Hi All -

The electric indirect read oil pressure gauge in my '57 180 engine instrument cluster is in the process of failing. It is slow to indicate pressure on startup. The mechanics who looked at the plane during prebuy in August and under my ownership agree that this is an indication issue (vs. an actual oil pressure problem).

Being a '57, my plane was among the first to be fitted with the indirect read (electric) oil pressure gauge. Since these have a habit of failing over time, Cessna came out with Service Bulletin SEB93-13 and helpfully sold a Rochester sender and gauge to replace the now discontinued Stewart Warner setup. In 1993 when the SB came out this replacement kit cost about $750; now the kit is pushing $1,500. For an oil pressure gauge.

So, we won't be doing that and I'm looking at alternatives.

Perhaps the simplest and least expensive option would be to buy some gauge from Aircraft Spruce and slap an "inop" sticker on the gauge in the cluster. I don't love this option because it is unsightly and makes my already jumbled panel a little more so.

I could remove the whole cluster and replace all those functions with a fancy primary electronic engine monitor. But, I already have a UBG-16 and a JPI fuel flow. I really just need an oil pressure gauge.

I could add oil pressure to my UBG-16 for a couple hundred bucks, but it isn't continuously displayed and wouldn't be a primary instrument replacement.

I could buy a salvage or new-old-stock Stewart Warner gauge and replace the failing electrical unit, but salvage gauges on eBay are in the $250 range and who knows if they are any good or how long they would last.

Finally, I could buy a Stewart Warner direct read gauge salvaged from the cluster of a different model Cessna for about $50 and slot it into my cluster. This would be my preferred setup, and from my research and study of photos online it looks like a mechanical gauge would screw into the same holes on the backplate of my cluster and has the same markings and faceplate as my current gauge. If I am right on this it would be my preferred solution.

Am I missing anything that would make this infeasible? Is there an approval issue I haven't thought of? Or, is there a better solution I haven't thought of?

Thanks! (And sorry for the big long setup to my question.)

That would best be asked of a good IA, who would either know or could more readily research whether that could be done.

A thought to consider, FWIW: a direct reading oil pressure gauge means running tubing into the cabin. A sudden leak would put hot oil all over the place.

I have not experienced a leak in a direct reading oil pressure gauge, but I have had the experience of a direct reading fuel pressure gauge leaking--not fun, and a bit scary. When my pard and I bought our TR182 new in 1978, Cessna very quickly came out with a "mandatory" SAB to replace the fuel pressure gauge under warranty. Why, I can't remember, and ours seemed to work fine, but I flew the airplane to Casper to the Cessna dealer, and a couple hours later, it had been replaced. Just about the time I was tucking the gear up, suddenly fuel was spraying on my pants. I made a quick return to land, and as soon as I could, I shut down the engine to stop the fuel from spraying. It was the new gauge itself that was leaking, not one of the tubing fittings.

So if it were mine, I think I'd be looking for a replacement for the electric set-up. Instead of trying to source it yourself, get ahold of your IA, and have him look for it--possibly from someone like Beegles in Greeley, off a wrecked airplane. All of us who own old airplanes have to get accustomed to going with good used parts, rather than always having to go with new.

Cary

How about just getting a EI oil temp/pressure gauge.
DENNY

Cary - Your point is well-taken - failure of the oil pressure line would certainly be a downside to direct read. However, it seems that using braided stainless lines reduces that risk. If it is the gauge itself that is leaking, as in your experience...true, hard to ignore the fact you have high pressure oil pumped right behind the dash. Maybe I am wrong in thinking that direct read is more durable/reliable long-term, in which case dropping in a salvaged electric replacement, as you suggest, makes more sense.

Denny - That is another option that I considered. The EI unit is $500, which I am hoping is more than I need to spend on an oil pressure gauge, and ideally I would like to keep my engine gauges together to maintain an efficient scan.

Have you looked into having your original sender & gauge overhauled?
This guy used to be located near me, now he's in Arizona.
http://www.fuelsenders.com/
I'm sure there are others.

Thanks Hotrod! I hadn't thought about a refurb of my gauge. I will give them a call and see what they recommend.

Most direct reading oil pressure systems I have seen have a special fitting on the engine case with an itti bitti ~.040, .060 hole in it so you get pressure but no volume.

Used to be soft copper lines but better lines are avail.

Some of the lectric block senders are the old pressure to / resistance setup
and can be real slow on the start-up and not show any fluctuations.
My last direct reading unit could detect prop gov. activity in turbulence.


My 2c

We just removed the factory cluster from my 1976 A185F. If you think I have any parts you need, I can try for any specific details to confirm it's what you want and make you a deal.

Thanks Mark. The oil pressure sender on my plane looks new, but I will verify that it works. If my sender is failing, then I have an easy and inexpensive fix on my hands.

My gauge was very slow and read consistently 15 psi low. This sender worked accurately with the stock gauge. My old stewart warner sending unit was bent/dented and center stud was internally loose though....lots happens in 58 years

Mark Y. wrote:My gauge was very slow and read consistently 15 psi low. This sender worked accurately with the stock gauge. My old stewart warner sending unit was bent/dented and center stud was internally loose though....lots happens in 58 years

That describes what I'm seeing pretty closely. In my research I have also read that pressure senders mounted to the crankcase can have their service lives shortened by the constant vibration. You're right, though. These machines are pretty rugged to have OEM gauges mostly working after 60 years.

Napa has the A/C Spruce part for $40

Same ole slow to respond units been around for ages.

Closing the loop (for now): I swapped the sender at annual and now have a steady oil pressure indication. Every once in a while the cheap option fixes the problem!

which sender did you end up going with? only thing I have found for mine in the part number listed is in the $800 range.....for a sender.

Kickrjason wrote:which sender did you end up going with? only thing I have found for mine in the part number listed is in the $800 range.....for a sender.

What? It is a $50 S-W sender

C180_guy wrote:

Kickrjason wrote:which sender did you end up going with? The only thing I have found for mine in the part number listed is in the $800 range.....for a sender.

What? It is a $50 S-W sender

Originally that is what I thought too. The replacement that I ordered from aircraft spruce stated it was "not for use in aircraft" in the documentation included in the part.

The installed sender in my aircraft


Cross-referencing the original part number only results in this listing online.


I cant possibly be the only person who has run into this. I find it hard to believe there is not a direct replacement out there that is indicated for a 1958 182A.

There is a direct replacement. It and the original are/were made by Stewart Warner. It is a 240 Ohm, 100 psi sender. Note, this discussion is assuming you still have the original S-W gage on your panel.

https://www.stewartwarner.com/product/t ... pn-279b-f/
https://www.amazon.com/Stewart-Warner-G ... 335&sr=8-1

By the way, all the 57/58 180/182s I have seen have the pressure transducer screw into the side of the LH engine case.

still have the original guages.

As for the mounting location. It is a Norland conversion engine and I can only speculate that this was a decision made by a previous mechanic and owner for a secondary direct read pressure gauge as the hose continues to a firewall termination. upon installation of a replacement sending unit, it will be returned to the original location.

Thank you for your help