I have to replace the Thermal Vacuum Switch on my 1979 231 V6 engine. I have purchased the replacement part but am wondering how it seals against coolant leaking? Does it need a crush washer ? The vacuum tubes on it must point up when installed. I saw a photo on the internet where there was Teflon tape on the threads of one that a guy was going to install. Advice appreciated.
Coolant sealing a Thermal Vacuum Switch
- Thread starter Rory
- Start date
From the factory service manual.
"The DTVS must be installed with soft sealant on the threads."
Teflon tape would likely do the same job as their sealant.
"The DTVS must be installed with soft sealant on the threads."
Teflon tape would likely do the same job as their sealant.
Generally, you would use a dab of pipe dope for that soft seal. Teflon tape also works. Sometimes, not always, the sensors come with pre-doped sealant already applied (dried but pliable stuff).
CSM calls for GM p/n 1050026 or equivalent.
Loctite 1525607 aviation gasket sealant works well as a substitute. Use just a little. Don't go crazy. You also would use this for the thermostat bolts that extend into the coolant passages on an Olds. Not sure about Chevy.
CSM calls for GM p/n 1050026 or equivalent.
Loctite 1525607 aviation gasket sealant works well as a substitute. Use just a little. Don't go crazy. You also would use this for the thermostat bolts that extend into the coolant passages on an Olds. Not sure about Chevy.
i worked with a fitter that used liquid first and tape second.seemed like a lot but..
Back in my days as a mechanic in factories I received similar advice from a pipefitter. His take was tape on the male threads and dope on the female threads and it will never leak. Never saw a leak when following this procedure.
Never saw teflon tape on G-body Olds V8 factory engine fittings. Either it was the goop or pre-applied sealer. If done properly, I don't see why any of that won't work, though.
That looks like a straight thread. It would need a crush washer or an o ring.
Do not use teflon tape, that is only for tapered pipe thread. NPT or PT.
Do not use teflon tape, that is only for tapered pipe thread. NPT or PT.
Thinking the same... A good wrap of tape would or could seal. Won't know until you get engine to operating temp.
But if you look at the threads... They appear to be straight cut and above the threads it is cut for about a 1/8th or 3/16th o-ring. Under the nut is the mating surface and if you inspect the boss, you should see it is machined flush as well. The o-ring pinches in there to seal any imperfection of the mounting.
Can you wrap it good or goop it up with paste? Probably. Will it be ok? Probably. It's only a 15 psi system.
Also that is aluminum going in to machined iron manifold? Don't over do it. Make sure not to cross thread and wrench it down snug. Both mating surfaces should be in contact, then 1/8 to 1/4 turn only. Should be no leaks if done right. Over torque it and you start stripping threads and now will predispose yourself to leaks.
But if you look at the threads... They appear to be straight cut and above the threads it is cut for about a 1/8th or 3/16th o-ring. Under the nut is the mating surface and if you inspect the boss, you should see it is machined flush as well. The o-ring pinches in there to seal any imperfection of the mounting.
Can you wrap it good or goop it up with paste? Probably. Will it be ok? Probably. It's only a 15 psi system.
Also that is aluminum going in to machined iron manifold? Don't over do it. Make sure not to cross thread and wrench it down snug. Both mating surfaces should be in contact, then 1/8 to 1/4 turn only. Should be no leaks if done right. Over torque it and you start stripping threads and now will predispose yourself to leaks.
Are part numbers the same? This later one is NPT or at least appears so. Above the threads is not machined as the other appears to be. Maybe all was just optical illusion due to angle of photos?
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