What to put on these threads?

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Dusterdenovo

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Ready to put a couple of fittings 'home' on the 408 but not sure what to put on the threads:

Coolant Bypass fitting: Thread sealer, Teflon tape, antiseize or ??

Fuel Pump inlet: Loctite, Thread sealer or ?

Thanks

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Teflon tape on both. Pipe threads are its intended purpose.
 
Keep the tape about 1 thread back from the end, you don't want pieces goofing up the fuel or water pump. The thing about Teflon tape, if you take it apart and reassemble it later, the pieces left behind in the female threads get pushed into the system. They'd foul up the check valves in the fuel pump.
 
Permatex thread sealant.
On another note: Nows the time to ditch the chrome thermostat housing.
They have been known to have leak issues.

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On the fuel pump I'd use permatex #4
On the water nipple tape is fine

I would also strongly suggest you get a different thermostat housing, the chrome ones can be a real treat to seal
 
The thread sealer goop is a little less likely to jack up your pump, but otherwise, the others covered it.
 
Isn't that fuel pump inlet a flare joint?
 
Isn't that fuel pump inlet a flare joint?

It does look like a flare joint to me inside, but the Holley docs say it's 1/4 NPT. Perhaps both?? Anyway, I'm connecting 5/16 fuel hose to it. The outlet is the same as the inlet, I'm expecting to go with a flare end hard line there.
 
But for real, engine builders like IMM suggest liquid teflon instead of teflon tape for the reasons listed in this thread.
 
On the stat housing I would drawfile the chrome off of the sealing surface. Wouldn't hurt to drawfile the manifold stat housing flange also (put a rag inside to catch fileings). dont overtorque the 2 bolts & I've had to use "the right stuff" gasket maker & a gasket to get em to seal tho technically TRS is a gasket maker as opposed to a gasket cement. drilling/tapping for new bolt holes at 6/12 0'clock is an option, for sure would not look OE but might do the job (ain't tried it yet). any antifreeze leak is a PITA
 
i know you havent asked yet, but since the timing cover is off, ill just mention not all of those holes are blind, so be sure to slap some sealant of your choice on there as you put it together
 
i know you havent asked yet, but since the timing cover is off, ill just mention not all of those holes are blind, so be sure to slap some sealant of your choice on there as you put it together

Thanks DIY, yes I used RTV on all those bolts/threads.
 
Filing the chrome neck's base (if they don't have an O-ring) usually doesn't work.
They just warp at the center from heat and will leak.
 
Keep the tape about 1 thread back from the end, you don't want pieces goofing up the fuel or water pump. The thing about Teflon tape, if you take it apart and reassemble it later, the pieces left behind in the female threads get pushed into the system. They'd foul up the check valves in the fuel pump.
This! Teflon paste not tape.
 
isn't teflon tape for use on pipe threads.Idea being reduced friction to
allow the tapered fitting further travel so it will seal?
 
Teflon tape, rtv, file the housing....Where's the bang your head on the wall emoji ?
 
What I posted about teflon tape is more of a personal preference. Most manufacturers of fuel oil pumps - commercial and domestic heating - say do not use teflon, fuel oil breaks it down, can ruin the pump, etc. So I avoid it professionally.
National pipe thread is tapered, and it is good practice to keep any sealant a half to full thread back from the end. In reality, once you install a water fitting in an intake, you'll likely never need to remove it again. Teflon is fine.
 
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