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Getting 108-3 N6635M back into the air

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Carsten H.
(@carl)
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Realgaskets makes silicone gaskets for the valve covers, pan, top cover, and push rod covers. They last and are reusable.

https://realgaskets.com/


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Michael Samson
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@clemensfam3sbcglobal-net.      I hope your oil temp sensor is not a capillary tube to the indicator like the one my plane.


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BRUCE
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Joined: 1 year ago
Posts: 128
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Got the prop balancer on order. No idea when it will ship.

image

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BRUCE
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Posted by: @ecos36gmail-com

@clemensfam3sbcglobal-net.      I hope your oil temp sensor is not a capillary tube to the indicator like the one my plane.

No, this is it:

oil sender

It has two wires coming out of it and that nut-like part that the wires protrude from is loose and jiggly. So when I drain the oil to replace a couple rubber joints in the oil lines I will pull it and test it.

Meanwhile I have been concerned about the state of the aging gas in my fuel system. It has been quite a few months since my trip to Las Cruces to get the non ethanol mogas and I have only run the engine a few times. So a pilot friend suggested I add some fuel stabilizer. Which I did this evening.

stabilizer[1] (580 x 1031)

Hoping the prop balancer arrives soon so I can use up some more of this gas!


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Dennis Crenshaw
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Joined: 16 years ago
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@clemensfam3sbcglobal-net  Bruce, one of the Franklin gurus, Dave James in MI, advised me that he had done a lot of vibration testing of a metal prop placement on the Franklin hub.  He advised me that clocking the prop at the 10 - 4 o'clock position with the #1 piston at TDC gave the best results.


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BRUCE
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Posted by: @dcn6102m

@clemensfam3sbcglobal-net  Bruce, one of the Franklin gurus, Dave James in MI, advised me that he had done a lot of vibration testing of a metal prop placement on the Franklin hub.  He advised me that clocking the prop at the 10 - 4 o'clock position with the #1 piston at TDC gave the best results.

Hmm...Thanks! I'll have to check where mine is.


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BRUCE
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Prop Balancing

The prop balancer arrived last week from Viking. It cost $150 for the week. It came with all parts and consumables, a scale and a pre-paid UPS label for return. Viking did a good job of providing everything needed. The work was not difficult and the results were tangible in a significantly smoother running engine.

I did have to drill out the mounts for the accelerometer and the optical pickup to fit the engine bolts on the Franklin. Here you see the two devices mounted.

20210511 105545[1] (1032 x 580)

The accelerometer is mounted vertical as close to the prop as possible and the optical pickup for RPM is aiming at a piece of reflective tape stuck to the back of the spinner rear plate with the prop blades vertical. The top blade is my reference blade.

The leads from both were zip tied over the engine and then routed to the air vent in the passenger window and to the hand held unit inside the cabin.

20210511 105611[1] (1032 x 580)
20210511 105633[1]

I started Sammy up and after warm up increased throttle to 2000 RPM. Pushing the “average” button, the device told me in a few seconds that I had a vibration of 0.3 IPS at 82 degrees. That is categorized as “rough” according to the manual and upon feeling it, according to me. 82 degrees is the heavy side of the prop so I needed to add weight somewhere near 278 degrees from the reference blade in the direction of rotation. That was a spot pretty close to the second spinner screw to the right of the top blade.

So I removed the screw and put two AN970-3 washers under it. This was just a guess. The device does not tell you what to add. Then I repeated the run.

Now the accelerometer told me I had  0.21 IPS at 71 degrees. I was pleased to see an improvement! So I put two of the same kind of washers under the third screw to the right of the top blade. And ran it again.

Now I am at 0.11 IPS at 132 degrees. Getting close! That is between fair and good according to the manual. And I can really feel the difference. So I added one washer to the first screw to the right of the top blade.

Bingo! 0.07 IPS at 108. .07 IPS is listed as “good”. It is good enough for me. And the engine runs substantially smoother at cruise RPM. Here are the washers installed.

As you can see, they overhang the back of the spinner and will impinge on the nose bowl.

20210514 094801[1]

So now my next job is to modify them by trimming and re-balancing.

20210514 101145(0)[1]

So next I removed each screw and washers, weighed and recorded their total weight, and ground down the washers until they were flush with the back of the spinner plate.Then I replaced the screw with a longer one. And in some cases I had to add an additional lock nut behind the spinner plate’s lock nut to add the appropriate weight.

20210514 104019[1]

Anyway I was able to match the weight on all three screws after grinding the washers. I re-ran the engine to check the balance once more and it came out the same.

20210514 104403[1]

Sammy runs well and much smoother.


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BRUCE
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Yesterday I removed the leaky oil filter so I can replace the aging rubber connectors. The good news is I dredged a very strong magnet through the bucket of drained oil and there was no metal sticking to it.

20210519 103513[1] (1032 x 580)
20210519 114845[1] (599 x 337)

I need to remove the vernatherm (well stuck) and then try to find out who to send the cooler to to fix the leaks if possible. Not holding my breath. I'm Mentally preparing to have to spend $1500 or more for a replacement. Sheesh.


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Carsten H.
(@carl)
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I had quite a tussle with my oil cooler a while back. Sent it to a company in Southern California for flushing and fixing the leak. Came back looking like a million, but it still leaked and engine quickly started to overheat. They made me a deal on one of their new direct replacements which has performed great even in 100°+ oat. The Original coolers were not as efficient as the new ones, and they tend to be gummed up with sludge.

My 2ç


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Dennis Crenshaw
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@clemensfam3sbcglobal-net   Bruce, my 2 cents worth-- don't waste your time and money on the old cooler.  They are H-E-A-V-Y and way past their prime.  Talk to Pacific Oil Cooler.  I'm not sure how it's approved, but I'm sure they can give you advice.  I have the old Seaplanes STC Harrison oil cooler, which was subsequently owned by Little Red Aero.  I don't know if that STC is available now. 


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Dennis Crenshaw
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Bruce, Univair has an Aero Classics replacement for the Stinson listed for $308.  It's an FAA approved replacement for the Harrison.  You should be able to get a 337 approval for the installation.  There is probably no provision for the vernatherm.  My Seaplanes STC (Harrison filter) does not use a vernatherm.  


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BRUCE
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Thanks Carsten, and Dennis, I spoke with Pacific today. They said to send it in. We will go from there. They will either provide a rebuild or a new one, either of which will be certified for Sammy.

I'll keep you all posted. Thanks!


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Carsten H.
(@carl)
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If you elect to repair I would strongly suggest that you pressure test the cooler in a bucket of water when you get it back. I didn't and ended doing a lot of extra work. 


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BRUCE
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Pacific confirmed the other day that they have my oil cooler. So while I wait to hear from them I am doing some little jobs now and then to keep busy. First, it's HOT! It's 102 in the hanger and expected to be 105 this weekend. I can at least bring in the two aluminum grills from the nose bowl and polish them in the cool AC!

In doing so I noticed a little detail that impressed me ...something the Stinson engineers thought about so long ago. The grill crosspieces (the "louvers") are shaped differently on each side to push cooling air into the engine most efficiently. Notice in the pics below.

Notice the right hand grill (as you are sitting in the cabin)

20210610 175745[1]

 has louver's shaped to direct the downward prop wash back into the engine and the left hand grill

20210610 175916[1]

 has louvers to deflect the upward prop wash onto the cylinders.

I would have never noticed this if I had not been polishing the grills by hand.

Stinson owners, please be honest...how many of you have never noticed this before?

 

 


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BRUCE
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By the way, density altitude here today is 7800 feet!


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