motor runs cold in winter

[bugg]

i have a 1940 t-craft with a 65 cont.
i have installed the univair oil pan thermal cover plus a 3" strip of duct tape
over the top of my grills.
my oil temp seldom reaches 120 degrees when the outside temp
drops below 30 degrees.
i read on a previous post to cover the "inside grill" with 100mph
duct tape to increase oil temp. what is meant by "inside grill"
i can dress to stay warm but don't want to hurt motor by running
it to cold.
does anyone know a safe way to increase temp?
thanks for your help.

[Guest]

Re: motor runs cold in winter

the hole under the prop should be covered to stop air from blowing in on the case and oil sump, this needs to be covered more so than the cylinder intake grills (imho)

what I said above is true but I am not sure what an inside grill is but perhaps that hole under the prop is what is being called the "inside grill"

[Dick Smith]

Re: motor runs cold in winter

This pix of a Taylorcraft belonging to a Canadian flyer shows the "inside of the grills" covered with duct tape, as is the opening located below the prop. I've done it this way without any problem. I usually just cover the hole below the prop with an aluminum plate and install the Univair cold wx wraps over the oil sump and the 4 induction tubes. I haven't found it necessary to use the tape over the inner grill portions unless it's -minus 20 or so. When I first used the tape on the grills, I used one width of duct tape over the inner portion of each grill...flew around and watched the oil temps...landed and added another piece(overlapping the outer edge of the previously-installed piece(s)...flew around some more and added another piece(basically blocking the direct air flow over the barrel of of each front cylinder, but not much of the finned area).
The duct tape will stick quite well to a warm cowling...or you can use a hairdryer to warm things. If you leave the tape on into the spring/summer...it will probably be hard to get off without some "Goof-Off" adhesive remover...(or it may peel some paint!) If I were experimenting with this idea...I would probably use some flat plastic pieces cut from a milkjug or antifreeze jug...drill some properly-spaced holes and fasten the "blockoff" over the selected location on the inner grill, using a good grade of Tywrap(you could use stainless safety wire, but don't booger-up those hard-to-find grill pieces) to attach each piece so as to prevent any movement. (I've seen metal covers made with bolted, adjustable slide pieces that allow you to change the amount of air passing through.) The "plastic/tywrap" method allows a quick experiment without much hassle and will give you an idea of what occurs when you restrict some of the cooling air. Remember, it may be very cold on the ground and the engine may "like" the reduced cooling...but if you climb up into an inversion where it is considerably warmer...you may need more cooling. Keep a close eye on your oil temp. Here in Alaska, where ski operation is very common...we have a lot of places to land and it's easy to set down and adjust the modified cooling setup. Use your good sense and your mechanic's oversight. Also remember that partially blocking the ram air to your heatmuff may effect carb heat and cabin heat. Dick
(The picture of the Aeronca shows a similar setup to reduce air flow)

[bugg]

Re: motor runs cold in winter

i covered the hole under the prop with 100 mph duct tape and went flying .
the outside temp was 24 degrees.
my oil temp went up to 125 degrees and stayed there for a 1 hr. flight.
that is around 10 degrees higher than usual at this outside temp.

at one point i even experienced heat inside the cabin.
this is usually only felt at 30 or higher outside.
this was a definite improvement.
i am thinking of installing an aluminum plate over the hole with sheet metal screws if it continues this way.
thanks for all the good advice,
larry bugg.

[jmvolpp]

Re: motor runs cold in winter

I use the "long johns" on the oil sump and air inlet tubes plus an aluminum plate over the hole below the prop. This morning's flight at 26F showed temp of 140, which is typical for this setup. The plate has an elbow at the top (inside) that slips under the top edge of the hole and is secured at the bottom by the 2 Dzus fittings in the cowl - makes for neat appearance without having to use metal screws.

Mike V.

[bugg]

Re: motor runs cold in winter

i made and installed a plate like suggested,
using an elbow on top and the 2 dzus screws on the bottom.
works great, very easy to install and remove.
thanks for the tip.
larry----------

[SOPWITH2K]

Re: motor runs cold in winter

It might be a good idea to double check the accuracy of the oil temp gage too.

Paul

BC12D - N95318

[vetdrem]

Re: motor runs cold in winter

Larry, I put the aluminum plate over the hole under the prop in November, and leave it there til March. On a mid 20's day, I can fly for an hour or so and only get to about 140 on the oil temp. I had my oil temp gauge rebuilt a few years ago, so I'm pretty sure that it is fairly accurate.

By the way, I put the skis on yesturday.

Louie

[VictorBravo]

Re: motor runs cold in winter

Larry, first cover the square hole under the prop. Then start covering the "slots" in the side grilles. I suggest that you start that by covering the first two or three slots nearest the prop on each side. The slots and the square hole together should make a difference in the oil temp. If you still cannot get to 180, cover the outermost "slot" on each side.

But remember, it is possible to have low oil temps and high cylinder temps, or vice versa. It is IMPORTANT that you do NOT go too far with these experiments unless you put on a 4-probe CHT, with the "spark plug" type probes on the lower plugs.

You also need to think about shock cooling at those low OAT temps. Make very slow power reductions and keep the airspeeds slow when you are reducing power. Do not cruise at higher altitudes, then reduce power and do a fast glide down so you can save gas.

Duct tape is a pain in the butt to remove. I highly recommend the Ty-Raps ("zip ties") and the plastic sheet as mentioned previously. A pocket knife and a few spare Ty-Raps in the plane allows you to make adjustments in the field in two minutes depending on temperature and how you are flying the plane.