Oil Cooler Winterization Plates: Is Yours On?



  • I have another question.

    My Arrow is getting a JPI Jr Flight Engineer panel installed and our first flight is soon. The JPI has oil temp displayed, I think. If there is a difference what number should I go by? My 50 year old Piper OEM or the new JPI computer?

    I bet the probs are in different locations in the oil system.

    1973 Arrow II factory AC removed

    G5’S, G275, GNX375 Still can get lost.

  • I live in TX and just put mine one. On a recent cold cross country to Oklahoma it was 0 degrees at altitude. I noticed my oil temps were only in the 140-150 range. Today it was 55 and oil temp was a steady 180.

  • The engine cooling systems are generally set up for ISA +/- 10 or so (by observation). So, if you are 8000 feet then 0 would be ~ ISA If you were less than 8000 feet you would be colder than ISA. It seems the winter plate is important for ISA-x temps near the ground and in the air to avoid overcooling the oil.

    Eric Panning
    1981 Seneca III
    Hillsboro, OR (KHIO)

  • I'm confused about an oil winterization plate for my '68 Cherokee 180 (28-5273). There does not seem to be a plate shown in the parts manual for this model, nor are there any of the placards that I had in the Warrior I trained in. Is there a winterization plate for this model? I took her up yesterday and noted the oil did not get close to operating temperature.

  • My “educated” guess is that you probably do not want to order one by part number directly from Piper ($$$).

    Might I suggest a call to Wentworth or other salvage company to see if they have one? I suspect it does not have to be from that exact model year. Measure the hole pattern on your existing airframe to be sure.

  • I have an oil cooler restrictor plate for my Arrow but have not put it on as it requires taking the top cowl off, removing the scat tube from the air inlet, putting the plate in place then replacing the scat tube then cowl. It works fine but temperature swings here are extreme and it is not uncommon to be below freezing in the a.m. and 20 degrees warmer by noon when the plate should be removed according to Piper. At takeoff today the OAT was 0 C and at 9500 MSL the OAT was -7 C but my oil temp was 171. The Vernatherm was doing its job just fine. I had turned the engine heaters (oil pan and cylinder bases) on several hours before I flew so at startup the oil temp was already 92 F. So I keep the oil cooler restrictor plate in the plane but probably won't use it much.

    Jim Torley
    1969 Arrow 200
    Based at KFLY (Colorado Springs, CO)

  • Wasn't planning on ordering directly from Piper, just unclear on where the plate would go on this model or what it would look like.

  • edited December 2022

    mr_penguin, I have a 1966 180 so two years older. However, with the top cowling removed, on the left side of the aircraft, you will see a large diameter hose going from the firewall mounted oil cooler to the vertical sheet metal engine baffle just aft of the rear cylinder. The large hole at the forward entrance to this hose is completely covered by the winterization plate which mounts with 4 screws over the hole. The screws are inserted from the back side of the engine baffle into 4 threaded posts at the corners of the plate.

    I’m hoping to change oil later today and will try to remember to take a photo.



  • Here are some pics:

  • Thanks Mike for the photos and description. That makes sense to me. I think mine will take the same style. I'll head over to the hangar today to check.

  • Found this diagram years ago and made one for my '81 Archer II. I don't have the lower notch to insert the bottom tab on my baffling so didn't cut them in. It seems to do the job with the two attachment screws up top just fine. Lives in the same spot as MikeJJ's above.

  • pilotsmall, thanks for sharing! Find an experimental aircraft builder and they could easily make this from scrap

    Eric Panning
    1981 Seneca III
    Hillsboro, OR (KHIO)

  • Please note the Piper winterization plate for the Cherokee 180 does not have a hole in it. You might want to check with an Archer owner to see if the original Piper part has no hole as well.

  • I can’t find a winterization plate for my aircraft. I looked through the engine manual and the aircraft parts manual. I have a PA-32-260, Lycoming O-540-E4B5. If I need it why is it so hard to find any documentation for the part?

  • I live in MN, this fall we had 30F OAT in October and then warm again after that. I was getting tired of swapping the factory plate on and off so I “fabricated” 4 different sized rectangles to experiment with partial airflow blockage. In reality, it didn’t matter much, but now I have four different options and the factory plate for deep winter (Dec-Feb)

    I put “fabricate” in quotes because I ordered the cut aluminum from https://metalscut4u.com/ - good/quick service, recommend them. You can get fancy cuts, but it adds more. I paid $30 for 4 rectangles (which is a premium, I get it) and it saved me a bunch of time/fiddling so I could get to the real experiment. Now I also have a cheap replacement for the factory plate, should I lose or break it!

    Jeremy Olexa, N2471U 1979 PA28-181 Archer II. Minneapolis, MN (KMIC)

  • edited December 2022

    At one time I was told the reason for the plate is of course to raise the oil temp, and the reason for that, is to cook off the moisture that can condense in the oil pan. If that is true, then is it less critical in low moisture climates? We typically see winter days with humility in the teens. Also, in S. Colorado we frequently have winter days in the 60’s with nights in the single digits. I’ve always just put it on when I feel like it’s cold enough to dictate in the winter.

  • Humility in teens is a rare thing - enjoy it when you can!

    (Sorry, couldn't resist.)

    I think you still need to watch the oil temperature. Keep in mind that combustion in the cylinders creates water vapor, and some of that ends up in the crankcase due to blow-by, so being in a dry climate does not eliminate the problem. One way or another you need to get the oil warm enough to cook that out on a regular basis. Best I can suggest is keep an eye on the oil temp. If you regularly fly in warm enough conditions to get it to 180 without the block-off plate, you'll be OK. Remember it's going to be cooler at altitude than on the ground.

    We have fewer really warm days here in New England, so I put in the full block-off plate in the 1966 Cherokee 180 as soon as the weather is consistently cold. (Used to be early November, now late November. Climate change.)

    On the flip side, in the summer I use a short block-off plate that covers the upper half of the big hole. (See MikeJJ's pics above - same engine.) Some years ago we installed a JPI engine monitor, and I found #3 cylinder getting significantly hot on climbout on warm days. That big hose to the oil cooler steals a lot of air from the cylinder! Covering half the hole lowered the climbout EGT on #3 by 10 degrees, and we've never seen the oil temp go over 180 even on the hottest days.

    • Andy
  • Hi, as Andy pointed out it is really the oil blow by to worry about. The faster your oil turns dark after an oil change the more blow by you likely have. With the carbon and lead is a significant amount of water.

    If the oil does not reach a temp high enough to drive out this moisture it sits in the case and a desert climate with wide temp swings can be worse. The reason is the hot daytime temps and increase the amount of water in the case air and then cool temps in the evening can drive condensation.

    There is an insignificant amount of humidity exchanged via the breather as there is really no driver for flow so almost all of the water in the case is coming from combustion regardless of the climate.

    You can get cylinder corrosion and I think this is moisture coming in via open intake/exhaust valves. My view is cam/crank corrosion is from combustion water. This water can also be acidic and eventually your oil runs out of buffers to neutralize this.

    When 100LL is gone this will open up new options for oils including synthetics that will go a long way to eliminate coking on the oil control rings. This will also help with reducing water blow by.

    Eric Panning
    1981 Seneca III
    Hillsboro, OR (KHIO)

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