Stuck oil control valve - High oil pressure

[Rynoth]

Quick backstory, my Turbo Aerovee has been experiencing 80PSI oil pressure for all of my initial engine runs. Yesterday I did my longest run yet for tuning my Aerocarb, which warmed the oil up to about 115 degrees by the time I was done, and the lowest oil pressure I saw was 73PSI. I drained the oil and inspected my oil pressure plungers.

My oil pressure relief valve plunger (flywheel end, short spring) seemed fine, the plunger came out with just a magnet.

My oil pressure control plunger (prop hub end, long spring) however seems to be stuck all the way in. I tried a magnet, then some forceps to try to get it out but couldn't get a real good grip and it wouldn't budge. I stopped there for fear of scoring the bore.

I've ordered a $17 VW oil piston puller. Hopefully this does the trick. I'll inspect the bore and polish down the plunger for a better fit (assuming no other issues.) I'll report back next week once I have the removal tool.

I'm not sure why it's stuck, I lubed the plungers up with white lithium grease and they seemed to fit fine when I installed them per the manual, but the engine didn't have oil run through it for a good 8 months after assembly. Possibly a bit of corrosion? They weren't inserted with any more force than the provided springs applied.

[rizzz]

This might help:
http://www.greatplainsas.com/iopr.html

[marsolgp]

Just my opinion and experience..... I doubt you have a pressure regulator problem, the sticking of the reg. piston is probably just 'suction', it's likely just being 'held' in by oil.... You could try rotating the prop to get oil circulating and it may push piston out....

If you are doing your engine runs with the cowling off, and in this cold weather, it's very difficult to get oil temperatures high enough to see oil pressures down into normal ranges.

Here's your dilemma, to find out if oil pressures will get down into normal range, you'll have to cowl it up and ground run it for several minutes (mine takes up to 15 minutes in this weather) to warm oil up..... BUT, excessive ground running on a new engine is not recommended.

[Rynoth]

I did determine why the oil control piston was sticking. I must have done a poor job masking the hole when I painted the case, when I yanked out the piston today it had a small bit of black paint stuck to it. I cleaned and polished it up, ensured it had smooth action in the entire bore and reinstalled.

I then cranked it up and still had relatively high oil pressure (75ish psi). At this point I'm calling it good (having checked the main oil pressure controls) and will hope that pressures come down once I'm willing/able to run the engine at full operating temps.

[marsolgp]

Keep us posted, once you get to run it up to normal temperatures..... Good Luck

Just to add my experiences: I went flying yesterday, OAT 12 degrees F. I had pre-warmed the oil to 77 deg. On start, my oil pressure was 87 psi and temperature dropped to 70-75 deg (at 1100 RPM). It took about 7 minutes to get to 100 deg and pressure was now down to 75 psi. By the time I taxied to the end of the runway oil temp was up to 110 deg and press down to 52 psi..... On T/O roll at 2900 RPM and oil temp of 115 deg pressure was up to 68 psi. As temperature increased in climb and cruise I ended up with 150 degrees and 39 psi..... When throttle pulled back to idle in the pattern, pressure dropped to 22 psi.

As an aside, I've learned from experience that if you run the engine above idle with oil press greater that 99 psi, the seal in the turbo will allow oil past and you will see it coming out the waste gate arm area and it will blow some out the exhaust and onto the ground and RH gear strut... Once pressure gets back down below 75 psi or so, there is no longer any oil coming from turbo, so it appears no permanent seal damage is done.

[Rynoth]

That's great info, thanks!

[skyrangernz]

That's probably what is wrong with my oil temp and pressure when for no reason, going from a normal pressure of 55psi and temp of 160F, the oil suddenly rockets to 230+F and pressure drops to zero. Fortunately, the first time a lovely grass airfield was dead ahead and no problems. Oil in sump full, no leaks anywhere, OAT 35C.
Came back at night when OAT was a lot less and no problems for quite a few flights. Since then, the aberration has happened twice. I have purchased a new piston kit but will use the existing springs.

[n502pd]

Very interesting. here is how I elliminated my suddenly high oil pressure. I added an oil filter, which did assist, but didnt elliminate the intermittant problem. i finally added very very strong neyodium(?) magnets fron a large salvaged dc motor, one strapped to the oil filter side, and a smaller one saftied to the drain plug. magnetic drain plugs dont, IMHO, have enough strength. since then, no further problems over two oil changes, and some 30 hrs. when investigating the problem, i found microscopic metal shavings causing the rear regulator to stick, and sometimes I could get it unstuck at the runway by abruptly advancing the throttle several times. to this day, i do this pre takeoff check, brakes on, full power to roughly 3200, and an oil pressure check to be below 75lbs. just as a reference, most times oil temps below 180, pressure 65 or so. using recommended oil.

Try the filter and magnets. debris appeared to be break in junk from what I can see.

[skyrangernz]

Thanks, guys. Lots of info but only for high oil pressure. I do lots of oil changes with the recommended Valvoline oil and filter it by using a pantyhose across the pail to see if any metal or fuzz appears. Nothing on the magnetic plug. Use an earth magnet and check the pail and pantyhose for metal. Replaced the pistons today. The rear relief valve had scratches on it but fell out when the nut removed. Front control piston clean and free. Kit only about $15.00 with springs but will use original springs. Test flight this week, hopefully.

[n502pd]

the scratches and the piston falling out are exactly what I had. I could not see any thing in the coffee filter and carb cleaner drench to look at the oil sample either.I also used green scotchbright on a rod chucked in my drill to lightly hone the bore just to make sure there was not anything stuck in the surface metal. I tried the spring kit also, but no real change for hi pressure, and mine was adjustable. I shortened my spring by one turn, reformed the end, made centering plug for the relief piston to keep the spring from rubbing on the bore. havnt had a reason to reinspect either ones yet, sort of like if it aint broke, dont fix it! my temps have never exceeded 200+ degs even from first flight. Most likely due to the double sized bottom oil cooler (duh?) for texas heat! I have winteritization kits for the cowling 'mouth' for winter flights. I should have some pix if you are interested, just send ur email in a PM to me!