oil stain on top of forward cowling?

DesertNomad

DesertNomad

Pattern Altitude
Joined
Jul 5, 2013
Messages
2,446
Location
Northern NV
Display Name
Display name:
DesertNomad
I have a Dakota and after adding a quart of oil and flying for a couple hours, I noticed what looks like a patch of oil stain on the top of the cowling, forward of the oil hatch on the pilots side. Could this be seepage from the constant speed prop? It did not seem to wipe off, so it could just be discolored paint... Not sure.

There is no oil anywhere on the prop, hub or spinner that I can see.

I am a new owner so still learning to observe all this stuff.
 
What was the oil level at after the flight and engine shut down? Was the stain on the cowling during pre flight? Was the dip stick secured during the pre flight after checking oil level.?
 
Could be a bunch of things. If your prop is seeping some oil, you'll find streaks of it on the rear facing side of the blade, and likely some droplets on your windscreen. A picture would be very helpful in this instance.
 
Feel around the aft side of the flywheel (that thing behind the prop with the starter gear teeth on it and that has the alternator belt on it). If there's oil in the back of it, the crankshaft seal might be leaking.

Dan
 
No change in oil level pre/post flight. No oil on blades or windscreen. Dipstick was secure. It might be discoloration in the paint (from the heat?). It only shows up in certain light so not sure how long it has been there. I'll check behind the flywheel in the morning as I am not at the hangar now.
 
Last edited:
Oil or discoloration? Well that's a tough one there :rolleyes:
 
Man with what wind and pressure do inside a cowl it could be coming from anywhere.

Try to clean it off with some GoJo (non pumice) hand cleaner and water, that'll cut oil off rather easily, if it's oil.

Outside from that, drop the cowl and start looking around. :dunno:
 
Last edited:
Carbon X does not seem to remove it and everything else is clean. I'll see if it removes it when it is warm.
 
After flying today, I think it is discoloration, but it is odd that it is not located on the hottest part of the cowling.
 
Pictures of it.

Also - there was recently some fiber sheets added to the inside of the cowling, which was then painted - could it be the fiber resin seeping through?

There is no evidence of oil anywhere and the stain does not come off with Carbon X.

Ideas?
 

Attachments

  • IMG_0593.JPG
    IMG_0593.JPG
    298.8 KB · Views: 30
  • IMG_0596.JPG
    IMG_0596.JPG
    288.1 KB · Views: 28
  • IMG_0599.JPG
    IMG_0599.JPG
    314.6 KB · Views: 30
DesertNomad said:
Pictures of it.

Also - there was recently some fiber sheets added to the inside of the cowling, which was then painted - could it be the fiber resin seeping through?

There is no evidence of oil anywhere and the stain does not come off with Carbon X.

Ideas?
Click to expand...

Maybe something happened to the paint at some point?

No biggie, if it bugs you take the top cowling off, find the old paint info from your logs, order up some new paint, take it to a hotrod shop and have them strip and shoot it for you.
 
Yup. That was actually done during the pre-buy to fix cracking which is common on Piper fiberglass cowlings (most of the ones on my field have it). Just weird and I am trying to learn my airplane and all the things related to being an owner.
 
I can't see it in the pictures.
You mentioned that there was some recent paintwork done on it due to some cracks. Where was the cracking? I assume at the front near where both halves attach to each other. Was the whole cowling painted? or was it spotted and blended? Is it single stage, (paint) or base/clear? Depending on the answers to those questions, it could be a form of "bleed through", and not oil related at all.
 
The crack in the paint was forward of the oil door about 2/3 of the way to the prop and the crack was 7-9 inches long or so. I am not sure of the painting technique, but the discoloration is exactly in the region where the crack was.
 
Last edited:
DesertNomad said:
The crack I the paint was forward of the oil door about 2/3of the way to the prop ant the crack was 9 inches or so. I am not sure of the painting technique.
Click to expand...

AHA! Could well be bleed through of whatever substrate was used for the repair. My guess would be that you're seeing a yellowish looking area?
White paint, for some reason, will do that from time to time when applied over certian fillers, and under coats. I think the main cause is improper cure time between strata, for the materials used.
 
Yup.. Yellowish.. Like clean oil. I am thinking it is resin filer or similar from the adding of fiberglass. I don't know how long it was allowed to cure. Maybe not long enough.
 
I have not talked to the guy that did the work as he is back in Texas and I am in Nevada but I'll ask my local guy about it as I have a few other items to have him address.
 
You must log in or register to reply here.
Back
Top