The International Cessna^® 170 Association

I put in the new baffle last fall at the time I did a top overhaul. The old ones were junkie and had a lot of extra holes and cracks. I had replaced the original temp gauge with a Scott about 10 years ago because it stopped working all together and tested it few years back because of continued high temps hitting redline during climb and hot weather flying. Since the new baffles were installed I can't get it above 150 degrees. I'm about ready to change oil so now would be a good time to test the gauge. Just wondering if 100 degrees is a normal drop because of the baffles.

Larry

That seems to me to be pretty cool for what is usually considered a relatively hot running engine installation. Cessna 170s are rather known for hot running rather than cool running. Most if the oil cooling is apparently predicated on the cooling of the oil returning to the oil sump through the push rod tubes, and this requires the inter cylinder baffles to be in good condition and properly installed. On some seaplane conversions an oil cooler was an aftermarket add on.to help keep the oil temperatures within limits due to the extended high power operation in getting off of the water and climbing with the drag of the floats.

Larry as BL has said a 100 degree drop or oil running at 150 is pretty unheard of though not impossible. You are correct in suspecting your oil gauge. Check it and if it is working properly, take pleasure in knowing you have done something many have wanted to do but few have been successful. in doing. For the record, what year 170 do you have and what size is the lip on the bottom of the cowl?

I have the s/n 1 set of Airforms baffles for the airbox-type baffles on my C-170A. I usually see 200°±F on the digital oil temp gauge. 150°±F is too cool in summer conditions.

Click on pictures to enlarge

Well, I drained the oil and pulled the bulb out of the case and stuck in a cup of boiling water. Temp got to 150 and stopped, so I will get a new gauge. Even with the faulty gage I can tell it is running cooler than the 240+it was running. I can touch the dip stick after shutdown without burning my hand. Bruce, I have a 48 with a 3 inch lip.

Larry

Larry Holtz wrote:Well, I drained the oil and pulled the bulb out of the case and stuck in a cup of boiling water. Temp got to 150 and stopped, so I will get a new gauge. Even with the faulty gage I can tell it is running cooler than the 240+it was running. I can touch the dip stick after shutdown without burning my hand. Bruce, I have a 48 with a 3 inch lip.

Larry

This discovery begs the question..... What WERE the PREVIOUS temps achieved?

(An inexpensive method to test oil temp gauges is to use a $5 BBQ (14-inch long probe) temperature gauge (mine came from Academy) stuck down the dipstick tube immediately after shutdown, and comparing to current indication in the cockpit.)

So, how many $5 BBQ temp gauges does it take to get the correct temp? One can't be trusted by itself, with two, which one is correct?, with three, do you just average? Or, when you buy the thing do you look at all of them in stock and pick one that reads like most of the others? I've always wondered about that when I buy a thermometer.

I got a PM asking about baffles in front of #5 and #6 cylinders. I think they are needed to keep #5 and #6 from cooling too much. My Airforms baffles have them but I do not have any pictures of them. What I do have is pictures of older C-172 front baffles to give an idea of what I am talking about. I don't know if this design is the best or not.

Click on picture to enlarge

Richard, those baffles are the newer (relatively speaking) style as my 172 doesn't have the front parts of those - I can see where it would cause the air to be directed DOWN through the cylinder fins on the front cylinders better which would also lead to less air sneaking by and missing the rear jugs. I plan to someday put the newer style on my plane for that reason, but it's something that I'm not in a huge hurry on. If some parts fell in my lap then I'd probably get around to it, that kind of thing.

hilltop170 wrote:So, how many $5 BBQ temp gauges does it take to get the correct temp? One can't be trusted by itself, with two, which one is correct?, with three, do you just average? Or, when you buy the thing do you look at all of them in stock and pick one that reads like most of the others? I've always wondered about that when I buy a thermometer.

I stand corrected....Academy only charges $3.99 for it.
http://www.academy.com/webapp/wcs/store ... =563837867

Sears also sells a 12" long thermometer, for about $6. They are commonly known as "candy" or "deep fry" long-probe thermometers.
The chineese tool store also sells them. They're good enough for this purpose.

In my opinion, ...not attempting to certify anything as an instrument shop....merely attempting to determine if a cheap cockpit gauge is anywhere near correct...... It's a simple matter to pick out the BBQ gauge which seems to indicate room temperature (one can compare the dozen or so sold by the store with each other), ...then arriving at home one can dip it into boiling water to see if it's near 210-F.... then go out and stick it down the dipstick tube.....thereby avoiding the messy and more complicated matter of removal of the aircraft instrument merely to see if it's a HUNDRED degrees WRONG...such as the above-mentioned matter.

Find one you like....take it home.....this is not rockette science.....

But George why would Larry want to do this AFTER he knows the gauge is bad.

gahorn wrote:I stand corrected....Academy only charges $3.99 for it.
http://www.academy.com/webapp/wcs/store ... =563837867

George-
Well, in that case, just buy a handfull!

hilltop170 wrote:I got a PM asking about baffles in front of #5 and #6 cylinders. I think they are needed to keep #5 and #6 from cooling too much. My Airforms baffles have them but I do not have any pictures of them.

Well, isn't that interesting. The Airforms baffles that I bought recently don't have the vertical pieces in front of #5 and #6.

sfarringer wrote:

hilltop170 wrote:I got a PM asking about baffles in front of #5 and #6 cylinders. I think they are needed to keep #5 and #6 from cooling too much. My Airforms baffles have them but I do not have any pictures of them.

Well, isn't that interesting. The Airforms baffles that I bought recently don't have the vertical pieces in front of #5 and #6.

DSCN1242_cropped.jpg

Perhaps it's because the ragwing had different baffles entirely ...than the later 172 system.

When the front cyls run cold....they really foul/lead up the plugs, also. (Need hotter plugs and/or fine wires...but the best solution is to mfr front baffles, IMO.)

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Meanwhile...here's a comparison between the '53 and later 170-B model baffles...and the early 172 baffles. Notice the early 172 was identical to the B-model, until later serials...when front cylinder baffles were incorporated instead of the ones previously used:

gahorn wrote: Perhaps it's because the ragwing had different baffles entirely ...than the later 172 system.

Well, yes, that is certainly true.
Perhaps I misinterpreted Richard Pulley's earlier post. I thought he said that his Airforms baffles for his 170A came with the upright pieces in front of the cylinders, and that he was attaching pictures of the 172 baffles to get the idea of the upright pieces across, since he had no pictures of the Airforms baffles in front of the cylinders on his 170A.

I will certainly be adding the upright pieces when I install mine (my current old wore-out baffles have had them for years).