73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Interior & Equipment => Heating, Ventilation & Air Conditioning (HVAC) => Topic started by: ncguy89 on November 09, 2012, 01:36:22 pm
-
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?
-
Have you ever used any stop leak additves?
-
not since i have owned the truck. idk if the previous owner did or not.
-
...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.
-
Very true
-
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.
-
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.
-
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.
-
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'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
Sent from my SAMSUNG-SGH-I717 using Xparent Blue Tapatalk 2
-
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.
(http://jburtphotos.com/images/heaterhose1.jpg)
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.
(http://jburtphotos.com/images/heaterhose2.jpg)
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.
-
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.
(http://jburtphotos.com/images/heaterhose1.jpg)
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.
(http://jburtphotos.com/images/heaterhose2.jpg)
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.
-
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?
Sent from my EVO using Tapatalk 2
-
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.
-
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?
Sent from my EVO using Tapatalk 2
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.
-
x 2 on the intake gaskets, did you make sure it match up to the water passage for the t-stat housing.they can slip also and get gasket sealer blocking passages ,especially using rtv
-
I doubt the wrong intake gasket would cause the heater to quit working. If that were true, you would have other, more obvious problems than the heater. Like water in the oil or a vacuum leak.
5 minutes to get the engine to temp sounds about right.
Getting the heater to work is really pretty basic and has few moving parts.Let's go back to the beginning and see if we can't do a diagnostic and pinpoint your heater problem. Please don't be offended but this is going to get really basic but don't skip a step. I know I sometimes have to backup and start at step one. :o
The engine cooling system seems to be working correctly. Warming up to temperature and not overheating.
We still haven't confirmed if there is actually coolant circulating through the heater core while the engine is running. (warm, not hot hoses) Or where your hoses are connected. Until we actually know this, everything is just a guess on our part. You have to help us here by being very specific with your answers.
We know the heater core is new and clear.
Did you replace the heater hoses? Are they running clear? No kinks or crud plugs.
Is the hose fitting into the intake clear of blockage/restrictions?
Here's one way to check coolant flow through the entire heater system without disconnecting anything.
If you have the hose connected to the radiator tank it is a simple check. It can even be done while the engine is cold.
Drain enough coolant out to get the level below the heater hose connection on the radiator.
Leaving the cap off, start the engine.
Look into the radiator filler neck and see if you are getting any coolant coming from the heater hose outlet.
There should be a strong stream coming from the heater into the radiator at all times. Even when cold and the heater turned off.
A dribble means a partial blockage and no flow means a complete blockage or the hoses are hooked up incorrectly.
If your return is going to the water pump, it's a little more involved but not as much work as you have already done.. You will need a buddy to help.
Do this while the engine is cold to prevent burns.
Disconnect and plug the w/p heater hose port.
Run the hose from the heater core to the radiator filler neck or a bucket.
Refill the system but leave some room in the radiator for coolant from the heater.
Have your buddy start the engine while you hold the heater hose into the radiator fill or the bucket and watch for coolant flow. (Keep the end of the hose higher than the top of the engine. It should only take a few seconds to see if there is any circulation.
If little or no flow, check each individual item starting at the heater hose connection to the engine. Fitting, hose, core, hose. Eliminate each piece as a problem along the system. If you have a good flow we can move on to other alternatives.
Keep us posted on your progress.
-
ok, to start off with there is coolant flowing through the heater core. i have already checked and confirmed this. the heater hoses are hooked up like this. the top hose coming out of the heater core goes to the water pump, the bottom hose from the heater core goes into the radiator. i put a piece of cardboard big enough to cover half of the radiator down between the radiator and a/c condenser yesterday and drove it to town and back and got a little warmer but still blows cool. just for sh*ts and giggles i put a piece of cardboard in front of the whole radiator and never overheated but heater started blowing warm air but not hot. the heater hoses get warm to the touch but not HOT. the radiator hoses get warm to the touch but not HOT. seems as if the truck is over-cooling. iv been doing automotive work for over 8 years professionally and NEVER seen this problem so this is a learning experience for me.
-
...the top hose coming out of the heater core goes to the water pump, the bottom hose from the heater core goes into the radiator....
I think you just identified your problem. The heater hose that routes to the water pump should, in fact, connect to the intake manifold. The way you have it plumbed, the water pump is drawing water through the heater core in the reverse direction from the radiator.
The heater hoses should route this way: hot water from the 5/8" intake manifold fitting flows to the heater core inlet; the 3/4" return hose flows from the heater core outlet to the radiator.
Cool reverse flow through the heater core may be why the prior core accumulated so much sediment. Correct the hose routing and your heater will likely drive you out of the cab.
-
I believe BD is correct.
Your temp gauge says you are running 190-200. Whether the hoses are warm or hot is kind of subjective as is the amount of water flow. What is hot for me may be warm to you. Trust your temp gauge. It sounds like your engine is running at temp.
It's worth a try to re-route your heater hose. It will only cost you time. (and some teflon tape)
If that's not it, we have some other suggestions.
I've been working on cars both professionally and as a hobby for over 50 years. (Yikes... :o it's been that long?) I still have to back up and tell myself not to assume anything... more often than I care to admit. ::)
-
well the only reason i have not done this yet is because its how my 84 was routed when i bought it and it still runs me out if i set it on LOW. and this is how the hoses were routed before the intake change and it worked before ( routed to the water pump is what i mean). idk i will try that tomarrow and see if i can get anything different.
-
Is your blend door working correctly? Maybe it's just pulling in mostly outside air.
-
i took the heater duct apart late last night and everything seems to be working correctly but could be one of them that work right apart but don't work together. so im doing some more investigation on that. ill let ya know what i find.
-
To rule out intake gaskets just remove the hose to the heater core from the intake manifold. If you have a problem the flow will be just a trickle.
-
You should have the hoses routed as described by BD or to the waterpump and intake but if you have the nipple on the radiator use the radiator.
-
i little update. everything in the heater box is free and moving. still going back and double checking everything. will be working on it a little tomarrow after church.
-
ok guys i got it figured out. BD was correct. i swapped the heater hose going to the water pump to the intake and the heats working fine now. i still do not understand how this past january before i done the intake and carb swap it was routed to the waterpump and working fine and now it didnt. makes no sense but since iv been working on cars have they really ever made sense? NO lol. anyways i appreciate all the help from you guys and glad i got it fixed it was starting to get cold lol.
-
The old intake didn't have a nipple on it? Maybe your plugged up heater core was heating up because of the restriction. :-\ Either way lesson learned - next time you hear us ask you questions several times (like how your hoses are routed) you'll listen to the experts ;) Heat is good this time of year
-
as said numerous times in this thread. the heat DID work before the intake swap. and i hooked it back up exactly as it was hooked up before i swapped intakes. why it wouldnt flow afterwards i dont know. but i was not saying anybody was wrong i was just trying to figure out how an intake swap made a difference in the way the coolant flow through the heater core. but after thinking about it i figured it out. anyways your right lesson learnt. thanks for the help!!!