oil temp in winter

[shortline]

Hello,
does anyone know the best way to raise the oil temp in my M7-235 b while winter flying in maine? right now it's barely getting into the bottom of the green/

[Norm]

I have an M7 260 and I just put some strips of duct tape over the leading portion of NACA vent that goes to the oil cooler. Keep adjusting the amount you cover up to get the temp where you want it. I think we need to be careful when OAT warms up to be sure to remove some of the tape on the cowling / vent.

[shortline]

thanks for the advice, but whats and NACA vent?

[a64pilot]

Something you don't have, but duct tape is the easiest solution.

[Norm]

I'm new to Maules so I'm not positive your 235 uses this type of vent for the oil cooler like my 260 does, but a NACA vent looks something like this: (this is a pic that illustrates the basic shape)



Basically a NACA scoop is a recessed vent that aerodynamically draws air into it from the surface boundary layer air stream with very little penalty of drag.

You'll have to know how your oil cooler receives outside air. On mine the NACA vent that draws in cool air to the oil cooler is on the right side of the cowling.

[xwildcat]

Yep, you need to limit the air flow to the oil cooler. My RV4 has three different "gates" that rest just in front of the oil cooler and I can change out according to the season. Each one looks like Swiss cheese with more or fewer holes.

[maules.com]

The later Maules have a NACA scoop, and you can block it from the outside. Earlier versions have a screen at the right rear baffle on top of the cylinders and you can build a swing door with control on panel, or block off the air with silver 500mph tape, or a portion thereof.

[a64pilot]

Jeremy,
What's the reason for the NACA scoop? Does it provide greater airflow for summer?

[flyer]

Jeremy

Do you have any specific info on how to build the swing door and the controls? I use duct tape now to cover the intake. Although I have tried, I cannot get my Maule to go anywhere near 500MPH.

Happy New Year

flyer

[maules.com]

A64, Maule is using a large scoop for the oil cooler and a smaller one for heat/freshair. The scoops moves more air than the 2 inch round holes with probably less drag.
The scoop for the oil cooler takes air from outside the cowling rather than the preheated air from the top of the cylinders, plus there is more air being drawn down through the right rear cylinders if there is no outlet at the rear baffle. Maule sells these scoops or ducts. The 260hp tended to run a little hot, though the newer Lopresti cowlings were the prime culprit as the egress was partially collapsing in flight.

Flyer, fabricate a piece of sheet metal that covers the hole in rear baffle and drill a hole for the 'door' to pivot on, offset to the side, so that if at any time your cable inadvertantly disconnected, the door would drop down and open the hole. Attach a simple push/pull cable as your heat or vent valves uses. Use a jam nut on the pivot bolt so it cannot come undone.
500mph is hard to achieve even if you point straight down after a midair with wings removed unless still attached to the 747 that hit you. So always use the correct speed of duct tape. Be prepared.

[akloon]

The duct tape works well, but be sure and monitor it closely on your first flight and again as the weather warms up. I've also had small success with running a higher RPM on the prop and pointing the baffling down on the front of the engine (attached to the lower cowling). It should be up for normal cooling.

Speaking of which, the knucklehead who owned this plane earlier removed some of the baffling for reasons unknown to me. Maule hasn't answered my requests for a drawing to replace said pieces. Anyone have a blueprint for this material? (Other than a Chinese one)

[maules.com]

Akloon, You can see the baffling in the Parts Manual or Parts CD.
BTW, I got an email from the 2nd owner (Miguel in the Philipines) last week. I told him the Feathered Bird is on to new adventures.

[akloon]

Thanks, Jeremy. You might ask him about the missing baffling! The LooneyBird, as I call it, is doing well and seeing a lot of Alaska. It's hauled plenty of moose meat, Copper river Reds, and ski gear. Probably not what it was doing in the PI.

[maules.com]

Oil Palm oleo for making soap and the executives thereof in Philipines.
Which piece of baffling do you suspect is missing?

[andy]

Jeremy: do you have any pictures or plans for a cockpit adjustable oil cooler baffle to increase the oil temps in winter? It seems like a good solution would be to add a short pipe segment with an internal pivoting circular damper between the air hose and oil cooler air inlet. My 1986 MX-7-180 runs about 150-160F oil temp with 30-40F outside air temps. I have a fixed metal baffle plate which sandwiches between the oil cooler and cover. It increases oil temps about 10F but it's a pain to install and remove when the weather changes often.

Andy