Car head gasket leak

Sealer normally wont' work in this type of thing. In the northstar engine if you mix the antifreezze mor than 50% it eats away the block and the studspull out of the block it will beeasy to checkby pulling a valve cover and try to tighten the bolts. You might want to try a junkyard and see if they have a cheaper alternative with another engine.

Head gaskets on these are not an easy job. Plan on spending 400$ alone just for the tool to install the new thread inserts, because the existing threads will not be good. Also, the easiest way to do this job is to remove the engine (drop the subframe-engine and tranny) at that point, you need to consider fixing the engine, or a junkyard motor. Id fix the current engine as it only has 85k on it. If you throw a boneyard motor in, who knows what condition it is in. Spend the money, get it fixed. While the engine is out, have them replace your thermostat, and waterpump to save headaches down the road.