Vernatherm Gasket

I have an O360 with a 90* oil filter adapter. Easy question, one would think, is the Vernatherm gasket just a crush washer? I’ve seen it listed as a specific vernatherm gasket, an oil seal, and a washer.. I have a kit full of crush washers but need some SA on if that’ll work. Any words appreciated…

The part you're looking for is a Lycoming 76510, it is NOT the same as an AN900 "crush washer"

You can use an aluminum or copper solid washer of the correct dimensions. The vernatherm (P/N 53E22144) comes with it.

I recently removed my vernatherm and reused the aluminum washer. No leak, never thought about it. YMMV

Brian, the installed reference thickness listed on a Rosta Vernatherm factory drawing is 0.0625". The Lycoming number is 76510 ($2.95 at Spruce), but I don't remember much about it, and I've had a shop-made soft aluminum crush washer in there for 10 years or more.

What is the crushed thickness of a AN900? Probably a bunch of them under vernatherms.
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DanH said:

...Probably a bunch of them under vernatherms.
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No doubt...

A thinner washer (crushed AN900 or other) is going to mean >more< engagement when the vernatherm does it's thing -- is that bad, is there going to be a deformation of the seat, or will the few 1000'ths make a difference in the amount of oil that's bypassed?

Just questions I'd rather not have to worry about...

bjdecker said:

A thinner washer (crushed AN900 or other) is going to mean >more< engagement when the vernatherm does it's thing -- is that bad, is there going to be a deformation of the seat, or will the few 1000'ths make a difference in the amount of oil that's bypassed?

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That's why I installed a thinner seal. For any given temperature above contact length, tip pressure will be higher.

DanH said:

That's why I installed a thinner seal. For any given temperature above contact length, tip pressure will be higher.

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What seal did you use Dan? My vernatherm leaks very slightly at the gasket. Replaced with the aluminum gasket but still very a few drops in a few hours.

SteveR said:

What seal did you use Dan? My vernatherm leaks very slightly at the gasket. Replaced with the aluminum gasket but still very a few drops in a few hours.

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Are you sure it is the vernatherm and not the tach drive? I get a small amount of oil out the unused tach drive. I put an O-Ring under the cap on the tach drive and problem was solved.

SteveR said:

What seal did you use Dan? My vernatherm leaks very slightly at the gasket. Replaced with the aluminum gasket but still very a few drops in a few hours.

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Just a shop made copy of the OEM solid aluminum gasket, but thinner.

SteveR said:

What seal did you use Dan? My vernatherm leaks very slightly at the gasket. Replaced with the aluminum gasket but still very a few drops in a few hours.

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Probably not enough torque when you tightened it. Alum crush washers need a decent amount of torque to actually crush when compared to the copper stuff, especially the AN ones that deform VERY easily. It needs enough force to deform a bit, as that is what creates the seal.

Please contact me

GrinchF16 said:

I have an O360 with a 90* oil filter adapter. Easy question, one would think, is the Vernatherm gasket just a crush washer? I’ve seen it listed as a specific vernatherm gasket, an oil seal, and a washer.. I have a kit full of crush washers but need some SA on if that’ll work. Any words appreciated…

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If you can contact me about your 90 degree adapter and vernatherm I would appreciate it.

Thanks

I was hesitant to overtorque the Vernatherm in an aluminum casting. I may try a little more torque. It is definitely the vernatherm, easy to confirm with a blacklight.

Is there a reason we can't use the copper crush type? Seems much more likely to seal, but maybe they are too weak and prone to blowing out in a pressurized application?

Gasket

I used a Dorman brand 095-017 . It will crush to a thinner cross section and result in about 5 to 10 degrees cooler oil when the temperature is being controlled by the vernatherm

SteveR said:

Is there a reason we can't use the copper crush type?

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Yes. Lyc wants the vernatherm installed at a relatively precise depth to do it's job properly. The alum gasket crushes only a very small amount. The copper AN gaskets crush A LOT. Note post above. He used a non standard gasket and the unit stopped behaving as it was designed to. Poster may have liked that effect, but you asked why. I also believe that the step on the vernatherm is too narrow for an AN type. Best to stick to recommended parts.

If you are afraid to torque it down more, take it apart, clean thoroughly and apply anaerobic flange sealant to both sides of the washer and reinstall. This uses sealant to seal vs a deformed washer. The risk of this approach is that when you disassemble, little bits break off and can clog things. ONLY use anaerobic sealant as the squeeze out on the inside will not get hard and will stay liquid and mix with the oil. Other sealants don't do this and can clog up passages.

gasket

There is plenty of step as the gasket ends up nearly identical to original I.D. and O.D. Also it works exactly as lyc. planned just .015 of an inch sooner.