Oil Temperature/Oil Pressure

[Frank DeBartolo]

According to the Continental Engines Specifications, oil pressure at cruising is listed as 30-35 PSI for the A65, A75, C75 and C85 engines. The Continental A-65-8 on my BC12-D generally perfoms according to specs unless the oil temperature goes above 180 degrees F. This usually happens after a sustained climb when outside air temperature at the surface (1,100 feet MSL) is above 80 degrees F. Today OAT was 27C or approximately 85 F and density altitude was 3,200 feet. These conditions cause the oil pressure to go slightly below 30 PSI to approx 25-28 PSI after a climb to 3,500 MSL according to the oil pressure instrument and the oil temp goes somewhat above 180 degrees F. My guess for oil temp was approx 185-190 degrees F according to the oil temp instrument. At or slightly below 180 degrees F (oil temp), the oil pressure is right around 30 PSI. In cold weather, the oil pressure stays higher around 32-35 PSI or slightly higher (might be as high as 40 PSI-depends on OAT). I use Aeroshell 100 (50 weight) in the summer and add Avblend. In winter I use Aeroshell W15 W-50. I would like some feedback from other T-Craft owners regarding this issue.

Frank DeBartolo
BC12-D
N43684

[lktiller]

Sounds normal.
I use AeroShell 15W50 year round.

[Jim Hartley]

Frank,I concur with Larry. I use 30wt in winter, 40wt in spring and early summer and 50 wt in late summer. In so doing I can keep oil temps as cool as possible and oil pressure as high as possible. If I always flew at a few thousand feet I probably would not be as dilligent on the weight of the oil but some times I climb to several thousand feet to cross the "tall hills" and it can take a while at gross and this is the time the difference in the weights of the oils are observed.

[Goneflyin]

Frank, mine runs about the same. Awhile back I changed my accessory case because the old one would lose it's prime, and started watching things closely. When mines at 175 or above, the gauge will read about a needles width below the 30, below 170 it runs in the 30 -35 lb range. I've watched the pressure for a 100+ HRS and the numbers have been consistent so I figure stable is good.
I had to run mineral oil in mine 3 times since I had the plane(400hrs) for various repairs and the oil pressure was 3-5 lbs higher with mineral than the regular straight weight. I wonder when Continental published the numbers how oil weight compared to todays oils viscosity, not just the number.

Bill

[larrysmith1016]

Re: Oil Temperature/Oil Pressure

Frank,I concur with Larry. I use 30wt in winter, 40wt in spring and early summer and 50 wt in late summer. In so doing I can keep oil temps as cool as possible and oil pressure as high as possible. If I always flew at a few thousand feet I probably would not be as dilligent on the weight of the oil but some times I climb to several thousand feet to cross the "tall hills" and it can take a while at gross and this is the time the difference in the weights of the oils are observed.

Yesterday I installed another rear case with new pump gears, new bushings, and new oil pump cover plate on an A-65-8. We pre-oiled the engine with pressure oil at an oil galley plug on the front of the crankcase. Oil pressure came right up to 30 and stayed there at idle. The aircraft took off and flew for 10 minutes and came back in with the oil pressure down to near zero, as it had done before with the other rear case. Oil temp never got over 180.

We have probably ruled out the rear case as a villain, but I wonder if I'm overlooking anything. I'm about to pull the engine and go through it again, because it sounds to me like oil pressure is leaking somewhere inside the crankcase. I rebuilt this engine and the new mains were nice and tight. The only thing I can figure is an internal crack in the crankcase or in a galley, or not enough pinch on the mains, or oil squishing out against the lifter bodies, or cam bearings, or? Jeez, this thing has me up pacing at night.

By the way, the engine runs wonderfully, purrs, makes plenty of power, compressions are all in the high 70's. Just the oil pressure dying as the engine gets warm.

Any ideas? I'm about to pull the engine and tear it down again.

[Frank DeBartolo]

Re: Oil Temperature/Oil Pressure

Could be crankshaft problems. That is what happened to me--the crankshaft was scored and could not be repaired. I had to overhaul the engine. I bought a yellow tagged crankshaft from Aircraft Specialties in Oklahoma. That was in 2004-2005. It runs good now after the overhaul and I can climb all I want--do slow flight on a hot day and oil temps and pressure stay real good.

Another question I have is how many people out there use multi-viscosity oil in their A-65s? I use Aero Shell straight weight and if I have 50 weight in it and it cools down a lot, I hesitate to fly, If I have 40 weight and it gets over 80 I hesitate to fly. To change to 30 weight is something I have not done and don't fly if it is under 25-30 degrees. Multi-weight would help but how does it hold up in 80-90-100 degree weather.

Frank D
N43684

[Pearson]

Re: Oil Temperature/Oil Pressure

Larry,

May we assume you have tried a different oil pressure gauge? Other than that, it sure sounds like something going on with the main journals, either the crank or the bearings. But you could be right about the crack in the case somewhere.

Frank

As far as oil, I tried muti weight for about 4-5 hours. Ended up draining it out and dumping it, never again. Oil pressure indications were all over the place with the multi weight. I use straight 30 wt in the winter and 40 in the summer. With the multi weight oil I would get good pressure on start up, which is my main concern, then at altitude it would jump up to 40 for a while. Later I would look down and it would show 5 psi. That will get your attention quick. Changed back to straight weight and it stays glued to about 30 psi regardless of temp.

[Frank DeBartolo]

Re: Oil Temperature/Oil Pressure

Richard,

Thanks for the info

Frank D
N43684

[larrysmith1016]

Re: Oil Temperature/Oil Pressure

Thanks to everyone who replied. We're probably going to send the case to Divco -- now $700, and the accessory case to Drake --- now $850 for new pump gear cavities and bronze bushings.

Anybody know any other companies that do this work? I have used Divco before and their price is reasonable, I reckon, but $850 for the accessory case?

Thanks again. I believe I will build another A-65-8 to specs, and a C-85-8, and have them waiting. Inflation is biting us these days.

I found some good mogas with no alcohol in it at the Chevron station. So there is every once in a while a silver lining in the clouds. I'll test it, by golly, before I'm sure of it.

Thanks again, and Hank Jarrett if you'll call with your address, I'll send those dented hubcaps your way.
Larry
828/545-2860

[Guest]

Re: Oil Temperature/Oil Pressure

Could be crankshaft problems. That is what happened to me--the crankshaft was scored and could not be repaired. I had to overhaul the engine. I bought a yellow tagged crankshaft from Aircraft Specialties in Oklahoma. That was in 2004-2005. It runs good now after the overhaul and I can climb all I want--do slow flight on a hot day and oil temps and pressure stay real good.

Another question I have is how many people out there use multi-viscosity oil in their A-65s? I use Aero Shell straight weight and if I have 50 weight in it and it cools down a lot, I hesitate to fly, If I have 40 weight and it gets over 80 I hesitate to fly. To change to 30 weight is something I have not done and don't fly if it is under 25-30 degrees. Multi-weight would help but how does it hold up in 80-90-100 degree weather.

Frank D
N43684

Hi Frank,

I have used Phillips xc20-50 for 20 years and it works perfectly.

Dave

[Joel Severinghaus]

Re: Oil Temperature/Oil Pressure

Frank,

My ship's previous owner used Phillips XC20-50, but I switched over to the AeroShell single grades, W65 (30W) in winter (with a Reiff pre-heater and intake cover) and W100 (50W) in summer. Couple of reasons:

Useful FAQ on their website at http://www.shell.com/home/content2/a...erbook.html#23

They have those great "Amoolia" Holstein T-shirts at Oshkosh every year;

One can pick up AeroShell by the case right here in Des Moines from Allied Oil & Supply (5201 NE 15th, just north of the Interstate) and save shipping costs.

[Frank DeBartolo]

Re: Oil Temperature/Oil Pressure

Joel,

Thanks for the info. My plan is to use the Aeroshell 65 (30 weight) this winter during the cold months, Aeroshell 80 (40 weight) in spring and fall and Aeroshell 100 (50 weight) in summer.

I have been using the 40 weight and 50 weight and not flying below 20-25 degrees, but I have a preheater now. Only problem with using the 30 weight is that because of the weather, I may not get many hours on the oil--also some days in the winter the temps get up around 50-60 degrees and 40 weight would be better. Also, I use Avblend ($18.00 per can). Expensive oil change if you only get 5 hours on it during a really bad winter when the weather is bad, and hangar doors are froze shut because the ground has heaved and the doors can't slide open. Also, sometimes the taxiways in front of the T-Hangers are not usable for several weeks especially during times when it keeps snowing and snowing and the drifts get high and the drifts don't get cleaned out.

Avblend is something that I strongly recommend. I have appx 300 hours since my overhaul and the last annual I had near new compression (80/79) on all cylinders. Engine uses one qt to appx 10-12 hours. I keep it pretty full and add oil 1/2 qt at a time. I think in summer, full oil keeps engine temps good. I think the Avblend really helps my engine-- and can't say enough good things about it. I try to buy my oil from the FBO because they are so helpful. I know Dave Boyer of Boyer Petroleum and you can purchase by the case there--but I try to patronize the FBO.

Thanks for the info,

Frank D
N43684

[astjp2]

Re: Oil Temperature/Oil Pressure

Larry, the reason the Accy case is 850.00 is because welding magnesium is a bitch and no other shop in the country will do it right. You can always get another accy case that is good, I bought one of the few aluminum ones and it was brand new but I got lucky. Good luck Tim

[akroflyer]

Re: Oil Temperature/Oil Pressure

Frank you might try a new oil pressure relief spring and plunger before you tear it down, it could be stuck open, Keith

[Ray36048]

Re: Oil Temperature/Oil Pressure

Also check the seat, there maybe crap on it. I am taking about the oil pressure relief seat, not the one you sit on.