I've loved this car but it's given me persistent cooling system problems with no end in sight. I think I'm finally going to retire this one. I've had water pumps, hoses, radiators (!!) and gaskets replaced and it's still leaking and causing problems. Everything else has been more than fine, so this is frustrating. (145k miles) It's very hard to work on this car because everything is packed in so tight and in difficult spots to reach. Small tasks can take multiple days.
The primary cooling system leaking problem is the lifter valley gasket under the intake manifold.
The owner's manual specifies that cooling system sealer be in the system at all times, and that it be renewed when the coolant is changed. GM recognized the problem but instead of fixing it relied on sealant!!
A car enthusiast friend recommended strongly that the Dex-Cool be dumped and replaced by regular or "compatible with any coolant" type coolant.
My radiator died, so I replaced it. New hoses of course.
The trans died - the final drive gears stripped - so I replaced the transaxle with a boneyard unit. The problem, according to a transmission rebuilder of many years' experience, is that the pipe that carries fluid from the pump to the gears comes loose, cutting off the supply. The gears, running without lubrication, eventually strip. When I replaced the trans I made sure to replace the flexible tubing connecting the two sections of the lubrication pipe. I crammed the "rubber" tubing in so that it pushes the pipes into their seats. I hope that this will make up for the shrinkage of the tubing that was why the pipe was pulled out.
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