Dual Oil Coolers?

LordofWar · #1 08-09-2017, 08:11 AM

Hello folks,
I have dual oil coolers installed on my Rv-6 O-320(160HP). One next to the #4 and one remote on Firewall routed from behind the #3.

Even with both of them partially closed off, my oil temp are way cooler in the winter. In the summer, they are around 190-200 on 100degree days with one oil cooler partially blocked.

I didn't find anyone with dual oil cooler here. Do you any of you have dual oil coolers installed? Do you feel it is worth the weight? or is it better to sort out the heating issues with one effective oil cooler with a shutter installed. Any Advice?

Thanks & Regards,

Raymo · #2 08-09-2017, 09:48 AM

IMO, a properly baffled 320 should not need dual coolers. There are options for larger and smaller coolers so maybe you have two small coolers?

It's a good idea to have the cooler professionally flushed (e.g. Pacific Oil Cooler Service). I am not sure of the interval but would guess it should be done during engine overhaul.

EDIT: I have a single cooler on my O360 and have about a 3rd of it covered in the summer to get the temp up to 190.

Timberwolf · #3 08-09-2017, 11:03 AM

I have dual coolers on my 6 with a pumped up IO-360 angle valve. I'm about to remove one and leave just the 7 row behind #4 to see if I can get sufficient cooling. I'm not a big fan of all the extra hoses and hardware lending itself to a possible failure point. Everything is already pack in pretty tight behind the engine with the prop governor and it's really hard to work on anything. I wouldn't think such a thing would be needed on a O-320

LordofWar · #4 08-09-2017, 11:33 AM

Thank you Ray and Timberwolf.
Both my oil coolers look like standard Vans Oil Coolers(7 row).
I believe I will evaluate my baffling, my #3 cylinder runs hot 400+(Max 420) on takeoff with OAT 100~110F, when the hole for the oil cooler on the firewall is left wide open. If I partially block this oil cooler hole(#3) during the summer(Texas) the oil temp climb to 230+ but my CHT is slightly better.

I want to get rid of one of the oil coolers esp since the fat oil lines going around, crowds the space behind the engine and I feel i can reduce the weight by a few pounds. I guess I need to check/mess with the baffling to make sure my #3 doesn't climb above 400.

Raymo · #5 08-09-2017, 12:54 PM

Other things, like electronic ignition and timing can also contribute to your problem but I agree that you should look at improving cooling first. Also make sure you have adequate fuel flow at WOT. If fuel injected, confirm proper fuel flow between cylinders (AKA: GAMI spread).

My #4 runs warmer (390-400) during climb unless I climb at 120 kts. Once level and in lean cruise, they are all 360-380. Prior to installing gear fairings, I had to retard the P-Mag timing a couple degrees to help control CHTs.

LordofWar · #6 08-22-2017, 05:16 PM

Wow, I removed one oil cooler mounted on the firewall. Took a tube of Red RTV in a Caulk Gun and went to town on the baffling. Sealed up the oil cooler behind #4 top and bottom to maximize air flow through the fins. Took a hammer and bent the baffling behind #3. Let it cure and took the plane for a test flight and tried to abuse it by climbing slow, higher power setting etc (6 Quart oil)

Result: On a 95Degree day, oil temp very slowly climbed to 190-200. CHT barely touched 380 max on #3 (big drop). In cruise #2 was running hotter than #3 and #4.

Next day, I went in with a borescope and inspected the baffle seals. Noticed baffle seal next to #2 was not flush, pushed it around with my hand and it was fixed. I reached to the front toward the prop and the baffle seal were sitting the wrong way. i could easily slide my hand over the seals(No sealing). I opened the cowl change the baffle seals in front to point the right direction(towards the engine) and carefully slid the cowl back on. Took it for a test flight.

Result: #2 dropped significantly. It wouldn't climb over 320Degrees. Overall temperatures looked much cooler.

Side Note: I dropped a cool 5 Pounds off the plane. The plane also seemed to be cruising at a higher speed at 3000feet compared to earlier and climbing faster(I don't have data to back it up). Could it be true? or maybe I was just climbing aggressively given the cooler temps. Speed Increase or Not, I'm quite happy!

Request everyone to feel their baffle seals after the cowl is closed.

TS Flightlines · #7 08-23-2017, 05:41 AM

Just a thought from someone NOT flying yet----before going with the trick of the week, good preparation and attention to details will make life a bunch less stressful. Having helped several builders with their projects, spending time on the little things, like baffle sealing, will pay off in the long run. Raymo spent alot of time on his baffling, and it pays off.

Tom