coolant leak ?

Discussion in 'General Chevy & GM Tech Questions' started by dsquared, Nov 30, 2009.

  1. dsquared

    dsquared Member

    I have a 97 K1500 w/230K miles. My question is how often should I have to top off the coolant expansion tank? I don't have any obvious coolant leaks(oil looks OK, no drips, no white smoke in exhaust) but was wondering how much I would loose to evaporation in expansion tank. I seem to have read about a coolant system pressure check that Autozone would do, is that the best way to check for leak?
  2. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    You should never have to top off the coolant. If it's using coolant you have a leak. The best way to check it is a pressure test cold. You can borrow the tester from Auto Zone and test it cold. If you test it hot it may not leak. If you can't find a leak cold you may have a combustion leak which can be sniffed out with by someone who has a smog station tester.
  3. dsquared

    dsquared Member

    If there is a intake manifold leak then it could get into the oil or the combustion chamber correct ? If in the oil there would be some evidence by looking at the dipstick am I right ? If in the combustion chamber could it be small enough to not produce any white smoke ?
  4. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    Correct. If it were leaking into the oil you would see moisture on the dipstick and cloudy looking oil. In the combuston chamber it would burn up and be hard to see in the exhaust.
  5. dsquared

    dsquared Member

    Back to the original question, would you not have to top off the expansion tank due to evaporation, especially in the summer ? Even in the winter with the hood closed all the engine compartment heat would tak e a while to dissipate leading to evaporation or am I off base ?
  6. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    Everything evaporates to a degree, even your engine oil! :)

    My coolant probably evaporates about 1/8" a year.
  7. dsquared

    dsquared Member

    That's very little indeed. My coolant "loss" is probably an inch or so in one month. Need to watch it more carefully such as park in the same place and check with engine cold and really monitor more precisely. Obviously Ii have a leak somewhere in the system. I'll pick up a pressure tester this weekend. How much pressure should I use and would this accelerate the leak permanently forcing a possible IM gasket repair sooner than later ?
  8. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    The pressure will be less than what your truck is running hot right now so the test can't hurt anything. Just pump it up to 15 ibs. That should be plenty of pressure to find the leak cold.
  9. kidashley25

    kidashley25 New Member

    The first thing to do is isolate the problem. Is it coming from the radiator, one of the radiator hoses, one of the heater hoses, the engine, or out from under the dashboard? Once you have answered those questions, you can move to the next step. If it's a hose, replace it (now would be a good time to replace all of them). If it's coming from the radiator, take it out and have it fixed. If it's coming from the engine, pour in some Bars Leak and sell the car. If it's coming from under the dash and your carpet smells like antifreeze, your heater core is shot. This one can be really easy to fix, or really difficult, depends on the car.

    The best thing is to isolate the problem and fix it. If your lucky it may just be a hose. Avoid stopleaks - they can gum up your radiator and especially your heater core.

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