Low Oil Pressure

[Corby202]

A friend of mine had intermittent oil pressure problems on his Jab 2200. Turned out to be the sender didn't like being screwed directly to the engine. Mounted it remotely, problem solved. This might not be your problem but perhaps worth considering.

[vwglenn]

Thanks Phil. I can say with certainty the sender is not the issue. Checked and double verified that it's working properly.

[snx590]

It turned out that my own oil pressure RDAC setup was not quite correct resulting in sightly lower than actual readings. I have about 140 hours on the engine now, about 10 after the hollow pushrod mods. The engine has always run smooth and strong (I have the Aerocarb) and the lower oil pressure at idle has not significantly changed during that time.
The RDAC needs a solid ground directly to the engine to ensure optimal readings, so double check for that. Did Pete and company do the rebuild in 2014? They have a lot of expertise with these engines gained over their 15+ year history with the dealership. Pete has always been helpful to me when I've contacted him in the past. He would be the best to advise if a trip to Shelbyville would be worthwhile.
Regards,

[DCASonex]

Did you check your electronic gauge in parallel with conventional one while in flight, or just while on the ground ? The chart posted shows quite rapid pressure loss, which points more towards something electronic than mechanical. Is a puzzle.

David A.

[vwglenn]

David- I did try that but the loaner gauge appeared to be non functional. I have a line on another gauge and I might revisit that. The oil pressure issue has only reared its head once in flight on a base leg. Every other time it's popped up on the ground while the engine is at idle.

Terry- I've contacted MGL about the ground issue and the RDAC is grounded properly. I've hooked up the ground to two different spots on the engine with the same results. My engine is running quite well. There appear to be no signs of oil starvation. The oil temps have been in the green the whole time. Jab USA did rebuild the engine. I sent an email to Pete yesterday and am waiting to hear back from him.

As I said, my suspicion is the relief valve is getting stuck open when the engine heats up beyond a certain point which leads me to believe the trip to Shelbyville would be just fine while the engine is purring along in a cruise profile. Currently the PSI is showing around 10 when it's reading low.

[DCASonex]

Glen,

This is totally off the wall, but check the washer that forms the seat for the PRV. Edge of hole on one side is sharp, the other smoothed off a bit. The smooth edge should be the seat. Nose of PRV spool should be smooth with no sign of any grove or indent. Unlikely, but perhaps the PRV spool hangs up on sharp edge. Also might be the washer's OD is too small for its hole, allowing it to move enough off center to briefly hang up there, held by lip or burr on the internal snap ring. Just guessing, but both of those are easy to check for. Steel spool should not hang up on hole in aluminum, as the aluminum should expand outward at a greater rate than the steel as temps rise.

David.

[vwglenn]

David- Pete mentioned the chamfer on the washer. Mine has very little. The washer is pretty snug and I seriously doubt any oil is passing around it.

Interestingly enough, I found this thread which mentions modifying the plunger to reduce the pulse effect which evidently is hard on the hydro lifter engines and some oil coolers...
http://www.avcom.co.za/phpBB3/viewtopic ... 81&start=0
...it also mentions a new PRV spring available from Jabiru.

Just got off JAb USA's site. Tha bad news for me is Pete is off for this week leading up to the 4th so I'm going to have to put my patience hat on. The good news is they started a new forum.

http://www.usjabiru.com/forum/index.php

[DCASonex]

Glen,

My concern with washer OD being a bit small was that it might position with hole off center preventing the spool's nose from seating, but suspect you have already looked into that.

David

[vwglenn]

Makes sense David. I worked the nose when I reinstalled it the last time. Seems to actuate fine. It didn't feel sticky or anything. There's not much throw left to it with three washers in there though. Somewhere I read you can use up to four but I don't think that would leave much room for it to open. I think I'm going to ask Pete to send me a replacement washer/plunger/spring and see if that makes any difference. One thing I haven't mentioned here is the swirly marks on inside of the pump cover. It looks as if the pump gears have or are rubbing it. Sent a picture of that to Pete in the email.

[kevin814]

Makes sense David. I worked the nose when I reinstalled it the last time. Seems to actuate fine. It didn't feel sticky or anything. There's not much throw left to it with three washers in there though. Somewhere I read you can use up to four but I don't think that would leave much room for it to open. I think I'm going to ask Pete to send me a replacement washer/plunger/spring and see if that makes any difference. One thing I haven't mentioned here is the swirly marks on inside of the pump cover. It looks as if the pump gears have or are rubbing it. Sent a picture of that to Pete in the email.

Hi Glenn,

Any update on the engine?

Kevin K.
Sonex 3300