Normal Oil Temps

[bashibazouk]

Hi All,

I'm curious to know what normal operating temps are in BC-65's and BC-12D's in the Southern and Western States. I have overheating issues. An overhauled engine has yielded the same hi oil temps and low oil pressure as well. Baffling or cowl shape? The engine I have installed runs with 40+ psi cold and quickly runs up to 200+ deg within 7 minutes and oil pressure drops off below 20 psi.

Josh

[jim cooper]

Re: Normal Oil Temps

oil pump rebuilt?

[cvavon]

Re: Normal Oil Temps

Josh my engine runs oil temp of 185 most of the time in summer saturday i flew a 23 mi flight 2000msl engine fire walled 74/43 prop 2300 rpm 107 mph on gps 185 oil temp that is with the front of cowl blocked off as it is always baffles are tight we flew to oklahoma on the 10 of june same way 2300 rpm 4 hrs 185oil temp also i have a 4 prob cht the cylender heads run front 300 deg front rt 305 rear 310 315 deg Oh oil psi idel warn 15 running 40 psi My cowl is a closed one and it was for a lycoming and has the 3/4 in lip across the bottom opening and also louvers as i said the kidney hole is blocked off

[Acroeric]

Re: Normal Oil Temps

My experience with high oil temps not associated with a bum engine has been inadequate gap at the bottom of the cowling. It is very common for a C-85 equipped BC12-D to run warmer than ideal. The fix for me has always been to open up the lower cowling a bit and make sure the baffles are good and tight. Messing with these clipwings that have hopped up engines has shown us time and again that cooling air exit is where the issue is. The inlets are plenty big.
E

[Mark Julicher]

Re: Normal Oil Temps

We regularly see 200 degree oil on hot S. Texas days. Sometimes you can climb to cooler air and remedy the problem.

Acroeric has it dead on... open the lower cowl opening by adding a spacer or just unfastening the bottom dzus fastener. Check your baffles are well sealed. Also, about half of the A-65s have lost the baffle on the bottom of the crankcase, therefore the air coming in at the opening under the propeller is not being directed along the lower crankcase as it should.

[bashibazouk]

Re: Normal Oil Temps

Jim, new oil pump and pressure regulator from Fresno. Thanks.

Chuck, I'm sort of surprised that your engine runs as cool as it does without the front scoop open in the summer, but those CHT numbers look okay. Thanks.

Eric, Bottom cowl has a 2" gap from the bottom of the fuselage. Baffles are tight. Inter-cylinder baffles are tight. Thanks.

Mark, "Tray" along the bottom of the engine is in place. Thanks.

I still need to try cutting louvers in the bottom cowl and that's my next move. Also, the scoop on the nosebowl looks a little off to me, or at least the squared off bit on the inside. I think it should let in more air. Does anyone have the dimensions for this? Sorry for the crude drawing. Did it on my phone. This would be looking from the back side of the nose bowl looking forward. Prop hole above and grilled inlets on either side of that, above.



Thanks,

Josh

[dennispip]

Re: Normal Oil Temps

You should sell that drawing at your local art museum...very abstract...and nice colors too. You may get enough for a new plane!

[bashibazouk]

Re: Normal Oil Temps

That's just cold. You should see my crayon work.

[M Jones]

Re: Normal Oil Temps

Josh, that's a thing of beauty! Just don't cut off an ear OK?

[Hank Jarrett]

Re: Normal Oil Temps

I know the part you mean. I made a new one for my nose bowl. It was easy to make and I didn't even have a break available. I just used some "C" clamps and some wood. Are you looking for the dimensions or a pattern? (or maybe my old one to use to make a new one).
Hank

[cvavon]

Re: Normal Oil Temps

Josh The gap at the bottom of my cowl is about 3 in wide and does not have a center bracket so it might spread when flying Chuck

[cvavon]

Re: Normal Oil Temps

here is a photo of the front of 26658 Chuck

[bashibazouk]

Re: Normal Oil Temps

Are you looking for the dimensions or a pattern? (or maybe my old one to use to make a new one).
Hank

Hank,

I have enough of your parts as it is! I made my own using the same technique. Just not sure if it's too tall, preventing airflow around the oil tank. I matched the measurements on the original part. Dimensions, please. And no, I'm not going to cut off an ear. That would halve MY cooling capacity.

Josh

[Hank Jarrett]

Re: Normal Oil Temps

I actually didn't make mine exactly like the original. The original was rubbing and had a hole in it, plus it didn't match up to the under case baffle that well. I started with the old one and make a cardboard one (several) till it fit up tight but didn't rub. Then I put it in with screws and nuts instead of rivets to check the fit. I think most of these planes were "fiddled with" at teh factory to get things like these to fit up right and over the years people have swapped parts around and things start to either open up or rub.
I plan to make a new top cowl for mine as soon as the engine is hung. The old one bulges up between the fasteners from the bowl enough to get a little finger in the gap (almost like having scoops on the front!). I am hoping the new nose will look a lot nicer and if sealed well will cool better than the old one. What scares me is as NASTY as my old cowl was, the engine always ran in the green. Now it will probably look great and over heat or run cold.
Hank

[bashibazouk]

Re: Normal Oil Temps

Okay, so here's the latest. I hacked some really ugly louvers in the bottom cowl (I am in the process of building a replacement), used some seaming pliers to bend a lip on the trailing edge, bent the tin under the case down to allow more air to flow under the engine.

Granted, I should have done these things one at a time to see which one made the biggest difference. Fie on your scientific method! The net result is that with OAT of 94+ deg, I ended up with oil temps of around 190 for over an hour which made me pretty happy.

I have been talking to lots of folks about this issue and it was suggested that the 205 deg limit is too low, anyway. I am not sure I agree with that, and it's irrelevant since the pressure drops off too far above 200 deg anyway. It is worth noting that ATC205 states:

"Maximum permissible cylinder head, barrel and oil inlet temperature, 550°F., 350°F. and 220°F., respectively. Oil pressure limits: 30 to 60 p.s.i.g."

Anybody care to hazard a guess at the reason for the discrepancy?

Thanks,

Josh