Remote oil thermostat

[jrevens]

... that is essentially the sump for this engine, don't you agree. ...
also I think if the oil is cooled and than put in the sump which is cooled from air coming in the engine area than it will be cooler.

Yes, of course... the tank is a remote "sump".
My point was that the oil will, or should be coolest when it is coming out of the cooler. The oil in the tank will tend to be cooled down from when it leaves the engine, but is probably still warmer than the oil leaving the cooler- it is in an area surrounded by warmer air. The chances are that the colder the oil is before it enters the cooler, the colder it will be exiting the cooler AND the more efficiently the cooler will operate because of a smaller temperature differential.

[Slyfox]

but the discussion I thought was on air in the system and air in the cooler when first fired up with a new system. I do believe also that there is about 10% flow through the cooler at all times. now for the na sayers on bleeding the system and using pressure as your guide. How do YOU know when the air is out?

[jiott]

Refering to the Rotax 912 Service Instruction SI-912-018, after you hook up the purging circuit and apply air pressure, you rotate the propeller BY HAND (says do Not use the starter) 20-60 times until you see oil pressure registered on the gauge. Of course while you are doing this you can visually observe the return oil flowing into the catch bottle you have installed. It will flow out along with blurps of air until it becomes a solid stream. You then reconnect everything normally and run the engine until warm for a few minutes. Then you shut down and check each valve lifter for a solid feel which only then insures you have properly purged out all air. Apparently the lifter area is the last and hardest place to purge, therefore it is the final thing to check. Sorry to repeat what is readily available to everyone, but not everyone bothers to read these things.

[Slyfox]

whatever I guess I'm not going to get anywhere here. again you are talking a new motor install. this discussion is on a line that was leaking and if there was air in the system from it if I read it right. again I will say crank the engine over with mags off. if the pressure is up you are ok. tighten the line and go fly.

[jrevens]

I appreciate the conversation here... available or not, it's good information and I need all of it that I can get. I didn't start this thread, but thank you all anyway.

[DesertFox4]

FYI guys, you can all vote or rate a thread at anytime for all those folks searching our archives in the future. If you like a thread please rate it and stars will be attached for future reference. Thanks to everyone for another good info filled thread.

[Kurt.A]

I too have been following this thread with curiosity. The fact that the eng oil cooler is plumbed into the suction side of the eng oil pump disturbs me. Automotive eng oil coolers are rarely used in the gasoline world however they are extensively used in the heavy duty or diesel engs. I have been a Tech for the largest Caterpillar dealer in the world for the last 28 years. Every single Caterpillar eng ever produced has the oil cooler on the pressure side of the eng oil pump and is also downstream of the eng oil filter. To me it is logical to cool the oil after the pump and filter for the following reasons:
1) Pressurizing oil with a pump produces heat.
2) Filtering cooled oil has the potential to open the filter bypass valve more often and for longer periods of time allowing unfiltered oil to enter into the lubrication system.
3) Having the cooler in the suction circuit leaves the system open to extra possible leak points on the suction circuit. This would allow the potential for a constant stream of air to be entering into the lubrication system. Yes air will enter the suction circuit long before a visible external oil leak will be observed.

With regards to having air in an eng's lubrication circuit as per the original post. I have seen many times the devastating results inside an eng to it's components from air bubble implosions. An implosion is the result of an air bubble collapsing at high pressure allowing the surrounding liquid to impact the metal with incredible force. This can be readily seen on eng bearings, crankshafts, the coolant side of cyl walls, eng oil pumps and the list goes on. I have never seen this damage to a valve train component including lifters however for the most part Caterpillar engs use solid lifters. IMO the air that has managed to enter the system gets purged from the oil prior to entering the valve train components as this is near the end of the lubrication circuit. The comment in a previous post made about ensuring the hyd lifters be completely filled with oil is also very critical to valve train stability. Hyd lifters should always be manually pumped full before installation to the eng.
Unless someone wishes to convince me otherwise I will definitely be changing the way my Rotax eng oil cooler is plumbed. Because Rotax says so does not count here. My sincerest gratitude to the board members that have brought this fact to everyone's attention.