Where does the oil temp probe go?

[hungstart]

In my just acquired 170 I just put a F&M oil filter adapter in my O-300D I noticed that the oil temp. probe was not in the oil screen as it is in this pic, but in the cover on the acc. case just to the left of the oil screen, the plug that has the safety wire as in the above pic. My question is should I move it back to the oil filter adapter or leave it in the other position?

Rick
N170MB

[GAHorn]

Rick, that other "cover" is the scavenge screen, which is an exceptionally coarse screen oft described to be capable of catching parts large enough to have the part numbers still on them.

It is not where the mfr intended the oil temp to be measured.

You should check your documentation/logbooks to see if there's any approval for that installation, and if there is....then you can leave it alone and be legal. (But I doubt you'll find anything approving it since the engine mfr intended the inlet temp to be measured ...not the scavenge temp.)

Meanwhile, if you read the STC paperwork of the F&M Enterprises you'll find their instructions, "item IX" will tell you to reinstall the probe in the end of their adaptor. To remain true to the approved method of installation, that's the only place the probe may be. Any other location is simply not approved, per the STC.

Also, for your information, the original location is intended to measure the "inlet" oil temperature which is at the exit-point of the oil pump. That large scavenge screen location is the oil pump pick-up point, not the oil "inlet".

[hungstart]

I remember now looking in the overhaul manual and seeing that it was the scavenge screen. I'm going to move it over to the F&M adapter. My question is what went in the hole that is in the scavenge screen that normally has the plug in the end of it that is now in my F&M adapter? I will ask the previous owner if he moved it to that position for a reason.

Rick
N170MB

[GAHorn]

Ordinarily the scavenge screen was safetied with a brass plug.

[hungstart]

Ordinarily the scavenge screen was safetied with a brass plug.

Duh, I understand that, but why was a plug installed there in the first place? Usually plugs are installed in locations like that because there are other sensors that were or could be installed there, possibly for testing during buildup, etc. I was just wondering if anyone knew what originally went there.

Rick
N170MB

[cessna170bdriver]

You should check your documentation/logbooks to see if there's any approval for that installation, and if there is....then you can leave it alone and be legal. (But I doubt you'll find anything approving it since the engine mfr intended the inlet temp to be measured ...not the scavenge temp.)

Meanwhile, if you read the STC paperwork of the F&M Enterprises you'll find their instructions, "item IX" will tell you to reinstall the probe in the end of their adaptor. To remain true to the approved method of installation, that's the only place the probe may be. Any other location is simply not approved, per the STC.

Also, for your information, the original location is intended to measure the "inlet" oil temperature which is at the exit-point of the oil pump. That large scavenge screen location is the oil pump pick-up point, not the oil "inlet".

The only precedence I can think of for installing the temp probe in the pickup screen is if the Cessna oil filter adapter kit is installed. The Cessna kit, unlike the F&M kit, has no allowance for installing the oil temp probe, so you must install it in the pickup screen. I did notice about a 15-20 degree drop in INDICATED oil temp in this configuration. I don't know how much of that was a bit of extra cooling due to the presence of the filter, or difference in temperature between the pickup screen and pressure screen. I suspect a bit of both.

Miles

[hungstart]

You should check your documentation/logbooks to see if there's any approval for that installation, and if there is....then you can leave it alone and be legal. (But I doubt you'll find anything approving it since the engine mfr intended the inlet temp to be measured ...not the scavenge temp.)

Meanwhile, if you read the STC paperwork of the F&M Enterprises you'll find their instructions, "item IX" will tell you to reinstall the probe in the end of their adaptor. To remain true to the approved method of installation, that's the only place the probe may be. Any other location is simply not approved, per the STC.

Also, for your information, the original location is intended to measure the "inlet" oil temperature which is at the exit-point of the oil pump. That large scavenge screen location is the oil pump pick-up point, not the oil "inlet".

The only precedence I can think of for installing the temp probe in the pickup screen is if the Cessna oil filter adapter kit is installed. The Cessna kit, unlike the F&M kit, has no allowance for installing the oil temp probe, so you must install it in the pickup screen. I did notice about a 15-20 degree drop in INDICATED oil temp in this configuration. I don't know how much of that was a bit of extra cooling due to the presence of the filter, or difference in temperature between the pickup screen and pressure screen. I suspect a bit of both.

Miles

That doesn't bode well for my oil temp when I move it back to the F&M adapter. I have been running about 210-220 F at the inlet screen. I think I need to validate the oil temp probe, going to have to haul the hot plate back out to the hangar. Didn't think I would need it out there anymore after I put the microwave out there.

Rick

[GAHorn]

I had a calibrated oil temp gauge recently installed when I made the F&M installation. I saw no difference in temperature indications whatsoever, before/after.

Remember, the red-line oil temp is 240-F when using straight-wt SAE 50.

Although the engine TCDS does not specify/approve increased oil temp when substituting multi-grade oils, I suspect it's merely because they did not test it. Those oils are not restricted in any other certified engine that I know of.

[Bruce Fenstermacher]

Read Mile's post again. He said you have to move it if you use the CESSNA filter adapter and that is when he saw the different temperatures. Had nothing to do with the F&M adapter.

[hungstart]

I had a calibrated oil temp gauge recently installed when I made the F&M installation. I saw no difference in temperature indications whatsoever, before/after.

Remember, the red-line oil temp is 240-F when using straight-wt SAE 50.

Although the engine TCDS does not specify/approve increased oil temp when substituting multi-grade oils, I suspect it's merely because they did not test it. Those oils are not restricted in any other certified engine that I know of.

Did you clock yours a little CCW looking from the rear? I did with mine for clearance from the engine mount and access to the filter.

Rick

[hungstart]

Read Mile's post again. He said you have to move it if you use the CESSNA filter adapter and that is when he saw the different temperatures. Had nothing to do with the F&M adapter.

Yes, he said he saw a drop in temp when his was in the scavange screen, that is where my probe is now. It stands to reason that if I move it back over to the pressure screen that I will see a rise in temps, therefore it does not bode well for me when I move it to the pressure screen position. I should see a temp rise is all else holds true.

Rick

[hungstart]

I had a calibrated oil temp gauge recently installed when I made the F&M installation. I saw no difference in temperature indications whatsoever, before/after.

Remember, the red-line oil temp is 240-F when using straight-wt SAE 50.

Although the engine TCDS does not specify/approve increased oil temp when substituting multi-grade oils, I suspect it's merely because they did not test it. Those oils are not restricted in any other certified engine that I know of.

Do you see higher oil usage when oil temp goes above 215F? Gary (the past owner) said that he saw higher oil consumption when it ran over 215 in the summer with 100W.

Rick

[Bruce Fenstermacher]

Read Mile's post again. He said you have to move it if you use the CESSNA filter adapter and that is when he saw the different temperatures. Had nothing to do with the F&M adapter.

Yes, he said he saw a drop in temp when his was in the scavange screen, that is where my probe is now. It stands to reason that if I move it back over to the pressure screen that I will see a rise in temps, therefore it does not bode well for me when I move it to the pressure screen position. I should see a temp rise is all else holds true.

Rick

Sorry Rick I'm following you now.

[GAHorn]

I did not have to "clock" my FM adaptor because I utilized a 45-degree fitting on my gascolator-to-carb fuel line. (My fuel line was over 5-years old and so I had a new one mfr'd which included a 45-degree fitting on one end of the hose. I did so without thinking of the additional cost of a 45-degree fitting on a mfr'd hose. That wa$ expen$ive. ($127 vs $37)
Don't do that. Simpler/Cheaper to install a common 45-degree AN fitting on a gascolator.)

My oil usage did not change since my oil temps never changed. (Your question implies that we make some "choice" as to what temps we run our oil. The only choice we make with that regard is operating techniques.)

My oil consumption used to be 1 quart every 4 or 5 hours until I quit maintaining a 7 to 8 quart level on the dipstick. When I allowed it to drop to regularly maintaining 6-quarts on the dipstick, my consumption dropped to 1-quart every 12-15 hours. I consider oil to be the cheap-part of flying, just behind tires,...since I operate primarily on grass. My current set of tires (Aero Classics from Desser) has 8 years and over 500 landings on them, and I expect them to last another 2 or 3 years depending on how many times I land at Austin Bergstrom where I have 1-1/2 miles to taxy every takeoff.

Regarding oil useage: I used to own a Baron with TCM IO-470 engines, and I ran the right engine on AeroShell 15W50 and the left on 100W (SAE50) as an experiment for over two years. The right engine would use no oil for about 5 hours then would begin to consume oil at the rate of about 1 quart every 5-7 hours until 25-hours. (Both engines had screens so oil was changed at 25.) It would show fast oil-pressure at start-up regardless of OAT. The engine required a top ovhl at 600 hrs. The left engine always consumed about 1-qt every 7-9 hours, was slow to build pressure when cold and would indicate 100 psi (red line) until it warmed up (usually right after takeoff. I typically had a 3-4 minute taxying warmup prior to takeoff regardless of OAT.) That engine, although slightly higher-time SOH, never req'd cylinder work. Both engines were TW Smith remans with channel-chrome cyls. Not a fully-scientific experiment admittedly, but it convinced me to use straight-wt oils and pre-heat rather than rely upon multi-wts whenever possible.

n632cm.jpg

[hungstart]

I did not have to "clock" my FM adaptor because I utilized a 45-degree fitting on my gascolator-to-carb fuel line. (My fuel line was over 5-years old and so I had a new one mfr'd which included a 45-degree fitting on one end of the hose. I did so without thinking of the additional cost of a 45-degree fitting on a mfr'd hose. That wa$ expen$ive. ($127 vs $37)
Don't do that. Simpler/Cheaper to install a common 45-degree AN fitting on a gascolator.)

My oil usage did not change since my oil temps never changed. (Your question implies that we make some "choice" as to what temps we run our oil. The only choice we make with that regard is operating techniques.)

My oil consumption used to be 1 quart every 4 or 5 hours until I quit maintaining a 7 to 8 quart level on the dipstick. When I allowed it to drop to regularly maintaining 6-quarts on the dipstick, my consumption dropped to 1-quart every 12-15 hours. I consider oil to be the cheap-part of flying, just behind tires,...since I operate primarily on grass. My current set of tires (Aero Classics from Desser) has 8 years and over 500 landings on them, and I expect them to last another 2 or 3 years depending on how many times I land at Austin Bergstrom where I have 1-1/2 miles to taxy every takeoff.

As you say, I do make a "choice" of where to run my oil temps in the operating procedures I use, i.e., if the oil temps heading up in climb I increase airspeed and slow the rate of climb, if it is heading a little higher in cruise then I want I reduce power a small amount or climb to cooler air. I make "choices" and judgements every time I fly as we all do.
You have your oil filter heading straight down? On my O-300D when I put it straight down, which is the way I would have preferred it, I had below the minimum allowed clearance on the engine mount strut, therefore I had to clock it a little bit CCW to get above the minimum clearance. If you look at it from the rear it is at about 4:30 to 5:00 o'clock.
From what I'm hearing on oil consumption if you run at 6 quarts it is lower than when you run at the normal "full" level. I will do a search on "oil consumption" and see what has been discussed previously rather than diverting this thread onto another topic. You have to understand this is a new aircraft/engine combination for me and every aircraft has it's idiosyncrasies’ and I'm going to ask a lot of questions. I just moved up from a C-140.

Rick
N170MB