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Topic: Heat

in Forum: C3 Cooling and Heating Systems


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Heat (1/10)
 1/7/10 1:37pm
jp75vette
Former Member

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Bloomfield Hills, MI - USA

Vette(s):
1975 Corvette coupe, 4 speed manual, 383 ci 9.5:1,Edelbrock dual plane Air Gap intake, Alum Heads,Comp Cam, roller Rockers, PS,PB,Tilt


Joined: 6/29/2008
Posts: 199

Which way does the water flow through the heater (no A/C on my vehicle)? There is a 5/8" hose that goes to the intake manifold and a 3/4" hose that goes to the water pump.

 
I have a 195 degree thermostat,  and I get some heat, but not a lot. I replaced the shutoff valve in the 5/8" hose, but it did not improve the situation much. I'm thinking of taking the valve out just to see if that makes a difference.
 
One other thing that I'm thinking a bout is that the heater core may not be working due to residue buildup inside or maybe even bloackage. I do not want to remove the heater core just yet so am wondering if there are any effective cleaner products that will maybe clean out the residue.
 
I need the heat in Micigan as I still intend the drive the car when the roads are dry.
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Heat (2/10)
 1/7/10 2:59pm
Ron 78Lifetime Member
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BINGHAMTON, NY - USA

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Joined: 7/19/2003
Posts: 3808

Ain''t that just the way it is,in the summer time when you don't want it ,it's hotter than hail in your Vette,in the winter time you freeze your bells offLOLLOLLOLLOLLOL .you can try to flush out the core it self by taking off both heater hoses and with a garden hose flush it out in reverse.but if it is really plugged and you try a full engine flush it usually totally plugs the core and you end up replacing it anyway.I think the hose coming from the water pump is the inlet line into the core,if I'm wrong somebody jump in and correct meRon 782010-01-07 12:08:02

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Heat (3/10)
 1/7/10 8:51pm
kstyerLifetime Member
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CUYAHOGA FALLS, OH - USA

Vette(s):
1975 C3 Red, T-Tops, Black Interior. All I need is time and money! Getting there!


Joined: 12/2/2003
Posts: 6424

Yep, a good flush will probably take care of it.   If both hoses are not very hot, as hot as the radiator hoses after full warm up, the core is blocked.kstyer2010-01-07 17:53:11
Heat (4/10)
 1/8/10 10:40am
my7t1Lifetime Member
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Dorr, MI - USA

Vette(s):
71 Colonnade Hardtop Coupe Torch Red with black interior originally L48 built to push around 360hp


Joined: 8/21/2002
Posts: 2581

You stand corected there Ron. The hose comming from the intake is the inlet or hot side. If you want to back flush you go into the water pump hose. If the core is plugged inlet hose will be hotter than the outlet. Be careful of chemicals. Some may be corrosive. I owuld just try flushing it with water. I have an advantage in my shop as I have a flush machine that pulsates water and air.

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Heat (5/10)
 1/8/10 11:24am
DaveMLifetime Member
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Flanders, NJ - USA

Vette(s):
1982 Black, ZZ4, Hooker Side Pipes, 3.55 Rear, Rebuilt & upgraded 700R4, All new suspension, brakes, & new Charcoal interior.


Joined: 1/27/2004
Posts: 2552

Disconect the hoses from the engine then back flush, you don't want any of that crap getting pushed into your cooling system. Good luck.
Dave


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Re: Heat (6/10)
 1/5/16 5:21pm
my80Vette
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Dacula, GA - USA

Vette(s):
1980 Corvette White and Black with Black interior. 350 V-8 Auto


Joined: 7/18/2015
Posts: 33

Not sure if this is same problem. But my sons 78 with air is only blower cold to Luke warm air on hear/defrost/vent. Not sure where to start. Any advice would be greatly appreciated. Thanks
Re: Heat (7/10)
 1/6/16 5:50pm
Vman73
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Gig Harbor, WA - USA

Vette(s):
1973 L82 4 Speed Coupe - Very original, well documented driver/survivor. 2016 Bend Regional NCRS Top Flight.


Joined: 10/2/2014
Posts: 405

my80Vette said: Not sure if this is same problem. But my sons 78 with air is only blower cold to Luke warm air on hear/defrost/vent. Not sure where to start. Any advice would be greatly appreciated. Thanks

I would begin with a flush of the heater core as described in the posts above. Follow that with a separate flush of the radiator and engine block. If nothing appears to be blocked, reconnect and refill. Warm to temperature, make sure your thermostat is opening and double check the temps of the hoses to and from the heater core. 

Your sons car may also have a cut off valve installed on one of the hoses to the heater core. That valve shuts the flow of hot coolant to the heater core when the A/C is on, make sure the valve is opening properly to allow flow to the heater core.

Good luck and let us know what you find.    


|UPDATED|1/6/2016 2:50:00 PM (AZT)|/UPDATED|


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Re: Heat (8/10)
 1/7/16 10:43am
dwa175
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leesburg, FL - USA

Vette(s):
1979 coupe and now 2007 c-6


Joined: 7/19/2014
Posts: 195

if I remember right there is a heater control valve rs below exhaust manifold  works in vac  I replaced it because I didn't like the way it looked,i don't drive this in winter in conn but insummer this car is hotter then hell. I would not use anything to back flush  water only,chem open the road to bad things   read post   most want is written is true     hope it works ,take your time.dwa175
Re: Heat (9/10)
 1/8/16 12:41pm
Kentvetteuk
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, - France

Vette(s):
1978 L48 Auto. Red with Oyster Leather interior. Owned since 1990.


Joined: 8/21/2002
Posts: 83

Not sure about the '73, but by '78 the heater system also has "doors" that regulate heat entering the car.  Our own 78 suffered a loss of heat last spring and the reason fr that turned out to be that the cable had come adrift of the control lever, positioned behind the glovebox. 

So, if the inlet and outlet hoses are both hot, check the operation of the heat control lever by taking the glovebox inner out and watching the lever move as you operate the control.


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Re: Heat (10/10)
 1/8/16 1:35pm
dwa175
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leesburg, FL - USA

Vette(s):
1979 coupe and now 2007 c-6


Joined: 7/19/2014
Posts: 195

yes   my 79  cable broke   a pain in the---        but replaced, that works fine dwa175
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