High oil pressure and consumption

[DannyDot]

I have a C-85-8 with about 60 hours from major overhaul. It's oil pressure is very high (over 50) and oil consumption is also very high (quart every 4 hours). Compression is all great (all over 75/80). No visible smoke and no plugs getting oily. Any ideas on what is wrong.

Danny Deger

[Guest]

Re: High oil pressure and consumption

Hi Dan, I think you should be getting about 16 hours on a quart.

Sometimes the breather draws it out, is the breather tube vented?

Also, my a65 gets about 14 hours on a quart but not if I keep it filled to 4 qts. It seems to stay at 3.2 qts on the stick forever but if I fill to 4 qts it goes to to 3.2 real quick.

So if I keep filling to 4 it appears to use more oil.

Dave

[Len Petterson]

Re: High oil pressure and consumption

If you check the bottom of fuselage you will see if it just goes over board, the belly be oily.
Make shure not to go over 3.5 quarts.This hold true for any small Continetal and Lycoming 0 235. One C 152 I flown wented out a lot of oil!
Too high oil pressure: Remove the relife valve cover and see if you have one or more washers under the spring?
If so remove one at the time,test it with warm oil!
Make shure the plunger is free and not binding in any way in it's cavaty.
Look for scoring on the seat and on the sides of the plunger.
The biggest risk with high oil prressure is what you can blow out the front seal,
A shaft seal as used in older engines can only handle about 100 psi and I just changed mine for a newer style what looks better.
Remeber Continetal reads oil pressure after it has gone trough the engine, residual pressure.
Lycoming read it's before the engine between the oilgalery and the pump. there fore they read a higher pressure when Continetal.

First lesson in Hydualics: Pressure is generated by resitanse to flow! If your bearings are bad the oil pressure will be lower when with new(er) bearings.
or if the pump is worn you can not maintaine oil pressure to spesification.
Often a worn pump will not give 40 psi with cold oil and no or low pressure when idle with hot oil.
First of all make shure the relief valve is OK. Much easyer then changing pump for nothing.
Len

[jstall]

Re: High oil pressure and consumption

I have a C-85-8 with about 60 hours from major overhaul. It's oil pressure is very high (over 50) and oil consumption is also very high (quart every 4 hours). Compression is all great (all over 75/80). No visible smoke and no plugs getting oily. Any ideas on what is wrong.

Danny Deger

Have your mechanic set your oil pressure down 10 notches, and take a look, higher pressure sure could cause it to burn more, also 1 per 4 hrs isn't that bad, considering the time, its possible you still don't have the rings seated good, ?? How did your run it at the first?? you want hi power need to really get it warmed up with High BMEP, to seat those rings, I wouldn't be too concerned yet, lower the pressure into the mid green for that engine, and run hell out of it give it another 50 or more

JS

[Guest]

Re: High oil pressure and consumption

I have a C-85-8 with about 60 hours from major overhaul. It's oil pressure is very high (over 50) and oil consumption is also very high (quart every 4 hours). Compression is all great (all over 75/80). No visible smoke and no plugs getting oily. Any ideas on what is wrong.

Danny Deger

What are the oil pressure limits?

I think 60 psi is the high limit and 15 the low

[Guest]

Re: High oil pressure and consumption

Have your mechanic set your oil pressure down 10 notches, and take a look, higher pressure sure could cause it to burn more, also 1 per 4 hrs isn't that bad, considering the time, its possible you still don't have the rings seated good, ?? How did your run it at the first?? you want hi power need to really get it warmed up with High BMEP, to seat those rings, I wouldn't be too concerned yet, lower the pressure into the mid green for that engine, and run hell out of it give it another 50 or more

JS

How does one do either of those, I don't think either are possible.

I am not sure the oil pressure is to high, it needs to be looked up

[Guest]

Re: High oil pressure and consumption

Danny,

I just looked in the manual, it says 30 psi min, 60 psi max at cruise speed so 50 is ok. Minimum at idle is 10 psi.

The plunger is set to relieve pressure a 60 (the max) so you are ok regarding the plunger and spring. Its merely a relief valve that bypasses oil back to the sump when the system/gallery/manifold whatever word you like gets to 60, that's all it does. All the bearings and so on get their oil from bleeding off the gallery.

FYI;

§ 91.9 Civil aircraft flight manual, marking, and placard requirements.
(a) Except as provided in paragraph (d) of this section, no person may operate a civil aircraft without complying with the operating limitations specified in the approved Airplane or Rotorcraft Flight Manual, markings, and placards, or as otherwise prescribed by the certificating authority of the country of registry.

(b) No person may operate a U.S.-registered civil aircraft—

(1) For which an Airplane or Rotorcraft Flight Manual is required by §21.5 of this chapter unless there is available in the aircraft a current, approved Airplane or Rotorcraft Flight Manual or the manual provided for in §121.141(b); and

(2) For which an Airplane or Rotorcraft Flight Manual is not required by §21.5 of this chapter, unless there is available in the aircraft a current approved Airplane or Rotorcraft Flight Manual, approved manual material, markings, and placards, or any combination thereof.

The point is that this says that the operating limitations should be marked on the panel/instr and so on.

[jstall]

Re: High oil pressure and consumption

This is correct, your aircraft flight manual, or if you don't have that you can come up with an engine manual at a good shop or even get one thru univair
anyway, get a manual for the A-65 or the 85 h.p. version, and take a look at the oil pressure limits, then adjust the pressure relief to obtain a decent value, "somewhere in the middle of normal" 1/2 between low to high or
equiv. My A-65-8 runs at 40 psi cruise and idles about 18 to 20
anyway, 80 lbs, would be way way over pressure, 60 is high also, but I'll bet it can be adjusted down.

[DannyDot]

Re: High oil pressure and consumption

Danny,

I just looked in the manual, it says 30 psi min, 60 psi max at cruise speed so 50 is ok. Minimum at idle is 10 psi.

snip

Thanks for the info. The red line on my gauge is wrong.

Danny Deger

[Guest]

Re: High oil pressure and consumption

This is correct, your aircraft flight manual, or if you don't have that you can come up with an engine manual at a good shop or even get one thru univair
anyway, get a manual for the A-65 or the 85 h.p. version, and take a look at the oil pressure limits, then adjust the pressure relief to obtain a decent value, "somewhere in the middle of normal" 1/2 between low to high or
equiv. My A-65-8 runs at 40 psi cruise and idles about 18 to 20
anyway, 80 lbs, would be way way over pressure, 60 is high also, but I'll bet it can be adjusted down.

60 is the high limit

[Guest]

Re: High oil pressure and consumption

Thanks for the info. The red line on my gauge is wrong.

Danny Deger

Sometimes the glass rotates and thows it off. I make a white line on the glass and the gauge frame so I can see if it has rotated. You could also use torgue seal to mark it and hold it in place, I do that too.

[Ragwing nut]

Re: High oil pressure and consumption

Does it have chrome cylinders? How much oil do you keep in the motor? Are you sure you have the right dip stick and not over filling it? The two don't necessarily mean one is affecting the other.

[N95334]

Re: High oil pressure and consumption

try Luscombe.org they have alot of neet stuff to do with engines and all the tech stuff on cont oil pressure limits, operations etc.
Hey I still love my Taylorcraft but her sister the Luscombe has a nice site too.

[tawadc95]

Re: High oil pressure and consumption

4 qt is not all that off for a break in if you are running mineral oil......you should be doing more than just up and down a few times (touch and goes)when you go out,such as a half hour or more at cruise. I assume since the plugs are clean the exhaust stack is oil free also?

[Jim Lauden]

Re: High oil pressure and consumption

I have a C-85-8 with about 60 hours from major overhaul. It's oil pressure is very high (over 50) and oil consumption is also very high (quart every 4 hours). Compression is all great (all over 75/80). No visible smoke and no plugs getting oily. Any ideas on what is wrong.

Danny Deger

IF YOU HAVE ACCESS TO ONE, SWAP THE GUAGE. SEE IF THERE'S ANY DIFFERENCE. DID IT ONCE WITH OIL TEMP, THERE WAS A DIFFERENCE!