Tom Baker Posted October 22, 2014 Report Share Posted October 22, 2014 When you do a pressure purge on a CTLS with the oil temperature thermostat, does the thermostat let oil through to fill the cooler or does it leave a big air pocket. This was something that just crossed my mind while doing the hose change on my airplane. Link to comment Share on other sites More sharing options...
Anticept Posted October 22, 2014 Report Share Posted October 22, 2014 The thermostat never completely closes as a precaution, so there is oil going through the cooler. Still an interesting question though! Is it enough to remove all the air in the cooler? That's the million dollar question... (or at least a couple thousand anyways) Link to comment Share on other sites More sharing options...
Roger Lee Posted October 23, 2014 Report Share Posted October 23, 2014 This has been talked about on other forums. The thermostat always allows some by-pass. usually 5%-10% depending on the make. I have seen people try to heat them with a heat gun. Usually not enough heat an when the cooler oil hits it it closes anyway. Then I have seen people heat the oil and that could work, but what a PITA that would be. The temp would have to be maintained over 180F. The real answer is just do the standard oil purge. Here's is where I take the purge a little more serious (with a thermostat). First when I purge I always rotate the prop more than in the book. This is one operation you don't want to take shortcuts with. I rotate 90-100 turns at a rate of 1 turn per second. If I have a brand new engine or one with a thermostat that has been emptied along with all the oil hoses I do two rotational purges. I can always see a 50 psi pressure at my rate on the instrument panel. The purges aren't any big deal they only take a short time to do. So bottom line is you do not need to do anything special, just an oil purge and don't worry about the thermostat. A small amount of air isn't terrible. If it were then every time we put a dry oil filter on we could have an issue. p.s. When you do a hose change the oil stays in the oil cooler. It should stay full. If for some reason you did empty an oil cooler it can always be pre-filled and so could the oil lines you are concerned about around the thermostat if you are worried. Link to comment Share on other sites More sharing options...
FastEddieB Posted October 23, 2014 Report Share Posted October 23, 2014 A small amount of air isn't terrible. If it were then every time we put a dry oil filter on we could have an issue. To clarify, best procedure is still to prefill a new oil filter with as much oil as possible, right? Link to comment Share on other sites More sharing options...
Roger Lee Posted October 23, 2014 Report Share Posted October 23, 2014 I am a believer in pre-filling, but can't do it on the new filter. You can't pre-fill a Rotax oil filter because they added the check valve. The older filters you could. In school they said don't worry about it and to just rotate the prop about 20 times to help pre-fill after you install it. From what I have observed most people don't do that. Link to comment Share on other sites More sharing options...
FastEddieB Posted October 23, 2014 Report Share Posted October 23, 2014 I've only used the older model filter - I bought a bunch of them with a case of Aeroshell Sport4 on eBay from a fellow who no longer had need for them. One or two more to go, I think. Link to comment Share on other sites More sharing options...
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