The International Cessna^® 170 Association

Hey All,

Since I've owned my airplane, it's always spit a bit of oil on the ground out the breather tube after shutdown, with nothing ever being present on the belly...so I'm pretty sure it's only at shutdown.

Recently, in the last 10 or so hours, I've noticed an additional drip on the floor and associated oil on the belly (I know...it lubes the tailwheel assembly). Since it was new, I figured I'd do some investigating.

I found that I went through a quart of oil in about 4.5 hours on the tach. In the 8 months I've owned the airplane (and the 100 or so hours I've flown), I can't say it doesn't use oil...I'd say it has always been a quart every 6.5 to 7 hours on the tach. Roughly 4 quarts per 25 hour oil change interval. It seemed high to me at first, but after reading on here it didn't worry me too much. The engine has 1500 on it since an overhaul completed a long time ago...

Since the inside of the cowl and the belly were both showing evidence, I cleaned up the engine and cowl and decided to run it and see if I could spot the seep/leak. I know a little oil leak can look like a murder scene at times, so while expecting something huge it's probably a small amount actually leaking.

Here's a pic of what I suspect: The picture is the #2 cylinder. It certainly looks like there's oil coming from the head-end of the pushrod tube.

In reading the forum, it looks like I can replace the pushrod tubes with the kit from Real Gasket, or perhaps there's a tool that is out there that does something I'm not sure I fully understand. Anything other than those options? Just keep going and enjoy the well lubricated tail wheel assembly?

The pushrod tube can be expanded with the proper tool in order to more tightly seal that tube-to-head joint.
I have one I can loan out if you’ll promise to return it within 2 weeks. Here’s how that would work:
You will send $100 to my PayPal acct. I will Priority Mail the tool to you. You will return the tool in 2 weeks. I’ll return $90 to you (deduction for what I spent on Priority Mail.).
Caution: I have heard that some ECI cylinders will not accept this tool, that the pushrod tube is smaller diameter than standard.

That is a fairly normal seep. Those that can't live with it try to fix it. You know both major options. The swaging tool George showed, and the Real Gasket pushrod tube replacement which has seals. The swaging tool takes just a bit less work than replacement with a Real Gasket tube. Both require the removal of the valve cover and rocker arm and push rod for the tube to be worked on. Many people have had good luck for many years just reswaging and there is a chance reswaging won't stop the seep. The RG solution probably I feel has a better track record but it is not the end all. RG seals, like the similar Continental solution found on larger, newer engines, will develop leaks over time. We change Continental seals out all the time about mid TBO. The RG solution is $106 a cylinder which included parts for two tubes.

And then there is the stop gap measure many try. Clean the leaking tube and crevice really well and stuff it full of high temp RTV. It may stop the seep or at least slow it down so something less than a seep you might be able to live with. I've really become fond of Dow Corning high temp 736 RTV. If you look in any SR-22 you will note practically the entire engine compartment is held together with it. I've seen it placed directly on turbo exhaust manifolds to space plumbing way. It sticks to about anything, skins over in a an hour, is semi cured in about 6 hours and of course current (cured ) in 24. If any RTV could seal this seep, this will do it and it will be there in 1000 hrs.

“Current” probably mans “cured”.