mind.)
I'm glad to see you changed the tach drive oil seal ((PN 642714)
the garlock-type round seal which is pressed into the tach-drive housing), which seems to indicate that you did NOT cut the combination generator/tach-drive gasket. This is all good.
Check carefully where the oil is originating. The starter? Starter drive pinion? Mags?
If the oil is coming from above the generator as you say, then you should look in that area for the problem. (The magnetos come to mind.)
I'm glad to see you changed the tach drive oil seal ((PN 642714)
the garlock-type round seal which is pressed into the tach-drive housing), which seems to indicate that you did NOT cut the combination generator/tach-drive gasket. This is all good.
Check carefully where the oil is originating. The starter? Starter drive pinion? Mags?
'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.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
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N73087
If that is the case, then the problem must be with the area between the gasket at the accy case. For one thing, the oil level in the sump is about that high. That area either is not clean, not properly sealed, or has a crack in the case, ....or....the studs which mount the generator are leaking from within the case. In that situation, they should be removed, the threaded holes cleaned, and the studs re-installed (or new studs installed) using sealant or epoxy. (The oil may be following the stud-threads from the sump thru the case and out to atmosphere. TCM recommends a product called "National Oil Seal compound, but Permatex works just fine.)
If the problem were the generator shaft seal, the oil would come from the bottom/internal area of the generator.
If the problem were the generator shaft seal, the oil would come from the bottom/internal area of the generator.
'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.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
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Pat Phillips
- Posts: 2
- Joined: Fri Feb 07, 2003 3:22 am
oil leaks
I put a trace dye in my engine and used a special black light. Its shows up seapage and weapage around mags, alternator, etc. You can see where the heaviest leaks are. Just clean (wash with brake kleen) and recheck agian and again....Good luck
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william halford
- Posts: 62
- Joined: Wed Jan 29, 2003 11:24 pm
I AM HAVEING THE SAME PROBLEM WITH OUR 170A. EVERY GASKET ON THE ACCESSORY CASE HAS BEEN CHANGED. I HAVE WASHED THIS ENGINE SO MUCH MY WATER BILL HAS WENT UP 10 BUCKS.
IT IS NOT A BAD LEAK BUT A NUSANCE LEAK. THIS BLACK LIGHT SOUNDS PRETTY GOOD. BUT I NEED MORE INFO ON THIS ADDITVE THAT IS PUT IN THE OIL .. WILLIAM..
IT IS NOT A BAD LEAK BUT A NUSANCE LEAK. THIS BLACK LIGHT SOUNDS PRETTY GOOD. BUT I NEED MORE INFO ON THIS ADDITVE THAT IS PUT IN THE OIL .. WILLIAM..
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DensityDog
- Posts: 64
- Joined: Fri Jun 14, 2002 3:38 am
Dave, have you fixed this leak? Check carefully to see if there isn't something keeping the generator mounting surface from being pulled tight up to the accessory case. Like a nick or burr on the generator, or on the accy case area. Look to see if the mounting studs have backed out enough make the nuts bottom out on the studs before the generator is pulled up tight.
Max
Max
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N73087
Another neat leak finding trick is to buy a can of foot powder spray. Be sure that it is the kind that turns into a white powder when sprayed on your skin. Spray it around the area of the suspected leak. Run the engine with the cowling on for a few minutes and then look for the area where the oil makes contact with the white powder. Cleans up easily with mineral spirits.william halford wrote:IT IS NOT A BAD LEAK BUT A NUSANCE LEAK. THIS BLACK LIGHT SOUNDS PRETTY GOOD. BUT I NEED MORE INFO ON THIS ADDITVE THAT IS PUT IN THE OIL .. WILLIAM..
jc
John
N2865C
"The only stupid question is one that wasn't asked"
N2865C
"The only stupid question is one that wasn't asked"
The foot powder aerosol sounds like the oldtimer's trick of spraying dye-penetrant spray on the engine. Works the same way (but probably doesn't cure the engine's athlete's foot.) 
'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.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
-
N73087
My generator still leaks.
I know the source. The lower oil pump gear shaft comes through the accessory case. There is a notch in the case, and a cutout in the gasket that allows oil to run back to the sump.
The pressure from that source is finding its way up to the area between the generator and tach drive housing, and venting to atmosphere on the left side of that space.
I have changed gaskets several times using different cements: Permatex in the can with the brush, Non-Hardening Permatex in the tube, and silicon.
The leak persists. When I examine the gasket, there is an area around the lower oil pump shaft that comes “unglued†on the case side of the gasket. This is where the oil finds its way out.
[/img]
I know the source. The lower oil pump gear shaft comes through the accessory case. There is a notch in the case, and a cutout in the gasket that allows oil to run back to the sump.
The pressure from that source is finding its way up to the area between the generator and tach drive housing, and venting to atmosphere on the left side of that space.
I have changed gaskets several times using different cements: Permatex in the can with the brush, Non-Hardening Permatex in the tube, and silicon.
The leak persists. When I examine the gasket, there is an area around the lower oil pump shaft that comes “unglued†on the case side of the gasket. This is where the oil finds its way out.
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