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Suggestions on oil leak from pushrod seals

Flying again!

Flying again!

Well Known Member
I had oil leaking from the pushrod shrouds on cylinders 3 & 5 on my O-540. I replaced them and no leaks for about 6 hours.

I have oil leaking from the o-ring seal at the head side of the cylinders, all 4 that I replaced. I made sure the area the seal fits in was clean with no grunge that could cause a bad seal.

I am wondering if it is a weak push rod tube seal spring. I thought I saw mention of a Lycoming SB that recommended using 2 springs to ensure sufficient compression.

Any thoughts or suggestions are welcome!
 
I am curious if you are pushing them in far enough. The O ring needs to be seated inside the cylinder not just against it. You sometimes have to seat them by hand prior to installing the spring keepers.
Ryan
 
Good point Ryan.

I pushed them in by hand until they "popped" in and the lower green seals had expanded. Couldn't push them in any further. That is why I am wondering if the springs are too weak.
 
close inspection

my O-320 pushrod shroud tubes leaked, not the seals.

Close inspection identified #2 tube was out of round at the case end, and was resolved by use of flaring tool; the dent on the bottom (adjacent to cooling fins) of #4 tube was not identified until I removed the tube completely.

Good luck!
 
esco said:
my O-320 pushrod shroud tubes leaked, not the seals.

Close inspection identified #2 tube was out of round at the case end, and was resolved by use of flaring tool; the dent on the bottom (adjacent to cooling fins) of #4 tube was not identified until I removed the tube completely.

Good luck!
Click to expand...

Guess I know what I will be doing this next weekend, pulling the tubes. Still wonder if I should change the springs....
 
Flying again! said:
I had oil leaking from the pushrod shrouds on cylinders 3 & 5 on my O-540. I replaced them and no leaks for about 6 hours.

I have oil leaking from the o-ring seal at the head side of the cylinders, all 4 that I replaced. I made sure the area the seal fits in was clean with no grunge that could cause a bad seal.

I am wondering if it is a weak push rod tube seal spring. I thought I saw mention of a Lycoming SB that recommended using 2 springs to ensure sufficient compression.

Any thoughts or suggestions are welcome!
Click to expand...

Some times a washer is installed under the spring clip; it tends to reduce the spring pressure. If you have these washers installed remove them. Inspect the spring clip it should not be flat. Inspect the area that the O-ring sets in the head for scratches, gouges. Polish if necessary with fine scotch brite pad. Inspect area of pushrod tube where the O-ring sets, some times this area is painted the paint can chip crack or peel. Paint should be removed from the o-ring groove and polished with fine scotch brite. When installing new seals they should be lubricated before installation, I prefer isopropyl alcohol.
On the older style narrow deck Lycoming pushrod tubes, they required two flat steel springs about .020? thick with a single washer under the springs .The newer style uses a single stamped spring about .030 to.035?thick, it is not flat, it has a lip on each end. It should not have a washer under it.
I hope this helps with your problem.
 
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