Had internal leak of antifreeze in the top half of the intake. Replaced head gaskets on up. Still have the same problem of internal leak
just replace whole plenum
Replaced the upper intake manifold as described in the official shop manual and the vehicle still won't start.
also the antifreeze will pit and destroy your rod and crank bearings '' may result in engine rap (rod knock) reduced engine life after repair
WATER WAS MAKING ENGINE MISS JUST BEFORE WOULD NOT START. ALSO HAD LOST LITTLE WATER AT A TIME FIRST.MOTOR SERVICE FIXED. ABOUT 250.00FOR PARTS AND LABOR JUST ABOUT SAME... SHOULD NOT HAVE TO PAY FOR CRACK IN PLASIC.....FACTORY MESS UP>>>>>>>> KENNETH BOYNE, CAR RUNS FINE NOW...
Just had the same problem with my son's car, $596 later to replace plastic upper plenum, seal, spark plugs, oil filter and oil change. Car would turn over but not start.
Same issue, coolant in the piston chamber, no help on a solution from GM. I'm in the process of a fix, probably need to get a new upper intake manifold.
My car is 1989, 300,000km, and from BC Canada. Last winter a o-ring near lower radiator hose developed leak. Car overheated and thought head gasket was shot. Before I got to fixing it car got to point it wouldn't start. Turned out to be hydro-lock. Could see slight bit of anti-freeze on side of the head so could assume that if it was hydro-lock which spark plug to take out. Car started really rough. Let it run for a bit and it cleared up some of the moisture. Turned off. Checked other plugs for moisture in the cylinders. When it comes right down to it we ended up just replacing the intake manifold gaskets and it's been good since.
At 95,000 miles I had this same problem. I replaced intake manifold cover. It happened again at 190,000 miles. The new cover has modification that should help. The standpipe that routs the exhaust gas through that area has been made smaller so that it does not touch the plastic manifold cover and thus keeping the intense heat away. You should stake the standpipe into the aluminum manifold to keep it in place.