Technical Y-Block Woes: Temp Sender Bung Leak

Looking for some free advice from any Y-Block guys. My problem is a coolant leak around the pressed-in bung in the cylinder head where the electric temperature sender threads in. Is this a common problem? And/or, what is the best solution? Any help is appreciated.


A little history: I bought a new SW temp gauge. The sending unit it came with had different threads than what was in the head (threaded bung pressed into head). In my infinite wisdom, I removed the bung/plug with a screw extractor and re-tapped it to accept the new sender (I was so proud of myself). I was careful when I re-installed it in the head.

I fired up the engine for the first time and coolant started seeping out from the bung; no leaks on the temp sender threads. I'm really kicking myself now, because I thought I was doing myself a favor by installing a brand new sender. Again, any help is appreciated.

 

If I understand your problem it is leaking above the threaded section where the sensor wire attaches too. If this is correct then the sensor is probably bad and will need replaced. I understand that it is not leaking from the threads so it is sealed good there.

 

Flex Seal

 

If what I’m seeing is correct it looks like you tapped it to deep?

 

Bars leak is your friend.

 

You can still get the adapters. A new one in a nice clean hole and some Loc***e should work.If it's really just a weeper then bars leak isnt an unreasonable fix.

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And you tried just plain old plumber's thread tape? I know the stuff is color coded, white for regular stuff, pink for petroleum based liquids, but the is one for hot water heaters that's pretty good. Or, Corrigan's Flex Seal idea. Other than your lower back, it can't hurt to experiment.

 

Alumaseal would be better than Barsleak.

 

Subaru coolant additive....looks like Barsleak but with smaller particles....Mandated by Subaru anytime the coolant system is worked on or after head gasket repairs. Meant to live for a few hundred thousand miles...would be right at home in our old clunkers.

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I would suggest K Seal
I have used it to seal a leaky Heater core and it stopped the leak for a couple of years now. Its not cheap about$12.

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you did use a pipe tap?I am pretty sure that is what you should have used.

 

Not a fan of radiator Stop Leak. Clogs heater cores, water p***ages and gets behind freeze plugs causing corrosion and leaks. I'd work at repairing the leak at the bung.

 

Only on one "Y" head,the bung press in leaked around the out side of bung. Turned out,I removed the bung and treaded head for a br*** add fitting that had come with my new temp sender. But all my other "Y"s did not leak. If it were me,an had to keep bung,I think I'd try tapping bung down in to head a little more{ like 1/16in.} too see if that stops,if not take it out/add sealer an tap it back in.

 

Ha, as seen on t.v.?!

 

Thanks for all of the input. I did use an NPT tap and it is not leaking from the threads, just the pressed bung. I never should have messed with it...

The stop leak stuff is very temping, but I ended up finding an NOS bung/plug and I am gonna try that with some loc-***e and a new original size sender.

Thanks again everybody.