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Discussion Starter #1
Hi, I need to know the tightening torques for:-

1) the oil pressure switch adapter to the engine block; and
2) the gearbox rear mount bolt (the one with the star washer).

I can't find these anywhere. Any clue?

Thanks and best regards,

Joseph
 

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you mean oil pressure switch under the inlet or low oil pressure tell-tale switch near the oil filter?

O/P switch (under inlet) is 8-10 ft.lb (10.8 - 13.5 Nm)
....just how do you get a torque wrench-socket on that though?:)

Low O/P tell-tale switch (near oil filter): no torque specified - use common sense, be gentle, remember they're aluminium threads!

The transmission mount: no torque specified, so just make sure it is tight.
 

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The oil pressure sender on the intake side uses a copper sealing washer. Either use a new one or anneal the old one to soften the metal. The oil pressure switch on the exhaust side has a tapered thread so use some thread sealant on it.
 

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Discussion Starter #5
Thanks all. I'm familiar with the chart above, this gives the torques required to tighten the bolts to abt. 70 to 80% of the yield strength. What we need is tightening in aluminium so common sense would say the values should be lower (unless the thread engaging length is substantial).

The switch on the exhaust side also has copper washers. Generally speaking only parallel threads would require some suitable sort of sealant. Tapered threads not, as the seal is accomplished by metal-to-metal wedging.
 

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imo, an item with a copper seal washer doesn't need sealant at all, the copper, being soft, effects the sealing (think sump, tranny or axle drain plugs....you wouldn't seal those!)
That's why you renew the washer each time.
 

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The switch on the exhaust side also has copper washers. Generally speaking only parallel threads would require some suitable sort of sealant. Tapered threads not, as the seal is accomplished by metal-to-metal wedging.
I have just checked three used pressure switches and they are all 1/8" NPT - tapered thread. They need sealant on the threads.
 

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Ed is correct. Straight thread connections (e.g., pressure gauge sender, oil drain) are sealed with a crush washer. Tapered threads you want to use sealant or teflon tape.

Theoretically the tapered threads do seal on their own, but the metal-to-metal contact is never perfect and the sealant helps prevent leaks.
 

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Theoretically the tapered threads do seal on their own, but the metal-to-metal contact is never perfect and the sealant helps prevent leaks.
And prevents over-tightening to make the seal. I prefer teflon paste or liquid to tape whenever possible.
 

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1/8" NPT is easily confused with M10 x 1.0 by someone who only familiar with metric threads.
 
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