68 Toronado intermittent heat

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Dayton
Posts: 3
Joined: Thu Jun 01, 2023 7:23 pm
TOA Membership Number: 0
Years Owned: I own a 1968 Oldsmobile Toronado since May 2023
Location: Illinois

68 Toronado intermittent heat

Postby Dayton » 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.

Ourkid2000
Posts: 28
Joined: Sun Jul 02, 2017 4:58 pm
TOA Membership Number: 0
Years Owned: 1966 Toronado deluxe

Re: 68 Toronado intermittent heat

Postby Ourkid2000 » Fri Feb 23, 2024 10:06 am

Although I'm no expert, that certainly sounds like your heater control valve is acting up. I know you said yours is new but some of the experienced fellows I've spoken with tell me these new valves are often troublesome. There is a version of that valve available that can be physically manually closed or opened rather than by vacuum signal. It would be easy enough to throw one of those in there and set it to the open position and see how your heat behaves.

Or you could just cobble some kind of bypass together with pipe fittings that would do the same thing.
Last edited by Ourkid2000 on Fri Feb 23, 2024 10:13 am, edited 2 times in total.

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Otto Skorzeny
Posts: 1720
Joined: Fri Feb 28, 2014 12:41 pm
TOA Membership Number: 0
Years Owned: 1966 Toronado

Re: 68 Toronado intermittent heat

Postby Otto Skorzeny » Fri Feb 23, 2024 10:12 am

Yes, it sounds to me like your heater control valve is malfunctioning. There are several companies that rebuild those valves. I believe the Toronado one is a Ranco valve but it might be Harrison.

Here are a couple companies that rebuild these and actually have new ones in stock.

Joe Hudacek Rebuilder of Ranco and RobertShaw heater valves. New Ranco heater valves for sale
6606 Banks Avenue
Superior, Wisconsin 54880
715-392-6169
Cell: 218-213-8906
http://www.heatervalves.net/


Jim Tucker Rebuilder of Harrison and Ranco heater control valves. New valves for sale 1950 -1975
29597 Paso Robles Road
Valley Center, California 92082
760-749-3488
http://www.heatercontrolvalve.com/

Dayton
Posts: 3
Joined: Thu Jun 01, 2023 7:23 pm
TOA Membership Number: 0
Years Owned: I own a 1968 Oldsmobile Toronado since May 2023
Location: Illinois

Re: 68 Toronado intermittent heat

Postby Dayton » Fri Feb 23, 2024 11:16 am

Thanks guys. I will get another valve and see about a rebuild on the old valve.......although I am not sure whether that old valve is the original. I kept it just in case it was.

As to a manual valve....I had never heard of one being sold anywhere. Building one wouldn't be too hard.

Today or tomorrow, depending on time i have, I am going to unhook the heater core hoses and flush the heater core separately using vinegar. I have used vinegar for many types of cleaning....works well. Then see what happens when I hook it back up. If doesn't work, move on to valves.

I am wondering, after reading through the service manual, about the possibility of doors in the heater core area not working correctly. Is it possible one of those is operating incorrectly? If so, what diagnostic steps do I take to start checking those? (Assuming that may be the problem)

Dayton
Posts: 3
Joined: Thu Jun 01, 2023 7:23 pm
TOA Membership Number: 0
Years Owned: I own a 1968 Oldsmobile Toronado since May 2023
Location: Illinois

Re: 68 Toronado intermittent heat

Postby Dayton » Fri Feb 23, 2024 11:21 am

Searching, I found manual valves. I am surprised I never heard of these, though I had never looked. I am going to order one.....it will be a great tool for diagnostic purposes.


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