Cleaning fiberglass surface soiled with engine oil

C

Chris Martin

Promoted Users
As I get ready to start panting my airplane, I read with interest the postings I could find here about the first cleaning before the sanding, W&G, etc.

Airplanes are a particular breed because the engine will spit oil so the surfaces are contaminated and although mine was not a bad spitter chugging along at 200 mph spreads even the tiniest drops of oil all over the surface. Good initial degreasing is a must. My airplane is primed with SPI Epoxy so that’s probably a good thing but some not so visible areas do have unprimed fiberglass and need to be though roughly degreased.

Any recommendations on what to clean the surfaces with? In the old days the recommendatiion was to use TSP. Chris H mentioned he uses Dawn and it may be good enough but maybe I should use something stronger. I have found Krud Kutter to be pretty good degreaser so that is an option.

Any thoughts?
Chris
 
Older Corvette hoods on AC equipped cars are known for topside paint bubbling due to the compressor throwing oil mist on underside of the hood. I have never read of anyone successfully removing that oil film to prevent the bubbles from returning down the road. Maybe it’s possible but I’ve not seen it.

Don
 
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Yup, I can see the areas with bare fiberglass having an issue, even permeating like you described. Any silicone based oils are known to permeate fiberglass and even delaminate it over time. The good news for me is that I had the surfaces sealed with the SPI epoxy so most of it should be fine (I have been told).
Chris
 
I have had to clean blown up hoods a few times. I used a combination of several washes with simple green, power washer, dawn soap and some prayers, lol

The last one was really bad, I think finally after 6 hard washes and letting it soak in the sun it finally stopped seeping out of the cracks. It was an extremely violent engine failure.

1681478710572.png


After primer I let it back in the sun for several weeks, I saw no issues and this was in June/July when it was baking outside. I figured by then if something was going to happen it would have.
1681479096172.png


And finally something did happen a few months later:
1681479324367.png


But to this day, I don't think that had anything to do with how I washed and painted the hood....who knows though, lol.
 
I only shared that for the humor of it! I have no idea if the oil in that hood would ever come back. The stuff I paint just gets destroyed so it doesn't really matter.
 
  • Haha
Reactions: MJM
Chris Martin said:
Yup, I can see the areas with bare fiberglass having an issue, even permeating like you described. Any silicone based oils are known to permeate fiberglass and even delaminate it over time. The good news for me is that I had the surfaces sealed with the SPI epoxy so most of it should be fine (I have been told).
Chris
Click to expand...
I misunderstood. Thought you had oil on bare fiberglass.
 
Most has SPI epoxy (maybe 99%). I have a couple of spots that are bare but not that exposed so probably OK. Not visible areas.
 
orangejuiced86 said:
I have had to clean blown up hoods a few times. I used a combination of several washes with simple green, power washer, dawn soap and some prayers, lol

The last one was really bad, I think finally after 6 hard washes and letting it soak in the sun it finally stopped seeping out of the cracks. It was an extremely violent engine failure.

View attachment 25002

After primer I let it back in the sun for several weeks, I saw no issues and this was in June/July when it was baking outside. I figured by then if something was going to happen it would have.
View attachment 25003

And finally something did happen a few months later:
View attachment 25004

But to this day, I don't think that had anything to do with how I washed and painted the hood....who knows though, lol.
Click to expand...
This only happens when you turn your A/C on before rolling up the windows, it over-revs the compressor compensator relief valve governor.
 
Thanks for the feedback. Although I did a search for cleaning fiberglass I saw a thread a couple of ones bellow this one that talked about strong degreasers (Zep). I will give that a go followed by Dawn (to make my hands nice and soft ).
Chris
 
yes the zep industrial purple degreaser is some fantastic stuff. i wash everything down with it. it melts pretty much anything including your skin so wear gloves. that is always my pre paint prep. whenever i get something coming in the shop for paint it will get washed down with that, rinsed well then i begin my prep on it
 
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