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Thread: Mysterious coolant leak

  1. #1
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    Mysterious coolant leak

    99 3.8 as you guys probably know by know, I replaced a leaky water pump last month (with a NEW, not a reman unit) and over the last year or so have replaced EVERY hose in the cooling system.

    what I'm getting is a slow coolant leak, about a cup worth every few days, nothing ever shows on the ground, It only happens when the car is running, because within a few minutes of shutting the car off the coolant odor dissipates, I just noticed what looks like some coolant on the front edge of the k-member, like what happened when the water pump went out last month and for the first few minutes after shutting the car off I can here a drip ....... drip ...... drip sound coming from the passenger side of the motor and that is where the odor seams to be coming from but I can't find it. Any ideas?

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  3. #2
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    well I found one leak, where the lower radiator hose goes into the block the clamp was loose. tightened it up, we'll see if thats all.

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    OK, still leaking, I was under the car yesterday and noticed a small drip of coolant falling off the transmission inspection plate or whatever that cover on the front of the trans is called. Where could that coolant be coming from?

  5. #4
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    Rear of intake manifold gasket?
    2000 Camaro Y87 3.42s, Built L26, 10:1, ST5 cam, GT35R stock T5. [email protected] RIP 6/21/14.

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    OK, a little update, I'm losing about half a gallon of coolant per week (approx 280 miles worth of driving) and this past weekend I did my oil change and replaced the PCV valve, the oil drained from the oil pan was good and dark like normal used oil but when I pulled the PCV valve it was coated in "chocolate milk" colored oil, would this point to the intake manifold gaskets? My new work schedule doesn't give me the time I need to take it to a mechanic but I would like to as accurately as possible describe the known issues when I put this thing up for sale in a few weeks.

  7. #6
    (╯□)╯︵ /(.□ . \) Sparky's Avatar
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    Not sure on the PCV valve but I know you can get that kind of funk on the oil cap due to moisture and oil vapor mixing. Could be same reason, especially if the car is driven on shorter trips.

    Only external locations I can think of for coolant to be dripping from towards the back would be those heater hose connections at the firewall. Other than that, I guess a gasket leak.
    - Jared
    1999 Camaro 3.8L A4. Cammed, so kind of fast.
    2007.5 Silverado LT Z71 5.3L 4x4. Slight lift, bigger-ish tires, not a slouch but slower than the car.


  8. #7
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    Quote Originally Posted by Sparky View Post
    Not sure on the PCV valve but I know you can get that kind of funk on the oil cap due to moisture and oil vapor mixing. Could be same reason, especially if the car is driven on shorter trips.

    Only external locations I can think of for coolant to be dripping from towards the back would be those heater hose connections at the firewall. Other than that, I guess a gasket leak.
    drive to work is 30 minutes
    drive from work to town for lunch is 20 minutes
    drive to town after work is 20 minutes
    drive home from town is 10 minutes and occurs within an hour after driving to town from work
    on the weekends it's the 10 minute trip to town a short hop and then the 10 minute drive home

    car normally warms up to temp in like 5 minutes so I don't think my drives are short enough to be causing that kind of lack of burning off, it didn't look like this the last time I changed it, the spring was "clogged" up with the same type of gunk that builds up on the oil cap you speak of but the oil on the PCV wasn't like this the last time.

    I doubt the drip is coming from the heater hoses, I would have noticed that but will double check tonight, does the 3.8 have any freeze plugs on the back of the motor? if not then I would say it must be the gasket.

  9. #8
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    Sounds like you have two problems if your losing that much coolant and it only happens when the engine is running it is probably a head gasket. The other problem is likely a small drip coming from somewhere. Do a compression check on the engine to determine if you have a blown head gasket.

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