Piper Arrow Oil Leak

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Arrow115

Pre-takeoff checklist
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The Woodlands, TX
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Chris
I have a Piper Arrow with the 200 horse Lycoming IO 360 C1C. I have been fighting oil leaks since day one.

Friday my electric fuel pump went out so I decowled the plane so we could get to the pump. I noticed what seemed like a lot of oil coming off of the #2 (pilot side front) cylinder intake tube. I cant figure out where this could be coming from. I have replaced the drain back tubes and valve cover gaskets. Any one have any ideas? It looks like it originates from where the intake bolts to the cylinder, but that doesn't make a lot of sense to me.
 

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Arrow115 said:
I have a Piper Arrow with the 200 horse Lycoming IO 360 C1C. I have been fighting oil leaks since day one.

Friday my electric fuel pump went out so I decowled the plane so we could get to the pump. I noticed what seemed like a lot of oil coming off of the #2 (pilot side front) cylinder intake tube. I cant figure out where this could be coming from. I have replaced the drain back tubes and valve cover gaskets. Any one have any ideas? It looks like it originates from where the intake bolts to the cylinder, but that doesn't make a lot of sense to me.
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Our MX guy said to check the oil return line. He said the rubber could be old or the clamps are wore out. He also said if it's not that look at the rocker box.
 
Check that the upper end seals on the push rod tubes are seated properly in the cylinder head. I had a leak there on an O-320. It wasn't installed properly on re-assembly after overhaul. I was able to re-seat it by pulling the tube up with no dis-assembly. IIRC the bottom seal is an O-ring that allows some travel on its sealing surface in the crankcase and the upper end is a cup that fits over the end of the tube and seats in the cylinder head. If it leaks there, it could run around the cylinder and drip off of the bottom
 
Pushrod tubes. It's always pushrod tubes. Even though it looks like it might be something else, it's pushrod tubes.
 
Thanks everyone for the advice. I brought up the push rod seal to my mechanic and he agrees, so I have ordered new push rod seals for all of the cylinders since they were last replaced at the last overhaul more than 10 years ago. New fuel pump ordered as well. I went ahead and bought a new one since the overhauled pumps were not that far off from the new price. Hopefully this does the trick.
 
ARFlyer said:
Our MX guy said to check the oil return line. He said the rubber could be old or the clamps are wore out. He also said if it's not that look at the rocker box.
Click to expand...

The rubber ends and clamps on the drain back tubes were replaced a year ago or so, but I will check those as well. I replaced the old rocked cover gaskets at the same time with the orange silicon ones (Real Gaskets), but I went a head and ordered another just in case it wasn't sealing for some reason.
 
Arrow115 said:
Thanks everyone for the advice. I brought up the push rod seal to my mechanic and he agrees, so I have ordered new push rod seals for all of the cylinders since they were last replaced at the last overhaul more than 10 years ago. New fuel pump ordered as well. I went ahead and bought a new one since the overhauled pumps were not that far off from the new price. Hopefully this does the trick.
Click to expand...
Do you need to pull the heads to replace the push rod tube seals? (curious because if not, I might do the same as well since mine seem to be leaking too)
 
BigBadLou said:
Do you need to pull the heads to replace the push rod tube seals? (curious because if not, I might do the same as well since mine seem to be leaking too)
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No, but you do need to slide the rocker shaft out and remove the rockers. (not a big deal, just don't get them mixed up) One nut holds a little clamp which holds both tubes.
 
tyndall said:
No, but you do need to slide the rocker shaft out and remove the rockers. (not a big deal, just don't get them mixed up) One nut holds a little clamp which holds both tubes.
Click to expand...
That is great news, thanks!

Disclaimer: I have re/built a few engines in my life so I know how to hold a wrench, I just do not have a lot of experience with aero engines.
 
Arrow115 said:
The rubber ends and clamps on the drain back tubes were replaced a year ago or so, but I will check those as well. I replaced the old rocked cover gaskets at the same time with the orange silicon ones (Real Gaskets), but I went a head and ordered another just in case it wasn't sealing for some reason.
Click to expand...

Be careful not to over-torque the rocker cover gaskets if you are using the silicon seals. The extra thickness will allow you to bend your rocker covers if over-torqued. Lots of people just wrench down on them if they are leaking, which only squishes the gaskets out and makes the problem worse. As long as you have the gaskets and both metal surfaces cleaned and free of oil, they should stay in place and allow you to get a good seal without using excess force.
 
I once rented a Piper Arrow that leaked so much oil I was pretty sure when the gear doors opened, a gallon of pooled oil just dumped. :eek:

I had a Gopro on the belly that took a picture every minute... The lens was so dirty after the 5th picture you couldn't tell what was going on.
 
BigBadLou said:
Do you need to pull the heads to replace the push rod tube seals? (curious because if not, I might do the same as well since mine seem to be leaking too)
Click to expand...

You may not need to replace leaking seals. Dimensions are such that installing the cylinders does not necessarily seat the outboard seals on the push rod tubes. The inboard o-ring has some freedom of "in-out" motion. If the seals aren't seated, it may be possible to just pull outwards on the tubes and seat them (worked for me). @BigBadLou
 
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