---------------------------------------------------------- Yak-List Digest Archive --- Total Messages Posted Tue 07/13/21: 1 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 12:36 PM - Re: Foaming Oil (Marcus Bates) ________________________________ Message 1 _____________________________________ Time: 12:36:23 PM PST US Subject: Re: Yak-List: Foaming Oil From: Marcus Bates Jon.....puzzling....I would first try changing the oil to another brand of M ineral oil. No reason for oil to be foaming, except perhaps air getting int o the oil tank. Might try routing breather pipe to another location. The s cavenger pump is to return oil from sump and rocker covers. Unless it is su cking air, there is no way it should make foam. I will be back in the Austi n area tomorrow evening. I have a M-14 manual, and will check it. Tried c alling Jill? Sent from my iPad > On Jul 11, 2021, at 1:26 PM, Jon Boede wrote: > > New M-14P, still break-in period. Has been in the air but fighting with hi gh oil temps. > > Previous flight end: 14.5L oil > (week passes) > Initial oil check: 10.5L oil > Today flight end: 13.5L > Oil is Aeroshell 120 (no W) straight mineral oil for break-in > > However... knowing that my oil wasn't really 10.5L because there wasn't +1 gallon of oil in the bucket, I ran the plane for 10 minutes outside the han gar. Carefully warmed it up to 50C oil temp 100C CHT, oil pressure 6+, not o ver 7. Cowl on. > > At the end of that period there was 16.5L of very aerated oil on the dipst ick! > > Since the pressure was good and the OAT was only 80F I went flying. > > On take-off the oil pressure was 6.5 (I'd turned it up the previous weeken d) and the oil temp was about 50C. T/O was performed at 760 MAP and 2600 rp m, which was plenty enough power to get airborne. > > Two circuits around the pattern and the inlet oil temp got to over 70C and was rising very, very slowly (i.e. not stable). CHT very reasonable, 150-1 60C at 680mm MAP, 2400 rpm once I levelled off. I flew at pattern altitude t he whole time. > > Oil pressure continued to drop and temperature continued to rise. After t he next circuit in the pattern, when oil pressure was about 3.7 and temperat ure about 77C, I landed. Oil pressure on taxi-in was 1 and temp continued t o be about 80C. > > Very aerated oil on stick, "foam" is what I'd call it. Was 16.5L with all the air in it. Doing the math, that means about 25% of the volume of the a ir/oil mixture was air. > > Brand new oil cooler. Brand new hoses. Oil dilution system has been capp ed off. > > At this point the only non-stock components in the system are: Craig Payne 's oil filter, and a custom hose from Jill (that has a 90-degree swivel fitt ing on each end). > > Any ideas how air is getting mixed into the oil? I'm pretty sure at this p oint that both the high temp and the pressure drop are due to the air in the oil but I can't understand how it's getting in there. > > Next moves are to bypass the oil filter and to try a different custom oil h ose. > > I'm all ears as to any other ideas. > > Jon > > PS. My oil overboard tube is cut to face into the wind, but both the othe r CJs in the hangar are similarly configured. It's not long enough to stick out below the cowl and I don't think that the prop blast would be enough to create aeration during the initial run. ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message yak-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Yak-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/yak-list Browse Digests http://www.matronics.com/digest/yak-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.