The International Cessna^® 170 Association

Like most everyone, I've got an engine covered in many areas with anti-corrosion compound...namely, ..AeroShell W100.

And I've had a difficlut time pin-pointing the exact area of the leak. If I run it short time on the ground the leaks don't present themselves for discovery. If I fly it around the patch and land.... the oil is everywhere, including the firewall!

Where,....Oh, WHERE! ...IS the source?

So I went to AutoZone and picked up their least expensive Ultraviolet oil leak detector kit, which consists of an ultraviolet pen-light, some dye (careful.... you want the OIL/HYDRAULIC fluid leak-detector dye, ...not the Freon or fuel dyes),...and some yellow-lens glasses (the better to see the ultraviolet-lighted oil.)

With a fresh oil-change performed, but BEFORE washing the engine down, I added the dye just before adding the last quart of fresh oil to the crankcase. I wanted to make certain the maximum amount of dye was washed down the oil-service tube on the engine and mixed with crankcase oil, so I made certain I followed the dye with a quart of oil, to wash it down.

I ran the engine for about ten minutes at about 1,000 RPM and then pulled the plane back into the hangar, closed the doors and turned off the hangar lights to make it as dark as possible, and took a look with the various areas of the engine that are always wet with oil, illuminated with the ultraviolet penlight and while wearing the yellow glasses.

"Surprise, SURPRISE, Surprise!" - Gomer Pyle

I had thought the oil was leaking from the engine thru-bolts, but the FIRST surprise was the dipstick tube! See the "without UV lighting versus WITH UV lighting" :
I was also surprised by the studs at the tappet-body covers.
An area of the No. 5 cylinder pushrod rubbers stayed wet, but the rubbers looked good, and I thought it would prove
to be the crankcase thru-bolt holding the left, front, engine-mount.
Wrong! An otherwise healthy-appearing pushrod rubber has apparently lost it's elasticity. Although it takes patience, and about a $30 investment in dye, penlight and glasses.... I am glad to know the real culprits in my oil leaks.
Now to FIX them.
I plan to clean the dipstick tube and tappet body cover/stud with solvent, then electronics cleaner, and apply Permatex #2 into the crevices, to stop the oil leak. (I've successfully used this technique on engine thru bolts and cylinder base nuts.) Let the Permatex dry overnight before operating.

The Pushrod rubbers will be replaced using Permatex Oil and Fuel Adhesive on new rubbers, split to wrap around the pushrod housing, and glued/clamped. I'll follow up on this untried procedure to report it's effectiveness.

Meanwhile.... for those of you who want to know the exact source of oil leaks, you might wish to try one of the Ultraviolet Leak Detection kits used and sold by automotive sources.

Even if I don't actually stop the leaks, I am re-assured that the source of oil is determined NOT to be a cracked case or other traumatic problem. I"m just glad to KNOW where that oil is coming from!

Hope this short article is helpful.

PS- It was really hard to take pics thru the yellow lenses of the glasses in order for the UV lighting to show up. Holding the camera, glasses in front of the camera-lens, holding the penlight with the other hand, twisted-up/around to illuminate the leak, and then finding a spare finger to focus, then activate the shutter, was harder than pouring in the dye and running the engine. Someone owes me a beer!

So your basically going to paint the outside of the cover at the stud and nut with Permatex #2? And this has worked for you before to seal in the oil.

Hmmmm.

I'm thinkng a light coat of Permatex #2 over the entire engine might just save $30 worth of dye and wearing goofy glasses.

BTW I think that is very nice of you to go through the trouble to take those pictures. Frank told us about this stuff but a picture is worth a thousand words. And now that you've made us believers of his idea, he owes you the beer.

George,
Thanks for that write up! That's impressive to see how clearly those leaks/seeps show up. In the past I've looked for leaks by spotlessly cleaning the engine and then spraying Magnaflux Spot Check developer (Athelte's foot powder spray also works I've heard) over the suspect area. But it makes mess. What you've shown looks way easier and more effective.

One thing my father-in-law did on his RV-6A to stop a pesky leak was similar to what you are planning except that they also added a vacuum to the case to help pull the adhesive/sealant in.

For your application I would suggest that you consider Permatex Ultra Copper, instead of number 2. It seals through oil. I would not use it on engine assembly but for your application I find that it is far Superior to the number 2. There is an Ultra Black also.

Now wait a minute Bruce, how did I get nominated to buy George the beer If I did buy him one he'd probably insist on a St Paulie Girl Seriously, those photo's should be helpful to all. I was unaware of the "kit" and as earlier mentioned, got my dye at NAPA & used my IA's black light. The penlight would be much more convenient. Again, repeating myself, when checking for oil leaks, you gotta get that oil hot or chances are you may not find the source. That hot oil loses so much viscosity that it can seep through places cool or warm oil won't. I need to do this procedure again myself as I am finding oil on the bottom of my oil filter and I think it is coming from some push tube rubbers. George, did I understand that you plan to take new rubbers & cut them so they will go over the tubes, then glue them back together? What kind of glue? Are you going to glue them first and after a drying period then add Permatex? (PS: I'll buy you a beer when we see one another )

To seal studs and thru-bolts, I remove the nuts and washers, wash the area with aerosol solvent, then again with electronics cleaner (which is non-residue and fast-dry). Then I paint Permatex No 2 into the seams/stud with an acid-brush, and reassemble, and let dry overnight. On a stubborn thru-bolt leak I added a tight-fitting O-ring onto the stud (in addition to the Permatex) beneath the flat washer at the base of the stud. It's worked perfectly now for 9 years.
I prefer Aviation Permatex No 2 as a TCM approved sealant.
I demonstrated a pushrod rubber that was split with an exacto, then re-glued together with Permatex (edit: LocTite Stik and Seal) Oil and Gas proof rubber-adhesive (AutoZone/Napa) and challenged a few guys to find any defect. No one noticed the rubber had been cut and reassembled, except those who were told beforehand that it had been so treated. Bruce and one of the locals noticed, and although with sufficient force the split can be re-opened, it is not a part that experiences this sort of force, especially once clamped again.
Pushrod rubbers do not hold any oil under pressure. The metal pushrod housing is merely a return-path for oil draining back down from the rocker boxes, and the only pressures are crankcase gas-pressure...which should be "nil" since the crankcase is vented. The pushrod tube even goes so far as to actually enter the tappet body cover, so a rubber does not normally even carry oil itself...it only provides an air-seal between the pushrod tube and tappet body cover. I expect it to work fine and will report results later.

George,

I'm curious as to why you didn't wash the engine down before adding the dye.

As George said I saw his test sample push rod tube rubber at convention. I seem to recall the glue had not fully cured but still the seam was nearly inseparable. I wouldn't have any problem using George's solution and I'm sure he'll find it satisfactory.

cessna170bdriver wrote:George,

I'm curious as to why you didn't wash the engine down before adding the dye.

Because I figured the dye would indicate the source of the leaks and I didn't see much reason to have to wash it down twice.

When I wash my engine I use "Gunk" brand foaming-aerosol, which is water-soluble/biodegradeable. After it dissolves the oil and grime, I wash the engine down with a garden hose and nozzle, blow it dry with compressed air. I then use a garden sprayer to mist the grass in front of my hangar (where I did the wash-down) with liquid laundry-detergent and spray the area with the garden hose again. Makes for an easy non-problem cleanup. This is probably illegal in California, but here in Texas it's considered re-cycling the oil back to nature. (The grass in front of my hangar is some of the healthiest on the ranch.)

Back in the olden days of Feb. '51, at the DeHaviland Canada factory, I picked up the first DH C 2 Beaver airplane the the Air Force bought for service testing.
The airplane had, as did all beavers, a used but rebuilt P&W R-985 engine. (The R-985 went out of production in '43). This engine had to be the cleanest running engine I ever flew. The DeHaviland Canada mechanics used a water based white paint like the developer used in dye penetrant testing.
I took the airplane all the way to Ladd AFB in Fairbanks, Alaska, and I don't remember it leaking even one drop of oil. That has to be a record for a radial engine.

I was wondering why you hadn't washed the engine as well prior to the test. I was thinking the reason was something more scientific like you wanted the oil coating to act as a wetting agent for the dye oil to flow better or something.

gahorn wrote:This is probably illegal in California, but here in Texas it's considered re-cycling the oil back to nature. (The grass in front of my hangar is some of the healthiest on the ranch.)

Washing your plane at the airport my MedEvac helicopter is based is not allowed unless it is in the main hanger which has a water oil separator in the collection system.

I could never figure out how they allowed our helicopter to sit out in the rain and allow that water to wash the oil residue off the helicopter components onto the asphalt. Maybe because it was adding virtually nothing to the gallon or more of JetA already spilled there from nearly every refueling procedure.

gahorn wrote:

cessna170bdriver wrote:George,

I'm curious as to why you didn't wash the engine down before adding the dye.

Because I figured the dye would indicate the source of the leaks and I didn't see much reason to have to wash it down twice.

So it was out of laziness rather than any technical reason... (I'm right there with you ).

gahorn wrote:When I wash my engine I use "Gunk" brand foaming-aerosol, which is water-soluble/biodegradeable. After it dissolves the oil and grime, I wash the engine down with a garden hose and nozzle, blow it dry with compressed air. I then use a garden sprayer to mist the grass in front of my hangar (where I did the wash-down) with liquid laundry-detergent and spray the area with the garden hose again. Makes for an easy non-problem cleanup.

You, George; using an automotive product on an airplane? I dunno...

gahorn wrote:[This is probably illegal in California, but here in Texas it's considered re-cycling the oil back to nature. (The grass in front of my hangar is some of the healthiest on the ranch.)

You'd be hard pressed to find ANYTHING in California that's not illegal, but that doesn't mean it doesn't happen. (Urinating in one's own back yard comes to mind... Nitrogen is nitrogen, eh?)

Here's a pic of the stuff I used to cut and re-glue the pushrod rubbers with. (Sorry for the previous misinformation...it is not a Permatex product...it is a LOCTITE "Stik and Seal" product, found at automotive parts houses. Alongside are two rubbers ...one of which was cut and re-glued. I've put a 10 lb pull on it and cannot seperate it.

Addendum: THIS PRODUCT IS DISCONTINUED AND NO LONGER AVAILABLE. THIS METHOD OF SPLITTING RUBBERS AND RE-GLUING THEM HAS NOT PROVEN USEFUL DUE TO THE UNAVAILABILITY OF THIS PRODUCT AND DUE TO THE RUBBERS LOSS OF INTEGRITY WHEN THEY ARE WRAPPED AROUND THE PUSHROD-TUBE. (They will not completely re-seal due to re-sizing.)- George

gahorn wrote:(Sorry for the previous misinformation...it is not a Permatex product...it is a LOCTITE "Stik and Seal" product, found at automotive parts houses.

Since 1972 Permatex and Loctite have been the same company. Permatex being bought by Loctite. Permatex then seemed to emerge from Loctite in the '90s eventually to buy out Loctite's foreign business.

In any case most if Loctite and Permatex products are the same. The Loctite brand being sold to industry and the Permatex brand being sold to the consumer market. I've looked for Loctite brand stuff before because that is what is specified by Continental in their sealants SB but could only find the Permatex Brand. Retailers showed me their catologs with both Loctite and Permatex in the same catolog and with both brands having the same product number. Several retailers remember the Permatex brand blister packs also having the Loctite name. Their MSDS sheets match as well.

So if you found this product with the name Permatex on it, I couldn't say for sure but, I'd bet it is the same product.