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Thread: High Oil Temp

  1. #1

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    Default High Oil Temp

    I've tried searching for this and wasn't able to find too much info. I'm running 225f oil temp on a 70f day. I've pulled the oil cooler (mounted on the baffle behind cyl 4), inspected and cleaned it, and everything seemed to ok. I do not believe I have a vernatherm. I have a spin on filter adapter. I removed the filter and filter adapter to make sure nothing was blocking it...checks good. I removed what I believe to be the oil filter bypass, looks like it's in good shape. My baffles appear to be sealing correctly. I'm at a loss. If it got to 225f on a really hot day I'd understand, but not on a 70f day. As my temp climbs my pressure decreases to just above the yellow, and when I'm in the pattern at lower throttle settings it will be in the yellow. My temp has always seemed on the higher side (205ish), but recently I've noticed it higher than normal. I increased the oil pressure a while back, but it didn't seem to help. Running w100plus oil. Any more ideas? Thanks all. o320 150hp. 57 PA20/22

  2. #2

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    Default Re: High Oil Temp

    What STC do you have for mounting it behind the #4? Get the installation instructions and verify that it is installed correctly. You can try changing the flow of the inlet by spacing it a little farther aft or adjusting a baffle at the lower end. You might want to check the differential pressure between the high pressure side and low pressure side in the cowling with a manometer set up.

  3. #3
    Gilbert Pierce's Avatar
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    Default Re: High Oil Temp

    Put a bright light behind the rear baffles in front of the fire wall and close the cowling. Look thru the cowling intake. You might be surprised at the light you see. I was when I had this problem.
    Do you have the seal around the carb intake that seals the font of the lower cowling?

  4. #4

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    Default Re: High Oil Temp

    Ok, so a bit of an update. my oil cooler was being bypassed. After airplane came up to temp, the oil cooler was still cool. I did not have a vernatherm. I installed one following my oil filter adapter installation paperwork to make sure everything was plumbed properly, as well as removed the spring and piston under the cap behind the oil filter assy. The oil cooler is warming with the motor now. Found some bad baffling and repaired it. I also modified the bottom of my lower cowling to mimic a buddy's pacer. Basically, adding a lip along the outlet of the bottom cowling to create more suction through the nose bowl openings. My oil temp is now about 200f. 25 degrees cooler than it has been lately. Still not ideal. I might increase oil psi to see if I can get it down a bit more. If it was hot out id be satisfied with 200f, but summer is coming and I'm worried what the temps will get to. Thank you for the tips so far. Any more input?

  5. #5
    Gilbert Pierce's Avatar
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    Default Re: High Oil Temp

    Increasing the oil pressure adds heat the oil. It’s called heat of compression. Probably not much heat is added.

  6. #6

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    Default Re: High Oil Temp

    Quote Originally Posted by Gilbert Pierce View Post
    Increasing the oil pressure adds heat the oil. It’s called heat of compression. Probably not much heat is added.
    I didn't know that. I had heard somewhere that it could help with higher temps. Thanks for the info.

  7. #7
    akflyer's Avatar
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    Default Re: High Oil Temp

    What oil cooler do you have? How many rows? Some opt for the larger oil cooler in warmer climates. Some get away with the 9 row, others are going to the 13 row. Sealing the baffles and getting proper pressure differential is key.

    What are your CHT's running?

  8. #8

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    Default Re: High Oil Temp

    Quote Originally Posted by akflyer View Post
    What oil cooler do you have? How many rows? Some opt for the larger oil cooler in warmer climates. Some get away with the 9 row, others are going to the 13 row. Sealing the baffles and getting proper pressure differential is key.

    What are your CHT's running?
    chts are all good. 350-360. Looks like my cooler has 7 rows, but im not too sure im counting correct. pn - 8406R.

  9. #9
    Gilbert Pierce's Avatar
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    Default Re: High Oil Temp

    My 7 row cooler works great in Tennessee heat. A friend of mine installed a 9 row and has to block off part of it to get his oil temp up in hot Tennessee. 7 row is more tha adequate if your baffle seal are in good condition wit no leaks.

  10. #10
    JPerkins's Avatar
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    Default Re: High Oil Temp

    Your comment about not having a lip on the outlet has me wondering. Every pacer I’ve seen has the lip; if yours doesn’t I wonder if the lower cowl was built correctly. You should have 1-1/2 times the area at the outlet opening as compared to the inlet. If not you might not be flowing adequate air though.
    Experimental cub here had that issue; high oil temps but CHT’s were ok. Finally convinced him to open the outlet after he wanted to try everything else and like magic his oil temps came down.

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