---------------------------------------------------------- Yak-List Digest Archive --- Total Messages Posted Fri 01/19/18: 5 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 10:08 AM - Re: Re: Super-cool oil temp (Bitterlich, Mark G CIV NAVAIR, WD) 2. 10:23 AM - Re: Super-cool oil temp (apatton2) 3. 11:09 AM - Re: Super-cool oil temp (Bitterlich, Mark G CIV NAVAIR, WD) 4. 11:11 AM - Re: Re: Super-cool oil temp (Walter Lannon) 5. 07:17 PM - Re: Super-cool oil temp (apatton2) ________________________________ Message 1 _____________________________________ Time: 10:08:56 AM PST US From: "Bitterlich, Mark G CIV NAVAIR, WD" Subject: RE: Yak-List: Re: Super-cool oil temp Richard, I happen to have some knowledge on this topic. Very early YAK-50's came with what guys in this country call a "Veritherm", but in truth is nothing but a thermostat. This device, when the engine was cool, by-passed the oil cooler and warmed the oil up faster of course. It is not binary... meaning just open or closed. It regulates temperature and will actually maintain oil temp where it is supposed to be, usually even with the oil cooler door wide open. At some point of time, there was a Russian directive, which I am sure you can find, that REMOVED these devices from the oil cooler. The Russian logbooks for my 1985 YAK-50 show this as being done. The result was that my oil cooler did not have the thermostat installed at all, and it took a very long time to warm up the oil in cold weather, just as this person is experiencing. The thermostat itself is set to by-pass the oil cooler, and when it starts seeing warm oil, it then runs the oil THROUGH the oil cooler. If it fails, it usually fails in the by-pass condition, which is... I think... why the Russians removed it. It is failed in that position, it will cook the oil and possibly ruin the engine. In any case, my oil cooler thermostat had been removed and so noted. I obtained one of these thermostats/veritherms out of a Russian oil cooler for an M-14 helicopter and put it back into my YAK-50 oil cooler (easy job really) where it now operates perfectly. I wrote all this up about a decade ago on the YAK list. My guess is that he does not have a stuck thermostat, but that instead he has not got one installed at all. Mark -----Original Message----- From: owner-yak-list-server@matronics.com [mailto:owner-yak-list-server@matronics.com] On Behalf Of Richard Goode Sent: Thursday, January 18, 2018 1:20 AM Subject: [Non-DoD Source] RE: Yak-List: Re: Super-cool oil temp --> Hello Andrew, I'm in Sri Lanka and therefore don't have access to all my technical papers in the UK. But I am pretty sure that all or some of the oil coolers have a thermostatic bypass valve, and until this opens, no oil goes through the oil cooler. I suspect yours is sticking, and therefore the oil is continuing to circulate through the oil cooler, and that is your problem. I will investigate this more and that you know options, but I suspect we could obtain a new valve. Regards Richard Rhodds Farm Lyonshall Hereford HR5 3LW United Kingdom Tel: +94 (0) 81 241 5137 (Sri Lanka) Tel: +44 (0) 1544 340120 Fax: +44 (0) 1544 340129 www.russianaeros.com I'm currently in Sri Lanka but this Mail is working,and my local phone is +94 779 132 160. -----Original Message----- From: owner-yak-list-server@matronics.com [mailto:owner-yak-list-server@matronics.com] On Behalf Of apatton2 Sent: Thursday, January 18, 2018 10:07 AM Subject: Yak-List: Re: Super-cool oil temp --> Re: "close the gills" - everything is closed (always is on warmup... I have several hundred hours in 50s and 52s). Hi Richard - thanks for the note! My last -50 (a 1982 model with series 1 engine) came up to temp very rapidly and would seem to almost always stay cool. I was wondering if there was any thermostatic regulation function in the oil system other than the manually actuated oil cooler door. Since I haven't seen anything that looked like a bypass valve for the oil cooler, I assumed that wasn't the case (I could be missing it, though). That said, I didn't think it would actually be built into the cooler itself! I'll look again at some of the translated documents that I have to see if any light can be shed on this. But if that's the case and this valve is "stuck" open, then that would explain the observed phenomena. Best, Andrew -------- Andrew Patton Yak-50 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=477392#477392 -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. ________________________________ Message 2 _____________________________________ Time: 10:23:02 AM PST US Subject: Yak-List: Re: Super-cool oil temp From: "apatton2" Hi Mark, Many thanks for your note. I will correspond with former owner and see if he can tell me anything about typical oil warmup time. In the meantime, could you point me to any places to check for a thermostat as you suggest? Have written to Avioservice in BG as they have been a good resource for hard to find parts previously, but I've not yet heard back. Many thanks! Andrew -------- Andrew Patton Yak-50 San Francisco, CA Read this topic online here: http://forums.matronics.com/viewtopic.php?p=477450#477450 ________________________________ Message 3 _____________________________________ Time: 11:09:24 AM PST US From: "Bitterlich, Mark G CIV NAVAIR, WD" Subject: Yak-List: Re: Super-cool oil temp Andrew, it has been 10 years ... so my memory is not picture perfect. But I do think you would have to remove the oil cooler to know for sure. As I recall it screws into a hole, and we had to remove a screw in cover, and replace it with the thermostat part. I am at work and do not have access to my manuals which MIGHT show it. I'm afraid that is the best I can do. The person who would know for sure would be Vladimir Yastremski. He is up the street from you in Ramona CA. Or down the street? Whatever. Mark -----Original Message----- From: owner-yak-list-server@matronics.com [mailto:owner-yak-list-server@matronics.com] On Behalf Of apatton2 Sent: Friday, January 19, 2018 1:23 PM Subject: [Non-DoD Source] Yak-List: Re: Super-cool oil temp --> Hi Mark, Many thanks for your note. I will correspond with former owner and see if he can tell me anything about typical oil warmup time. In the meantime, could you point me to any places to check for a thermostat as you suggest? Have written to Avioservice in BG as they have been a good resource for hard to find parts previously, but I've not yet heard back. Many thanks! Andrew -------- Andrew Patton Yak-50 San Francisco, CA Read this topic online here: http://forums.matronics.com/viewtopic.php?p=477450#477450 ________________________________ Message 4 _____________________________________ Time: 11:11:29 AM PST US From: "Walter Lannon" Subject: Re: Yak-List: Re: Super-cool oil temp Mark; The same problem was addressed in the Canadian production of the North American Harvard (predecessor of the T6) to accommodate very cold winter operation. A different method was used consisting of what they called a "surge valve" in the oil out line that opened whenever the scavenge pump pressure reached 83 psi. and directed oil to the tank rather than the oil cooler. Scavenge pump pressure is not regulated so temperature is a major factor in oil out viscosity. I suspect a thermostatic device would be more efficient but also far more subject to failure. Walt -----Original Message----- From: Bitterlich, Mark G CIV NAVAIR, WD Sent: Friday, January 19, 2018 10:01 AM Subject: RE: Yak-List: Re: Super-cool oil temp Richard, I happen to have some knowledge on this topic. Very early YAK-50's came with what guys in this country call a "Veritherm", but in truth is nothing but a thermostat. This device, when the engine was cool, by-passed the oil cooler and warmed the oil up faster of course. It is not binary... meaning just open or closed. It regulates temperature and will actually maintain oil temp where it is supposed to be, usually even with the oil cooler door wide open. At some point of time, there was a Russian directive, which I am sure you can find, that REMOVED these devices from the oil cooler. The Russian logbooks for my 1985 YAK-50 show this as being done. The result was that my oil cooler did not have the thermostat installed at all, and it took a very long time to warm up the oil in cold weather, just as this person is experiencing. The thermostat itself is set to by-pass the oil cooler, and when it starts seeing warm oil, it then runs the oil THROUGH the oil cooler. If it fails, it usually fails in the by-pass condition, which is... I think... why the Russians removed it. It is failed in that position, it will cook the oil and possibly ruin the engine. In any case, my oil cooler thermostat had been removed and so noted. I obtained one of these thermostats/veritherms out of a Russian oil cooler for an M-14 helicopter and put it back into my YAK-50 oil cooler (easy job really) where it now operates perfectly. I wrote all this up about a decade ago on the YAK list. My guess is that he does not have a stuck thermostat, but that instead he has not got one installed at all. Mark -----Original Message----- From: owner-yak-list-server@matronics.com [mailto:owner-yak-list-server@matronics.com] On Behalf Of Richard Goode Sent: Thursday, January 18, 2018 1:20 AM Subject: [Non-DoD Source] RE: Yak-List: Re: Super-cool oil temp --> Hello Andrew, I'm in Sri Lanka and therefore don't have access to all my technical papers in the UK. But I am pretty sure that all or some of the oil coolers have a thermostatic bypass valve, and until this opens, no oil goes through the oil cooler. I suspect yours is sticking, and therefore the oil is continuing to circulate through the oil cooler, and that is your problem. I will investigate this more and that you know options, but I suspect we could obtain a new valve. Regards Richard Rhodds Farm Lyonshall Hereford HR5 3LW United Kingdom Tel: +94 (0) 81 241 5137 (Sri Lanka) Tel: +44 (0) 1544 340120 Fax: +44 (0) 1544 340129 www.russianaeros.com I'm currently in Sri Lanka but this Mail is working,and my local phone is +94 779 132 160. -----Original Message----- From: owner-yak-list-server@matronics.com [mailto:owner-yak-list-server@matronics.com] On Behalf Of apatton2 Sent: Thursday, January 18, 2018 10:07 AM Subject: Yak-List: Re: Super-cool oil temp --> Re: "close the gills" - everything is closed (always is on warmup... I have several hundred hours in 50s and 52s). Hi Richard - thanks for the note! My last -50 (a 1982 model with series 1 engine) came up to temp very rapidly and would seem to almost always stay cool. I was wondering if there was any thermostatic regulation function in the oil system other than the manually actuated oil cooler door. Since I haven't seen anything that looked like a bypass valve for the oil cooler, I assumed that wasn't the case (I could be missing it, though). That said, I didn't think it would actually be built into the cooler itself! I'll look again at some of the translated documents that I have to see if any light can be shed on this. But if that's the case and this valve is "stuck" open, then that would explain the observed phenomena. Best, Andrew -------- Andrew Patton Yak-50 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=477392#477392 -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ________________________________ Message 5 _____________________________________ Time: 07:17:14 PM PST US Subject: Yak-List: Re: Super-cool oil temp From: "apatton2" Thanks much, Mark and co, for the further help. I got a picture of the thermovalve today (at least I'm pretty sure this is it). -------- Andrew Patton Yak-50 San Francisco, CA Read this topic online here: http://forums.matronics.com/viewtopic.php?p=477461#477461 Attachments: http://forums.matronics.com//files/screen_shot_2018_01_19_at_71547_pm_122.png ------------------------------------------------------------------------------------- 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.