Oil cooler
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
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Gayle Huff
- Posts: 1
- Joined: Mon Jul 22, 2002 6:10 pm
Oil cooler
I own a 1950 C-170A with a C145 engine. I am wanting to install an oil cooler to help with higher engine temps when pulling a glider. I would appreciate any assisstance that could be given as to accomplishing this. There seem to be no STC's for adding an oil cooler. Does anyone know of someone who has done so, maybe using a 337? I would appreciate your help. Gayle H.
I am working on a personal project to do exactly that now. I don't know how long it will take. The Swift method is ineffective, according to the owners, because their oil source and return is from two areas equal in pressure. I intend to utilize the spin-on filter adaptor that FM (El Reno) makes, and adapt it to the cooler prior to filtering the oil.
oil cooler
The following is part of a thread on another website concerning adding an oil cooler to the O-300D:
"reguards (sic) oil temp: on my 0-300 which gets hot in arizona desert temps of 110 degree. I added a stewart warner oil cooler, and a remote oil filter. the cooler is mounted on the rt bafle (sic), the filter on the right firewall. my temps on takeoff at 1000 ft , ot temp, 110 degrees. temp guage (sic) reads middle of green... yea! with good design and proper construction, faa field aproval (sic) is easy..use parts catalog for 172 float plans"
"reguards (sic) oil temp: on my 0-300 which gets hot in arizona desert temps of 110 degree. I added a stewart warner oil cooler, and a remote oil filter. the cooler is mounted on the rt bafle (sic), the filter on the right firewall. my temps on takeoff at 1000 ft , ot temp, 110 degrees. temp guage (sic) reads middle of green... yea! with good design and proper construction, faa field aproval (sic) is easy..use parts catalog for 172 float plans"
Gary
oil cooler
I have installed an oil filter cooler from jc whitney Part number 81zx4694y. this is a finned heat sink that slips over the filter, the picture on their web site explains this pretty good. this has lowered my oil temp from 205-210 to 185-190. I had plans for adding a shroud and scat tube, like the rapco system for vacuum pumps, but I am happy enough at the 185-190 temp. I considered this to be a minor mod so no 337 required. your local a&p / faa may call this a major change and require more paper work.
I've subsequently decided against developing an oil cooler installation kit for our airplanes. I made the decision based on several discoveries.
1. This engine was specifically designed to avoid external oil lines or coolers. The pushrod tubes are a return path for oil pumped to the rockers and serve as an oil cooler on engines with healthy cooling baffles. (Check the inter-cylinder baffles immediately between and below the cylinders, as well as the rest of the cooling baffles for condition and security. There must be a proper pressure-differential from above and below the cylinders.)
2. There is no reason a healthy engine will suddenly start experiencing high oil temps. This engine was designed for temperate to sub-tropical climes and should not have an oil temperature problem provided all is in good condition.
3. A major cause of high oil temps (other than faulty baffles) is leaking exhaust-flange gaskets. This causes hot exhaust to blow on the pushrod tubes which heats up the return oil. (That was my own problem. I replaced the gaskets and risers (the short ex. stacks that bolt to the cyl) because my riser flanges were warped and not sealing completely. After I took care of that, my pushrod tubes remain clear of hot exhaust stains.)
The coupling that mates the riser to the mufflers can also be a source of exhaust leaks that blow on the tubes. I fixed that with muffler tape before re-installing the couplings.
4. The other most common cause is faulty oil temp gauge. Even new gauges sometimes experience failure in a short time. Go down to Academy or some other outdoor barbeque supplier and purchase a barbeque thermometer that has a long probe. Academy sells them with 18" probes for $3.99. Fly your airplane til it seems to get hot, land without much cooling, shut down and stick that probe in your oil thru the dipstick fitting. When I did that I found my cockpit gauge was showing 220-240 degrees F, but the thermometer showed only 180! I couldn't believe it, so I checked the thermometer in boiling water. It was exactly correct. I removed my gauge, took it to the instrument shop, who confirmed it to be reading almost 60 degees high, even though it was only 75-100 hours old. I had purchased it new less than 16 mos ago.
Remember, if you use SAE 50 straight-weight oil your oil temp redline moves up from 225 to 240 degrees F. per the type certificate data sheet. Oil temps near the redline are not a problem. Oil temps too LOW are a problem. (Swift owners have updraft cooling systems as standard and complain of too low oil temps. This is because their pushrod tubes are getting cold cowling inlet air directly upon them. They suffer from condensation and internal rust as the result. Be happy you have a 170.)
The automotive part from JC Whitney might seem like a good idea but it's not an approved aircraft part (regardless of whether or not you consider it a minor mod) and therefore will need some sort of approval, probably a Form 337, block 3 (field approval). It also likely reduces the clearance from surrounding parts/engine mounts stipulated in the filter STC and therefore will violate that STC. It definitely adds weight to the filter and vibratory stresses to the filter adaptor and accy case. (I like the idea actually, and thought about doing this some time ago. But ultimately I decided it would also absorb the heat from the engine compartment and might actually prevent the oil filter from dissipating it's heat. The killer for me was it's lack of approval from the filter STC, and the fact that I found the cause for my high oil temp readings and fixed them.)
(And before you jump me about using muffler tape,...I already investigated that and found that both Cessna and RAM do exactly the same thing with no objections from FAA.)
1. This engine was specifically designed to avoid external oil lines or coolers. The pushrod tubes are a return path for oil pumped to the rockers and serve as an oil cooler on engines with healthy cooling baffles. (Check the inter-cylinder baffles immediately between and below the cylinders, as well as the rest of the cooling baffles for condition and security. There must be a proper pressure-differential from above and below the cylinders.)
2. There is no reason a healthy engine will suddenly start experiencing high oil temps. This engine was designed for temperate to sub-tropical climes and should not have an oil temperature problem provided all is in good condition.
3. A major cause of high oil temps (other than faulty baffles) is leaking exhaust-flange gaskets. This causes hot exhaust to blow on the pushrod tubes which heats up the return oil. (That was my own problem. I replaced the gaskets and risers (the short ex. stacks that bolt to the cyl) because my riser flanges were warped and not sealing completely. After I took care of that, my pushrod tubes remain clear of hot exhaust stains.)
The coupling that mates the riser to the mufflers can also be a source of exhaust leaks that blow on the tubes. I fixed that with muffler tape before re-installing the couplings.
4. The other most common cause is faulty oil temp gauge. Even new gauges sometimes experience failure in a short time. Go down to Academy or some other outdoor barbeque supplier and purchase a barbeque thermometer that has a long probe. Academy sells them with 18" probes for $3.99. Fly your airplane til it seems to get hot, land without much cooling, shut down and stick that probe in your oil thru the dipstick fitting. When I did that I found my cockpit gauge was showing 220-240 degrees F, but the thermometer showed only 180! I couldn't believe it, so I checked the thermometer in boiling water. It was exactly correct. I removed my gauge, took it to the instrument shop, who confirmed it to be reading almost 60 degees high, even though it was only 75-100 hours old. I had purchased it new less than 16 mos ago.
Remember, if you use SAE 50 straight-weight oil your oil temp redline moves up from 225 to 240 degrees F. per the type certificate data sheet. Oil temps near the redline are not a problem. Oil temps too LOW are a problem. (Swift owners have updraft cooling systems as standard and complain of too low oil temps. This is because their pushrod tubes are getting cold cowling inlet air directly upon them. They suffer from condensation and internal rust as the result. Be happy you have a 170.)
The automotive part from JC Whitney might seem like a good idea but it's not an approved aircraft part (regardless of whether or not you consider it a minor mod) and therefore will need some sort of approval, probably a Form 337, block 3 (field approval). It also likely reduces the clearance from surrounding parts/engine mounts stipulated in the filter STC and therefore will violate that STC. It definitely adds weight to the filter and vibratory stresses to the filter adaptor and accy case. (I like the idea actually, and thought about doing this some time ago. But ultimately I decided it would also absorb the heat from the engine compartment and might actually prevent the oil filter from dissipating it's heat. The killer for me was it's lack of approval from the filter STC, and the fact that I found the cause for my high oil temp readings and fixed them.)
(And before you jump me about using muffler tape,...I already investigated that and found that both Cessna and RAM do exactly the same thing with no objections from FAA.)
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zero.one.victor
- Posts: 2271
- Joined: Tue Apr 23, 2002 12:11 am
Re: oil cooler
I looked in my JC Whitney catalog for these,couldn't find it. guess I'll check the website. What was the price?n3439d wrote:I have installed an oil filter cooler from jc whitney Part number 81zx4694y. this is a finned heat sink that slips over the filter, the picture on their web site explains this pretty good. this has lowered my oil temp from 205-210 to 185-190. I had plans for adding a shroud and scat tube, like the rapco system for vacuum pumps, but I am happy enough at the 185-190 temp. I considered this to be a minor mod so no 337 required. your local a&p / faa may call this a major change and require more paper work.
An old 170 News had an article by a member who fabricated a similar heat-sink for his spin-on filter,he said it worked great too. Another old 170 News has an article by a member who fabricated a shroud for the filter & ran a scat hose to it,like you describe. He claimed good results also.
Anybody have any experience with a seaplane lip? Contrary to what you're thinking,a seaplane lip is NOT what you get when you slip on a wet float & run your face into a dock piling!
I experimented with a seap-lane lip installation on my ragwing a few years ago. I fabricated a 2-1/2" lip that attached to the original 3/4" lip at the bottom of the lower cowl,where the cooling air comes out. This lip is supposed to speed up the air going by under the opening,thereby creating a low-pressure area which draws more air thru the engine for cooling purposes. I'd heard great things about this concept from a few people,but other than looking ugly and creating drag,I couldn't determine that it did much for my high oil temps so I abandoned the idea.I tested my oil temp guage & it's accurate within about 5 degrees. In hot conditions,I tend to run oil temps pretty close to the original redline (225),which I don't think is too good. This is using both Aeroshell W100 and Phillips XC20-50. Ideally,I think oil temps should be between 180 & 200 degrees. If the JC Whitney heat sink will help me achieve this,I'm all for it. Paperworked or not!
Eric
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Dave Clark
- Posts: 894
- Joined: Mon Apr 22, 2002 6:25 pm
Eric the "seaplane lip" works on most types of airplanes so it should work on the 170. I had a pretty wide lip on my cowl that came with the conversion and knowing the Lycoming ran a little cold I cut it way down before I repainted as it does add a bit of drag.
George you've brought up some very good points however we have a little known and less talked about mod in AZ to help the situation a lot. We open the air inlet just below the prop so that the oil pan gets a lot more air. I don't know of anyone getting any type of approval on it because I guess it's so unlikely to be noticed. It can be made much bigger but requires a new doubler be made and some riveting. For those who have temp problems I would suggest this mod after looking closely at the engine itself for the things you mentioned. It helps an amazing amount.
George you've brought up some very good points however we have a little known and less talked about mod in AZ to help the situation a lot. We open the air inlet just below the prop so that the oil pan gets a lot more air. I don't know of anyone getting any type of approval on it because I guess it's so unlikely to be noticed. It can be made much bigger but requires a new doubler be made and some riveting. For those who have temp problems I would suggest this mod after looking closely at the engine itself for the things you mentioned. It helps an amazing amount.
Dave
N92CP ("Clark's Plane")
1953 C-180
N92CP ("Clark's Plane")
1953 C-180
There was a very good article in Sport Aviation (EAA magazine) about a year or so ago surrounding the reconstruction of the Vickers Vimy and the engine cooling problems they suffered. They tried and tried to re-invent the wheel before someone pointed out to them that about 1930 it was discovered the way to increase engine cooling on an air-pressure-cooled engine is not to make the inlets larger...but to make the exits larger. (Roy LoPresti also uses the concept in his remakes of factory cowls on Mooney's etc.)
I would not encourage anyone to make unapproved (re-invent the wheel) mods to their airplanes and engines in the quest for lower oil temps on a C145/O300 engine. TCM field reps take on a "knowing" tone of voice and are not encouraging about these sort of mods. They explained to me that this engine is quite happy with it's lack of oil cooler and also point out that this engine takes it's oil temp at the pressure side of the pump...one of the hottest locations...not the exit side of an oil cooler like most other engines. They also stated that the oil temps at specific locations of this, and other, engines is considerable hotter than that indicated on our engines and...to quit worrying. There is no history of C145/O300 engines suffering any mechanical failures due to it's oil temps.
So I fixed my exhaust and quit worrying. (My oil temps here in hellish-Texas run 220-230 in the ambient 100+ degree summers and 200-210 in the shirt-sleeve-weather winters. Even on the occasional 20-degree F freezes we have here, it still runs around 200 in flight.) This is ordinary in a 170 according to TCM.
(As a side note, my oil pressures are 50-60 on an accurate gauge, even when the oil temp is indicating high.)
Remember, the multi-weight oils are not approved for temps above 225, only the straight wt. SAE 50 (100W) oils are.
I would not encourage anyone to make unapproved (re-invent the wheel) mods to their airplanes and engines in the quest for lower oil temps on a C145/O300 engine. TCM field reps take on a "knowing" tone of voice and are not encouraging about these sort of mods. They explained to me that this engine is quite happy with it's lack of oil cooler and also point out that this engine takes it's oil temp at the pressure side of the pump...one of the hottest locations...not the exit side of an oil cooler like most other engines. They also stated that the oil temps at specific locations of this, and other, engines is considerable hotter than that indicated on our engines and...to quit worrying. There is no history of C145/O300 engines suffering any mechanical failures due to it's oil temps.
So I fixed my exhaust and quit worrying. (My oil temps here in hellish-Texas run 220-230 in the ambient 100+ degree summers and 200-210 in the shirt-sleeve-weather winters. Even on the occasional 20-degree F freezes we have here, it still runs around 200 in flight.) This is ordinary in a 170 according to TCM.
(As a side note, my oil pressures are 50-60 on an accurate gauge, even when the oil temp is indicating high.)
Remember, the multi-weight oils are not approved for temps above 225, only the straight wt. SAE 50 (100W) oils are.
Re: Oil cooler
Gayle, the problem with the 170 will be the cylinder head temps more so than the oil temp. With the slow speeds used in glider towing, the CHT will get hot, make sure your baffling is good shape. I don't think an oil cooler will help all that much unless your making some really long tows.Gayle Huff wrote:I own a 1950 C-170A with a C145 engine. I am wanting to install an oil cooler to help with higher engine temps when pulling a glider. I would appreciate any assisstance that could be given as to accomplishing this. There seem to be no STC's for adding an oil cooler. Does anyone know of someone who has done so, maybe using a 337? I would appreciate your help. Gayle H.
Karl
oil cooler
I agree with the plan of taking care of the cause of the high oil temps, before adding extra methods to cool the oil. Knowing the cause of the problem is the first step to repairing it.
Since I have several items installed that slow my airspeed/cooling airflow below what cessna planned for at cruise I feel that I needed more cooling to compensate for the lower air flow. My cruise speed is 95mph at 2550 rpms, similar to a stock 170 in climb. I run the multi weight oils and have seen my oil temp into the red in climbs. My cyl temps also gets close to red line, but I have not found an easy solution for that. I do not have the knowledge to redesign the cowling and I don't have the money to pay an engineer.
ken
Since I have several items installed that slow my airspeed/cooling airflow below what cessna planned for at cruise I feel that I needed more cooling to compensate for the lower air flow. My cruise speed is 95mph at 2550 rpms, similar to a stock 170 in climb. I run the multi weight oils and have seen my oil temp into the red in climbs. My cyl temps also gets close to red line, but I have not found an easy solution for that. I do not have the knowledge to redesign the cowling and I don't have the money to pay an engineer.
ken
As an aside, ...I met a 150 operator (O200 engine using the same cyls as our airplanes) in McCamey, Texas (dry, hot, west-dusty-Texas) who had high oil temps. When we looked at his engine it was encrusted with caked on dirt that had been attracted to the oil tank, lower engine case, and pushrod tubes. We pressure-washed it and changed the oil and test-flew it. His oil temps dropped from 240+ to 200 area.
I'm sure within a month it was running hot again because when we post-flight inspected it for leaks the engine was absolutely coated with fresh engine oil. (Unknown time: SMOH.)
I'm sure within a month it was running hot again because when we post-flight inspected it for leaks the engine was absolutely coated with fresh engine oil. (Unknown time: SMOH.)
Oil cooler STC
Although the picture is from a C-140, this STC for an oil cooler is also approved for the C-170 according to Steve's Aircraft website. However, I noticed that the 170 is not listed on the FAA's website when looking up this STC number.
http://www.stevesaircraft.com/oilcooler.php
http://www.stevesaircraft.com/oilcooler.php
Last edited by n2582d on Sat Mar 08, 2008 8:31 pm, edited 1 time in total.
Gary
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Robert Eilers
- Posts: 652
- Joined: Sat May 08, 2004 12:33 am
My 1952 170B has, what is being described as, the Arizona mode. The oil pan inlet has been enlarged (nice job) - was done by the previous owner who flew in the Phoenix area - owned the airplane for thirty years. The larger inlet definitley affects oil temps. In fact during the winter here in Northern California it actually becomes a problem getting the oil temps hot enough. However, it sure is nice during the 100 degree summers.