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Low oil pressure, overhaul time?

Riley

SPONSOR
Western PA summer, daytona winter
My cub is a 1978 pa18 150 with an 1800 hour plus or minus first run o320a2b. Oil pressure is well into the green at high cruise setting but is dropping into the yellow arc at the lower end of the green power setting. Plugs are fine wire but I am starting to see fouling and oily plugs. I have been seeing weird mag drops that do not respond to aggressive leaning. I have already "dialed up" The oil pressure.
I have had 150 wonderful hours since I bought this cub from this site, and have come to respect the advice of the folks here. Although this may not be the best time to do an overhaul in my personal financial picture, I would appreciate thoughts as to the right moves to keep this great machine in the proper condition. If an overhaul is appropriate I have a very good IA and the resources to see it through, but will probably lose this flying season.
Advice please?
Riley
 
You should at least do a partial teardown to start with, and see if you come up with something that is affecting your oil pressure. Could be something blocking the pickup, or worn oil pump gears.....it's worth a look before deciding to go for the full rebuild.
 
What would a partial teardown entail? Can you get to the Oil pump without splitting case? Engine burns quart every 4 to 5 hours and seems ok. Biggest worry is dropping oil pressure (aeroshell 100 ) when warm and at below 2000 rpm. Also somewhat concerned about. Oily plugs causing 175 rpm mag drop. 33 years at 55 hours per year may be a bit too long in the tooth for absolute reliability, or am I being overly critical?
 
My recent experience is that low oil pressure with high oil temperature means it is worn out.
Dave
 
33 years SMOH? I wouldn't spend much time looking for clues. If it took a sudden turn for the worse? Maybe I'd chase it. But at 33 years? Probably not. Isn't Lycoming's recommended life limit 2000 hours or 12 years? I'd like to see what a 33 year-old cam looks like.

No criticism, just talking.

SB
 
Lycoming has some deals on factory engines with a trade in of a first run core. That would keep you flying with minimum down time.
 
@ Pacerfgoe : That is an asinine suggestion. Would you really throw money at a high-time (worn-out) engine? Please, help me understand your logic here.

Stewart B's advice is sound.

A 33 year old engine with 1800 hours SMOH I would say is time for an overhaul, especially since your starting to have issues with the engine.
 
...I have already "dialed up" The oil pressure....

if its not making metal, I'd keep looking for the problem.....

did you take it apart & clean the ball/plunger & socket there?

if there is crud on ball or where it seats or a chunk of something acting like a bypass it will not matter how much you tighten spring/"dial it up"...... or if plunger is a bit cockeyed in there maybe???
 
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@ Pacerfgoe : That is an asinine suggestion. Would you really throw money at a high-time (worn-out) engine? Please, help me understand your logic here.

Stewart B's advice is sound.

A 33 year old engine with 1800 hours SMOH I would say is time for an overhaul, especially since your starting to have issues with the engine.

Well I can tell you that I would investigate the problem further before I ponied up $15K or better for an overhaul. I ran an O-235-C1 that was built in 1949 until 1998. It started using a quart of oil every 2-2 1/2 hours so I pulled it apart. When I tore it down it had worn out the rings and that is all. It depends if you have the time and expertise to investigate the cause and if it can be repaired short of overhaul.
 
I see where your coming from on *repairing* the current engine. How much would it cost someone for such an investigation? Then after said investigation, what would the repair cost be if it's the problem you think it is?

My perspective is that in 15 years.....Will the OP be money ahead overhauling the engine now? Or Will he be money ahead repairing his engine now and then dropping the cash on an engine in say...4 years from now? (take into consideration inflated costs..may not be significant, but noteworthy IMO)

I would think he would save money by getting another engine now. By repairing the current engine your just delaying the inevitable. Also, if a guy decides to repair such an engine, you *may* end up throwing more money at it in the future that result from high-time engine issues.

I dont know..six in one - half a dozen the other.
 
My old 0320 was running fine, just over 2000. Since I plan to keep this toy for awhile, I figgered a rebuild was definitely in my future. I decided to rebuild now, rather than later, and enjoy my Bart engine while I owned it, not rebuild for the benefit of the next owner. Just sayin'. :)
 
@ Pacerfgoe : That is an asinine suggestion. Would you really throw money at a high-time (worn-out) engine? Please, help me understand your logic here.

Stewart B's advice is sound.

A 33 year old engine with 1800 hours SMOH I would say is time for an overhaul, especially since your starting to have issues with the engine.

I really don't think doing some investigating before making a decision to overhaul is "Asinine".
Maybe the oil pump is just on its way out, or as I suggested a possible blocked pickup tube.....it wouldn't be the first, on the other hand, he may find a real problem and have to face overhaul now. You don't know until you look.
As others have said, just because the engine is at TBO, doesn't mean it can't perform for 500 or more hours. My friends just went over a C-120 with a 48 year old engine....couldn't find a thing wrong with it......then it flew across Canada to Nova Scotia without so much as farting.
The opening poster said that right now isn't the best time for him to be overhauling an engine, so maybe he can get away with sinking a few bucks into the engine, get it airworthy, and enjoy the plane......while he saves for the eventual overhaul.

I don't have boat loads of money, thats why I make these practical suggestions to get some further life from whatever component it is.....
 
I really don't think doing some investigating before making a decision to overhaul is "Asinine". ...

right,

so many just replace big assemblies of parts(we call them 'parts changers', not 'mechanics' or 'trouble shooters') because they can't, or are to lazy to figure out the real $20 part that's actually misbehaving..... (yes they get the job done.. in a blood shot meat, shot gun fashion.... and probably make a commission on it...)

spending more to replace everything around the real problem with new, doesn't mean you are smarter..... just that you can spend extra $$$$......
 
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Riley,

Here's a good article about oil pressure. http://www.sacskyranch.com/eng26.htm Maybe something here applies to your engine. Maybe not. With oily and fouled fine wire plugs I'm not sure the relief valve is the first suspect. What does your mechanic say? Maybe these guys here will convince you to top that 33 year-old bottom end. Not me.

Do you know what most guys say after they've abandoned an old, tired engine and replaced it with a freshly overhauled engine? Not much. They're usually smiling too big to talk. I've never heard anybody get out after flying the new engine and say they wished they had their worn-out engine back.

Good luck with yours.

Stewart
 
Pay now or pay later.....

I would run it this summer (watching closely for metal in the oil w/oil analysis every 25H) and then decide on an owner assisted rebuild or buying a new engine in October. I would start investigating with the most non evasive parts first. Another thing to factor is the time (and $$) it takes to put band aides on it vs. a rebuild. If you find an obvious culprit to your problems before then.....you probably bought yourself some time.


Tim
 
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If you are doing lots of the labor yourself, just how much is it to pull the pan and accessories case to look at the oil system??????

It could be the simple thing...

Then again, fouled plugs indicate lots of oil, just going to the wrong place... Valve guides????

Stewart has a point, if you have to pull pan and accessories off to deal with pressure, then need to pull the cylinders for valve guides, then maybe have to replace valves...

It is never an easy choice. The trade in idea would appeal to me, because I could fly it until the new engine is ready to install, then swap out and be back in the air with a real reliable engine that has a factory warranty, (which also means enough $$$ to stand behind real troubles).

Question I ask when considering repair/replace of parts, or cheap get by: If I am at the end of Cape Newingham making a turn back to Togiak at 600' with an 800' overcast, nothing between me and the Russian coast, cliff face tops around 1,500', and it is another five miles to the nearest place to put it down on land, do I want to ponder the money I have saved in selecting my options??????

What if your children are on board?

I hope it is simple to fix. Good Luck
 
Cleaned the oil oil pressure relief valve as per the sac sky ranch instruction, no debris or crusties noted with magnifying glass, check ball seems centered and seating surface proper. No change in oil pressure characteristics. Oil pressure not horrible just on the low end of the green at high cruise and in the high yellow below 2000 rpm. Biggest concern is oily plugs. The cub is my fun airplane, I use a 182 to do my traveling. I guess I am looking forward in a weird sort of way to performing the overhaul. New set of decisions to make, such as steel, nickel, or overhaul existing cylinders. Oherhaul bendix or new slick mags, 150 or 160, (I can buy recreational conventional gas in the next state, Ohio).
This site and the knowledge and experience of the active posters has given me the confidence of a positive outcome, THANK YOU ALL!
I once had the confidence of youth, now I have the cynicism of experience, perhaps this overhaul will install a bit more confidence in me.
 
Probably worn or stuck rings causing the oily plugs. Camguard has a flush they developed for the TSIO360 in the Cirus for unsticking and cleaning deposits out of the ring lands. Also might put a washer under the oil pressure spring and see if the pressure changes in cruise at normal temp.
 
you're smarter than I look!

Jeeze, I HOPE SO!!
just pullin' yer chain... haven't yet seen your ol' wrinkled mug.
You coming to Nimpo this year? No griz spotted in the neighborhood this year, just a couple blacks (& they don't eat much).
Your WSFPA pres. comes every year, this year he has the floor for half an hour or so.
]
Note to all you eavesdroppers: If anyone wants to see the June BCFP N-letter, send me your eddress. OR... SJ, can I somehow post a .PDF?
 
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Try the Cam guard and if that does not work for the ring issue for the plugs call

Pine Mountain Aviation Danbury Connecticut
John Drenchahn 203-730-0771

He rebuilds engines, that is all he does. Just did Tim Allens and it came out great. Used Lycon parts with all balanced and ported parts.

Great guy! had Tim back in the air in less than 60 days. You are close enough to drive it to his shop.
FMD
 
Jeeze, I HOPE SO!!
just pullin' yer chain... haven't yet seen your ol' wrinkled mug.
You coming to Nimpo this year? No griz spotted in the neighborhood this year, just a couple blacks (& they don't eat much).

Leave your glasses off, and it won't be so bad - -

Nope, not going ANYWHERE until this 12 is in the air. If I'm diligent that will be this summer. School's out, and today is my first day of summer vacation. Wheeee!
 
To the original post and the described conditions, I recall being in a very, very similar position once. And with sincere respect to Mike and Steve, my mechanics advised me very similarly to your advice on this thread. As mechanics they wanted to maintain my engine to meet or exceed airworthiness standards. Or as I called them, minimum standards. I saw it differently. I was motivated to achieve maximum performance and reliability with minimum maintenance. I went with my gut feeling and bought a factory reman. In doing so I not only solved the oil pressure, oil leaks, blow-by, and other worn-out engine issues but got a significant boost in power as well. Not that I did an upgrade because I didn't. The new engine made rated power where the old engine clearly hadn't been. My mechanics never considered that. Fresh engines are better than worn-out ones. That's a fact. Like Nimpo has said, refreshing that engine is coming soon enough no matter what Riley does. From my viewpoint, there's no time like the present. Easy to say, too, since it isn't my money!

SB
 
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That's so true Mike. I had an 0-470S with oil pressure drops when warmed up. Mechanics checked everything; oil pump, relief valve, etc. Turned out to be the ECI pressure gauge- had a faulty sender (when hot).
Jim
 
Let's define low oil pressure as it relates to the engine speed and factory limitations. I want my equipment to be as good as it can be because of where I fly. If it is in the green, low or high RPM , the fact is it's in the green. Green means good. Sounds like your engine will go to TBO and farther.
 
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Already added a washer under the spring cover, I will try cam guard to assist with oil on plugs. Stewartb your advice is hitting home , I will advise as I get quotes.
 
Mr. Riley,

Risking that you may have done a search and I may be repeating myself, I'll lay out the 0-320 rebuild option that I took. If your mechanic has the skills, the time, and is willing, ask him if he'll do a field overhaul and let you participate. Send the case to Divco. Send everything else to Aircraft Specialties for inspection and/or replacement. They static balanced my rods, inspected/machined/coated my cam followers, lifter bodies, gears, crank, and provided many other services I've forgotten. They also sold me a new cam that had been checked using the Cam Doctor program. Some of my parts were rejected and replaced with new. I then bought new nickel cylinders from ECI and had the mags and carb overhauled by a local shop. Reassembly was fun and easy. The main stumbling point for me where my mechanic stepped in was in the gears. We put the lower end together and painted it on one day and finished the assembly the following day. It was a blast. It runs great. Balanced, flow matched, and I know every bearing clearance and bolt torque because I put it together myself. I checked, double checked, and triple checked. All in all a very satisfying experience. You may not choose to use the component parts that I did but the procedure is a sound one. I'll do it again when I need another engine overhaul. Well, maybe not, because my next engine will be an IO-550 for the Cessna. :)

You have many options. Best of luck with whatever path you choose.

Stewart
 
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