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Old 08-12-2017, 01:20 PM   #1
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Default Coolant Leak

I was wondering if anyone can help me. I feel like Im at such a loss right now. I own a 1999 Chevy Tahoe 5.7L and yesterday it was spitting and sputtering acting like a loss of power. I pulled out the spark plugs and noticed they had some oil and coolant on them so I changed all plugs and then also changed the air filter at the same time. Everything seemed ok after that. This morning I started the truck and was on my way to the county fair with my kids about 30min away and I got 1/2 way there and stopped at a gas station to get something to drink. I came out of the store and noticed something leaking so I crawled under the truck and stuck my hand out and coolant was dripping onto my hand coming from the back of the engine. We quick headed for home and got home safely but as soon as we put cardboard under the truck the leak began to get worse and worse within moments. Yesterday when we replaced the spark plugs and air filter the coolant res tank was right on the COOL line so we know everything was ok then but this morning its leaking bad. I took a bunch of photos while under the truck hopeful someone can help point me in the right direction. Just boggles my mind that the levels were great last night and now this morning it does this out of the blue. I hope my photos can help someone help me. I dont have the funds to go to a mechanic. I am pretty mechanical myself but just cant figure out where the leak is coming from. Thank you in advance for any help someone can provide.
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Old 08-16-2017, 10:19 AM   #2
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Sounds like an intake manifold gasket or a head gasket, or both. The head gasket can cause both oil and coolant in the cylinder. The intake gasket would typically be just coolant in the cylinder, and leaking out the back, but if the gasket broke in the right place, oil could be vacuumed up from the oil galley into the cylinder.

When you turn off the engine, pressure will build in the cooling system due as it's absorbing heat from the engine still, but not flowing. So seeing a leak a few minutes after shutting off the engine indicates some part fo the cooling system is failing on the higher pressure.

I'd start with pulling the intake and inspecting, then replacing the gaskets. You'll have three gaskets on the Vortec - one on the upper plastic manifold, and two on the lower (one for each side against the heads).
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Old 10-23-2017, 02:05 PM   #3
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Mine had the same problem. Almost. It was not leaking, but the water disappeared. At the end it was the intake gasket which was broken in direction to the firewall.
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