[Kent Dellenbusch]

Kent Dellenbusch on June 29, 2026 at 7:45 pm #27754

In reply to wesley ballou (#27711)

Wesley,

Many of the early 1960’s Pipers used the same oil cooler regardless of engine size. The oil coolers used in the PA-28-140, 160 and 180 was also used in the PA-28-235 (as you have referenced) but also the PA-24-260 Camanche and PA-32-260 Cherokee 6.  On hot days, this 7 row “Harrison style” oil cooler was and is not enough .

For many years I flew a PA-32-260 and even on a mild 85 degree day I would experience exactly what you are saying. Temperatures jumping toward redline and then just staying there. Due to airframe design, I did not have the option of adding rows to the oil cooler. My initial action was to install an Aero-Classics oil cooler P/N 8001602. This oil cooler is the same size as the 8000075 however it uses a different fin design that provides lower airside pressure drop while having a higher fin density/count. My experience with this oil cooler was that while the engine oil temps would still climb, the climb rate was much slower. The temps could still push the redline but as soon as I leveled off they would slowly start dropping back into anormal range, 185F.

While much improved I wanted better, I then installed an Aero-Classics 8001588. This oil cooler was the same fitment however its oil flow length is about 1 inch long than the 8000075 and 8001602. I did have to notch the baffling upward to allow the additional oil cooler to get airflow. This oil cooler was wonderful. I could hang off the prop in a climb with temps eventually pushing 220F toward the end of a climb. Once leveled off the temps would come bombing right back to normal at 185F and remain there for the remainder of any flight.

 

Hopefully this is helpful. If you would like to email me, I will send you prints for all of these oil coolers so you can visualize the differences between these oil coolers. I’ll also add that while all these oil coolers are FAA-PMA approved, they may not all have eligibility for your exact airframe. A 337 field approval could fix this.

 

Thank You,   Skid Saurenman

 

1677 Curtiss Ct.

La Verne CA. 91750

909-596-1630

fax 909-596-1753

[wesley ballou]

wesley ballou on June 24, 2026 at 5:54 am #27711

In reply to wesley ballou (#25690)

Good evening, folks.  After considerable research, I think I have found the problem of my PA-28-235 oil temperature overheating.  I have an oil cooler P/N 8000075.  That is compatible with the Pa-28-160 and 180.  In some sites it is also listed as the oil cooler for the PA-28-235.  I have found out that that oil cooler is adequate for the smaller 4-cylinder engines but is insufficient to cool the 235 hp Lycoming 540.  In searching for a larger, more efficient replacement, I looked up the oil cooler P/N for the PA-236 Dakota.  That P/N is 8000074, which is a larger 9 row cooler.  It is almost the same size as the 8000075 but is slightly thicker.  It was not listed in any of my findings as being compatible for the PA-235.  McFairlane lists an oil cooler as suitable which has 13 rows and is quite a bit larger.  Additionally, it states that it replaces the Niagara 20006A or the Harrison 8434108.  McFarlain did not know if it would be suitable to replace the 8000075 that I have now.  They suggested I call Piper to see if they could give some advice or suggestions.  As of yet, they have not replied to my inquiry.  I was hoping you might be able to give me some information on oil coolers with a larger capacity or higher efficiency that would maintain the oil temperature in a reasonable range.  As it stands right now the airplane is unflyable because the oil temperature pegs out within 5 minutes of being airborne in the 95 degree in Texas.  Thanks for taking the time to look at this and provide any information that you can.

[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.