heater cold.

[ncguy89]

ok guys i have a 84 chevy c30. the heater blows cold even when the truck is up to temp. the hoses to the heater core are warm but not hot. i know the thermostat is good, iv checked most connections behind the dash that i could see. im running out of ideas. i have checked all vaccum lines and nothing. any ideas on what it could be? could the heater core be clogged up?

[454Man]

Have you ever used any stop leak additves?

[ncguy89]

not since i have owned the truck. idk if the previous owner did or not.

[bd]

...the hoses to the heater core are warm but not hot.  i know the thermostat is good...  could the heater core be clogged up?

At operating temperature, the heater hoses should be as hot as the radiator hoses.  If the radiator hoses are hot and the heater hoses aren't, you probably have compromised coolant flow through the heater, aka plugged core.  Hence the question...

Have you ever used any stop leak additves?

On the other hand, if the radiator hoses never get hot either, there's a thermostat issue.

[454Man]

Very true

[ncguy89]

ok, so i know the thermostat is good i replaced it twice and no difference, also have a temp gauge threaded into the thermostat housing and it wont read until the thermostat opens and then it runs at about 190 to 200. i have pulled the hoses and flushed the core and got a nasty mud pile outta it so i replaced the heater core and still no difference (just a fyi it took pressurized water to get this mud to even budge from the heatercore the rest of the system is clean). it seems to take forever for this truck to get up to operating temp but after about 5 minutes of driving it will. i have literally tore this interior apart to no prevail of any vaccum leaks nor any seized up parts in the duct system. im lost.

[ncguy89]

also in the middle of changin these thermostats i left it out and sealed it up and drove it for 20 minutes and acted like it wanted to get a smidge warm but as soon as i stopped and let it idle it would go back to ice cold.

[bd]

Don't take offense to this question: is the cooling system clean or swampy?  How many rows is the radiator core?  What kind of radiator fan setup?  Post a pic of the heater hose routing and connections to the engine.  Depending on how cold it's getting where you are, if the heater is blowing hot after 5 minutes, there really may not be a problem.  Or, you may need to install a winter-front to restrict airflow through the radiator in the winter months.

[Captkaos]

When you are refilling the coolant after the thermostat change did you make sure you actually filled it up completely?  It's possible that you have air trapped in the system.

[caliphatman8123]

I've done that on my grand prix when I lived in WI and didn't realize it... froze on the way home from work at 6am in the morning... easy fix but pain when it's 40 below...lol:o

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[84burb]

There are a couple things which could be causing your problem that haven't been addressed yet.

The location of the hoses is based on a stock 84 small block configuration. There can be an infinite number of variations, however, the basic principals of the coolant flow remain whether you have a different setup or not.
1 - Are your hoses hooked up correctly.
The 5/8" supply hose (pressure side) should be connected to a fitting on the intake manifold next to the thermostat housing.



The 3/4 hose is the return side of the system. It should be connected to a bung on the right hand radiator tank directly below the radiator fill.



If the coolant level is low enough in the radiator, you can take the cap off and see if there is coolant flowing through the heater by watching how much is coming into the radiator. Even when the engine is cold. There should be coolant flowing through the heater whenever the engine is running. This acts as a bypass for the coolant so there is not an excessive buildup of pressure before the engine warms up and the thermostat opens. Alternativly, the return hose could be connected to a fitting at the top of the water pump.

2 - You said you "got a nasty mud pile" out of the heater core. That can be a sign of restricted coolant flow, as there is not enough volume in the hoses to keep it flushed out.
Check the fitting on the intake/waterpump to see if it hasn't gotten partially plugged by rust, corrosion, or "nasty mud".  You should probably pull the fitting out as the bottom of it is where the buildup is usually worst and can't necessarily be seen by looking down from the top.

[ncguy89]

been busy lately so havent had time to do anything. ok now to answering questions.

Don't take offense to this question: is the cooling system clean or swampy?  How many rows is the radiator core?  What kind of radiator fan setup?  Post a pic of the heater hose routing and connections to the engine.  Depending on how cold it's getting where you are, if the heater is blowing hot after 5 minutes, there really may not be a problem.  Or, you may need to install a winter-front to restrict airflow through the radiator in the winter months.

the coolant system has been flushed and new coolant put in since new heater core was installed and replaced water pump as it was seeping from the hole on bottom. i had the radiator boiled out before reinstalling and its a factory radiator. it has a fan w/ clutch on it. everything is hooked up exactly as it was last winter when  the heater was working.

When you are refilling the coolant after the thermostat change did you make sure you actually filled it up completely?  It's possible that you have air trapped in the system.

i used a pressurized machine to flush the system and even left the cap off and let it idle for almost 5 minutes and im positive its completly full. the heat stopped working after i installed the new intake and carb. but i hooked everything back up exactly like it came apart.

There are a couple things which could be causing your problem that haven't been addressed yet.

The location of the hoses is based on a stock 84 small block configuration. There can be an infinite number of variations, however, the basic principals of the coolant flow remain whether you have a different setup or not.
1 - Are your hoses hooked up correctly.
The 5/8" supply hose (pressure side) should be connected to a fitting on the intake manifold next to the thermostat housing.



The 3/4 hose is the return side of the system. It should be connected to a bung on the right hand radiator tank directly below the radiator fill.



If the coolant level is low enough in the radiator, you can take the cap off and see if there is coolant flowing through the heater by watching how much is coming into the radiator. Even when the engine is cold. There should be coolant flowing through the heater whenever the engine is running. This acts as a bypass for the coolant so there is not an excessive buildup of pressure before the engine warms up and the thermostat opens. Alternativly, the return hose could be connected to a fitting at the top of the water pump.

2 - You said you "got a nasty mud pile" out of the heater core. That can be a sign of restricted coolant flow, as there is not enough volume in the hoses to keep it flushed out.
Check the fitting on the intake/waterpump to see if it hasn't gotten partially plugged by rust, corrosion, or "nasty mud".  You should probably pull the fitting out as the bottom of it is where the buildup is usually worst and can't necessarily be seen by looking down from the top.

as stated above i done a pressurized flush and replaced water pump and had radiator boiled out and it has a new heater core so i would figure its clean. the mud pile in the old heater core would not budge without putting a pressure washer tip in it so it was clogged and hard as a rock. i wouldnt figure the system would be clogged any more i havent had any overheating problem or anything.

[VileZambonie]

So you replaced the intake and then noticed the problem? What intake did you put on? You know there are different intake manifold gaskets right?

You may have already answered this but how are your hoses routed to the core?

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[454Man]

What degree t stat are you using? It looks like you have the supply line coming from the intake and the return going to the radiator.

[ncguy89]

So you replaced the intake and then noticed the problem? What intake did you put on? You know there are different intake manifold gaskets right?

You may have already answered this but how are your hoses routed to the core?

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i put a edelbrock performer intake on to swap it over to 4bbl. it had a 2bbl on it. i used felpro intake gaskets for my engine.

What degree t stat are you using? It looks like you have the supply line coming from the intake and the return going to the radiator.

im using a 195 t-stat.