68 Toronado intermittent heat
Posted: Thu Feb 22, 2024 8:08 pm
Fellow Toronado owners, I need some help with my 68. When I first start the car I get heat idling and even driving at 10mph down my mile long lane. The heat level is very hot coming out of the vents.....until it stops working. About a mile into highway speed, heat drops off and does not come back until I let it cool down and start it up again. By cool, I mean almost stone cold. If switch the temp bar from hot to cold there is minor difference in air temp...this after heat stops. After heat stops the temp when on hot is ever so slight warmer that when on cold but definitely not enough to stay warm here in Illinois, lol.
Some background information:
--It is the manual heat/ac control.
--Car has 43k miles.
--Coolant system is full and burped for air.
--Coolant system has been flushed. Flush
revealed some thin brown sludge...normal
amount from a flush. No sign of sealers
having been used.
--Radiator fluid is 50/50 mix.
--Vacuum lines are all soft and smoke checked.
No leaks.
--New thermostat, checked old one and it
worked fine. Both are 195 degree.
--4 season valve is new.
--Both hoses are hot going to heater core.
--I have checked all vacuum connections, as
well as the smoke check.
--I disconnected the heater core hoses and
blew air through it....air moved freely and very
little dirty brown came out towards the end. I
ran air till nothing came out except air.
--All vent choices work on the climate control.
--AC is charged and works fine.
--No kinks in hoses and all coolant hoses are
new.
-- No signs of a coolant leak anywhere, no
overheating and odd noises from anywhere
under hood or inside the car.
Since 1985, I have owned several 69 to 70 Oldsmobile Delta 88s and a 98. I have never encountered this problem before and I do not know what else to check. The fan motor works fine, however it blows at only high speed, it's either on or off, no adjustment. I doubt this is a factor in the heat issue.
Have any of you encountered this problem? Do you have suggestions as to what else to check? Any help is greatly appreciated.
Some background information:
--It is the manual heat/ac control.
--Car has 43k miles.
--Coolant system is full and burped for air.
--Coolant system has been flushed. Flush
revealed some thin brown sludge...normal
amount from a flush. No sign of sealers
having been used.
--Radiator fluid is 50/50 mix.
--Vacuum lines are all soft and smoke checked.
No leaks.
--New thermostat, checked old one and it
worked fine. Both are 195 degree.
--4 season valve is new.
--Both hoses are hot going to heater core.
--I have checked all vacuum connections, as
well as the smoke check.
--I disconnected the heater core hoses and
blew air through it....air moved freely and very
little dirty brown came out towards the end. I
ran air till nothing came out except air.
--All vent choices work on the climate control.
--AC is charged and works fine.
--No kinks in hoses and all coolant hoses are
new.
-- No signs of a coolant leak anywhere, no
overheating and odd noises from anywhere
under hood or inside the car.
Since 1985, I have owned several 69 to 70 Oldsmobile Delta 88s and a 98. I have never encountered this problem before and I do not know what else to check. The fan motor works fine, however it blows at only high speed, it's either on or off, no adjustment. I doubt this is a factor in the heat issue.
Have any of you encountered this problem? Do you have suggestions as to what else to check? Any help is greatly appreciated.