Streaks behind fuel vent.

[Richgj3]

I have vented caps on both tanks on my 170B. I’m seeing streaks behind the center vent. No only with full tanks but all the time. When I got the plane last May it had one vented cap and one non vented. I changed right away so I can’t say if it did the same thing before I changed the cap. The tanks burn evenly. The did on the trip home before I changed the cap also.

Thoughts?

Happy New Year

[GAHorn]

One of the reasons Cessna relocated the vent to beneath the left wing was to deal with complaints of fuel on the cabin top, windshield, and fuel smells in the cabin. It’s common if you have full tanks and wheel-land accompanied by heavy-braking for fuel to “vomit” out the overhead vent. The stains are persistent... but can usually be removed with M.E.K. (Which itself is becoming difficult to purchase.... “substitute” solvents are similar but not the same.)

[Richgj3]

Just an update to this old thread. I have found Carbon X which is the stuff you buy in the gallon jug and then dilute to clean exhaust stains off, also does a great job removing fuel stains.

I did not try the MEK suggestion as at my age I’ve probably reached my limit of MEK contamination. I did try mineral spirits which worked partially but the Carbon X worked well.

Rich

[gfeher]

Rich, were you removing avgas stains? Do you know if Carbon X also works on auto gas stains? I have another aircraft (not my 170B) that has auto gas stains that I've tried to remove with many things without any luck.

[Richgj3]

Gene

I was removing avgas stains. I have to admit, some had been there quite a while since it’s difficult to reach the top of the cabin. The fresher stains came off easily with the mineral spirits but the older ones were not responding to that. The Carbon X got them easily with hardly any pressure.

But, they were not auto gas stains. If I manage to find some at the airport (I and others have some older cars out there) I’ll try it. I don’t think Carbon X will hurt anything. My 170 is polished but the cowl is painted and I use it on all surfaces with no issues.

Good luck

Rich

[gfeher]

Thanks Rich. I’ll get some with the next Spruce order I place and let everyone know how it works on auto gas. If I don’t have luck, I’ll find plenty of other uses for it

[GAHorn]

I had a 206 back in the late ‘80s that developed a leak at the wing root and left avgas stains down the aft doorpost. I found that a rag soaked in avgas would easily remove the stains.

[Richgj3]

George
Agreed

Avgas woks on the fresh stains. I let the ones on top where it’s difficult to reach stay too long. It’s bare polished aluminum there. I could polish them out but I couldn’t reach them all. The Carbon X on a rag on the end of a mop handle did the trick.