brass fittings leak

[JimHo]

I have an A4 with a Moyer fWC conversion. The coolant fittings are all brass and leak.

I plan on rebedding them with new pipe dope, but though I'd ask here before I start to see if you all have a better idea.

Thanks - Jim

[Al Schober]

Jim,
Pipe threads will leak if they're not sealed. The shape of the threads goes metal to metal on the flanks, leaving a leak path at the root and crest of the threads.
Personally, I use the Permatex blue RTV silicone for water connections. I don't like the Teflon tapes.

[JimHo]

Thanks Al - I will give that a shot.

By the way, these were installed by the previous owner and there is signs of a dope on the threads - though I don't know what kind. Also, anecdotally, the leaking seemed to get worse in late fall when the temperatures dropped.

[marthur]

The cold weather thing makes sense. All of the copper based alloys (brass, bronze) will expand and contract more than ordinary steel. That means they will loosen slightly in the steel engine.

I used this property to get my old bronze temperature sender out of the block a few years ago. Ken's excellent suggestions about a 6 point socket and breaker bar were almost but not quite enough. So I warmed up the block by running the motor and applied dry ice to the sender. It was just enough to get it out with a mighty heave on the breaker bar.