I have put about 25 hours on my 170 in the last 2 months and I want to change my oil tomorrow after my flight. I have a few questions about the oil screen. When you take it out are there peices that are easily lost? Or is it all pretty straightforward. I thought I heard talk of some other screen that had to be cleaned at the same time, does that sound familiar to anyone? I am assuming that the screen is the large square nut on the back of the engine under the accesory case? I know, dumb questions but I would rather ask than make a mistake. Thanks
Ken
Oil Change
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
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N1478D
- Posts: 1045
- Joined: Mon Apr 22, 2002 5:32 pm
Hi Ken,
Great questions! No, it stays together and it is straight forward. Problem is, there are more questions. It would be very beneficial to you if you could have a mechanic do it the first time who is willing to teach you while he is doing it. For example, the proper way to tighten the crush washers and how to check for metal, etc.
It is a simple job that is enjoyable to do, and if you fly much, you will be doing it often. One of the handy things I use is a length of hose, I believe it was heater hose off of the truck, that slips tightly over the quick drain and is long enough to reach the drain can. I've also cut a can and attached a bail to hang under the plug to catch the oil that comes out when the screen is removed, to reduce oil mess. It is really helpful to have a thin wrench, I believe it is 1 inch but not for certain, to hold the nut part of the screen assembly. A normal wrench is too thick to fit in there. I bought mine online thru Snap-On Tools. Also, it is best to change the oil while it is warm vs cold.
Great questions! No, it stays together and it is straight forward. Problem is, there are more questions. It would be very beneficial to you if you could have a mechanic do it the first time who is willing to teach you while he is doing it. For example, the proper way to tighten the crush washers and how to check for metal, etc.
It is a simple job that is enjoyable to do, and if you fly much, you will be doing it often. One of the handy things I use is a length of hose, I believe it was heater hose off of the truck, that slips tightly over the quick drain and is long enough to reach the drain can. I've also cut a can and attached a bail to hang under the plug to catch the oil that comes out when the screen is removed, to reduce oil mess. It is really helpful to have a thin wrench, I believe it is 1 inch but not for certain, to hold the nut part of the screen assembly. A normal wrench is too thick to fit in there. I bought mine online thru Snap-On Tools. Also, it is best to change the oil while it is warm vs cold.
Joe
51 C170A
Grand Prairie, TX
51 C170A
Grand Prairie, TX
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km74
- Posts: 46
- Joined: Mon Oct 21, 2002 5:59 am
Hey Joe,
Thanks for the response. I had a 120 a few years ago and changed the oil a few times on that. It also had an oil screen and a crush washer. I reused the washer several times with no bad effects but I think it was dumb luck. Any suggestions on how to do it properly? I don't like to bother the mechanics around here unless I need their help, it always ends up costing me alot of money. I guess you should replace it every oil change. I am not at the plane now and havent looked closely at it yet but I thought a normal sized wrench should be able to loosen off the filter. What I did before to check for metal was to put the filter in a pie pan and look for anything out of the ordinary (ie:metal, etc). Is this acceptable? I also used to take the cowling off to do this and I am assuming that it is the same for this beauty. Any other hints would be appreciated. Thanks again.
Ken
Thanks for the response. I had a 120 a few years ago and changed the oil a few times on that. It also had an oil screen and a crush washer. I reused the washer several times with no bad effects but I think it was dumb luck. Any suggestions on how to do it properly? I don't like to bother the mechanics around here unless I need their help, it always ends up costing me alot of money. I guess you should replace it every oil change. I am not at the plane now and havent looked closely at it yet but I thought a normal sized wrench should be able to loosen off the filter. What I did before to check for metal was to put the filter in a pie pan and look for anything out of the ordinary (ie:metal, etc). Is this acceptable? I also used to take the cowling off to do this and I am assuming that it is the same for this beauty. Any other hints would be appreciated. Thanks again.
Ken
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GAHorn
- Posts: 21290
- Joined: Fri Apr 12, 2002 8:45 pm
Ken, there are two screens at the bottom rear of the accessory case. The one to the lower left (looking forward) is the oil pump suction screen. Don't bother with it. It's so coarse the only thing it'll catch will have a serial number on it.
The larger screen to the right of the suction screen with the large square nut on it is the oil pressure screen and that's the one you want to pull every oil change without fail. (It will collect carbon and all sorts of bits of trash and, having no by-pass capability, it will eventually clog up and reduce or block oil pressure to the engine.) Wash it carefully in a coffee can or similar thing with Mineral Spirits, which you can buy inexpensively at the hardware or paint store. Pour the contaminated mineral spirits through a coffee filter or cloth and catch the junk and test it with a magnet to detect any steel/iron parts. If you find any show it to your mechanic. Look for any peices of copper or aluminum (shiny metal not attracted to the magnet) and if any peices larger than this O are there, or if more than a few are present you might also get a mechanic to look at it. The black particles are likely just carbonized oil which are created by oil splashing up under the hot piston domes. To confirm it's carbon and not metal, hit it with a hammer and see if it shatters (carbon) or spreads (metal). After the screen is cleaned, re-install it.
Now for the most likely way to cause a problem......tightening things up.
Most of these pressure screens have an oil temperature capillary bulb inserted into them and held with a brass or steel nut. That capillary bulb has a soft copper skirt on it that the nut presses against to form an oil seal. If you tighten that thing too much you'll crush/cut the skirt and your oil will dump overboard in flight and you'll likley lose the engine over it.
The sequence should be to remove the nut and capillary from the screen. Then remove the screen and clean/inspect it. Install a new copper crush washer (AN900 gasket) on the screen and re-install it until it bottoms out. Then tighten it an additional 1/8 turn. Re-install the oil temp bulb and tighten the nut until it bottoms and then only slightly snug it beyond that (less than 1/16 turn.) After you add the oil, start it and check for leaks. Then safety-wire the screen. (If you're the confident type you can safety it first then check for leaks.)
When you get tired of dealing with this obsolete screen which will only filter large pieces and which holds no dirt, you can convert to a spin on filter. The one I recommend is the one from http://www.fm-enterprises.com/ This makes it a cleaner and simpler process of changing oil, with less likelihood of causing damage. You'll get a genuine filter that will keep most of the dirt from continuously circulating through your engine, and you'll also gain a by-pass feature within the oil filter. You won't have to deal with ordering replacement copper gaskets anymore either.
Good luck.
The larger screen to the right of the suction screen with the large square nut on it is the oil pressure screen and that's the one you want to pull every oil change without fail. (It will collect carbon and all sorts of bits of trash and, having no by-pass capability, it will eventually clog up and reduce or block oil pressure to the engine.) Wash it carefully in a coffee can or similar thing with Mineral Spirits, which you can buy inexpensively at the hardware or paint store. Pour the contaminated mineral spirits through a coffee filter or cloth and catch the junk and test it with a magnet to detect any steel/iron parts. If you find any show it to your mechanic. Look for any peices of copper or aluminum (shiny metal not attracted to the magnet) and if any peices larger than this O are there, or if more than a few are present you might also get a mechanic to look at it. The black particles are likely just carbonized oil which are created by oil splashing up under the hot piston domes. To confirm it's carbon and not metal, hit it with a hammer and see if it shatters (carbon) or spreads (metal). After the screen is cleaned, re-install it.
Now for the most likely way to cause a problem......tightening things up.
Most of these pressure screens have an oil temperature capillary bulb inserted into them and held with a brass or steel nut. That capillary bulb has a soft copper skirt on it that the nut presses against to form an oil seal. If you tighten that thing too much you'll crush/cut the skirt and your oil will dump overboard in flight and you'll likley lose the engine over it.
The sequence should be to remove the nut and capillary from the screen. Then remove the screen and clean/inspect it. Install a new copper crush washer (AN900 gasket) on the screen and re-install it until it bottoms out. Then tighten it an additional 1/8 turn. Re-install the oil temp bulb and tighten the nut until it bottoms and then only slightly snug it beyond that (less than 1/16 turn.) After you add the oil, start it and check for leaks. Then safety-wire the screen. (If you're the confident type you can safety it first then check for leaks.)
When you get tired of dealing with this obsolete screen which will only filter large pieces and which holds no dirt, you can convert to a spin on filter. The one I recommend is the one from http://www.fm-enterprises.com/ This makes it a cleaner and simpler process of changing oil, with less likelihood of causing damage. You'll get a genuine filter that will keep most of the dirt from continuously circulating through your engine, and you'll also gain a by-pass feature within the oil filter. You won't have to deal with ordering replacement copper gaskets anymore either.
Good luck.
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zero.one.victor
- Posts: 2271
- Joined: Tue Apr 23, 2002 12:11 am
The crush ring for the pressure screen is an AN-900-28,the 28 being the size. I could never manage to check the screen without making a big mess.
Ditto George's comments about the spin-on filter. I had this on my "to-do" list for about 3 years,but never did get one til I had the engine overhauled about 2 years ago. I bought mine from El Reno in Oklahoma,but it's made by F&M. El Reno is real good to deal with,but I hear F&M is also. The kit costs about $300 US as of 2 years ago.
The spin-on filters cost around $13-14 US. Some folks exend the oil change to 50 hours,from 25 with the screen. I usually go 35,or 40 max.
The spin-on is way less messy,filters the oil much better,plus collects evidence of internal trouble (metal) better.
Well worth it.
Eric
Ditto George's comments about the spin-on filter. I had this on my "to-do" list for about 3 years,but never did get one til I had the engine overhauled about 2 years ago. I bought mine from El Reno in Oklahoma,but it's made by F&M. El Reno is real good to deal with,but I hear F&M is also. The kit costs about $300 US as of 2 years ago.
The spin-on filters cost around $13-14 US. Some folks exend the oil change to 50 hours,from 25 with the screen. I usually go 35,or 40 max.
The spin-on is way less messy,filters the oil much better,plus collects evidence of internal trouble (metal) better.
Well worth it.
Eric
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km74
- Posts: 46
- Joined: Mon Oct 21, 2002 5:59 am
Well, my first oil change went off without a hitch. There was no metal and very little carbon in the filter(I was expecting the worst since it is the first oil change under my ownership, sometimes people are surprised what can be missed in a prepurchase). I replaced the crush gaskets on the drain and the oil filter. The one on the drain looked like it had reused a time or two. Thanks for all your help.
Ken
Ken
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David Laseter
- Posts: 156
- Joined: Sun Oct 13, 2002 11:24 am
Put my finger in the screen hole when changing the oil a few hrs ago. I was really suprised to find a lot of grit and more metal than I wanted to find. The lower half had been rebuilt, new bearings and all, 60hrs earlier. I had mechs change the oil 20hrs after the engine work. We flew down from AK (40hrs) and I was changing the oil again. So I took a clean white shop cloth and wiped as much out of the screen hole as I could, more crud. Then I poured a 1/2 quart of fresh oil through the engine to hopefully flush any more out and swabbed it again. Flew the plane for 3 hrs and checked again, this time when I cloth swabbed it, nothing showed up and I looked at it with a mirror and it was clean and shiny inside 
And the screen was clean. So, I figure the mechs just didn't reach in there and take the time to get that grit out, before.
Any thoughts on this procedure? Is there a flush that could be poured through to wash the grit out. I thought about diesel but thought again! Maybe a squirt / flush bottle with a U tube designed tip, so I could get behind the grit and flush it out
Oh, thanks for recommending the 6" saftey wire twisters George?
And the screen was clean. So, I figure the mechs just didn't reach in there and take the time to get that grit out, before.Any thoughts on this procedure? Is there a flush that could be poured through to wash the grit out. I thought about diesel but thought again! Maybe a squirt / flush bottle with a U tube designed tip, so I could get behind the grit and flush it out
Oh, thanks for recommending the 6" saftey wire twisters George?
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GAHorn
- Posts: 21290
- Joined: Fri Apr 12, 2002 8:45 pm
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zero.one.victor
- Posts: 2271
- Joined: Tue Apr 23, 2002 12:11 am
I usually pour a slug of gas into the filler -- after I drain the oil but before I pull the hose off & close the quick drain--as a flush. I let it evaporate out before I start adding the new oil.
Likewise,I used gas to clean the screen before I went with a spin-on filter.
Spirits are reserved for the pilot!
Eric
Likewise,I used gas to clean the screen before I went with a spin-on filter.
Spirits are reserved for the pilot!
Eric
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wa4jr
- Posts: 437
- Joined: Mon Apr 29, 2002 2:44 am
Since we are talking about flushes and stuff...I just thought I'd ask a couple of related questions. I've been steered away from using automotive engine flushes in my O-300 by an A&P friend, even though I've used them for years with good results on my automotive engines. How about a bottle of Marvel Mystery Oil added and run for five minutes at idle prior to oil change? Perhaps not as "aggressive" as GUNK engine flush and would still loosen up some of the crud and get it ready to come out with the old oil?
Here's a real can of worms! I read in the SRAM about some members having success using Slick 50 in their engines. I am tempted to try this based upon testimony of members in the SRAM, but would like to hear from others who may have used a quart of Slick 50 in their engines. Good stuff or bad stuff?????
Here's a real can of worms! I read in the SRAM about some members having success using Slick 50 in their engines. I am tempted to try this based upon testimony of members in the SRAM, but would like to hear from others who may have used a quart of Slick 50 in their engines. Good stuff or bad stuff?????
John, 2734C in Summit Point, WV
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russfarris
- Posts: 476
- Joined: Wed May 15, 2002 2:25 am
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