Howdy Gang!
New poster here, but I did a search on all of the forums to see if there was a similar topic, but alas, nothing...

Anyway, I really need some help in trouble-shooting the elevated oil temps that I have been indicating in the last few "test flights". My mechanic and I are completely baffled.

Here's what we've replaced/checked thus far:
1.) Verified clean flow through oil cooler.
2.) Replaced vernathurm (oil Thermostat)
3.) Cleaned out sump screen <-- hand some carbon/coke deposits
4.) Checked screen again... nothing.
5.) Checked oil cooler immediately after flight... It was HOT.

HIGH OIL TEMPERATURE - Trouble shooting from Lycoming:
1. Insufficient oil supply.
--check... @ 8 qts.
2. Insufficient cooling air.
--checked... All baffling new & good condition
3. Improper grade of oil.
--checked... Using Aeroshell AD 100Wplus
4. Oil cooler or lines plugged or partially plugged.
--checked... BUT possibly plugged somewhere else in the system...?
5. Thermostatic bypass valve not operating properly or seating squarely.
--Replaced with new from Maule.
6. Excessive blow by.
--Checked. All compressions are great.
7. Defective temperature gage.
--Checked. JPI is also indicating same problem (digitally)

So now what? Is there any kind of "flushing" additive to the oil to allow any potential "blockage" to be removed?? Would Avblend be of any benefit or is that pissing away $$??

Thanks in advance!

how are you CHT's check the mixture?

I had been reading this post a while back, some interesting stuff about the tunnel lip affecting cooling. Check it out. http://maulepilots.org/forums/viewtopic.php?t=602&highlight=oil
I think you stated it is a Maule.
Erick

Hello plotshots,
after you check the cowling air egress, if it collapses you can fasten a stiffener across it if it already has a 2" lip.
Is your oil cooler receiving it's air through the right rear baffle behind #5cyl?. The later cowls have a naca scoop on right upper portion of the lower cowl for oil cooler air, thus utilizing fresh outside air at accelerated speed instead of the preheated air from top of the engine. Maule will/may sell you this kit.
Call me and I'll explain.
Jeremy

Hot oil temp has been a subject that has been discussed quite a few times on the Maule site. Although you are talking to the right guy Jeremy forgot more about Maules than many of us know.
Just curious what temps are you seeing and at what OAT. oil temp? CHT?
Try the Maule site as well links below:

http://maulepilots.org/forums/viewtopic ... l+temp+cht

http://maulepilots.org/forums/viewtopic ... l+temp+cht

THanks for the responses! I really do appreciate them.
Here is a bit more history on my situation:
1. I have owned the plane for over 3 years and the oil temps (even on the hottest of days) has been at 186 F to 193 F on the JPI and confirmed on the panel gage. So all of these elevated temps (205 F to 215 F) have been a recent occurence in the last 3 fairly short flights.
2. Also, ever since I have owned it, the oil pressure needle likes to "vibrate" as if there is an air bubble trapped in the oil pressure indicator line off of the back of the engine. Either case, the oil pressure has always indicated in the green with no other unusual indications.
3. The air is going through the oil cooler after cycl. #5... Curious if there could be a possibility of baffling flapping down and blocking or partially blocking the oil cooler...? That just seems a little odd, since the baffling has not changed in the past 50 hours, BUT I should check that again. Is that the gist of your comment, Jeremy?
4. CHTs are all at 330 to 380 +/-. There have been no appreciable change there over the past 3 years, either. I usually run 50 to 75 F ROP.
5. Dokmow - thanks for the link to Maules.com. I read through the post and quite a few of the symptoms are very similar to mine, but it seemed like that person had a just purchased the aircraft without much history to it.

Again, thank you all and keep replying. Something has to work that doesn't have to make me go bankrupt...

Nope, I've had it for several years and 4 or 5 hundred hours. If your oil temp has suddenly jumped I'd check compression, you could have broken rings. How many hours on the engine? Also look on your vernatherm to verify that there is a ring worn around the entire seat. If not Lycoming has a tool to reface the seat. Of course the vernatherm works exactly backwards to a car thermostat, the vernatherm closes to force oil through the cooler. Unfortunately you can't replace the vernathermn seat in a (D) IO-540 like you can others.
If your engine is old, I'm betting blow-by which will raise oil temp. Poor baffling or the lower engine cowling collapsing should raise cyl head temps too.
You can temporarily clamp a small, but long piece of angle to the bottom lip of your lower cowling, that will rule out the possibility of it collapsing without having to do anything permanant.
The oil cooler is real easy to remove and have flushed, I wouldn't put anything in the engine to flush it, if it were clogged, I wouldn't want whatever the clog was running around until it clogged something else like a bearing oil hole.

You have an IO, and therefore shouldn't have the 2" lip on the lower cowling. Maule makes a metal lip than can be installed IAW their drawing to increase air flow through the engine if you'd like. It also will reinforce the lower cowl if it is collapsing. But in your case obviously something has changed, I think you should find out what has changed and correct it and not band aid the problem with "fixes".
Just my opinion. Compression check and inspecting the vernatherm, flushing the oil cooler etc. doesn't cost much.
I'm pretty sure the NACA scoop would have to be field approved, I don't think the IO540W1A5D's have drawing coverage for it, and you didn't use to have a problem, so you need to find what has changed and fix it.
If you find a fix, please let me know what the problem was.

We did replace the vernatherm and noted that it was not completely shiny all around the head, but mostly so. Lycoming stated that this could be a issue, but that does not explain the "jump" suddenly in the past few test flights.

We also did a compression check on all cyclinders as an SOP for the annual inspection and for the potential of blow-by. Fortunately, there is no evidence of an kind of compression loss resulting in blow-by. In fact, all of the compressions looked really great.

Lycoming was more concerned about the wagging oil pressure needle gage. It oscillates a needle width inside the green arc very fast. Kinda like a Jack Russel Terrier on crack. My mechanic and I are going to hook up two temporary gages to verify the panel gage reading and also the pressure differential between the front and back of the engine. He and I think that the fluctuating is a result of an air bubble trapped in the tap off line, but we'll bleed the line and verify with the other two temporary gages. That condition has existed since I have owned it and both A&P/IAs I have had work on the airplane have not noted a concern about that condition... But I am not leaving any rock unturned to find the root cause.

As for the bottom cowling "collapsing" under the airspeed pressure, I find it very hard to believe that a very stout fiberglass bottom would start flexing without showing at least some stress cracks. And why suddenly in the past 3 test flights? Weird. But like I stated before, no rock unturned...

...So I am still stumped and I don't have any clear course(s) of actions; just theories and a loud sucking sound from my wallet.

I have had the wagging needle sporadically as well. It was present for the last 2 flights and then yesterday it was back to normal. However there has been little or no change in my oil or CHT.
As you are aware the change from the norm is cause for concern with your situation.
Good Luck

Just trying to point out the cheap things to check first. Actually the vernatherm seat could be all of the sudden, but before I recut the seat I would flush the cooler first.
Recutting the seat moves the seat further from the vernatherm which of course means the vernatherm moves further before it seats and forces oil through the cooler. I have seen the seat be the reason for high oil temps in a Pawnee.
You didn't tell us how many hours / years on the engine.

I have seen a sudden jump in oil temp be the messenger of something real bad going on in the bottom end too. Cut the filter and look for metal, I don't think that is the case here, but it is easy and cheap to eliminate.

Last thing, ensure that you don't have two aluminum washers under the vernatherm. I have seen it, the aluminum washer can bond to the case and look for all the world like part of the case, so when the vernatherm is replaced with it's new washer, you end up with two washers which hold the vernatherm farther away from the seat, and it can't move far enough to effectively close.

a64pilot, thank you very much for the advice and thoughts on my issues. Well, I should say my plane's issues. There's absolutely nothing that can be done about me. I am just plane crazy.

Anyway, I am actually taking tomorrow off to devote to trying to investigate several options with my mechanic on this oil enigma. We're gonna look into the oil pressure, the baffling, the cowling, the vernathurm (esp. the double-washer concept), blockages, and find the culprit... Or at least rule out potential culprits. I am determined to find the root cause of the issue. I have hope that tomorrow will bring me a good day with a positive result...

I'll keep everyone posted.

Thank you ALL for your help an insight to this matter!!

CHEERS!

Maule had a problem with pulseing oil pressure guages quite a while back and managed to control many of the planes vibrating guages by putting a smaller orifice on the angle fitting that comes from the top right rear of the crankcase.
Are your two lower cowl bottom #10 screws in place. One missing can change things, believe it or not.
Is a scat hose misplaced or flopping about affecting air egress?
The external NACA scoop oil cool duct replaces the top baffle hotter air duct on later IO540's and is on the type certificate and #5 gets cooled better, #6cyl now becomes the hottest usually instead of #5.

Double check me here Duane.

guys, mine is a o-540 carb, not efi model. turbo-normalized. oil cooler
is mounted on firewall if you can believe that, with a scoop for the oil
cooler, off the top of the rear cylinder. this i believe is most of my hot
oil problem, but i've managed to work around it with a few ideas.

if you fly it like the book wants, 23 squared, ya gotta run the cowl flaps
open at least half if not more. most of my flying in the mtns is 1/3
throttle, which eliminates the problem alltogether. cruise flight i've
learned to fly it @ 21inches and 2200 or so on the rpm. this after lot's
of hours works best for my 182. keeps the cyl head temps 375 and less.

my real solution will be a 550 conti. next go round . probably the best
solution i believe. a turbo-normalized 550 is a far superior power plant,
both in fuel usage and heat issues.

the interesting thing to me is cruise flight. like i said, 23 sq delivers
140 or so on the knots with the complete stol kit and v.g.'s.
burns 16 + on the gph. but run it more conservative as above, burn
5-6 less on the gas, 20% cooler all-around and only 5 kts slower...!

all in all a good motor, just not a great one. any other ideas would be
greatly appreciated....jo

Well, I flew up to KMYV and on my way up there, the oil temp maxxed out at 200 F... Same engine settings (20" & 2250 rpm = 12.5 gph = 110 kts) that I always use. We put the gages on the engine (1 at the oil pressure tap-off & 1 at the front of the engine). There was a 10% difference and that is expected for normal operation per Lycoming. We also bled the oil gage and it's somewhat stopped the wagging. OK, well, it's reduced. Of the way home, it only varied by 1 degree.

...So all systems are normal...?

Next I need to make a logbook entry to denote the "gremlin bells" installed in the engine and the 2 lbs. of pixie dust in the baggage compartment...

On a serious note, I think my real issue is the carbon build-up due to smokey/dusty/ashy air that we all fly through, but especially this past summer with all of the historic forest fires. So that means more oil changes for the next few hundred hours to scavenge it all away.

I am using Avblend now, but does anybody know of a quicker way to breakup and dissolve the carbon flakes?

Your saying flying in ash laden air caused an accumulation of carbon flakes in your oil? Even if your air filter were junk, I'm not real sure that would happen. Dirty air will dirty up oil of course, but any good oil will keep it in suspension and an oil analysis would tell the tale for sure.
I keep lead sludge out of our 210's IO-550's oil by putting in a bottle of Marvel Mystery oil in it and flying it long enough to heat all of the oil and let temps stabilize, then land and dump the oil ASAP, not allowing the oil to settle. I don't think MMO is anything but detergent in a solvent based carrier, I don't pretend there is any majic, but it does seem to be a decent flush that does not harm anything. The 210 has just the opposite problem of my Maule, it's oil runs too cool even though I run the snot out of it, the big Conti seems happiest if run hard and rich.
My 540's oil temp will hit 220 in a climb on a hot day, stabilize around 200 in cruise, and 180 in the descent. I've come to believe it's normal for a Maule. Oil cooling, like the exhaust is the responsibility of the airframe manufacturer. Both Lycoming and Exxon think those numbers are fine and there is nothing to fix. Exxon actually thinks I'm better running in the low 200's as opposed to 180 as I'll cook off any moisture. They say their oil is fine if run for the full 50 hours even if continously run at 240.
If Jeremy is correct and there is drawing coverage for the NACA inlet, I may go that route, mostly to cool #5 eventhough my cyl. temps never get above 380, I won't let them. Enrichining the mixture brings cyl. head temp down quickly, but doesn't help oil temp.The funny thing about my Maule is it runs hottest when just tooling around slow and easy, it cools off some when I turn the power up and of course the airspeed with the power. The 29's aggravated the temp issue because they slowed me down.
Cooling, especially oil is why I'm told you don't see many Maules pulling gliders and banners. I don't know if that is true or not, but I don't think mine would be a good tow plane. Maule of course knows it's marginal, or why else would they have that extra duct blowing air on the side of the cooler? Which of course robs more cooling air from #5.
FWIW, my wife's CTS-V Cadillac's oil temp runs continously in the 20* range, Maybe 200 isn't really that hot?

I put some good, long flyin' time in this weekend by flying down to KSBP (San Luis Obispo) and back (a little over 4 hrs) and the climb-out maxxed at 217 F and cruise was 193F to 198 F once everything stabilized, so I guess the Maule is back to happy now, but I have no conclusive reason why she was so hot 'n bothered before...

Thanks for everybody's help and input! I am still going to keep a cautious eye on the oil temp gage, though...

CHEERS!