Oil cooler cooling

[Bayport Piper]

I have an oil cooler that runs a bit on the hot side. Its an original Piper oil cooler. Mounted on the rear, top, center back in 1950 by Piper. I was wondering if anyone had experience with these. I was told that maybe running a scat tube to it may do the trick since it only gets the hot air off the cylinders trying to cool it. Thanks John

[Gilbert Pierce]

I have an oil cooler that runs a bit on the hot side. Its an original Piper oil cooler. John
What do you consider to be a "bit on the Hot side"?
The people that make and sell oil say it is better to have your oil temp at 200 then 180 as it gets rid of the water that is manufactured during combustion faster.
The location of your cooler is where Piper put it 58 years ago.
The air that flows into the oil cooler mounted on the rear baffle is not heated by the cylinders. The top of the engine is at a positive pressure compared to the bottom. The air flows around the cylinders and out the bottom picking up heat. The top of the engine compartment is a plenum. Under ideal conditions there is very very little air movement there, just pressurized air. Air is squeezed down thru the cylinders picking up heat and OTHER air molecules that have not picked up any or much heat are squeezed thru the oil cooler.

I have a rear baffle mounted oil cooler on an O-320 powered Clipper. My oil temperature averages 110 to 120 degrees F above ambient. Never seen it get above 220 however.

If you really have hot engine oil, 220 and above I would start looking at your baffles for leaks. Leaks in the baffles reduce the plenum pressure and reduce the airflow around your cylinders and thru the oil cooler. What is your cylinder head temps? Are they also high? If not you may have high blow by letting hot combustion gases past the rings into the crankcase heating your oil.

Also, there should be a leather seal between your air intake filter and the cowl. This prevents air from bleeding into the lower part of the cowling increasing the pressure there and reducing the airflow from above.

Piper drawing shows this oil cooler location on Drawing #12690 bottom left hand corner. This applies to the early Pacer with the O-235-115hp and O-290-125HP engine. The O290D2- 135 HP had the cooler in nose bowl chin.

[Steve Pierce]

What temperature is it running? Have you checked the accuracy of the gauge?

[Bayport Piper]

Temp was running at 220. It hit 230 after about an hour, luckily I arrived at my destination. I haven't checked the accuracy of the gauge but it seemed to be doing its jobs until now. Engine baffles are like new. I just recently replaced a front seal and had a jug replaced about 15 hours ago. Last checked the leak test it indicated 74 all around and 70 on the new chrome jug. They are all chromed. I'm running 100 mineral for the first 50 hours for the sake of the cylinder. I should add that I had just purchased the plane in April. Before that it had been sitting in a climate controlled hangar for 6 years. Had it brought out of storage and annual complete by a reputable IA.

[jetech]

Have you seen these videos http://www.lycoming.textron.com/support/training/videos.jsp ? They have some good information.

[Stephen]

Can you post a picture of your oil cooler set-up. I don't understand how it's mounted at the rear and in the center. I mounted mine on the left side at the rear, it ran 180 to 200 degrees, recently I installed a new Stewart Warner, and it now runs even cooler.

[Steve Pierce]

Here are some pictures in the "For Sale" section.

viewtopic.php?f=12&t=466 (http://www.shortwingpipers.org/phpbb3/viewtopic.php?f=12&t=466)

[Vagabondblues]

Has the cooler ever been flushed out? I have the same cooler soaking in shell sol, which I take out daily and blow out with shop air. It has now been a month and small particles of sludge are still coming out. By sludge I mean that I can smear it on a rag. Also, do you have a "viscosity valve" versus the vernatherm? The valve is simply a plunger in a bore that is held down onto a seat by a spring. If you have the viscosity valve have you checked to see if it is seized or even scored enough to prevent it from working.

Chuck

[smcnutt]

Has the cooler ever been flushed out? I have the same cooler soaking in shell sol, which I take out daily and blow out with shop air. It has now been a month and small particles of sludge are still coming out. By sludge I mean that I can smear it on a rag.

Wayne on the other board had an interesting way to clean out the oil cooler. It involved filling it 1/2 way with solvent and mounting it on a BBQ rotisserie motor to continuously slosh it back and forth while changing the solvent out every day or so for a week. I was planning on giving this a try this winter.

[Tom T.]

I have an oil cooler that runs a bit on the hot side. Its an original Piper oil cooler. Mounted on the rear, top, center back in 1950 by Piper. I was wondering if anyone had experience with these. I was told that maybe running a scat tube to it may do the trick since it only gets the hot air off the cylinders trying to cool it. Thanks John
I think I might have the same oil cooler as you do. I had it flushed out before reinstalling it after the restoration. It has never been a problem and temps are perfect. I will try and post a picture of it here. I think you can see the duct on the top rear baffle for the air intake and the mounting bracket on the firewall.

[Bayport Piper]

well I found a specialist that deals with cooler overhauls. R&E oil coolers. They charge $95-100 and turn around is usually 4-5 days. Ill let you know how it turns out. I think I'll be taking my plane off the market, its too much fun to fly it.
Cheers John