69 GTO 400cid is getting coolant into the #4 intake port.
Asked by mcajda Nov 28, 2015 at 06:18 PM about the 1969 Pontiac GTO
Question type: Maintenance & Repair
It sucks down 1/2 gallon of coolant, in a
short drive, with white smoke from the right
tail pipe. Pulled the intake off and there was
a puddle of coolant on top of the intake
valve. Replaced the intake gasket, thinking it
was bad. That was no help. 2nd time apart, I
see the coolant ports are not close to the
intake port for that cylinder.
I don't see any cracking in the intake port,
but I can't see any other possibilities.
Any ideas?
4 Answers
Bad head gasket probably. A warped head is another possibility. Has the car been overheated recently?
Head? What if you used tracer dye, then took it apart and inspected the port with a black light? If there is no upstream source of coolant, it has to be from the cylinder or from the head's water jacket. a crack by a valve can show up on a vacuum gauge. a crack between the valves should leak during a pressure test with those rockers backed off closing both valves. If it is easy, you can slip the head, If the head is suspect and you have money, not patience, theres magnafluxing and pressure testing.
during in-car testing, cranking with the plug out clears the accumulation. after repair, cranking with small amounts of oil can raise lost compression. if the mess in there affected it. My guess is that cylinder head goesto a very well equipped machine shop with locally recommended machinists.
Head gasket? what? then it, what, splashes up while the valves are open? from the piston, but on the intake port? the piston travels down while the intake valve is open, right? or is there some way that pcv, breather, or CCV hose redeposits coolant and lets it in through the intake? My experience is prior to the year, difficult for me to picture the assembled unit. sorry , dont mean to confuse you guys.
