It is real common for these engins to blow head gaskets at around 100K miles. I also recommend you don't even start the engine again until you fix the problem. While the heads are off, have the valve guide seals replaced. This is another common problem on these engines. You will have the timing belt off so might as well replace it. This is more work, but you might as well fix it also. I would also replace the water pump unless you know it has been replaced. Actually, that goes for the belt also. The timming belt runs the water pump. I have had several of these engines in Caravans, all with over 200K miles, and all ran great.

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84 500 SEL (307,xxx miles)