[wesley ballou]

wesley ballou on January 9, 2026 at 12:49 pm #25690

Happy New Year Folks:

In response to your recent suggestion, I’m sure the oil suction screen has been checked. It has had 2 annuals and oil changes since I have been having the high oil temp issues.
The oil temp probe has been removed and calibrated with the oil temp gauge on several occasions. The temperature from the probe has been verified via a direct reading of the oil itself.
We have not done an engine crankcase pressure test.
I apologize about the engine time. I must have miscommunicated that. The engine does NOT have 1980 hours; it only has about 700 hours since major overhaul.
I was wondering if you had any further information about the double bypass oil cooler on the Piper Pawnee. I talked to the folks from Pacific Oil Coolers and they didn’t seem to know anything about it. I was also wondering if there was another location authorized for the oil cooler, or if there was an added or secondary oil cooler that could be added to the system to bring down the temperatures. I don’t have an issue with flying at 220 degrees; I am just a little concerned about what the oil temp will be like this summer. Additionally, climbing at 500 feet per minute at cruse climb power settings is agonizing knowing it is capable of 1000 fpm or getter at best climb speed.
As always, thank you all so much for your comments and suggestion, and anything you could add would be sincerely appreciated.

Thanks, Wes

[James Grahn]

James Grahn on January 9, 2026 at 11:23 am #25688

I would not use MMO in Lycoming oil for the simple reason that it will decrease the oil’s viscosity.
Another suggestion though might be to recheck timing. Oil will absorb the access heat generated by an aggressively timed engine.
But, in my opinion, 220 is not out of bounds. Water boils at 218. You want internal moisture to boil off.
BTW, I am an A/P with some experience on high compression mods.

[STEVE]

STEVE on December 12, 2025 at 5:58 pm #25679

Hi Wesley and Charlie;
A local mechanic told me that his father installed what’s called a double pass oil cooler in place of the single pass cooler. The double pass cooler is installed on the same O-540 series engine on a Piper Pawnee. 
I’ll call the Oil cooler people Monday to get a part numbers and ask about an approval for installation. 
Myself, Martin and Rex (three pretty experienced A & Ps) brainstormed this problem. Questions from our session:
1) has the engine oil suction screen been inspected lately
2) although I can’t visualize this, one guy told me to make sure to install the oil temp probe for the 830 is installed according to the directions in the installation manual. 
3) Have you done and engine crankcase pressure test? I have attached a Continental SB that will provide details on this procedure. I don’t believe Lycoming has printed a crankcase pressure test document. We’re checking for high crankcase pressures. Hi pressure indicate excessive combustion pressures leaking past the rings which will increase the temperature of the oil as it circulates in the case. 
Way back in 2022 when this thread started you told me the engine had 1980 hours. Are you still running the same engine?? 
What are the hours now?
Steve

Attachments:

• TCM-SB-M89-9CrankcasePressures_2025-12-13.pdf

[wesley ballou]

wesley ballou on December 11, 2025 at 9:13 am #25678

Steve, Charlie, and all the rest.After doing everything we could think of to combat the high oil temperatures, I was finally able to get my PA-28-235 airborne.  I was careful to pick a day that had some cooler temperatures.  Outside air temperature was 15 C 59 F.  Started the plane, taxied out and did the run up.  By then oil temp was 100 degrees.  Took off immediately and by 500 feet the temp was 180.  At that point I pulled the power back to cruse climb and adjusted pitch for 500 feet per minute climb.  This got more airflow in the engine than the best rate of climb sped of 100 mph.  Leveled off at 2,000 feet and pulled power back to about 65% power.  The oil temp continued to climb until it reached about 220 degrees.  At that point the oil temp stabilized at about 220.  After a few minutes, I proceeded to climb at 500 feet per minute using the cruse climb power setting.  I went up to 6,500 feet and the oil temp remained stable at 220 degrees.  Cursed at 65% power for about an hour and a half.  At this altitude, outside air temp was about 5 C or maybe a little less.  I came back to the airport entered the traffic pattern at 1,100 feet.  Did a touch and go, another full pattern and a full stop while the oil temp remained stable at 220.  What I get out of all of this is that the oil cooling system is working, but it is just not very efficient.  What remains to be seen is if the oil temperatures will remain manageable when the outside air temperatures get hotter.  Also, I find it a bit frustrating to hold the climb to 500 feet per minute when the aircraft is capable of a lot more if climbing at best rate of climb speed.  One question I had was what type of oil cooling system is used in the Piper PA-28-236 Dakota, and if any of those aircraft have any issues with oil cooling.  Any comments or feedback that you all have would be appreciated.

Thanks, Wes

[STEVE]

STEVE on October 22, 2025 at 4:35 pm #25646

Wesley,
I want you to fly your airplane and get the oil temperatures up to normal operating temperatures. 

Then set up for normal cruise power settings. 

Write down the outside air temperature, and the oil temperature.

Based on your description, it seems as though you’re basing your high oil temp conclusions based on ground running.
Ground running is not what airplanes are made for.

Knowing these engines are made to operated in a dynamic atmosphere that takes place while flying, I plan my flights to minimize ground running. 

There’s no where near enough cooling ram air delivered to either the cylinders or the oil cooler during ground running. 

If you’re worried about anything with the engine, it’s perfectly acceptable to conduct this test flight over head above your airport.

After the flight, please let me know what your oil temperatures are after a stabilized cruise at your normal cruise power settings. 

One other suggestion; try a different oil. Most of the flyers around here are having good luck with Phillips Victory oil. You can put in the multi-grade but I suggest using the straight 100 oil first. 

Best,
Steve

[wesley ballou]

wesley ballou on October 19, 2025 at 11:27 am #25645

Good afternoon Steve, Charley and any others that may be reading this.

As I had shared before I had the plane for a year and had no issues.  I had no work done on it except for an annual inspection.  Then I started having high oil temperatures.  After two years of trouble shooting and trying to correct the issue, I am still having problems with high oil temps.  Most recently my mechanic checked everything he could think of.  So far this is what has been done:
New baffles the entire engine bay and cowling.
Replaced the vernatherm with a new one.
Checked the vernatherm opening in hot oil.  It was visibly noted to be opening and was measured at 180 degrees.  Probably was opening prior to that, but it was not readily visible in the oil due it opening very slowly.
Replaced the oil cooler
Replaced engine oil temp gage with new gage and temp probe.  These two items were calibrated before installing.
Oil temp probe placed in oil and heated. Oil temp checked with thermometer.  Oil temp gage was accurate with the thermostat.
I have been using multi grade oil since I bought the plane 3 years ago. 

After all of the above things were accomplished, the latest runup was done on the ground in 85 degrees F OAT.  Aircraft was pointed into a slight breeze.  Engine was set at 1500 RPM and within 13 minutes of engine start, the temperature was well over 200 degrees and rising.

Has anyone had any experience with Majic Mystery Oil?  I understand that it does good in removing sludge in all types of engines, but although it is not recommended by Lycoming, they don’t specifically say not to use it.  I’m thinking there may be some sludge in the system somewhere that is restricting the flow of oil. 

Does anyone have any other thoughts or suggestions?

Thanks, Wes

[STEVE]

STEVE on May 6, 2025 at 9:01 am #23095

Hi Wesley,
Glad you’re making progress.
The high oil temperatures you’re seeing at definitely on the high end of acceptable. One plus is that today’s oils are much more able to handle high temperatures than the oils of previous decades. 
Your statement from your first post that told me ” It flew fine for the past year.  Now I am experiencing high oil temperatures”
seems to be pretty provocative.
What was changed between “fine” and “high oil temperatures”
Was engine work done? Did you install an engine monitor to replace the original oil temp gauge? Did you change brands or start using a multi grade oil? 
Have you and your mechanic checked the length of the vernathern oil temp control valve and the valve seat as I suggested in my Aug 2024 response? 
I’m asking because something must have changed to cause the change in oil temperatures. I’m suggesting you and your mechanic look at mechanical things that could have caused the change.
Perhaps it’s time to get your oil cooler inspected and cleaned.  The best shop to do that is Pacific Oil Cooler Service (www.oilcoolers.com) The folks at Pacific are very wise about oil coolers–they may be able to add insight to your suggestion to move the cooler or install a bigger cooler.
In my mind, moving the cooler or installing a bigger cooler is similar to my Dr. giving me a pill for a health issue–it’s a cure for the symptom; not the cause of woe (higher than normal oil temperatures)
Best,
Steve

[CHARLIE MUELLER]

CHARLIE MUELLER on May 6, 2025 at 4:22 am #23094

Wesley-

I have had better experience with managing my high oil temps by doing two things this past September at my Annual.

I also increased the oil pressure and I removed a rectangular panel in the lower cowl directly below the carburetor. I think this has helped with air flow down through the cylinders. The real test will come in June as the temps in S. Florida are more regularly in the 90s. My issues are during climb also.

I’ll let you know what I experience over the next few months.

[wesley ballou]

wesley ballou on May 5, 2025 at 10:44 pm #23093

Steve & Charlie

I have had some success with the ongoing high oil temp issue. We increased the oil pressure. Just put a washer in the oil pump. The oil runs on the high side but is still within limits. This seems to circulate the oil so it gets through the cooler a little faster. I still have trouble in the climb with the oil temp getting to the red line. When I get to altitude it seems to settle into the high normal range. This is when outside air temperatures are in the low to mid 80’s. My concern is that when it gets to be summertime here in Texas and temperatures get in the mid 90’s and above, I will not be able keep it within limits until to altitude. I have had thoughts of putting a higher capacity oil cooler in. Additionally, I was looking into moving the oil cooler to a location that it would get better airflow like some of the newer model PA-28’s. I was also looking into the possibility of increasing the vents on the bottom of the cowling or possibly installing a cowl flap to increase airflow until I can get to altitude and power back to cruse power. Any thoughts on any of these suggestions?

Thanks for taking the time to read this and any feedback you could provide would be appreciated.

Thanks, Wesley

[STEVE]

STEVE on August 5, 2024 at 10:31 am #22675

Hi Wesley, and Charlie;

I have attached a file that contains troubleshooting steps for high oil temperatures.
It’s pretty self explanatory.
One of the easier checks is removing the vernatherm (thermostatic bypass valve) and measuring the length–see page 4 of the attachment. Then submerge it in light oil that’s heated to 150 deg F. Measure it again. It should be at least 0.160 longer; if it isn’t you’ll need to get a new one. 
A vernatherm that doesn’t extend won’t force oil through the oil cooler.

Another check of the thermal control system is to look at the sealing surface of the vernatherm, and the sealing surface inside the engine case to see if; 1) check for wear on the vernatherm surface and on the vernatherm contact surface on the engine case.

Lycoming Service Instructions 1316A is attached–it provides information on oil cooler causes, and solutions.

Let me know what you find

Steve

 

Attachments:

• LYCHiOitTemps.pdf
• SI1316ACoolerByPassSeatRepair.pdf