Continuing Problems with Oil Temps

[lr172]

I have an IO-320 6A. The oil cooler is a Mocal 10 row (same as Setrab and heard several reports of success with 7 row version) mounted on the baffle behind #4. Hoses are new; replaced this spring, -6 size.

I had goods success last fall, with temps remaining in the 190 range even in 90* ambient days. This spring I noticed higher temps reaching max's of 220-225 at 75% power levels. I have replaced the cooler, as I thought it may have become blocked with all the carbon I had in the oil during break-in (due to a glazed cylinder). I have two different verhatherms that I have tried (neither new). The one I flew with today was tested last night. I put it in 190* water and observed a growth of .230" I saw Dan's post and his tested at .248" The minimum is .160 or .180. It would seem that the Vernatherm is working properly.

I don't really know where to go next. I can't see in the vernatherm cavity and I have considered removing the oil filter housing (lycoming style with V/T pointing down) and replacing with screen to rule out issues with the bore that the vernatherm seals. I think that I also have a spring and plug laying around to bypass the vernatherm all together. I have also considered buying a new vernatherm.

Does anyone have suggestions or seen similar problems they could share insight from?

Thanks,

Larry

[Toobuilder]

I'm sure others will jump in here but the first thing that catches my eye is the #6 hose size. Thats pushing it as far as Im concerned. And if you throw in a couple of 90 degree fittings, it makes it worse. Might explore running the #8 hose, keeping it as short as possible, and 45 or 180 degree fittings wherever you can.

[lr172]

Originally Posted by Toobuilder

I'm sure others will jump in here but the first thing that catches my eye is the #6 hose size. Thats pushing it as far as Im concerned. And if you throw in a couple of 90 degree fittings, it makes it worse. Might explore running the #8 hose, keeping it as short as possible, and 45 or 180 degree fittings wherever you can.

Thanks Michael. There is one straight fitting, two 45's and one 90. All are hose fittings, so a generous radius. I have read quite a few posts on the the subject of -6 lines and it seems the flow is adequate, but could increase pressure. It was my understanding that many engines, including certified, run these lines. I also had good success with this, even during the high heat of break-in. I realize that 8's are better, but it worked for me last fall

Larry

[Kyle Boatright]

Let's see a few under-cowl pictures:

1) Your baffles and seals.
2) The intake area for your cooler.
3) The exit area for your cooler.

On my -6, I originally undersized the hole in the baffles for the baffle mounted cooler. After 6 months (?) of fighting oil temperatures, I opened the hole up as large as I thought practical, which gave immediate benefit.

[vic syracuse]

Hoese to/from the cooler really should be -8. You would be really surprised if you looked at the flow rates of the oil pump. In a typical Lycoming the complete oil quantity is sometimes cycled in a minute.
Sure there are a lot of other factors, but choking it down to start with is not helping. What works in certified airplanes is not always transferable in our very-tightly-cowled engines.

Vic

[lr172]

Originally Posted by Kyle Boatright

Let's see a few under-cowl pictures:

1) Your baffles and seals.
2) The intake area for your cooler.
3) The exit area for your cooler.

On my -6, I originally undersized the hole in the baffles for the baffle mounted cooler. After 6 months (?) of fighting oil temperatures, I opened the hole up as large as I thought practical, which gave immediate benefit.

I'll take a couple of pics. I forgot to mention that I think my baffles are in decent shape. My CHT's run 340 with #2 at 360* at 75% power. I stay under 400 even in hard climbs. My cut-out for my cooler fully matches the size of the cooler and the bottom of the opening sits just above the fins of #4, so not blocked by the cylinder. Area behind the cooler is wide open and not obstructed.

Larry

[lr172]

I am trying to install the plunger and spring to force everything to the cooler. That should help me troubleshoot the verntatherm / housing and confirm I am cooling as I should with my cooler and hoses.

I have a plunger, but I am not sure I have the right spring. Does anyone have the relaxed length of the 69436 spring used with this plunger? The one that I have sits proud of the top of the threaded opening by a good 1 1/2" It makes me suspect that is is the correct spring.

Larry

[BobTurner]

Try easy things first, even if unlikely. Pull your temperature probe, provide a ground, and hold it in boiling water. What does it read?

[lr172]

Originally Posted by BobTurner

Try easy things first, even if unlikely. Pull your temperature probe, provide a ground, and hold it in boiling water. What does it read?

A Good idea. I did that during my initial troubleshooting. It read within a few degrees of a quality thermometer at 200* It also mirrors ambient temps closely on cold startup.

[vic syracuse]

So I just received an email from a very trusted friend who tells me that they did some testing on the early RV-4's and found they could RAISE the oil temps by using larger lines and that using smaller lines actually made the oil cool better.
I would never have guessed that.

Vic