SonexBuilders.net

Hi all this is ONEX N110NX. I haven't posted since my first flight about three years ago but thought I might through this out there even though it has been covered before. Yesterday I was going out for a short flight but aborted my take off due to fluctuating oil pressure. The result of another blown oil cooler. I lost one on a 68 degree day, unbelievable but from then on I never move the airplane until the oil temp reaches 100 degrees. This time the outside temp was 40 degrees but this plane lives in a heated hanger that is kept at least 45 degrees. Since I have been using this procedure for over a year I am wondering why this seems to still be an issue again. Are these oil coolers just Chinese junk or is there another way to make these oil coolers stand up to cooler temps? Mine of coarse is top mounted and oil pressure runs a steady 68 PSI. For the rest of the cold months (I live in middle Tenn.) I will bypass the oil cooler. Maybe that will be my policy from here on oil cooler in the summer remove it for the winter. I just hope I can find a reliable one. Now I'm back to worrying each flight for awhile.

just out of curiosity why are you pushing 68psi? That seems high. Can you turn your psi down to somewhere in the 50ish max range? It may save your coolers

Discussion and new oil pressure valve:

http://www.headflowmasters.com/vw-oil-p ... -body.html

Sorry if this has been posted before

After much dicking around with blow cooler, blown oil filter gaskets and bulging ballooned oil filters, I have found a solution.
Gene Berg makes an oil pump cover with a pressure relief valve built into the cover. If the oil pressure at the pump goes over 150 psi, the relief valve opens and dumps oil back into the suction side of the pump. It works.. oil pressures are finally under control.
http://www.geneberg.com/product_info.ph ... cts_id=358

BV

At least my Aerovee has 2 pressure regulators. One near the end of the oil passage where the gauge connects and it limits the oil pressure the engine gets. There is also a regulator that bypasses the oil cooler if the pressure accross the cooler get too high. Perhaps the oil cooler bypsss regulator is stuck, it may not show up on the gauge.
Jerry

Also, on a side note, I bought a genuine VW OEM oil cooler from a VW garage that had one in stock. Alas it was the last one. It may have been slightly used but it was a genuine VW cooler. I asked the mechanic what they are using now for replacements. He said the brand from Mexico was most equivalent to the OEM one, Metrix brand.

I know 68 PSI is well above the 50 PSI that is recommended but after blowing the first oil cooler I talked with SONEX tech and Kerry didn't seem too concerned with that as much as not increasing the RPM until the oil temp reaches 100 degrees. I have flown now with the oil cooler by passed and now my oil pressure is 58 PSI. Seems odd but that seems to be the case now. Sure is confusing me. Still can't believe an oil cooler would rupture even at 68 PSI.

GLENDSMITH wrote:Still can't believe an oil cooler would rupture even at 68 PSI.

Same here. Here is an example of a standard aircraft oil cooler. Proofed to 400 PSI.

https://niagaraairparts.com/wp-content/uploads/2017/03/20002aspecifications.pdf

Wes

My first oil cooler burst within 3 seconds of first engine startup. I complicated my installation by adding an oil filter but that should have had nothing to do with the oil cooler bursting. I also have had oil filter gasket blown out and bulging filter cases. Problem solved now with the pressure relief built into the pump cover.

where did you get the cover with the relief valve? is the cover steel or aluminum? Thanks for any info!