34V flys

[T. C. Downey]

First time since 1992 that the aircraft has been legally in the air. Around 10:00 today my CFI buddy showed up with his 170/51-A I had 34V ready for his preflight and he saw a couple things I had missed, I fix them and we mount up.

After we taxied to the 11 runway at BVS we noticed the oil pressure had dropped a bit. We did the normal run up, oil pressure back in the green, mags check was good.
WE announce our departure, and push all the big knobs forward. and in about 250' we are airborne, I trim it ou so the picture out the window was right, look down and the Airspeed was 70, climbing out at 1100' per minute. I turn cross wind and level off and pull the power back to 2450, and My friend says the oil pressure was falling, I look at the oil temp and it was center of the green. I decide to continue the pattern, and land, rolling out I notice the oil pressure was 0, and all the way back to the hangar that did not change.
I decided that I was not working on the hot engine, So we went to lunch at the Airport Cafe. After lunch, My CFI was headed home to PAE and I was headed back to the hangar to see what was wrong with 34V.

I started to pull the oil pressure regulator and see if that was the problem, when I hear a 170 coming, sure enough my CFI was back, After he gets out of his aircraft he tells me it will not make full power. After trouble shooting we find that #5 has no compression and the combustion chamber was full of oil. and decide we won't be able to fix that today.
So I go back to work on 34V, pull the pressure regulator, and see the spring in the regulator was kinda bent, (?), So I grab a new one of the shelf and reinstall the regulator, run it up, and it holds 45 PSI.

And around the pattern again, it is fixed and hold 45 all the way around the pattern.

Big mile stone today, for a busy ol mech.

[Ryan Smith]

That's awesome Tom! Congratulations! Any pictures of the big event?

[T. C. Downey]

That's awesome Tom! Congratulations! Any pictures of the big event?

Sorry No, I was a little busy

[T. C. Downey]

Nice job Tom. Must have felt good to get it up in the air.

First time it has flown since 1992, It was nice to get it in the air.

[Bruce Fenstermacher]

Nice Tom, congratulations. So glad the oil pressure problem was so simple and you hit the cure right away.

[GAHorn]

Try to post a picture of the bent relief spring.

[T. C. Downey]

Try to post a picture of the bent relief spring.

It went into the scrap barrel yesterday. I have no idea what happened it was a new one when it went in. and was operating properly all thru the test period on the cell, several taxi tests. but gave up on the test flight. First time for every thing I guess.

Plus the picture posting issues I have using my camera to this page.

[Larry Holtz]

I had the opposite problem when I reinstalled the C-145 after OH last year. Oil pressure spiked to the peg. After several tries with different washers, I got it back down to top of the green. I believe your 170 is just a llttle older than my 4026V. I plan on heading your way today and check out the tullip bloom. I'll try to stop in.

Larry

[T. C. Downey]

I had the opposite problem when I reinstalled the C-145 after OH last year. Oil pressure spiked to the peg. After several tries with different washers, I got it back down to top of the green. I believe your 170 is just a llttle older than my 4026V. I plan on heading your way today and check out the tullip bloom. I'll try to stop in.

Larry

There shouldn't be any washers in the regulator, If you don't get the proper oil pressure after overhaul some thing is wrong internally with the build. or you started out with a wrong spring. We find many with some ones better spring installed, remove them and replace with the proper spring.

[GAHorn]

The current production spring is Blue in color.
It has a specification which can be reproduced with minimal equipment:

The oil pressure relief spring should be compressed to 1.56 inches and the pressure should be 6.06 to 6.31 lbs if new, and 5.75 lbs minimum if used.
Another method to check it is to cut a tube, rod or other piece of metal to 1.56", then place it upon a firm surface of an accurate scale (postal or bathroom, etc).... within the coils of the spring. Now, using a flat piece of metal on top of the standing-spring ...compress the spring while observing the scale reading. When the scale suddenly increases due to the rod having been contacted (the spring has compressed to the length of the rod)....you can make note of the maximum scale reading achieved prior to that increase, and compare it to the specification.

[T. C. Downey]

The current production spring is Blue in color.
It has a specification which can be reproduced with minimal equipment:

The oil pressure relief spring should be compressed to 1.56 inches and the pressure should be 6.06 to 6.31 lbs if new, and 5.75 lbs minimum if used.
Another method to check it is to cut a tube, rod or other piece of metal to 1.56", then place it upon a firm surface of an accurate scale (postal or bathroom, etc).... within the coils of the spring. Now, using a flat piece of metal on top of the standing-spring ...compress the spring while observing the scale reading. When the scale suddenly increases due to the rod having been contacted (the spring has compressed to the length of the rod)....you can make note of the maximum scale reading achieved prior to that increase, and compare it to the specification.

Or you could simply install it and see what the pressure reads

[GAHorn]

... Or you could simply install it and see what the pressure reads

A little like installing main bearings without measuring them and waiting to see what kind of oil pressure you'll see in the hopes the bearings were correct.

[T. C. Downey]

... Or you could simply install it and see what the pressure reads

A little like installing main bearings without measuring them and waiting to see what kind of oil pressure you'll see in the hopes the bearings were correct.

You're a little over the top with that scenario, we don't have to separate the case halves to put a spring in the oil pressure regulator. Plus when you use the proper parts you will get a true reading.

[GAHorn]

... Or you could simply install it and see what the pressure reads

A little like installing main bearings without measuring them and waiting to see what kind of oil pressure you'll see in the hopes the bearings were correct.

You're a little over the top with that scenario, we don't have to separate the case halves to put a spring in the oil pressure regulator. Plus when you use the proper parts you will get a true reading.

That was exactly MY point, Tom. I was suggesting that people identify and install the correct part...so they'll get a true reading. Your previous post (in response to that) seemed to imply to install whatever part was found on-hand and hope for an acceptable reading.

[T. C. Downey]

That was exactly MY point, Tom. I was suggesting that people identify and install the correct part...so they'll get a true reading. Your previous post (in response to that) seemed to imply to install whatever part was found on-hand and hope for an acceptable reading.

Weren't we already talking about new springs when I said install it and see what you get?
How would you know if you removed an Original spring by looking at it?
There is no marks on the old springs.
After overhauling we always try the old spring, just to see what we have, and when the pressure is low, we try a NEW spring.
I certainly would not disassemble the brand newly overhauled engine simply because we put a new spring with a blue mark on it and got low pressure.