sv 540 oil pressure and consumption ???

Aircraft powered airboat discussion.
Post Reply
chases pee paw
Southern Airboat Member
Posts: 9
Joined: Tue Mar 01, 2016 5:18 pm

sv 540 oil pressure and consumption ???

Post by chases pee paw »

I have a straight valve 0540 and when at idle cold start oil pressure is between 70 - 80 psi . after engine has gotten to operating temp at idle pressure is around 5 - 10 psi. what would cause this , main bearings , rod bearings , oil pump ? engine seems to consume a lot oil also. doesn't seem to be smoking , leaking or any through vent tube . this engine is new to me and I don't know the history behind it. it does seem to have plenty of power but the oil pressure and consumption has me very concerned . am I looking possibly at a complete rebuild or maybe something simple ? how about a rough price range for repair or rebuild by a reputable mechanic ? thanks for any and all info given in advance. this is my first Lycoming and don't know much about them.

User avatar
John Fenner
Southern Airboat Member
Posts: 2889
Joined: Tue Feb 14, 2012 12:26 pm
Location: Miami(Cuba) Fl.

Re: sv 540 oil pressure and consumption ???

Post by John Fenner »

Well, if ring lands are worn it will superheat the oil and cause this without any smoking to your knowledge, best bet is to have a leak down test done to evaluate the condition of it.
I never finish anyth,,,.

Strangiato
Southern Airboat Member
Posts: 9
Joined: Wed Feb 10, 2016 7:17 pm

Re: sv 540 oil pressure and consumption ???

Post by Strangiato »

x2. Heat build up in crankcase from blow by, thins oil and drops pressure.

chases pee paw
Southern Airboat Member
Posts: 9
Joined: Tue Mar 01, 2016 5:18 pm

Re: sv 540 oil pressure and consumption ???

Post by chases pee paw »

Let me get this right , worn ring lands can cause super heating and thins the oil . Which also causes the the engine to consume large amounts of oil without a trace from the vent tube , leaks or smoking ? And a leak down test should be able to tell me this correct.. I don't want to replace cylinders ,pistons and rings then have to split the case later because that isn't the problem.. thanks you for 5he information and knowledge. Just learning about these aircraft engines and don't want to get screwed like some of the horror stories I've heard of in the past

User avatar
Planeguy
Southern Airboat Member
Posts: 179
Joined: Sun Sep 06, 2015 4:49 pm
Location: OK

Re: sv 540 oil pressure and consumption ???

Post by Planeguy »

There are only 3 ways oil can leave the engine:
1. burned in the combustion chamber
2. blown by the rings and pushed out the vent as vapor
3. external leak

Blow-by can do what the others suggest but I would also check the oil pressure regulator before I tore anything down. The minimum oil pressure for that engine is 25 psi at idle with a maximum of 115 psi during warm up. Normal operation is 55-95 psi. Maximum oil temperature is 245°F. The oil would have to get a ways above 245° to thin down enough to put you that far out of the range if everything else in the lubrication system is okay. If you don't already have one, I would install an oil temperature gauge. It is every bit as important as the pressure gauge and would help diagnose this problem. An internal leak could explain the low oil pressure. Of course my information hinges upon the correct grade aviation oil being used.
Attachments
Lubricating Oil Recommendations.pdf
(150.34 KiB) Downloaded 28 times

Outlawaircraftengines
Site Supporter - I
Site Supporter - I
Posts: 1019
Joined: Mon Sep 04, 2006 9:49 pm
Location: Plant City
Contact:

Re: sv 540 oil pressure and consumption ???

Post by Outlawaircraftengines »

40-60 when hot is normal after a rebuild. sounds like worn rod/main bearings.
Gary Barber
Outlaw Aircraft Engines
www.outlawaircraftengines.com
863-698-0383

chases pee paw
Southern Airboat Member
Posts: 9
Joined: Tue Mar 01, 2016 5:18 pm

Re: sv 540 oil pressure and consumption ???

Post by chases pee paw »

Oil used is aeroshell red label .engine also is a narrow deck , if that means anything or not. Engine seems strong and has power , the concern is pressure at idle after warm up and consumption. When cold oil psi is between 80 and 90 . Any estimate on prices would be helpful. If cost is too much the I would probably be changing to continental . Don't like the idea of a dry camshaft at start up . Especially if it sat for any length of time. Thanks for your time and knowledge.

mwood7800
Southern Airboat Member
Posts: 985
Joined: Thu Feb 03, 2005 5:32 pm

Re: sv 540 oil pressure and consumption ???

Post by mwood7800 »

Best guess for overhaul around 7k, do it yourself for 5k

Strangiato
Southern Airboat Member
Posts: 9
Joined: Wed Feb 10, 2016 7:17 pm

Re: sv 540 oil pressure and consumption ???

Post by Strangiato »

Find a reputable airboat mechanic near your area. Have him go over the whole boat and express your concerns. The money you pay them may save you a fortune later. Alot of these guys have a wealth of knowledge and know exactly what to look for. If you can find someone who specializes in building your type engine, that would be best. Good luck, keep us posted.

User avatar
kwanjangnihm
Site Supporter - IV
Site Supporter - IV
Posts: 2073
Joined: Sat Mar 30, 2013 8:23 pm
Location: Bartow FL

Re: sv 540 oil pressure and consumption ???

Post by kwanjangnihm »

Strangiato wrote:Find a reputable airboat mechanic near your area. Have him go over the whole boat and express your concerns. The money you pay them may save you a fortune later. Alot of these guys have a wealth of knowledge and know exactly what to look for. If you can find someone who specializes in building your type engine, that would be best. Good luck, keep us posted.
x2

also fill in your location!! :thumbleft:
He'll cut your throat, baby, stick you in the back, drive off in your Cadillac.
He's more trouble than you think, he'll kill your sugar, leave you in the drink.

User avatar
John Fenner
Southern Airboat Member
Posts: 2889
Joined: Tue Feb 14, 2012 12:26 pm
Location: Miami(Cuba) Fl.

Re: sv 540 oil pressure and consumption ???

Post by John Fenner »

Get it up to temperature, shut it down and feel the cooler to see if it is warm, be sure battery is disconnected. My buddy's 180 is doing the same thing as yours is, the ringlands are worn on the pistons, it shows no blowby out vent tube as compression seats the rings to the lands, the leak down test shows good, however the residual heat gets past the Rings when they unload from the lands then draw oil up on intake stroke, we are going with the Combustion Technologies 10:1 forged pistons to cure this problem and get all of the energy out of 100ll avgas.
I never finish anyth,,,.

chases pee paw
Southern Airboat Member
Posts: 9
Joined: Tue Mar 01, 2016 5:18 pm

Re: sv 540 oil pressure and consumption ???

Post by chases pee paw »

I am located in central fla . Ok, I think I understand a little bit . I change one cylinder a while back . Running at night , all header tubes glow slightly except the cylinder I changed. When running on the hill to park the header tube glow even brighter. But also I have a small blue flame at the end of the exhaust tips. Which indicates all is burning well in the cylinders , correct? It they were burning lean the exhaust would be burning a yellowish orange correct? If my thinking is somewhat correct and what you are telling me is true about the ringlands . 5 of the 6 cylinders are letting excess heat passed the rings causing 5he oil to burn without indicating blow by or heavy smoke.leaving it hard to detect.

Outlawaircraftengines
Site Supporter - I
Site Supporter - I
Posts: 1019
Joined: Mon Sep 04, 2006 9:49 pm
Location: Plant City
Contact:

Re: sv 540 oil pressure and consumption ???

Post by Outlawaircraftengines »

Need to check the camshaft, lycoming engines love to eat camshafts
Gary Barber
Outlaw Aircraft Engines
www.outlawaircraftengines.com
863-698-0383

Post Reply

Return to “Aircraft Power Only”