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  #21  
Old 08-16-2022, 09:09 AM
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Saville Saville is offline
 
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Quote:
Originally Posted by DanH View Post
Apparently it is common, given you read about it a lot:

What I read about a lot is that you must get the oil temps up to 180. I don't read a lot about people having trouble doing that. If I had, I would have read their posts to get remedies. Perhaps my search didn't find them.

Brad and Mike seem to suggest the vernatherm could be defective,

Which I also suggested in my original post and which you said, outright, that it was working fine and was not the source of the problem.

i.e. locked in the extended position, or extending prematurely at a temperature lower than spec. I doubt it, but I'm always in support of checking to be sure.

So evidently you now think it's possible (though unlikely in your opinion) that the Vernatherm isn't working.

Unscrew the vernatherm. There will be a visible wear ring on the conical tip. Measure from the underside of the gasket to the wear ring. A cold, fully retracted vernatherm should ballpark around 3.120". If extended and locked so as to block the bypass port, it will measure 3.280". Please report back.

The Rosta temperature vs extension spec below.
.

Thanks for the information on how to check for a defective Vernatherm.
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  #22  
Old 08-16-2022, 09:36 AM
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Roadjunkie1 Roadjunkie1 is offline
 
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Default Oil temperatures and cooler air flow

Quote:
Originally Posted by Saville View Post
So every Fall I attach an aluminum plate to the backside of my oil cooler to try and keep the oil temps up. It seemed to work ok though the temps were never very high.
My solution: this is cockpit-controlled. The intake is a 2 inch duct off the back of the baffle and the outlet is a gated 2 inch duct. I leave the gate closed at startup and open it prior to departure. The gate is open in this picture. Temps in the 160-180 range and easily controlled using the gate. Intake is placed so that it does not interfere with airflow over the cylinder.

In the winter I have two simple small round aluminum blocking plates with extensions that fit in the hole, one blocking half the 2 inch intake, the other blocking 3/4 of the intake as the temperatures cool that neatly fit inside the intake fitting. That keeps temperatures above 160 in colder months.

The cooler is attached to the engine mount by a self-made steel bracket: solid as a rock and moves with the mount. I have never had a break in the scat tubing from the baffling to the cooler.
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  #23  
Old 08-16-2022, 11:21 AM
Hwood Hwood is offline
 
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Okay, I'll jump in on this!

It is possible to check the vernatherm by putting it in a pot of water and bring it to a boil...and with a thermometer in the water, you can see the vernatherm extend at about 180. Barrett recommended this to me and I was able to verify its operation while trouble shooting oil temp excursions. Just another thing to check.

FWIW...on my previous -8 (IO-360) I had trouble getting the oil warm enough. I tried the shutter and it was not effective enough. Eventually went to the foil tape on the inside of the cooler and it worked like a charm.
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  #24  
Old 08-16-2022, 02:33 PM
Iluke Iluke is offline
 
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To the original question of whether cool oil temps are unusual, not for me.
Mine is a stock lycoming IO360 factory experimental bought through Vans. One slick, one EMag. RV 7. Fixed pitch prop.
I see 160 _ 170 with the cooler blocked with OAT from 20 to 70.
This past July with OAT over 80 I saw 185_190. I took the cooler block off ant saw 160ish again.
Itís never lower than 160.
I run LOP at 75%

So, I canít say itís common, but I can say it is not unique.
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  #25  
Old 08-17-2022, 05:44 AM
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Saville Saville is offline
 
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Quote:
Originally Posted by Hwood View Post
Okay, I'll jump in on this!

It is possible to check the vernatherm by putting it in a pot of water and bring it to a boil...and with a thermometer in the water, you can see the vernatherm extend at about 180. Barrett recommended this to me and I was able to verify its operation while trouble shooting oil temp excursions. Just another thing to check.

FWIW...on my previous -8 (IO-360) I had trouble getting the oil warm enough. I tried the shutter and it was not effective enough. Eventually went to the foil tape on the inside of the cooler and it worked like a charm.
Thanks for the info.

Can you, please, describe the "foil tape on the inside of the cooler" technique a little more?
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  #26  
Old 08-17-2022, 05:44 AM
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Saville Saville is offline
 
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Quote:
Originally Posted by Iluke View Post
To the original question of whether cool oil temps are unusual, not for me.
Mine is a stock lycoming IO360 factory experimental bought through Vans. One slick, one EMag. RV 7. Fixed pitch prop.
I see 160 _ 170 with the cooler blocked with OAT from 20 to 70.
This past July with OAT over 80 I saw 185_190. I took the cooler block off ant saw 160ish again.
Itís never lower than 160.
I run LOP at 75%

So, I canít say itís common, but I can say it is not unique.
Was your cooler block on the air intake of the cooler or on the back of the cooler?

Thanks for the info
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  #27  
Old 08-17-2022, 10:43 AM
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DanH DanH is offline
 
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Originally Posted by Saville View Post
Which I also suggested in my original post and which you said, outright, that it was working fine and was not the source of the problem.
The reported conditions are not inconsistent with normal vernatherm operation in a carbed parallel valve.

Quote:
So evidently you now think it's possible (though unlikely in your opinion) that the Vernatherm isn't working.
I think it's easy to check.

Per a conversation with a Rosta engineer some years ago, the most common failure mode is hardening of the wax motor's rubber piston due to age, the result being failure to extend properly. Retraction is powered by an external spring. There are no close tolerance sliding surfaces between the wax motor cartridge and the vernatherm body, so a jam due to debris or deposit seems unlikely. But hey, anything is possible.

Quote:
Thanks for the information on how to check for a defective Vernatherm.
You're quite welcome. Please report back.
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  #28  
Old 08-17-2022, 01:10 PM
RV8JD RV8JD is offline
 
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Quote:
Originally Posted by Saville View Post
Can you, please, describe the "foil tape on the inside of the cooler" technique a little more?
I've applied the AL foil tape on the front side of the oil cooler so I can fold it up or down, depending on the season and how much of the cooler I want to cover, as I mentioned in post #17. You may have to unbolt the cooler so you can get the AL foil tape all the way down to the bottom of the cooler, since the cylinder is in the way otherwise.

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Last edited by RV8JD : 08-17-2022 at 01:14 PM.
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  #29  
Old 08-17-2022, 03:34 PM
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Saville Saville is offline
 
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Originally Posted by RV8JD View Post
I've applied the AL foil tape on the front side of the oil cooler so I can fold it up or down, depending on the season and how much of the cooler I want to cover, as I mentioned in post #17. You may have to unbolt the cooler so you can get the AL foil tape all the way down to the bottom of the cooler, since the cylinder is in the way otherwise.

Ah I was confused when in #17 you said "...backside the cooler..." I think of the backside as the side closest to the firewall. But that's just me.

But your picture clears it up now. Thanks for the info.
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  #30  
Old 08-17-2022, 03:56 PM
RV8JD RV8JD is offline
 
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Originally Posted by Saville View Post
Ah I was confused when in #17 you said "...backside the cooler..." I think of the backside as the side closest to the firewall. But that's just me.

But your picture clears it up now. Thanks for the info.
I see. In post #17 I was saying that attaching an AL plate to the rear side (backside) of the cooler, as you did, only raised the oil temps about 10įF. Placing the AL foil tape to the front of the cooler is much more effective since it blocks flow though the cooler.

Glad the pic helped.
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