Fluctuating oil pressure troubleshooting

Well, after 200 hrs on the 6A, I decided I was unhappy with my oil temps, which were running a bit high. At 75F OAT and 2500 RPM, I was seeing 210-212F on long trips (more than an hour). The max I had seen was 220F at 88F OAT. I really would like to keep the oil no more than 200F at high temperatures in cruise speed. If I can get up to altitude, say above 5000', OATs are normally low enough (65F) where oil temp is around 200F, so the problem is with high OATs, i.e. summer months here in VA. In the winter months, I stuggle to get up to 170F.

My engine is an ECi 360, which a number of persons have indicated seem to have higher oil temps. I've done everything to seal off any leaks in the baffling, and feel the system is pretty solid in that regard. I finally decided to try a different oil cooler (I have the standard Niagara 20002A. which is the van's EA II). I talked with Wayne, at Pacific Oil coolers, and he recommended their Aero Classics 8001602, which is their replacement for a Stewart Warner 8406R. It has the same dimensions and mounting as the Niagara, but it is more efficient as it has more than 50% additional cooling fin surface area. Looking at the two coolers, it's easy to see this.

So I swapped the coolers and took a test flight. With OAT at 90F (about 98F on the ground), I saw a maximum oil temp of 201F. I'm not confident of my results yet, because I only flew for 0.8 hrs and varying RPM. My issue was that oil pressure was cycling between 75 and 130 psi- very rapid changes. The period was probably 5-10 secs. you could see the numbers scrolling on my EMS (Vision 2000C), up and down but not step changes. Prior to the cooler swap, I typically cruise at around 65 psi. No other variables but changing coolers. I did have one anamoly when swapping. I disconnected the top line first, then put a vinyl tube on the fitting and figured I'd gently blow out the oil from the cooler, back into the sump, to lessen the mess when I disconnected the lower fitting. Found out that the oil didn't go back into the sump here when it started dripping out of the cowling onto the hanger floor, via the crankcase vent tube . I purged about 1/2 a quart this way.

On the way home, I purchased a mechancial pressure gage to tee in by the oil pressure sender. First thing to check is that the sender is indicating properly. Other things I suspect is possibly air in the system (two others came up with that conclusion) or sticky pressure relief valve. The air makes some sense, but its seems an awful big coincidence that the relief valve would fail just now.

Any ideas from the engine knowledgeable crowd to troubleshoot tomorrow? I had a similar instance on one previous occasion where the oil pressure was rapidly cycling. I shut down the engine and restarted it and it went away. I chalked it up to the EMS having a glitch and rebooting (powering down and up) corrected. I did this three times today with no luck. I appreciate any suggestions.

Oil temp and pressure

Tim,

What type of sending unit does your system have? I ran into a similar problem with my Grand Rapids Engine monitor. Mine was a oil pressure issue, rapidly changing pressure readings from ~40PSI - 99PSI (upper limit). I replaced the VDO sending unit but the problem re-appeared about 6 months later. I finally added a ground wire which seems to have solved the problem. I also have a 6A with an AeroSport Power IO360 (ECI), I do not see oil temps anywhere near that high even at ~90*F. I have the standard Vans Oil cooler circa 2003. Have you verified the temp sending unit by placing it in hot water of a know temp?

Skid

Skid,

I think my sending unit is a VDO also. It has two leads going to the EMS unit. Where did you add a ground? The sender is mounted in a large rubber adel clamp, so not grounded currently. I haven't verified the temp sender, other than it reads very closely to ambient temperature at startup. Probably something I should do if the cooler temps are consistent with the new SW oil cooler.

Oil pressure issue

Tim,

I simply put a worm gear hose clamp around the sending unit to clamp a wire to the unit, then ran the wire to a grounding point. It doesn't sound like yu have the same type of sending unit, here is a picture of the type I have;

http://www.egauges.com/vdo_indS.asp?Sender=150PSI_10Bar&PN=360-021

Th unit grounds through the case and has one wire which goes to the engine monitor.

Skid

Not 100% sure but I think the ground wire suggested will solve your problem. On my first RV I mounted the Vans sending unit in the adel clamp as you have noted and had the same issue. It must be grounded. I later moved it to the firewall manifold installation which provides the ground and no wire is required.

Pat

Oil pressure issue

My sensor is mounted to the manifold on the firewall. I was still having issues with the oil pressure so I added the ground wire. The fuel pressure sending unit has not had any issues and it's mounted in the same manifold.

Skid

Solved- apparently just air

So I bought an air gauge and 1/8" tee to put a mechanical gauge in common with the oil pressure sender. My sender has both a positive and negative wire, so is already grounded. I checked all the wiring connections again, and found no problems. I figured I would start the engine and confirm there was still a problem. Everything was normal. I took the airplane out and taxied it around, even up to 60 mph on the runway. Still no problem. Put the cowling back on, and flew the plane for 45 minutes in the 95F temperatures, everything indicating normal. The only thing I can come up with, is that air was introduced when I "blew" down the oil cooler into the crankcase vent. It all seems to have worked its way out now. Hopefully, that's all there is to it. The best problem is no problem!

Oil Pressure

Tim, glad to here it may just have been some air in the line. I have seen the sending units with the ground wire on them, wish mine did. I'm not sure if I can use those units or not, I'll have to check with Grand Rapids at Oshkosh.

oil pressure

I would strongly recommend that you increase the oil pressure to at least #75.