So is coolant always flowing through my heater hoses?

ForceFed70

That's why they call it "dope"
Founding Member
Dec 6, 1999
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Was just looking at my heater hoses trying to figure out how coolant flows through them. Looks like one hose goes to the intake manifold near the thermostat, and the other hose conects directly to the water pump.

Can anyone tell my the direction of coolant flow? It appears as tho coolant flows out of the intake manifold, through the heater core, and then back to the pump where it's circulated through the engine again. Can anyone confirm this?

I don't have AC in the 70 so I do not believe there is a valve controlling coolant flow to the heater core.

I'm looking for a place to mount a 2nd temperature sensor and was wondering if somewhere in the heater hose would work.
 
rbohm said:
waterpump to heater core to intake manifold is the coolant path you seek.


If this was the case, wouldn't the heater blow cold air? AS I understand it, the waterpump is fed cold coolant from the radiator. Meaning the coolant in the water pump area would be cool. Or is the coolant in the engine block always circulating?
 
dont forget that when an engine is warmed up you have coolant temps in the radiator that are much hotter than you would think. all you need is 140 degree air to feel quite warm.
dont forget that the rad only cools the coolant down to around 120-140 degrees in temp at best, which is plenty for warming up a cars interior.
besides you still get a mix of hotter coolant from the engine as the bypass hose still bleeds coolant from the engine back to the water pump even with the thermostat wide open.
 
Hmm... OK, well I need this 2nd temp sender for my fuel injection conversion. I would like to try and measure engine temperature as accurately as possible. Doesn't sound like heater hoses will have the same temp coolant as the manifold.

My heater seems to work fine.
 
70_Nitrous_Eater said:
Hmm... OK, well I need this 2nd temp sender for my fuel injection conversion. I would like to try and measure engine temperature as accurately as possible. Doesn't sound like heater hoses will have the same temp coolant as the manifold.

My heater seems to work fine.

do you happen to have another port on the manifold that currently has a plug in it??? i know my edlebrock had an extra for some reason.

if not maybe you can buy a tee fitting that threads into the existing manifold port
 
On my 70 with A/C, the control valve is between the heater core and the intake mainifold which led me to believe that the flow was from the intake to the heater core and from the core to the water pump but maybe not. Does your thermostat housing have the port on the top of it? I've heard of people using that port for a temp sender. Some 70 and maybe others had this port for the dual vacuum diaphragm distributors.
 
rbohm said:
waterpump to heater core to intake manifold is the coolant path you seek.
You've got it bass-ackwards, it flows from the intake to the heater and back to the water pump. The clue to this is the direction the water pump nipple faces, it's the same as the one next to it that the bypass hose fits over.
 
D.Hearne said:
You've got it bass-ackwards, it flows from the intake to the heater and back to the water pump. The clue to this is the direction the water pump nipple faces, it's the same as the one next to it that the bypass hose fits over.


Thanks for the clarification, i was hoping i wasn't going off the deep end:(
 
As for which hose goes where on the heater core nipples, it'll work either way. Based on my experience with heater cores cutting loose at high rpm's, it's a good idea to put a cut off valve in both, that way if the core does spring a leak, you can shut it off and isolate it.
 
jbuening said:
On my 70 with A/C, the control valve is between the heater core and the intake mainifold which led me to believe that the flow was from the intake to the heater core and from the core to the water pump but maybe not. Does your thermostat housing have the port on the top of it? I've heard of people using that port for a temp sender. Some 70 and maybe others had this port for the dual vacuum diaphragm distributors.

No it doesn't have this port.. but I suppose it would be pretty easy to buy one that does.

I'm still confused as to why there would be vacum hoses connecting to the thermostat housing.
 
The vacuum hoses connected to "ported vacuum switches" that were threaded into the water outlet (thermostat housing). These were used to turn on and off the operation of the vacuum advance based upon engine temps. Granted they could have and probably did turn off other items but vacuum advance was the most common, EGR and other came later.

I will be going thru the same thing this winter, I am going to install this kit,

http://www.mass-floefi.com/index.html

I am trying now to figure out the best way to add the required pump and the return line. this kit was recommended to me

http://www.thedetailzone.com/Tanks Fuel Pump Install.htm

But I'm pretty sure I can come up with something that is a lot less expensive and won't interfere with the floor of the trunk. Here is a link to some photos of my car. http://www.cardomain.com/ride/597572
 
66HertzClone said:
The vacuum hoses connected to "ported vacuum switches" that were threaded into the water outlet (thermostat housing). These were used to turn on and off the operation of the vacuum advance based upon engine temps. Granted they could have and probably did turn off other items but vacuum advance was the most common, EGR and other came later.

Clever! So when the engine is cold there is more vacum advance.... Do you happen to know what years/engines this was used on?

66HertzClone said:
I will be going thru the same thing this winter, I am going to install this kit,

http://www.mass-floefi.com/index.html

The mass-flow kits are definately nice! Although too rich for me unfortunately... and I don't like the fact that you cannot tune it. However, this may be considered an advantage by others.

I'm going to use the Megasquirt ECU. It's alot more difficult as you have to figure everything out on your own (which sensors, injectors, etc). BUT it's all free..the plans/schematic is published and ment so that you literally build your own ECU. Or you can find them pre-built for about $100 more than what it would cost you yourself. Asside from the price, the other main advantage is that it's 100% programmable. You can use any sensors, or combination of fuel injection equipment...you just have to program the ECU to accept it. It's basically a computer that is programmed to do EFI. It's so flexible it can be used on anything from a 16cyln aircraft engine right down to a single cyln two-stroke dirtbike.

One I have the basic installation done, I plan to eventually controll the nitrous system via the ECU.

If your a handy guy who isn't afraid of electical wiring, I'd look into the MegaSquirt ECU.

66HertzClone said:
I am trying now to figure out the best way to add the required pump and the return line. this kit was recommended to me. But I'm pretty sure I can come up with something that is a lot less expensive and won't interfere with the floor of the trunk.

http://www.thedetailzone.com/Tanks Fuel Pump Install.htm

You have a few options here. Personally I'd try it 1st using the stock pickup. If you find that it's sucking air and is a real pain..you can always convert later. From what I understand it's not usually a problem until you get down to about 1/4 of a tank.

The other option is a surge tank. Basically what you do is keep the stock pump and have it fill a small containter. Then connect your high pressure pump to this container. Running 2 pumps kinda sucks, but it's a heck of alot cheaper and easier to do..not to mention you can keep your tank stock. Do a google search on "surge tank" for more info.

Personally, I plan on using the stock pickup...if it's a problem I'll do something about it later. For a return line I plan on removing the factory fuel sender unit/pickup and then drilling a hole in it and welding on a fitting. The other common thing to do is to tap into the rubber fuel filler hose.

66HertzClone said:
Here is a link to some photos of my car. http://www.cardomain.com/ride/597572

Beautiful looking car! You can tell that you really put alot of time into it!
 
I see we have similar tastes. The megasquirt is definitely in the near future. Are you gonna run something like an Accel throttle body (appears similar to a carb) with a spyder intake, stock 5.7L lightning lower intake with a 5.0L cobra upper (i think hood clearance problems occur if you use the 5.7L upper), or get one of those 90° elbows that mount to the top of a spyder intake and accepts a standard 5.0L or similar Mass Air throttle body (link)? Just curious which route you are going.

As far as the return line, some people use the drain plug hole in the gas tank for the return line. Only repo tanks have the drain plug though IIRC.
 
I bought a Holley commander 950 throttle body off of Ebay. Here's a pic...

attachment.php


It's oversized at the moment, rated at 900cfm with 4x 85pph injectors. But that's the great advantage of a programmable ECU, you can really tame it down. The long term plan is to go with a supercharger. At which time the throttle body and injectors will be the perfect size. It would just require mounting of the supercharger and reprogramming the ECU with a laptop.
 

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70_Nitrous_Eater said:
Clever! So when the engine is cold there is more vacum advance.... Do you happen to know what years/engines this was used on?



The mass-flow kits are definately nice! Although too rich for me unfortunately... and I don't like the fact that you cannot tune it. However, this may be considered an advantage by others.

I'm going to use the Megasquirt ECU. It's alot more difficult as you have to figure everything out on your own (which sensors, injectors, etc). BUT it's all free..the plans/schematic is published and ment so that you literally build your own ECU. Or you can find them pre-built for about $100 more than what it would cost you yourself. Asside from the price, the other main advantage is that it's 100% programmable. You can use any sensors, or combination of fuel injection equipment...you just have to program the ECU to accept it. It's basically a computer that is programmed to do EFI. It's so flexible it can be used on anything from a 16cyln aircraft engine right down to a single cyln two-stroke dirtbike.

One I have the basic installation done, I plan to eventually controll the nitrous system via the ECU.

If your a handy guy who isn't afraid of electical wiring, I'd look into the MegaSquirt ECU.



You have a few options here. Personally I'd try it 1st using the stock pickup. If you find that it's sucking air and is a real pain..you can always convert later. From what I understand it's not usually a problem until you get down to about 1/4 of a tank.

The other option is a surge tank. Basically what you do is keep the stock pump and have it fill a small containter. Then connect your high pressure pump to this container. Running 2 pumps kinda sucks, but it's a heck of alot cheaper and easier to do..not to mention you can keep your tank stock. Do a google search on "surge tank" for more info.

Personally, I plan on using the stock pickup...if it's a problem I'll do something about it later. For a return line I plan on removing the factory fuel sender unit/pickup and then drilling a hole in it and welding on a fitting. The other common thing to do is to tap into the rubber fuel filler hose.



Beautiful looking car! You can tell that you really put alot of time into it!

No but there are a lot of different ones available. A helpful counterman who can use "books" to look up parts can be very helpful with these. Different temperature units and turn the vacuum on or off are just some of the variables.

I looked at the Mega squirt unit early on. My problem is the amount of time required. With a one year old son and a working wife time is more valuable than the cash. Worst case I could install the MassFlo kit in a weekend, the Mega system much longer due to the build time required up front. It has a lot of "cool" factor since you construct it no doubt about it. I have seen some aftermarket kits that allow for "tuning" of the mass flow systems, should I need to do something those are always an option.

I will use the original tank but keep it at least above 1/4 full. I am considering purchasing a new filler neck and having a tube and fitting welded in place for the return line. I will run a new supply line up the right side frame, mount the filter and regulator on the right side inner fender well area. I will use most of the original supply line for the return. Just re-route it so I can attach it at the firewall near where the rail ends. This way I won't have lines hanging all over the place under the hood. I like things clean and neat under the hood.

Thanks for the compliment on the car, you are oh so correct about the time invested. Nearly all of that before the baby arrived, things are much different now.