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High Oil Temps with Aero-Shell Sport

D

Dave12

Well Known Member
High Oil Temps after 1st oil change

Just performed my 1st oil change at 25 hrs. and changed from Mobile One V-twin to Aero Shell Sport, which i was told was developed for the Rotax. Took a x-country trip today and on initial climb out noticed higher oil temps. Watched very closely what was going on and have determined that The A/S oil brought temps up at least 10 degrees. IMO my 12 has oil temps that trend upward, more than I would like, but that could be me going from Lyc/Cont. to the Rotax and just getting used to it. I was unable to climb from sea level to 3500' without the oil being scorched. As I said, the situation was under control but was none the less eye-opening. At 4900 rpm/103 Knots/2100'/22 Celsius/ the temps were 250 Deg. . I have seen 240 degree temps before, but not at a low rpm, level flight and reasonably good speed. Make no mistake, this oil wanted to go higher and would have if not closely managed. Looks like it's back to Mobile One. As per Lockwood's advice, my static prop rpm is 4900. Has anyone else had this problem? Thanks in advance.
 
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What rpm do you see just after take-off, at Vx (75 knots)? Seems your prop is too coarse and the engine is lugging. Before going back to Mobil 1, reset the prop to get 5100-5150 rpm just after takeoff at Vx during the climb. I also heard what Lockwood had to say at OSH and did try his prop setting. My oil temperatures were higher.

Think Lockwood may have been working on Vern's RV-12, and maybe he will chime in.
 
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Marty, I see approx. 5040 rpm at 75 knots. I understand your logic and agree with it, but have found that the static rpm of 4900 has lowered the temps to manageable numbers. The interesting point of this is that two almost identical conditions produced drastic changes with just the changing of the oil types.
 
Dave, I agree with the others on adding 100 rpm, but don't understand high oil temp issues at 71F. You may have other problems as well. You just changed the oil. Might sound silly, but I would go back over the steps and double check all. Something strange here.
Dick Seiders
 
Dave,

Very hard for me to believe just a different oil could cause this drastic a change. There's got to be something else going on here. Oil cooler blocked, instrumentation problem, etc. etc.

I've been using the Sport oil from day 1 and the only time I've ever seen the oil temp just into the yellow range was on the full throttle test flights to 10,000.

John
 
I have been running the Shell Aero Sport in New Blue for over 300 hours. Static RPM is 4900, RPM at Vx is 5100 +/-. Not even on hot days do I see oil temps in cruise rise above 200 to 205. Mostly stays in the mid to low 190's. Only in long, extended hi power climbs do I ever approach the top of the green arc on oil temp. Then I just pull the power back a bit and nose it over and it comes down.

This is just my experience FWIW.
 
Thanks for all the input guys. I went to the airport today, did a complete oil change and purge. Installed Mobile 1 V-Twin oil and did a test flight. Oil temps were around 250 + or -. Re-pitched the prop to a static rpm of 5000 tested again. Temps went down but still in the yellow arc but I can keep them in the mid to low end of the arc. The only thing I have not changed is the oil filter that was changed during the service. I did notice that the oil pressure seems to be just slightly lower. It was typically dead center of the green arc and now it is still in the green but on the lower side. I am beginning to wonder about the filter. I triple checked everything under the cowling and found nothing out of place. I am beginning to wonder if I have entered the "Twilight Zone". Truthfully, I have never enjoyed the temps some of you all are seeing, but staying in the green arc was not a problem prior to Saturday. I have ruled out the Aero-Shell as the culprit. It's hard to believe it's the filter, but I will find out.
 
Hey Dave - -

Can you post a picture of your lower cowl large opening, as seen from just below the spinner ?

John Bender
 
It is trimmed to the scribe line, thanks, but I don't think that is my current issue. I know there has been problems with builders leaving them untrimmed.
 
Hey Dave - -

Was curious. I think I just cut to the line. Some did not do that. I have not had a temp problem and I have a Thermostasis oil therm, and a Heater Damper Door, and I still don't seem to have a problem even on the real hot days this summer. I have not done testing to see if mine is reading correctly, or maybe low, but all seems to be workng ok.

John Bender
 
I have also thought about the temp. probe being inaccurate, but the CHT is also heading north along with the oil.
 
Dave,
Have you double checked the lower cowl to make sure that the oil cooler is seated correctly and that the gasket is in place on the bottom of the water cooler?
Joe Gores
 
Dave,

You have got a lot of guys scratching their heads on this one! From your last post, it seems that the whole engine is running hot - oil temps and head temps. In other words, this is a generalized system problem, not just something specific to the oil. My advice would be to check everything common to cooling - such as all the air flow paths through the oil cooler, coolant radiator, top engine shroud, lower cowling opening, etc.

Also, from what I can gather, this engine has run on the hot side from the very beginning. So, rather than focus on anything changed at the time of the oil change, go back to the plans and triple check EVERYTHING that has to do with cooling.

Keep in mind that this engine requires THREE types of cooling: Oil, liquid, and air. A problem with any one of the three systems can cause a general overheating scenario.

Stick with it, you will find the answer!

John
 
Oil Temps on Extended Climbs

I have also encountered oil temps that just inch into the yellow range on extended climbs (more than 3000 feet) on warmer days. I know that others have seen this as well. However, my CHTs are always fine and if I just pull back power and pitch down a bit, the oil temp comes right back down. I know there has been some speculation that having a hot muffler right behind the oil cooler does not help things.

Jeff
 
John, I will stick with it, in fact, I am wearing this thing like an ugly hat. IMO this 12 has produced higher temps than I would like, but still never like it is now. It would occasionally dip into the yellow on the climb tests during 90-100 degree weather, but was still well within reason for the conditions. I just removed the cowling and had our local Rotax Cert. Mech. look at it and at the end of our meeting, he was doing the same thing everyone else is, scratching his head.

Jeff, I never saw high cht's before Sunday which was the first flight after the dreaded oil change. I believe that it is something stupid that I have done and boy, it is elusive. I will keep all posted and thanks for all the input!

BTW, I want to edit the title of this post. Can one of you gentleman tell me how? duh.
 
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Maybe there is a foreign object in the scat tube. Bird's nest?
Could there be air in the oil system?
I am trying to help by scratching my head too.
Joe Gores
 
OK, I forgot to remove the cowl plug......not. I went to the airport tonight and pressurized the system to 15 psi, spun the prop by hand and developed 67 psi. Still drawing at straws here. I will run it tomorrow and see what happens. So, for now I am still scratchin'. BTW, I have been unable to edit the title of this thread. The Aero-Shell is not the culprit here. Apologies to Shell.
 
HEY DAVE - -

Another thing. When the plane has set over night, and I am assuming inside a hangar, if you turn on the Dynon, how close are all the temps ? ? ?

( OIL, CHT, EGT )

John Bender
 
Dave12 said:
OK, I forgot to remove the cowl plug......not. I went to the airport tonight and pressurized the system to 15 psi, spun the prop by hand and developed 67 psi. Still drawing at straws here. I will run it tomorrow and see what happens. So, for now I am still scratchin'. BTW, I have been unable to edit the title of this thread. The Aero-Shell is not the culprit here. Apologies to Shell.
Click to expand...

Just another long shot; did you clean the screen in the oil tank and the bottom of the oil tank and if so are you sure the plate that holds the bottom of the screen is in right side up? Just from memory I think that if it were upside down it could slow oil flow and thus cause higher oil temperature.

Good luck.

Best regards,
Vern
 
Thanks Vern, but I did not have the tank apart. Another change that I have noticed is that once the oil starts to warm and the oil pressure drops from the high 60's to the high 50's to low 60s' , the gauge has radical swings, as much as 15 degrees. I have read the threads on the relocation of the oil pressure sender. I spoke with Aaron from Lockwood today and was told that they have developed a replacement for the ball which is part of the oil pressure relief system. He said that the new part is not completely round, but more mushroom shaped. Aaron said that this part has stopped the fluctuation in pressure. While I am not counting on this new part to solve my woes, I am going to try it. I did not have this rapid fluctuation prior to the oil change. Anyway, I do appreciate all the input and the "Head Scratching". I will keep all posted.
 
I installed the "mushroom" as part of a modification including a new spring and a new cap. It did not solve my oil pressure fluctuation problems but now I have a 2000 TBO engine. Some or all of these parts were required to increase my TBO from 1500 hours. If you already have a 2000 TBO engine you may already have these parts but it doesn't hurt to check since, if my memory is correct, the mushroom isn't part of the TBO increase.

Make sure all of your connections are tight and clean. If that doesn't do it you might be on your way to failure of the sender. I've had both. Now my fluctuations are much more moderate but still there. This is not uncommon, at least with the Flight Design CT.
 
Found the problem

First, thanks to all for your input. After a fair bit of lost sleep and a number of phone calls, Aaron of Lockwood's did some recon on this subject and suggested that I install a ground strap from the firewall to the Rotax. It turns out that the ground that runs from just behind the oil tank to the starter lug is only a sufficient ground for the starter. This is due to the way the starter is constructed which incorporates o-rings and the like. He said that they have seen this problem before. I took about 10" of ground braid and some crimp connectors and ran an additional ground from behind the oil tank to a drilled boss on the right rear cylinder head. Problem solved!!!!
Regarding the issue of the wild oil pressure swings, I did install the new "mushroom" style relief valve. It does appear to be an improvement. I had swings of 10-15 psi. I still have swings but only 3-4 psi which is far more acceptable.
I flew the 12 on a brunch run with some buddies today and never did the oil temps leave the green. IMO they are still higher than many of you see, but are within the green and well within Rotax limits. I am suspecting either the D-180 or the temp probe and will research the issue more. Anyway, thanks to all.
 
Dave12 said:
on a brunch run with some buddies today and never did the oil temps leave the green. IMO they are still higher than many of you see, but are within the green and well within Rotax limits. I am suspecting either the D-180 or the temp probe and will research the issue more. Anyway, thanks to all.
Click to expand...

Would be interested to know if the additional ground affected the oil temperature. On the ground, read the oil temperature, then remove the extra ground momentarily and take another reading. May have been just a lower OAT that day?? Please let me know.
 
Marty, I don't know if the strap actually effected the oil temps, but it did effect their readings. Regarding the OAT, it was cooler this past Sunday, but the oil temps are now consistent with the numbers I saw during the summer. I will check and report back the next time I have the cowling off. I have to say, it is nice to not have oil temps and CHT's wanting to go red! whether they were accurate temps or not!
 
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