02 Montana Coolant leak?

Question

So after smelling coolant for a few months (no noticeable leaks), I finally have a 2x2 ft puddle in my laneway.

Coolant is understandably low, both in the reservoir and the rad cap/top. Upon removing the rad cap, there is a bunch of GUNK, like black rubbery goo, and lots of it. The van still runs Dexcool. While running, there are no visible leaks from any rad hoses or the water pump.

Any ideas where it's coming from? And what is the gunk (we are talking big tablespoon size chunks)?

Thanks:)

02 Pontiac Montana EXT

3.4 litre 125,000kms

Answer 1

The black goo is from a product called Bars Leaks, which someone has added, usually more than one little bottle.  Somebody wanted to plug a leak, and that is only temporary!

There is a small chance of intake gasket leak, as was common on older 3.4's, but GM was suppose to have corrected that by 2001 or '02.

Also, have your heater core checked.  It is a job for the pros, or a Rad Shop.

Answer 2

dexcool does this from  when the engine was built we use acid to clean out gm dealers sell this in parts department and if it dont come clean you will have to replace radiator,thermostat,heater core check with gm dealer for a recall on it this is NOT cased by stop leakand where is leak left under motor toward back you need to have more info. than left

Answer 3

Rather than guessing go to a RADIATOR SHOP and find out for sure and get it fixed.

Answer 4

Does it have a rear heat/air cond. system? If so, it could be leaking from one of the lines that runs to the rear system. You will know if it has one if there is a switch for the rear fan speed on your dash.