Tip #4 Vernatherm Installation

[Mitch]

I had a customer ask me how to install a vernatherm in a Carbon Cub, so here it is. First we will remove the bypass spring and piston. In order to remove these we will first remove the threaded plug that keeps these two items in place.
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Remove the spring, then remove the piston using a pick or piece of wire. The piston is down the passage a ways. BE CAREFUL NOT TO SCRATCH OR NICK THE WALLS OF THE RELIEF PASSAGE WHEN REMOVING THE PISTON.
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Once you have retrieved the spring and piston, reinstall the threaded plug (torque to 300inlbs) and safety the plug. Now lets move on to the oil screen housing shown below.
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Remove the oil temperature probe from the housing and loosen the vernatherm plug. Now remove the four bolts that hold the housing to the accessory drive case and remove the housing. On Carbon Cubs there isn’t enough room between the housing and firewall to install the vernatherm.
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Remove the vernatherm plug and oil screen (now would be a good time to inspect and clean your oil screen). Screw the vernatherm into the housing and reinstall the screen. DO NOT TIGHTEN THE VERNATHERM AT THIS TIME. VERIFY THAT THE GASKET BETWEEN THE VERNATHERM AND HOUSING HAS BEEN INSTALLED.
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A new gasket should be used between the accessory drive case and oil screen housing (make sure both surfaces are clean before installation). Reinstall the oil screen housing and torque the housing bolts to 15inlbs. Tighten and safety the vernatherm (torque to 300inlbs), reinstall the oil temperature probe. Test run the engine and check for oil leaks. If you don’t have any oil leaks, you have just successfully installed your vernatherm.

[rmkrause]

Hi Mitch,
I found that if you blow air into one of the oil ports(the smaller of the two) the steel piston will come right out. This stops the possibility of nicking the side wall of the chamber it sits in.
Dick Krause

[kiwibob]

It's mentioned in another thread but Pete D says "Make sure they take the original "pop-it" style oil pressure regulating valve out when they put the vernatherm in. They will hit each other if both are installed."

I can confirm that this is correct (#193 had the oil filter factory installed and my engineer was not expecting the oil pressure regulating valve to be there so did not remove it)

[randylervold]

It's mentioned in another thread but Pete D says "Make sure they take the original "pop-it" style oil pressure regulating valve out when they put the vernatherm in. They will hit each other if both are installed."

I can confirm that this is correct (#193 had the oil filter factory installed and my engineer was not expecting the oil pressure regulating valve to be there so did not remove it)

Good catch, thanks!

[Pete D]

It's mentioned in another thread but Pete D says "Make sure they take the original "pop-it" style oil pressure regulating valve out when they put the vernatherm in. They will hit each other if both are installed."

I can confirm that this is correct (#193 had the oil filter factory installed and my engineer was not expecting the oil pressure regulating valve to be there so did not remove it)

The "pop-it valve" I referred to is also called the "bypass spring and piston" and is shown in the first two photos below.

[Joseph206]

The "pop-it valve" I referred to is also called the "bypass spring and piston" and is shown in the first two photos below.

Hello All,
Question.
Noticed on last flight that oil temp would rise to 190 Degrees and then stay ther for a minute then fall off to 150 Degrees and then do it all over again. Is there some kind of thermostat in the system???. I dont think there is , but why does it cycle? Also it was 15 degrees out and no cover on oil cooler and cowl flaps full open for summer use.
Thanks
Joe
P.S. Oil filter adapter installed.

[Pete D]

Hello All,
Question.
Noticed on last flight that oil temp would rise to 190 Degrees and then stay ther for a minute then fall off to 150 Degrees and then do it all over again. Is there some kind of thermostat in the system???. I dont think there is , but why does it cycle? Also it was 15 degrees out and no cover on oil cooler and cowl flaps full open for summer use.
Thanks
Joe
P.S. Oil filter adapter installed.

Has the plane been retrofitted with a vernatherm? If not, you are probably seeing the pop-it valve (aka bypass spring and piston) opening and closing. 190 degrees its closed and no oil is circulating through the cooler, then when it drops to 150 is when the valve opens and the oil that has been sitting up in the cooler circulates back into the system, its pretty cold so it drives the oil temp down. Usually with a vernatherm there is a slight amount of circulation that keeps the oil temp a little steadier.

Assuming you have the pop-it valve and nothing is wrong with the gauge or sending unit you could try some foil tape on the oil cooler. Tape a couple of inches of it off at a time until you can get a nice steady 180* in normal cruise. I'm going to guess you will end up 1/3 to 2/3 of the cooler taped off for winter/early spring ops.

[Joseph206]

Has the plane been retrofitted with a vernatherm? If not, you are probably seeing the pop-it valve (aka bypass spring and piston) opening and closing. 190 degrees its closed and no oil is circulating through the cooler, then when it drops to 150 is when the valve opens and the oil that has been sitting up in the cooler circulates back into the system, its pretty cold so it drives the oil temp down. Usually with a vernatherm there is a slight amount of circulation that keeps the oil temp a little steadier.

Assuming you have the pop-it valve and nothing is wrong with the gauge or sending unit you could try some foil tape on the oil cooler. Tape a couple of inches of it off at a time until you can get a nice steady 180* in normal cruise. I'm going to guess you will end up 1/3 to 2/3 of the cooler taped off for winter/early spring ops.

Hi Pete,
I do not have a Vernatherm in it yet , I have one to put in it.
I really don't like it going to 190 Degrees, I would like it to be steadier. I didn't realize there was a popit valve in it.
It must be lighter than a Vernatherm for cubcrafters to use instead of vernathem.
Thanks
Joe

[Pete D]

Hi Pete,
I do not have a Vernatherm in it yet , I have one to put in it.
I really don't like it going to 190 Degrees, I would like it to be steadier. I didn't realize there was a popit valve in it.
It must be lighter than a Vernatherm for cubcrafters to use instead of vernathem.
Thanks
Joe

Yes, unless optionally retrofitted all factory Carbon Cubs are outfitted with the pop-it valve.

190 isn't going to hurt anything but it would be better to keep it steadier. The foil tape can help with that by keeping the flow through the cooler more consistent vs starting and stopping it. A quick and easy fix that doesn't weigh anything. Our factory airplane is currently configured that way.

[Joseph206]

Yes, unless optionally retrofitted all factory Carbon Cubs are outfitted with the pop-it valve.

190 isn't going to hurt anything but it would be better to keep it steadier. The foil tape can help with that by keeping the flow through the cooler more consistent vs starting and stopping it. A quick and easy fix that doesn't weigh anything. Our factory airplane is currently configured that way.

So, the pop it valve is just a primitive thermostat that works on , as the temp rises the pressure rises and pops the valve?????

Add: Sorry it cant be, as the temp rises the pressure goes down. I am confused on how the popit valve works.