Slow oil pressure gauge.

N419A · Post by **N419A** » Mon Dec 05, 2005 7:17 pm

My oil pressure gauge is very slow to rise when first starting my plane. It is considerably worse in the cold. In warm weather when starting pressure would come up to about 10 psi then pop up to normal range. In cold weather when starting it hovers just above red line then creeps up to normal over five to ten minutes. Could this be oil working it way into the line and gauge over time slowing the gauge when cold. If I pull the line and gauge clean it and put in new kerosene this should help? Have there been oil pump problems that mimic this problem. Any incite or knowledge is appreciated.
Thanks, Paul

blueldr · Post by **blueldr** » Tue Dec 06, 2005 3:08 am

Copper tubing tends to get clogged internally over a long period of time due to something in the oil--sulphur, maybe. If you have old 1/8" copper tubing to the oil pressure gage, flushing with a solvent will help, but the best bet is to install new tubing. Actually a high pressure hose is better yet.

c170b53 · Post by **c170b53** » Tue Dec 06, 2005 3:29 am

Although a long shot, oil pressure should be slow to rise confirming that a restrictor is installed in the AN fitting attaching to your oil line coming out of your case. If its really slow maybe the restrictor typically .030-.040 is restricted.

N419A · Post by **N419A** » Tue Dec 06, 2005 5:37 am

Thanks, I think I'll clean and replace the tubing and see what that does.
Paul

cessna170bdriver · Post by **cessna170bdriver** » Tue Dec 06, 2005 5:55 am

Paul,

I think you are on the right track to check and clean the line, then refill with light oil or kerosene. Make sure it is as full as you can get it. Any air left in the line will have to be compressed, which means cold engine oil will have to flow through the restrictor, which will take time.

What is your oil temp when you are having the problem? Maybe more preheat will help.

Miles

N419A · Post by **N419A** » Fri Dec 09, 2005 1:08 am

The problem is more predominant when cold. I preheat with a small electric heater and a timer switch, I usually set it to turn on 4 hours before flying (when away from electricity I use a small catalectic propane heater and let it run all night), the oil drips freely from the dipstick and is warm to the touch maybe 60-70F. Even after I've flown for a while shut down for a few minutes then restart it will take a little will for the pressure to rise to the normal range. I usually wait for the pressure to reach the normal range before take off. I have to taxi from my yard down the road to the airstrip then back taxi to either end before take off so it gets warmed up good.
Paul