Sonoma is smoking and leaking coolant

Discussion in 'GMC Truck Forum' started by travisr528, Jul 9, 2011.

  1. travisr528

    travisr528 New Member

    Jul 8, 2011
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    Ok let me start at the beginning. One day I was driving to the store about 1mile from my house. I noticed that the smoke was coming from under the hood and the temp was about 245-250 degs. I quickly pulled over popped the hood to inspect. I noticed white smoke coming from the back of the engine. I was low on coolant and my oil was a quart low as well. I filled them both and drove home. I drove home with the ac off so I could listen for any unusual noises, just before I pulled into my driveway I turned on the ac and then my truck died. I notice the water pump was leaking through the weep hole when i got home and parked.

    Ok so I replaced the thermostat (failsafe) and the water pump. Worked fine for about a week then I noticed it started run a little hot again. Coolant was low again. I filled the coolant again in both the radiator and the reservoir tank. The next day I started the truck and noticed white smoke pouring out the tailpipe. I started driving and within 5 minutes or about .75 miles it stopped. That evening I got home removed the thermostat and found that it had failed in the open position. Oh another thing I forgot to mention is after replacing the coolant when I changed the wp and t-stat I hear a bubbling noise from the reservoir tank every time I turned off the truck. So I bought a gm t-stat to replace again. While I was working under the truck I notice the coolant was leaking on the right side of the engine and could follow it where it was dripping but I can not see where it is originating from, it is not coming from a hose or a connection from what I can tell. I don't see any oil in the coolant and I don't see any coolant in the oil. The leak seems to be on the engine it self. Is this possible?

    I am also experiencing rough starting and it sounds like it is sputtering when I first start it up. I give it some gas and it sound better. I change the plug, wires, and coil packs with no improvement.

    Any ideas as to what is wrong? Please help me.
  2. kronhenry

    kronhenry Senior Member

    Apr 21, 2011
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    you didnt pour the coolant in while it was hot did you if so its possible you may have cracked the head or the block
  3. leolkfrm

    leolkfrm Full Member

    Mar 2, 2008
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    sounds like at least the head gasket is blown, pull it and have the head checked
  4. chevychase

    chevychase Senior Moderator Staff Member

    Oct 15, 2010
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    Yeah sounds like you have a gasket blown... leaking into cylinders ... but not oil side.
    May have warped heads when you got it hot.
  5. zombie1969

    zombie1969 Senior Member

    Jun 30, 2010
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    You could try stop leak.My grand am started leaking 3 years ago and hasn't had a problem since.

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