Hot Running O-200A TCM engine help?

[Pokette]

After testing a couple of extensions I had Jim make about a 2" one canted forward. Here is the result:

OF course now it is in the 80's instead of 100, and low humidity, but when I flew with it, temp stayed below 205...
hopefully it will provide enough cooling when the ambient is above 90 and into the 100's.

 

[N86250]

Thanks for the oil info Jim, But with that correction for the Cessna aren't you just cooling the probe? Not a real fix to hot running engine.

The blast tube on the oil screen housing is definitely a poor man's oil cooler. I also thought it was just fooling the gauge until an old timer put a gauge in the oil tank drain hole. It lowered oil temps by more than 10 degrees and both gauges read identical temps. He explained the blast tube cools the housing. The housing then cools any oil that contacts it. The temp bulb is inside the oil screen and gets no direct effect from the blast tube. The bulb is affected by the cooling of the oil only when it is recirculated. jrh

 

[Pokette]

well alrighty then!
a bunch of 10 degree fixes and i will be into the green all the time!

 

[Steve Pierce]

Here is some testing Jerry Burr did on his O-200. I don't think he had the same results. http://www.shortwingpipers.org/foru...ature-Probe-Blast-Tubes&highlight=temperature

 

[bowhunter]

I have always used the blast tube for cooling on my 0-200 (J-3 w/ pressure cowling). A discussion on this site got me second guessing the effectiveness of this method of cooling. I have noticed that my oil pressure goes up and down with the temp. as you would expect it to, with or without the blast tube cooling. I can see how the cool air from the tube could trick your temp at the screen, but can't figure out how it can change your oil pressure if it is only cooling the bulb. Am I missing something here?

 

[fobjob]

I went from 390 + OAT=CHT down to 305+ OAT= CHT in small increments. Now, I don't eat up cylinders, and the suction side pressure went from +2.8 inches down to 0 inches. So, usually, the problem is getting rid of the heated, low pressure air, or you are dumping cool high pressure air into the low pressure side without it going past the cylinder fins, hence my question about any open area down the front of the motor, bypassing the cylinder fins. :-?

 

[Pokette]

I'm not really sure what your question is, but... by increasing the egress area at the bottom of the cowling you are reducing the pressure and drawing more air over the fins.

 

[btracy]

Now that your plane is behaving you need to make it to the Ohio bush plane fly-in on your way to East TN.

 

[NimpoCub]

I just did a few mods to my lower cowl to fit a new mufflerless crossover exhaust system (from Vetterman) and made quite a difference.
(0320B from Bart)

An aside: My old Piper exhaust (with bail intact) would allow my new engine to spin up to 2650 RPM, and the new system now spins up to 2800. It makes a NOTICEABLE diff in TO performance! Neighbor has timed my TO's in the past @ 12-13 sec's, but hasn't timed the "new & improved" yet, but I notice a diff! (I think about 100RPM more static.)

Back on topic: I added a 2" lip to the existing 1" lip @ the bottom of the cowl (like Pokette), and it dropped my 'cruise' cyl temp by almost 10* C. Then, on advice of Scott Perry (Hood River guy) I added 'ramps' in front of the # 1&2 cyl's, which effectively warms the front cyl's and cools the rears, my cyl temp (#4) by another 10+* C.

So, my #4 cyl temp changed from about 430* F to about 390* F. in level cruise. In a long climb it had been to about 480* F, now it only gets to about 440. I think read somewhere that the absolute top limit is 500.
We're much happier now.

 

[Tim]

Nimpo, what brand of temp. instrument and probes are you using

 

[fobjob]

Nimpo, drill about 10 1/4 inch holes in your ramps, and the front cylinder CHT's will drop down, and the rear CHT's should stay the same. :-?

 

[NimpoCub]

The CHT is the original Piper guage, I think.
The advice came from Scott, who has probes in all 4 cyl's, (A CC rebuild) and he said the ramps effectively evened out the temps. I only have the sensor on the #4 cyl (around the spark plug thingie).

I have the probe sensors & guages for all 4 cyl's, (bought a couple years ago) but didn't install them as it was too much "stuff" (clutter). Maybe I should do a temp. install to check everything, then put 'em back on the shelf.

Think I NEED holes in the ramps/deflectors?? Seems like it would be pretty chilly right out there in front.

 

[fobjob]

Well, there IS a lot of difference between our two climates....

 

[SammyQ2]

Oil temps

TCM says the max temperature is 225 and I am above that so I think it is a problem. My POH says max temperature is 240 and so far I have not heard why my POH is different than what TCM says.

No worries John

I also wondered about the discrepancy between the TCM TCDS and the POH. I talked to a TCM tech rep and he told me the TCDS is old, old, old, and has not been updated, in reference to the oil. He said when the data sheet was written, 225 was the maximum that the current oils could handle. Now that better oil is the standard throughout the industry, the new limit is 240. They just haven't updated the TCDS.

Sam.

 

[AntiCub]

I don't have easy access to a 150 here, but if you have one at your airport you might see if a cool air blast tube is directed at the oil screen housing.

Jim
O-200 powered PA18 replica under construction

My 150 had a channel under the crankcase that was part of the baffling, with a pair of oval holes in the cowling just below the spinner. This pushed cool air along the underside of the engine then directly onto the oil sump. never had trouble with high oil temps, in fact I typically had the opposite problem, with temps never getting above about 150F.

Phil

 

[cubdriver2]

My pa11 and J4 both have the same lower baffling that I thing helps pull heat away from the case. My J4 is a -12 with a oil filter and the Tempest vacuum pump cooling shroud on the oil filter is good for a 10F drop in temp. Spruce part # 10-23965.

Glenn