Searching for Oil Temp Thermistor

kontiki

kontiki

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Kontiki
The Oil Temp sender on my Grumman Tiger is bad. It's a Stewart Warner 362-EW. The part (or specs) are not listed anywhere. Anyone got any idea where I can find one?
 
RotorAndWing said:
Do a google search on the information you have.
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I actually searched all of website sources suggested before posting, and a dozen more. So far no straight up P/N match. This is another one of those problem parts for a vintage airplane.






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Call David Fletcher with Fletch-Air in Texas.. google Grumman gang or AYA (american yankee association) and you will find numerous links or references to find him. His family ran and maintained a large cheetah/tiger rental fleet in Houston for years and years until his parents retired and David relocated to the Hill Country in Central Texas.
 
weirdjim said:
And we know this how?

Jim
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Good question Jim.

I believe I ruined it. I had all the cowls off to address a battery leak and while I was in there, among other things I re-routed some wiring (the oil temp wiring was one of them). When I went to re-secure the wire back on the the terminal post, the post was spinning. And, when I did my engine run, the needle didn't move.

I did make sure I had continuity, but really didn't try inserting a 28.5 ohm resistor to see if it indicated red line (ref the AMM). I could fairly easily bread board up a 1W 28.5 ohm resistor and check it. Given that it's starting to look like it's going to be a PIA to get I should probably do that.

This was the first time I had the cowl off and I found all manner of little things I didn't like:missing fasteners, wires tie wrapped to the engine mount, wire connectors tie wrapped to a hose, bolts that weren't long enough to go all the way through lock nuts, wiring everywhere.
 
kontiki said:
I actually searched all of website sources suggested before posting, and a dozen more. So far no straight up P/N match. This is another one of those problem parts for a vintage airplane.
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I hope you'll find that this isn't brain surgery and a sender is a sender when it come to most simple instruments like oil temp, particularly in older planes. I may be wrong....

I checked mine by buying a long stem thermometer and stuck it in the dipstick hole when I shut down. It matched my instrument so I knew it was correct.
 
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flyingriki said:
I hope you'll find that this isn't brain surgery and a sender is a sender when it come to most simple instruments like oil temp, particularly in older planes. I may be wrong....

I checked mine by buying a long stem thermometer and stuck it in the dipstick hole when I shut down. It matched my instrument so I knew it was correct.
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One of the local guys on the field offered to lend me one to get me going. At that point, neither one of us had any idea what the temp rating actually is. I can't see just throwing any old thing in there.

I have rented planes for flight training that always indicated too hot. They had the wrong sender in there to keep it in service until they got the right sensor. Most training flights don't last that long, I'm sure it's one of those things.

I believe the 362's are all 100-240 deg F, with variations in physical sizes (per a survey of old Stewart Warner Catalogs). I pulled it out of the airplane today, measured it, checked thread pitch etc. I haven't looked up NPTF dimensions yet.

I can find 362-XX, none -EW. I'm sure this will work out. If I can find one that will fit for the right temp range in another airplane parts catalog, I believe I can just use it Ref AC AC 23-27 Parts and Materials Substitution for Vintage Aircraft.
 
So....if it's Stewart Warner why not match it up with one at the auto parts store and check it with a thermometer. Might save you time and money?
 
flyingriki said:
So....if it's Stewart Warner why not match it up with one at the auto parts store and check it with a thermometer. Might save you time and money?
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Well so far I haven't seen any SW temp sensor that operates in the correct temp range with the correct physical dimensions to fit like the original. I'm not anxious to use an untested config that involves extra adapters and no gasket.

The other thing for me is to explore first hand what the options are for maintaining a small GA airplane. I'm an engineer at an airline in my day job. I'd like to make sense out of things if I can.

My personal view is that most FAA policies with regards to engineering make sense. It's breathtaking how many people in the business take the "cargo cult" approach.

With regards to auto parts, a part can look the same and just be a piece of junk. FAA MIDO rules try to control that.

On my pad I skip a lot of background explanations because it's a poor typing tool.

As a last resort I can buy the approved JPI temp kit and upgrade my installation. Sometimes that's the only reasonable answer for obsolescence.





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kontiki said:
Good question Jim.

I believe I ruined it. I had all the cowls off to address a battery leak and while I was in there, among other things I re-routed some wiring (the oil temp wiring was one of them). When I went to re-secure the wire back on the the terminal post, the post was spinning. And, when I did my engine run, the needle didn't move.

That is a pretty good indication that there is something amiss with the sensor.

I did make sure I had continuity, but really didn't try inserting a 28.5 ohm resistor to see if it indicated red line (ref the AMM). I could fairly easily bread board up a 1W 28.5 ohm resistor and check it. Given that it's starting to look like it's going to be a PIA to get I should probably do that.

33ø in parallel with a 220ø gives 28.7ø which should be close enough. Why 1 watt? That seems awfully hefty.
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kontiki said:
I believe the 362's are all 100-240 deg F, with variations in physical sizes (per a survey of old Stewart Warner Catalogs). I pulled it out of the airplane today, measured it, checked thread pitch etc. I haven't looked up NPTF dimensions yet.

You don't need to check dimensions. You go down to the hardware store and into the plumbing fittings. You pull out a coupling that looks about the right size (the TLAR test). If you can thread the old sensor in two or three threads by hand, you have figured out the thread size.

I can find 362-XX, none -EW. I'm sure this will work out. If I can find one that will fit for the right temp range in another airplane parts catalog, I believe I can just use it Ref AC AC 23-27 Parts and Materials Substitution for Vintage Aircraft.

You can bet your bottom dollar that American didn't have a special made to order S-W sensor. Just like Cessna didn't have Ford make them up a special alternator or door handles. There is a one-size-fits-all S-W sensor that accomodates all size threads from 1/8 npt through 1/2 npt with threaded bushing adaptors.

What's all this stuff about "gasket". I've never seen a gasket used with pipe thread before.

Jim
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Jim, I'd have to double check but I thought there were some temperature sensors used on Lycomings that have straight threads and a crush washer under them rather than a pipe thread. I may be wrong, I haven't looked at a temperature sensor that closely for a while.
 
Without all details in a 12V circuit, 28ohms alone would require greater than 1 Watt (work out the math) and AMM recommendations for performing same test on another system said 1 Watt and it worked as advertised.

Once my work week starts it's easier to check specs than to get to a hardware store. There are several pipe thread specs, NPTF dry thread was specifically designed for fuel/ oil systems with no thread dope. I also like looking at specs because I usually learn something, and all of this is part of exploring life for me.

My installation has a crush gasket. I recognize the old S&W parts were the COTS selections of the day. I personally don't like the one size does all kludge of adapters and sleeves with mystery threads made from mystery metal for the caveat emperor world of auto parts.

The thought of a solid plug with the RTD inside is more assuring for oil system. Night IFR in the clouds; do I want to deal with the possibility there might be oil on my windshield? Nah.

I knew this was a regulated industry when I bought this thing. I've made a decent living from it. I'm ok trying to work within it. Doing my own work puts most options within my reach. Other pilot owners warned me the first year would be a tough one, especially on my first airplane.


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kontiki said:
Without all details in a 12V circuit, 28ohms alone would require greater than 1 Watt (work out the math) and AMM recommendations for performing same test on another system said 1 Watt and it worked as advertised.

Other than an insane need to teach, you can use a thousand watt resistor for all I care. HOWEVER, Brother Ohm is not so easily dismissed. You don't have a 28 ohm resistor directly across a 12 volt battery, you have a meter in series with its own internal resistance. If you had the 28 ohm resistor directly across the battery, it should be a 5 watt resistor. YOU do the math ... I'll even give you the equation rather than having you look it up: P=E^2/R=144/28=5.14 watts. Now if you want to believe AMM (whoever they are) who am I to say different other than you sometimes need to do your own research.

Once my work week starts it's easier to check specs than to get to a hardware store. There are several pipe thread specs, NPTF dry thread was specifically designed for fuel/ oil systems with no thread dope. I also like looking at specs because I usually learn something, and all of this is part of exploring life for me.

Explore life to your heart's content, then fix your airplane.

My installation has a crush gasket. I recognize the old S&W parts were the COTS selections of the day. I personally don't like the one size does all kludge of adapters and sleeves with mystery threads made from mystery metal for the caveat emperor world of auto parts.

If your installation has a crush gasket, then I submit you do NOT have pipe threads. Think about it. WIth pipe threads the seal is made by tapered threads which do NOT get seated all the way to the bottom of the thread (or the seal is worthless). A gasket is used for STRAIGHT threads. NOw, which do you have? What you don't like and what will fix your airplane are two separate and independent items.

The Latin phrase is "caveat EMPTOR".

The thought of a solid plug with the RTD inside is more assuring for oil system. Night IFR in the clouds; do I want to deal with the possibility there might be oil on my windshield? Nah.

If you do night IFR single engine you are a braver man than I. Or perhaps the term isn't "braver".

I knew this was a regulated industry when I bought this thing. I've made a decent living from it. I'm ok trying to work within it. Doing my own work puts most options within my reach. Other pilot owners warned me the first year would be a tough one, especially on my first airplane.

I worked my way through college with the airlines. They taught me the difference between what I learned in engineering school and the real world of airplanes. I hope your airline has that sort of teaching talent on staff.

Jim

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Jim, I participate in GA for a hobby. Your whole presentation reeks of someone that has a problem. I have no time for you.
 
kontiki said:
Jim, I participate in GA for a hobby. Your whole presentation reeks of someone that has a problem. I have no time for you.
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You are correct. I've been trying to teach a pig to sing, and all it does is frustrate me and annoys the pig.

I'm sure a callow novice engineer has no time for somebody who has spent nearly 60 years crafting his trade in the profession.

Go build your houses with a micrometer. The world needs a good belly laugh.

Jim

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You're wasting your breath Jim. Another rookie owner know-it-all....... :dunno:

Any wonder the airlines can't make money....?
 
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weirdjim said:
You are correct. I've been trying to teach a pig to sing, and all it does is frustrate me and annoys the pig.

I'm sure a callow novice engineer has no time for somebody who has spent nearly 60 years crafting his trade in the profession.

Go build your houses with a micrometer. The world needs a good belly laugh.

Jim

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I saw this coming back at post #7...
 
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Doggtyred said:
I saw this coming back at post #7...
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I couldn't care less. Sounds like he's suffering from something. Too much for me.

I've learned to try to stick to the issues. I really am busy, and usually knee deep in thorny issues. I do appreciate everyone's ideas. Final call is mine.
 
I was able to get in contact with Stewart Warner and I have the spec sheet for the 362EW and a more modern 362AD-J sender. Can anyone host them on the forum?
 
weirdjim said:
Well, he's in Memphis, so I suspect the "airline" is FedEx. Even a clod like this can't screw up the money machine that FedEx has built.

Jim
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Conehead, that explains a lot. I had one that couldn't understand why the antenna screws were stripping out. When I asked what size apex tip he was using I got a blank stare. When AA deleted avionics guys on the line a lot of problems went away.
I have no prob with avionics guys, just the ones that bid that department to hide their mechanical incompetance. Good spark chasers are hard to find.
 
Get one that fits the engine, I doubt Grumman built that.
 
weirdjim said:
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Pipe threads. There are tapered pipe threads: NPT, National Pipe Taper, and NPS, National Pipe Straight. I have changed these senders many times but have never meaasured them to see what thread they are. They DO use a crush gasket but those threads are straight and could easily be 3/8" NPS. Remember that the dimension for pipe thread is the nominal inside diameter, not the outside diameter as in most other thread applications. A 3/8" pipe thread is around 5/8" OD.

This place implies it's a 5/8"-18 thread, not pipe: http://www.parts4aircraft.com/westach-oil-temp-sender-5-8-18-unf-c2x9383439

3/8" pipe is also 18 TPI. Howver, you don't want to mix them up. Their thread diameters are not the same.
 
Dan Thomas said:
Pipe threads. There are tapered pipe threads: NPT, National Pipe Taper, and NPS, National Pipe Straight. I have changed these senders many times but have never meaasured them to see what thread they are. They DO use a crush gasket but those threads are straight and could easily be 3/8" NPS. Remember that the dimension for pipe thread is the nominal inside diameter, not the outside diameter as in most other thread applications. A 3/8" pipe thread is around 5/8" OD.

This place implies it's a 5/8"-18 thread, not pipe: http://www.parts4aircraft.com/westach-oil-temp-sender-5-8-18-unf-c2x9383439

3/8" pipe is also 18 TPI. Howver, you don't want to mix them up. Their thread diameters are not the same.
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The one in my AA1B is 5/8-18 UNF not pipe thread. A few more posts and I guess i'll have the privileges to post the spec sheet from S-W. Just need a 3/8 NPT to 5/8-18 UNF adapter..
 
I have a solution with a Stewart and Warner part that has the same thermistor as the original 362EW and therefore the same Ohm resistance curve as the original. It includes the same thread and a new crush washer so no adaptor. I have a few extra and will sell for $100 each plus shipping. I can provide the documents for your A&P to do the approval for this replacement.
 
zn105 said:
I have a solution with a Stewart and Warner part that has the same thermistor as the original 362EW and therefore the same Ohm resistance curve as the original. It includes the same thread and a new crush washer so no adaptor. I have a few extra and will sell for $100 each plus shipping. I can provide the documents for your A&P to do the approval for this replacement.
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What's the part number and manufacturer?
 
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