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#1
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Cherokee 140 Oil Temp Creeping Up
I have owned this Cherokee 140 since 1994. I have logged over 1000 hours
in it through the original and the now installed overhauled engine. Oil temps were usually at 180 degrees (both engines)when OATs were between 50-80 degrees or so. It would read 1 needle mark higher when it got to be 95+ outside. In the last 150 hours or so, it has been drifting up and is now reading about 2 needle marks above 180 degrees (200 degrees or so?). I replaced the oil cooler because of age. It was cheaper to replace it with a new PMA'd unit than to have it checked/cleaned. I swapped the Vernatherm. No difference. Do the gauges/senders drift off with age. I am going to test the sender/gauge with hot water and a thermometer. Once it gets to that mark, it seems to stabilize. Baffles are all in good shape. What else causes temps to drift high? I know that shifting main bearings can cause this, but I doubt the engine would continue to operate for this long if this were the case. I do wonder though because the cold oil pressure is right at redline on takeoff. After 5 minutes it goes back down into the middle of the green. Thoughts/theories? Thanks, Mike |
#2
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Cherokee 140 Oil Temp Creeping Up
Mike, was the oil filter adapter also changed or was its vernatherm seat
ground when the vernatherm was changed? If the new vernatherm doesn't fit the seat in the oil filter adapter, the vernatherm fix would not be complete. When my vernatherm was changed and the seat ground, it fixed a hot oil problem in my Archer. -- Best Regards, Mike. http://flickr.com/photos/mikenoel/ "Mike Spera" wrote in message m... I have owned this Cherokee 140 since 1994. I have logged over 1000 hours in it through the original and the now installed overhauled engine. Oil temps were usually at 180 degrees (both engines)when OATs were between 50-80 degrees or so. It would read 1 needle mark higher when it got to be 95+ outside. In the last 150 hours or so, it has been drifting up and is now reading about 2 needle marks above 180 degrees (200 degrees or so?). I replaced the oil cooler because of age. It was cheaper to replace it with a new PMA'd unit than to have it checked/cleaned. I swapped the Vernatherm. No difference. Do the gauges/senders drift off with age. I am going to test the sender/gauge with hot water and a thermometer. Once it gets to that mark, it seems to stabilize. Baffles are all in good shape. What else causes temps to drift high? I know that shifting main bearings can cause this, but I doubt the engine would continue to operate for this long if this were the case. I do wonder though because the cold oil pressure is right at redline on takeoff. After 5 minutes it goes back down into the middle of the green. Thoughts/theories? Thanks, Mike |
#3
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Cherokee 140 Oil Temp Creeping Up
On Sun, 07 Jun 2009 16:31:00 -0500, Mike Spera
wrote: What else causes temps to drift high? I know that shifting main bearings can cause this, but I doubt the engine would continue to operate for this long if this were the case. I do wonder though because the cold oil pressure is right at redline on takeoff. After 5 minutes it goes back down into the middle of the green. Thoughts/theories? After you've checked the usual suspects, I'd also check the nose bearing. I had very similar symptoms in a Lyco IO360A1A that was due to leakage at that point. However, after stabilization, the my oil pressure would also be slightly low (still well within the green, but closer to the lower margin). --ron |
#4
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Cherokee 140 Oil Temp Creeping Up
Mike Spera wrote:
I have owned this Cherokee 140 since 1994. I have logged over 1000 hours in it through the original and the now installed overhauled engine. Oil temps were usually at 180 degrees (both engines)when OATs were between 50-80 degrees or so. It would read 1 needle mark higher when it got to be 95+ outside. In the last 150 hours or so, it has been drifting up and is now reading about 2 needle marks above 180 degrees (200 degrees or so?). I replaced the oil cooler because of age. It was cheaper to replace it with a new PMA'd unit than to have it checked/cleaned. I swapped the Vernatherm. No difference. Do the gauges/senders drift off with age. I am going to test the sender/gauge with hot water and a thermometer. Once it gets to that mark, it seems to stabilize. Baffles are all in good shape. What else causes temps to drift high? I know that shifting main bearings can cause this, but I doubt the engine would continue to operate for this long if this were the case. I do wonder though because the cold oil pressure is right at redline on takeoff. After 5 minutes it goes back down into the middle of the green. Thoughts/theories? Thanks, Mike My oil temp always read low and I took the aircraft temp gage probe and a multimeter that I had that had a temp probe and heated a small tin can of oil to 180F, put both probes in the oil, and then marked the aircraft gage so I would know exactly where 180F was. The O-360 oil was reading lower than 180 always. -- Regards, Ross C-172F 180HP Sold KSWI |
#5
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Cherokee 140 Oil Temp Creeping Up
High oil temps can also be caused by excessive blowby. Does the oil
stay clean & is the consumption normal? |
#6
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Cherokee 140 Oil Temp Creeping Up
In article ,
Ross wrote: Mike Spera wrote: I have owned this Cherokee 140 since 1994. I have logged over 1000 hours in it through the original and the now installed overhauled engine. Oil temps were usually at 180 degrees (both engines)when OATs were between 50-80 degrees or so. It would read 1 needle mark higher when it got to be 95+ outside. In the last 150 hours or so, it has been drifting up and is now reading about 2 needle marks above 180 degrees (200 degrees or so?). I replaced the oil cooler because of age. It was cheaper to replace it with a new PMA'd unit than to have it checked/cleaned. I swapped the Vernatherm. No difference. Do the gauges/senders drift off with age. I am going to test the sender/gauge with hot water and a thermometer. Once it gets to that mark, it seems to stabilize. Baffles are all in good shape. What else causes temps to drift high? I know that shifting main bearings can cause this, but I doubt the engine would continue to operate for this long if this were the case. I do wonder though because the cold oil pressure is right at redline on takeoff. After 5 minutes it goes back down into the middle of the green. Thoughts/theories? Thanks, Mike My oil temp always read low and I took the aircraft temp gage probe and a multimeter that I had that had a temp probe and heated a small tin can of oil to 180F, put both probes in the oil, and then marked the aircraft gage so I would know exactly where 180F was. The O-360 oil was reading lower than 180 always. Are the baffle seals in good condition, and curved forward when the cowl is in place? Also, check the intercylinder baffles, to make sure that they are properly installed. Any discrepancies in those areas will cause the cooling air to bypass the cylinders and lead to higher temperatures. Most production planes have very inefficient cooling, anyhow. -- Remove _'s from email address to talk to me. |
#7
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Cherokee 140 Oil Temp Creeping Up
I was seeing oil temps in the red, oil pressure ok but I still landed
immediately. Turns out the wire on the oil temp unit on top of the engine (don't know what that is) was loose. Correct wrench to remove the nut, washer and wire. Clean everything. Replace. Tighten correctly (yes, an A&P was there - next door hangar). No more problem with oil temps. The easiest & cheapest fix I've ever had. |
#8
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Cherokee 140 Oil Temp Creeping Up
Orval Fairbairn wrote:
In article , Ross wrote: Mike Spera wrote: I have owned this Cherokee 140 since 1994. I have logged over 1000 hours in it through the original and the now installed overhauled engine. Oil temps were usually at 180 degrees (both engines)when OATs were between 50-80 degrees or so. It would read 1 needle mark higher when it got to be 95+ outside. In the last 150 hours or so, it has been drifting up and is now reading about 2 needle marks above 180 degrees (200 degrees or so?). I replaced the oil cooler because of age. It was cheaper to replace it with a new PMA'd unit than to have it checked/cleaned. I swapped the Vernatherm. No difference. Do the gauges/senders drift off with age. I am going to test the sender/gauge with hot water and a thermometer. Once it gets to that mark, it seems to stabilize. Baffles are all in good shape. What else causes temps to drift high? I know that shifting main bearings can cause this, but I doubt the engine would continue to operate for this long if this were the case. I do wonder though because the cold oil pressure is right at redline on takeoff. After 5 minutes it goes back down into the middle of the green. Thoughts/theories? Thanks, Mike My oil temp always read low and I took the aircraft temp gage probe and a multimeter that I had that had a temp probe and heated a small tin can of oil to 180F, put both probes in the oil, and then marked the aircraft gage so I would know exactly where 180F was. The O-360 oil was reading lower than 180 always. Are the baffle seals in good condition, and curved forward when the cowl is in place? Also, check the intercylinder baffles, to make sure that they are properly installed. Any discrepancies in those areas will cause the cooling air to bypass the cylinders and lead to higher temperatures. Most production planes have very inefficient cooling, anyhow. Not sure if you are responding to the OP or me, but my temperatures (when I had the plane) were always low. And, yes the baffling was correct. I am sure there were some "leaky" places. -- Regards, Ross C-172F 180HP Sold KSWI |
#9
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Cherokee 140 Oil Temp Creeping Up
On Jun 9, 9:06 am, Blanche wrote:
I was seeing oil temps in the red, oil pressure ok but I still landed immediately. Turns out the wire on the oil temp unit on top of the engine (don't know what that is) was loose. Correct wrench to remove the nut, washer and wire. Clean everything. Replace. Tighten correctly (yes, an A&P was there - next door hangar). No more problem with oil temps. The easiest & cheapest fix I've ever had. Rising oil temps with electric gauges can sometimes be blamed on a poor engine grounding strap or alternator ground cable. If there's resistance between the engine or alternator and the airframe, the electricity looks for other paths and can find a small one via the oil temp sensor (which is screwed into the oil filter adapter and is thereby grounded), through the sensor and up to the gauge, through the gauge to the bus. The electron flow is in the same direction as the gauge's normal flwo from the sensor and so any additional flow will cause a higher gauge reading. I would suspect a ground connection that is losing its effectiveness as it heats up. Back of the alternator, ground strap at the engine or even on the mount, alternator ground at the firewall. Clean and tighten them. And then run a small wire from some small bolt on the engine accessory cover near the temp sensor, through the firewall and to the gauge backplate. That's a Cessna fix for the issue. Dan |
#10
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Cheap Fixes. Was: Cherokee 140 Oil Temp Creeping Up
thread creep
Blanche, your story reminded me of an incident I had a couple years ago. I flew from Jeffco, Denver (BJC) to Centennial, Denver (APA) to have a mechanic look at something. I parked in front of his hangar and shut down. the prop stopped vertical, so, as was my custom at the time, I cleared the area and blipped the starter to move it. Click. Click. No prop movement. The starter was fine at Jeffco and inoperative at Centennial. It turned out that the lug on the high current lead at the starter motor had broken completely free from the wire. Cheapest fix I've ever had. What are the chances of discovering the problem while sitting right in front of the mechanic's hangar! Jon /thread creep "Blanche" wrote in message ... I was seeing oil temps in the red, oil pressure ok but I still landed immediately. Turns out the wire on the oil temp unit on top of the engine (don't know what that is) was loose. Correct wrench to remove the nut, washer and wire. Clean everything. Replace. Tighten correctly (yes, an A&P was there - next door hangar). No more problem with oil temps. The easiest & cheapest fix I've ever had. |
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