1998 Pontiac Transport Montana
3400 V6
Done to repair = Thermostat was replaced but problem still there
tech = JK
question = Hi, I have a 1998 Pontiac transport Montana. The heat will
go from hot to cold then back from hot to cold then the temp will rise
to hot then drop down to about 60 d then to about 100/110 and the heat
will blow hot for about 5-10 min then same thing all over again i
replaced the thermostat and the problem still there any help will be
appreciated thank you
JK
Sounds as if you are getting air in the cooling system. Some common causes of
this are leaking lower intake gasket, or blown head gaskets. The rear
headgasket is prone to this condition. From under the van, the pass. side of the
rear cylinder head may show signs of leaking externally. If that is the case, it may
also be pushing compression into the cooling system. Air in the cooling system
will affect the heater in the manner you have described. You may want to let
engine run with radiator cap off and look for bubbles. Or remove the spark plugs
and inspect for signs of burning coolant.
It is possible that the replacement of the t-stat fixed the heater problem, but you
have air in the system from that procedure. This would act as if you still have the
same problem, but in fact just need to bleed system.
Back
3400 V6
Done to repair = Thermostat was replaced but problem still there
tech = JK
question = Hi, I have a 1998 Pontiac transport Montana. The heat will
go from hot to cold then back from hot to cold then the temp will rise
to hot then drop down to about 60 d then to about 100/110 and the heat
will blow hot for about 5-10 min then same thing all over again i
replaced the thermostat and the problem still there any help will be
appreciated thank you
JK
Sounds as if you are getting air in the cooling system. Some common causes of
this are leaking lower intake gasket, or blown head gaskets. The rear
headgasket is prone to this condition. From under the van, the pass. side of the
rear cylinder head may show signs of leaking externally. If that is the case, it may
also be pushing compression into the cooling system. Air in the cooling system
will affect the heater in the manner you have described. You may want to let
engine run with radiator cap off and look for bubbles. Or remove the spark plugs
and inspect for signs of burning coolant.
It is possible that the replacement of the t-stat fixed the heater problem, but you
have air in the system from that procedure. This would act as if you still have the
same problem, but in fact just need to bleed system.
Back
