pinhole leak in coolant expansion tank

[92EcoDiesel Jetta]

I still have a temporary pressure gauge plumbed in at the coolant expansion tank from when I was sorting out leaks at the coolant flange (since fixed). It would read anywhere between 5 to 17 psi depending onhow hot the engine is. A few days ago, I noticed no pressure registering on the gauge. and some wetness from the expansion tank. A closer inspection revealed a pinhole leak at the top of the expansion tank about 1/2" from the cap. Is this a usual failure of the expansion tank? What's it made of? Polyethelene or Polypropelene? I'll have to order a new one, good they are only about $13. I think I may plumb the coolant pressure gauge permanently into the dash. Anyone done that?

[jtanguay]

if its on the tank itself why not use a soldering iron or heat gun?

[92EcoDiesel Jetta]

if its on the tank itself why not use a soldering iron or heat gun?

I thought about doing that to save a few bucks but it seems the plastic is old and stressed from too many expansion / contraction cycles and new leaks may develop. What I don't want is the tank coming apart resulting in total coolant loss and an overheated engine.

[Rabbit on Roids]

if you fix it and it still leaks, you are not out any money. if it leaks again or yo ucant fix it, throw it away and get another one.

[92EcoDiesel Jetta]

I patched it just to see if it'll work but I am still going to replace the expansion tank. I sanded the pinhole then wiped clean with alcohol, apllied 5 min JB weld over it. the JB weld did not want to stick to the plastic and I had to rub it it before it'll stick. after it cured I applied some Loctie gasket sealant over the epoxy. I'll take it for a drive later and see it it'll hold pressure.