Heater Hose Routing Re-Visit

[neteng01]

Hi All,

I know this is an old thread, but I have an interesting question that maybe someone can help me with. I purchased a new to me 1972 C10 a couple months ago. The PO changed out the original motor with a 1989 Trans Am 2-port 350 motor with a serpentine belt. He told me that the water pump rotates backwards on these motors?? no idea on my side. The problem is that I cant get my heater to work for the life of me. I have a new core, blend door works fine, all new vacuum lines, all new heater hoses, cleaned out heater box so no obstructions. Blower works on all speeds, all new ducting under the dash, and just about everything else is working.

My question is this, the PO ran the heater hoses with the 3/4 hose from the top port of the heater core to the radiator, and the 5/8 hose from the bottom port of the heater core to the water pump. He has several temp sensors in the intake for electric fans and temp gauge. The hoses seem to get hot, slowly, but my heater always blows cool, even with all doors in proper positions. The only thing I have not changed is the thermostat since the motor seems to run at normal temps.

I am at my last nerve here and cannot seem to figure what the issue is. I know that modded motors can cause some challenges, however, he swears that it all worked last time he tried and that I must have something clogged or wrong. Could the water pump connection be the issue here?

Any help or opinions would be greatly appreciated. My C20 is warm as ever but I am feeding as it should via manifold and radiator connections.

[Andy4639]

Here are the AC factory drawings.
U need to take the hose off the radiator and put it like the drawings show.


This is the best I can do. It's straight out of the manual. From what I see it's showing the bottom heater core hose going to water valve then going to intake.
Top heater core hose going straight to water pump.
These are both for AC trucks, I don't know if a non AC truck heater hose route would be any differant are not.

[Stocker]

Originally Posted by neteng01

The PO changed out the original motor with a 1989 Trans Am 2-port 350 motor with a serpentine belt. He told me that the water pump rotates backwards on these motors??

With serpentine belt setups, the water pump rotates backwards compared to a conventional V-belt setup. Said another way, you need a reverse-rotation water pump if you have a serpentine belt.

My question is this, the PO ran the heater hoses with the 3/4 hose from the top port of the heater core to the radiator, and the 5/8 hose from the bottom port of the heater core to the water pump.

I can only tell you how my hoses are routed (stock 350 with A/C). I have no heater hoses connected to the water pump. Hot water is pumped from the intake manifold (near the thermostat) through a 5/8" hose to a valve on the inner fender, then to the lower heater core nipple. Water exits the heater core from the top nipple, through a 3/4" return hose to the radiator nipple.

Sounds like you need to make sure that your 5/8" hose is attached to the proper source for hot water. I'm guessing it may not be, but I'm not familiar with your engine.

[Andy4639]

To add to this, and this is me thinking here.

neteng01,
My question is this, the PO ran the heater hoses with the 3/4 hose from the top port of the heater core to the radiator, and the 5/8 hose from the bottom port of the heater core to the water pump. He has several temp sensors in the intake for electric fans and temp gauge. The hoses seem to get hot, slowly, but my heater always blows cool, even with all doors in proper positions. The only thing I have not changed is the thermostat since the motor seems to run at normal temps.

If your pulling water out of the water pump to the heater core then back to the radiator it's bypassing the motor and never getting hot enough to warm up the heater. U are circulating luke warm water all the time.
Does this make since.

[neteng01]

Thanks Stocker, I think you are correct. This is the big issue with another owners thought of a "cool motor configuration" My C20 is as you describe, but since I have no available ports on the manifold to re-route, I may need to identify if I can do without one of his options... I think the 5/8 connection to the water pump is cycling a bypass and just pushing cool water all the way around... Since other posts indicate the radiator connection OR the water pump connection, I may be just moving pre-thermostated cool water... Gotta love "custom" mods... Ugh..

I appreciate the input, I guess it is back to looking at what can be custom configured myself..LOL

[neteng01]

Thanks Andy, I think you are absolutely correct... Thanks so much for the input and thoughts.

[Stocker]

Any way you can research that motor to find out where the hot water is supposed to come from?

[neteng01]

I have been trying to do that but there are so many variations of the motor. I will keep trying though. If anyone on here has seen this before and can speak to the flow on this motor, please feel free to chime in as well..:-)

Thanks to all so far for the ideas and help, at least I know now that I am not crazy...lol

[stsalvage]

hay buddy i'm in Moreno valley is the truck drivable on the freeway and make it down to Moreno valley.I have a few of these trucks and i love working on the heater core issues.All my trucks the heater Core and oil persure and gas gauge must more or i wont drive the truck.I will send you a email to your own box and send you my number.I have a shop at my house that is 3000 square feet we work one cars and trucks here been doing it for over 44 years.I'm off perris Blvd and the 60 freeway and Dracaea ave 92551 zip code

[Andy4639]

Found this by googling


http://www.2carpros.com/articles/how...g-system-works

[jondancer]

Who sells good heater hose, mine under the dash is falling apart. .?
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[Lee H]

That intake should have a place to put a heater hose nipple, maybe near the rear?
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[Katrina/10]

The 5/8 hose has to connect to the intake manifold. If you have a TBI motor, there is a plug in the back by the distributor. Use that for a hot water source and it will work fine.

[neteng01]

Thanks Katrina/10. Not sure on the motor type, I know it is a 1989 Trans Am 2-port 5.7. I am posting some pics for all to see. I don't have the AC hooked up yet since it is a mod engine, and I am running a straight to heater core config with no vacuum valve off the AC system. I think the sensor in the manifold inlet is either for the electric fans or the after market temp gauge inside. I haven't traced it back yet, but I think this is where my bypass is happening.

Lee H, I do have a inlet port on the intake in front, but the PO put a sensor in there. The one on the back of the manifold by the carb looks like a vacuum port, its smaller like the PVC T port on my C20. Unless I am looking in the wrong place.

This is the whole truck. It's my son's first car, lucky kid lemme tell ya, I had a 71 gremlin...LOL.. It a work in progress...

[neteng01]

Jondancer, I purchased my new heater hose at Autozone. They had both the 3/4 and 5/8 in stock and seems like great quality. I paid 11.00 total for a 5 foot length of each and it worked just fine. Hope that helps.

[Zable49]

Hello All, I did notice something on your picture. Your temp sensor location within your intake. Well I have a nipple on mine which goes to the heater core instead of the hose going to your radiator. And my sensors are on my heads.

This might give you a direction to think about.

Good Luck.

[neteng01]

Thanks Zable, yes, that is the issue, the PO ran the sensor there for the temp and the head has the electric fan sensor. The other side has another sensor so I am out of holes..lol. I want to run it from the manifold, to the core, from the core to the radiator like my C20. Just gotta find a place for all the mod equipment he has on this thing. I wish it was a stock 350 for the year, but he had grander ideas.... Its a 1989 Trans Am 2 port motor with a 700r trans, so there are many "neat mods" done that are inter fearing with the normal stuff... Like my heater..lol.

[Katrina/10]

I think i misunderstood what you meant by two port, I thought you meant TBI but I think what you meant was, Tuned Port. Which the engine could have been, but someone has removed the tuned port intake and installed a carb intake. In that case you have to treat it like any other carb intake, put your 5/8 hose connection in the front where the sensor is. The sensor will have to go somewhere else.

[neteng01]

Thanks Katrina/10, you may be right on the motor type being a Tuned port, but the PO modded the intake on it and apparently added this one. The 2 middle intake bolts were drilled on each side to be able to mount. Not the greatest solution, but above my head. I like the stock solutions myself. I agree that I need to move the sensor, just got to figure out if it is for the add on temp gauge. If it is, I can remove it and try to get the original working if the drivers side sensor is for that one. I think he may have just left the original in and added a new one. Easiest path I guess...

I appreciate all the input and will post back after I figure it out. My thanks to all... You all are awesome.
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[Katrina/10]

Right, that definitely IDs the heads as later models, since the center bolt holes are at a different angle. But, to stay on subject, getting your heater working, is what you need to do for the hose. If you don't know what that sensor in the intake is, you'll just have to trace it out and see if you can find where it goes to. You may be able to do without it. Good luck!

[69mine2]

I have heater problems also does anyone have a diagram for non ac truck?
I did similar checks as stated earlier with cleaning ducts , vents , etc
thanks

[Lee H]

Welcome to the board. Lots of diagrams out there. Simply: lower heater core to intake manifold, upper heater core to water pump. Some applications have the upper hose going into the radiator but then the circulation is not as good and does not keep the heater core as hot. Good luck with getting some heat in your ride.

[69mine2]

thanks
let get my butt in the garage !

[Zable49]

Originally Posted by neteng01

Thanks Zable, yes, that is the issue, the PO ran the sensor there for the temp and the head has the electric fan sensor. The other side has another sensor so I am out of holes..lol. I want to run it from the manifold, to the core, from the core to the radiator like my C20. Just gotta find a place for all the mod equipment he has on this thing. I wish it was a stock 350 for the year, but he had grander ideas.... Its a 1989 Trans Am 2 port motor with a 700r trans, so there are many "neat mods" done that are inter fearing with the normal stuff... Like my heater..lol.

Oops, yeah now I remember reading that earlier you said that. My bad. Well maybe you might be able to splice into the wiring so you can use your OEM sensor for your fan too. However I have never done that so I dont know if it would work or not. But that would remove a sensor from the equation.

Good Luck

[ERASER5]

Neteng01, your issue is that both heater hoses are hooked to a RETURN port and no SUPPLY. No water is flowing INTO the heater, it may flood the heater core, but it is not flowing. The supply (lower heater hose) should connect somewher on the intake manifold. There should be several holes to place a nipple. The RETURN (upper heater hose) can go the to water pump or the radiator (pick one that is convenient).