A-65 BC-12 Oil Temp running hot

[PhilP]

Hi there All...
I was on the site some time ago looking for a Taylorcraft to buy.


Well..I solved that problem thanks to a generous individual in SLC. Weeks and Weeks later inbetween working I've finally got it to Florida and now to it's final stop south of Chattanooga, TN. Here's my dilemma...

Now the whole way home it was hot and heavy(2 people/bags) but after some coaxing and thermalling it made it through the high elevations this summer and down to Florida with the Oil Temp never really getting past the top of the green/bottom of the yellow arc. The trip actually went quite well.

However lately it's been getting worse and although temps are definately hitting 100 degrees, the little 65 managed to get JUST short of redline on it's way from North Florida to NW Georgia. We landed before it hit the red and a few hours later hopped 15 miles to a friend's hangar for the night with the temp just short of redline before we landed.

The next morning it was 68/72 degrees and we made it home but not without the oil temp sitting halfway up the yellow arc. The next morning I took it out flying and there's now oil running down the struts on either side. And it's had a pronounced wistle when idling since I bought it(exaust leak?)

I didn't have time to pull the bottom cowling and look for the source that morning. The top looked clean(of course...c-65 is upsidedown)other than the oil filler tube having a bit of oil running down the side.

I've flown behind little continentals on many many airplanes, often a bit heavier than normal, in the summers, and never worried about the temp going off the scale, let alone well into the yellow arc.

Does anyone have some key things I should look at next time I'm home? Bottom baffling? Getting an oil cooler? It's got 50W oil...Aeroshell. Since it's been running hot consumption is up as well.

Thanks for the help guys. It's a low time engine, maybe 80 hours since a recent overhaul. Compressions were good. I'd just like to finally enjoy it without a big hiccup now thats it's finally home!

[Guest]

Re: A-65 BC-12 Oil Temp running hot

Hi there All...
I was on the site some time ago looking for a Taylorcraft to buy.


Well..I solved that problem thanks to a generous individual in SLC. Weeks and Weeks later inbetween working I've finally got it to Florida and now to it's final stop south of Chattanooga, TN. Here's my dilemma...

Now the whole way home it was hot and heavy(2 people/bags) but after some coaxing and thermalling it made it through the high elevations this summer and down to Florida with the Oil Temp never really getting past the top of the green/bottom of the yellow arc. The trip actually went quite well.

However lately it's been getting worse and although temps are definately hitting 100 degrees, the little 65 managed to get JUST short of redline on it's way from North Florida to NW Georgia. We landed before it hit the red and a few hours later hopped 15 miles to a friend's hangar for the night with the temp just short of redline before we landed.

The next morning it was 68/72 degrees and we made it home but not without the oil temp sitting halfway up the yellow arc. The next morning I took it out flying and there's now oil running down the struts on either side. And it's had a pronounced wistle when idling since I bought it(exaust leak?)

I didn't have time to pull the bottom cowling and look for the source that morning. The top looked clean(of course...c-65 is upsidedown)other than the oil filler tube having a bit of oil running down the side.

I've flown behind little continentals on many many airplanes, often a bit heavier than normal, in the summers, and never worried about the temp going off the scale, let alone well into the yellow arc.

Does anyone have some key things I should look at next time I'm home? Bottom baffling? Getting an oil cooler? It's got 50W oil...Aeroshell. Since it's been running hot consumption is up as well.

Thanks for the help guys. It's a low time engine, maybe 80 hours since a recent overhaul. Compressions were good. I'd just like to finally enjoy it without a big hiccup now thats it's finally home!

Hi Phil, welcome

A few thoughs;

Give temperatures in degrees F rather than colors, can't tell much from that.

The whistle might be an intake leak but it.

Is the gasket good on the oil filler cap?

What struts are you talking about? Landing gear tir struts or wing struts?

[cpirrmann]

Re: A-65 BC-12 Oil Temp running hot

What is your pressure doing while it runs hot? Mine runs hot too but never over 208 or so and my pressure drops accordingly, but never below red line. It has been suspected that my bypass spring is either too weak or too strong (I don't remember which) but as long as it stays in range, I was advised to leave it go but keep an eye on it. I run Aeroshell 100 in mine. Located in south central Georgia, haven't tried it in 100 degree weather.

Mine whistles at idle too, but that's the air going through my vacuum venturi on the side.

[Ragwing nut]

Re: A-65 BC-12 Oil Temp running hot

Check your timing and engine compressions first. Then check baffle seals, make sure you have the oil tank baffle installed under the intake spider. Check the opening on the back of the cowl if not a stock lower cowl.

Mike

[PhilP]

Re: A-65 BC-12 Oil Temp running hot

I'm sorry I didn't clarify...

The oil temp got right up to 215F. I've tried various settings on rpm from 2100-2300. When it's heavy running 2300 seems to help it get a bit more on the step so you're not mushing around nose high, and the engine seems to run a bit cooler than at 2150 when heavy... Either way it runs hotter than it should. Even in the mornings at 70F with 6 gallons of gas and my very petite co pilot...over 200-205-210

I saw the oil on both forward wing struts just below the windows...pretty good amount being blown onto them. That happened the day after my 2 day journey up from Florida. Like I said...I'll get back to you guys more on the leak next time I'm home and have a chance to take a good look at whats going on under there.

The wistling is probably from my venturi as well, just didn't want to rule anything out.

Thanks guys...

[VictorBravo]

Re: A-65 BC-12 Oil Temp running hot

The oil may very well be from the front crankcase seal. Or it could be coming out the breather, which is usually not TOO far from the bottom of the cowl... and strange airflows could possibly deposit the oil on the strut. If there is oil on the front engine cowl behind the propeller, and streaks on the rear of the prop blades, it's the seal.

If it is the breather... first thing to do on that issue is to turn the crankcase breather elbow 180 degrees so it is pointing "up" instead of down, and then re-route the vent tube above the crankcase, back towards the firewall, and THEN down and out the bottom. This simple change cut my oil consumption in half.

As far as oil temp there is some good news. Modern engine oils and additives are much better than they were in 1946. A modern oil like Aeroshell is still safe to run at 220 F even though the needle on the gauge will be disconcerting. Synthetic oils will work at even higher temps than that.

The T-craft cowl and cooling system is not a very efficient design and has some serious built-in limits. You can increase the deflection of the "lip" at the bottom of the cowl under the firewall, and it will help a little... but the choke point is still the distance between the bottom curve of the firewall and the inside of the bottom cowl. The single most important thing you could do without redesigning the system is to tighten up the baffles, especially the one under the crankcase and above the carburetor. All the ones I've seen on Taylorcrafts are poorly fitting and do not completely enclose the airflow under the engine like they should. I built a new baffle for this area that made a 20-30 degree reduction in oil temp. It was a significant amount of work but worth it IMHO. I posted photos in a thread titled "cooling baffles" or similar, about two or three months ago.

During the hot months, you might try putting tape over the CABIN heat opening on the front baffle behind the cowl grills. Leave the Carb heat hole open of course. This make a little more of the air coming in go through the cylinders instead of to the heater.

As Mike said, the baffle seals and how they seal between the engine and cowling are important. Clean up all that stuff for sure.

The "Reynolds Aviation" STC is a popular and effective way of making sure all the air flowing around the engine goes through the cylinder fins, and not through gaps in the baffles. Spend an hour with your local mechanic crumpling up pieces of Reynolds Wrap aluminum foil and stuffing it in all those gaps.

If there is a large gap around your air filter, it is allowing high pressure air into the lower cowl, which is OPPOSING the flow through your cooling system.

The hole in the cowl where your exhaust goes through is also doing the same thing... letting air in where it should be going out. A simple non-structural aluminum fairing lip over that opening has paid off well for me.

Hope some of this info helps. If you are not mechanically oriented then you should definitely have your airplane mechanic with you when you are doing any of this. Most of what I am suggesting here would IN MY OPINION fall easily under "minor alteration" and be within the authority of an IA mechanic to do. If you have a wet behind the ears Cessna or Piper mechanic that is gun-shy about this stuff, chances are you have the wrong mechanic IMHO.

Some mechanics would rather see you not change anything, keep the plane 100% certified by the book... and have you sieze an engine inflight. The same mechanics will usually be very happy to overhaul your engine for you afterwards

Some mechanics and owners feel that making their airplane run safer or cooler, extending engine life and increasing reliability... is worth far more than panicking over the fine print in the rulebook (within reason).

I made my choice, and you gotta make yours

[cpirrmann]

Re: A-65 BC-12 Oil Temp running hot

Very useful information and tips. Thanks

[PhilP]

Re: A-65 BC-12 Oil Temp running hot

Thanks for the reply's so far.

I forgot to mention. I have seen the Oil Pressure just a bit below 30 at the lowest. When the temp was up at redline it was still indicating right on 30 psi.

I'll let you guys know what I can see next time I'm home after I run it a bit and pull the bottom cowl.

[tawadc95]

Re: A-65 BC-12 Oil Temp running hot

check the oil screen.

[NY86]

Re: A-65 BC-12 Oil Temp running hot

How much oil was in the sump? The lower it gets the hotter it'll run!

[Mark Julicher]

Re: A-65 BC-12 Oil Temp running hot

The lower cowl outlet opening has a dramatic effect on oil temp. If you unlatch the center dzus fastener, (the one that holds the lower cowl to the stand-off at the bottom of the firewall), the cowl will sag open just a little and this will lower oil temps about 10 to 15 fegrees F. This trick will help on a cross country where you need a quick fix.

A longer term fix is accomplished as per Victor Bravo's comments.