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Oil tight O235-C?

Philly5G

Registered User
England
I really want to be able to open the cowlings and see them clean and free of oil!! Has anyone succeeded in getting an O235-C completely oil leak free? If yes, I’ve got something to aim for and aspire to :)


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Philly, When an 0-235 has high time on it, it gets oil wet. When it gets to the point that you can't stand it anymore it is time to overhaul. At this point in time they are usually still running well. When the hours exceed the official TBO by a considerable amount, the parts replacement costs go up.
 
Philly, When an 0-235 has high time on it, it gets oil wet. When it gets to the point that you can't stand it anymore it is time to overhaul. At this point in time they are usually still running well. When the hours exceed the official TBO by a considerable amount, the parts replacement costs go up.

Yes, this pretty much sums up how I feel!! The engine starts and runs well and the RoC is ok, not sparkling but ok, it’s just that the oil leaks bug me!!

When overhauled, can the leaks be minimal or preferably none at all? :)


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The leaks are a combination of hours of use on the engine and age in years since it was last assembled. The years show in the drying of seals rendering them inefficient or otherwise unable to perform their duty.

In my opinion, a PA-12 with the original 0-235 engine even when freshly overhauled has never been a sky rocket in the performance department. Just overhauling what you have will not a Super Cub make it. But then I believe that we have been over this previously.
 
A stock pa12 with a strong running o235 with the right prop and a pilot that know how to fly the airplane correctly.Will run circles around a lot of other higher horsepower airplanes
 
A stock pa12 with a strong running o235 with the right prop and a pilot that know how to fly the airplane correctly.Will run circles around a lot of other higher horsepower airplanes

And this is the key point, do I stay with the oil tight O235C or do the O320 upgrade. I’m ok with the O235 performance, as that’s what it is in its current original format, but don’t like the oil mess. I’ve flown aircraft with less and more performance and can cope with both. If the O235 making oil tight is achievable reasonably, I’ll do that. If making it oil tight is close to 320 upgrade STC, I’ll do that. Feedback please :)


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Philly, As I recall from other posts your 0-235 is getting close to the TBO time. In order to completely make that engine dry and to be satisfied that it will remain so for some time, you are looking at the cost of a major overhaul. You need to check on that cost in the UK as well as what the cost would be to trade for a reasonably low time or newly overhauled 0-320. You will be trading props as well. Then only you can make the decision. If it were me, I like as many cubic inches as possible. The operating expense should be close to the same with the bigger engine as long as you moderate your throttle use.
 
If you have case halves that are fretting and causing oil leaks you will need the cases milled and line bored at overhaul. This is a good thing to have checked/done on any overhaul. Can this be done at a reasonable price in the UK. The key to getting oil leaks under control is to properly identify the source of the leak. This usually means the first step is removing all the cowling and complete cleaning of the engine so it is bone dry, replace cowling and test run. The big leaks will show up with just 5-10 min of ground runup. If you find one fix it and repeat step one. Once the big ones are done fly it for 15 min remove cowling and check for leaks with a flashlight when you find one fix it and repeat step one. This may take days/weeks and having the cowling off/swinging engine several times, but it is a lot cheaper than a rebuild. I prefer REAL GASKETS Silicone valve cover and oil fill tube gaskets. If you have a case have leak do a search and you will find instructions on how to fix it with JB WELD and vacuum cleaner. I would agree with Skywagon8a a 150 may be the way to go at rebuild time.
DENNY
 
A 160/320 is a really good upgrade for a 12. You get a nice boost in power without much weight penalty. If you go with a Niagara cooler, a 20a rear mount alternator and a Skytech starter you can eliminate nearly all of the weight gain and CG impact.
 
Philly, As I recall from other posts your 0-235 is getting close to the TBO time. In order to completely make that engine dry and to be satisfied that it will remain so for some time, you are looking at the cost of a major overhaul. You need to check on that cost in the UK as well as what the cost would be to trade for a reasonably low time or newly overhauled 0-320. You will be trading props as well. Then only you can make the decision. If it were me, I like as many cubic inches as possible. The operating expense should be close to the same with the bigger engine as long as you moderate your throttle use.

It's on 1651.4 hours now, I've found the revised Lycoming TBO time of 2400 hours, but I don't know if my engine has the increased strength pistons, so I'm assuming not and therefore do you know the original TBO please?
 
From Lycoming Service Instuction #1009P dated 9/26/1969 the TBO for the 0-235 is 2000 hours. This is based on a use of 30 hours per month and that the total time between overhauls does not exceed six years. Beyond this period of time it is the prerogative of the operator.

How long ago was your's overhauled if ever? Judging by your comments it is my opinion that your seals are tired due to age. Mechanically you likely have many hours remaining, albeit wet ones. The decision will be when you decide that you have had enough. Barring any obvious mechanical troubles this could be some time. As I have mentioned before, back when I was working full time as an A&P at a small airport during the early 1960s we were running the 0-235 in Piper Colts for flight instruction purposes. These engines would be run well over 2,000 hours, then removed and overhauled primarily due to oil leaks. Usually very few mechanical defects were found.
 
"A 160/320 is a really good upgrade for a 12. You get a nice boost in power without much weight penalty."

^^^^ If at all feasible, and certainly if the costs are close, this is the way to go.

First major change to my -12 when I first got it. I believe I had to put -18 tailfeathers on at the same time, but the plane was a real go-er at that point: still very light, very nimble, but with a ripsnorter up front. Just the ticket.
 
"A 160/320 is a really good upgrade for a 12. You get a nice boost in power without much weight penalty."

^^^^ If at all feasible, and certainly if the costs are close, this is the way to go.

First major change to my -12 when I first got it. I believe I had to put -18 tailfeathers on at the same time, but the plane was a real go-er at that point: still very light, very nimble, but with a ripsnorter up front. Just the ticket.

Sounds BRILL :)
 
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