Need Help: Water Pump Removed - Heating Issue?

[camaro1969]

Background: 1969 Camaro, running a 350 sbc, aluminum radiator with electric fan (sucking air from grill inwards), 180 degree thermostat. While driving, I tend to start overheating quite quickly. Within 5 minutes of my drive, i reach 180 degrees, within 20 minutes i am about 200, and if I am idling in traffic at 200, I will reach about 220-225 within 4-5 minutes.

To find the bottom of my over heating problem, I pulled my water pump to see whether it could be a counterclockwise rotation on a v-belt system.

Are you able to tell by the picture whether the water pump i have is the correct water pump for my application? I run the belt on the grove side of the pulley and the pump pulley rotates clockwise (looking from in front of the car).

That being said, the water pump is a generic china brand, Dynapak np1063, I couldn't find more details, other than there is a "B" casted in the inside of the water pump housing. *see image* Can you recommend a good water pump replacement, american made?

Thanks

https://www.dropbox.com/s/lihd2fztdt9xwg2/20140531_094530.jpg
https://www.dropbox.com/s/8aickcoph2sz2cz/20140531_094538.jpg

[Vince@Meanstreets]

Has it ever boiled over?

[Che70velle]

Vic, those numbers aren't insanely uncommon. My z06 corvette was the same way. Does the car eventually boil over?
What do you know about the engine as far as over bore, compression ratio, and ignition timing? Does your radiator have a shroud on it, or just a fan mounted on the core?
I can't help you at all concerning the water pump.

[camaro1969]

it has never boiled over. the hottest its got to was about 235, and i got it home just in time to let is cool down.

overbore is .30, originally a 327 block. I do not know the compression ratio and i haven't checked the timing, i can check.

fan has a shroud build on it.

[Vegas69]

At the rate your temp rises, I bet your cooling fan is undersized. If the rest of your cooling system checks out, better electric fans or a gm clutch fan and shroud are in your future. Two twenty five in traffic is just to hot for an old school small block with a carb.

[GregWeld]

Here's what I always ask guys when they come to my place with an "overheating" issue.


What are you going by for your temperature?


The gauge?

An infrared gun that has taken temps on the inlet and outlet of the radiator to see if there's a temp drop?

Does your "gauge" match the readings of an recent assessment of the motors temp?


WHERE in the motor is the temperature gauge? Head? Block? Near Thermostat?


If the gauge creeps up in stop and go traffic - or at a stop - does the gauge show immediate cooling off if you begin to move? Or does it stay high?



What does the gauge read - say - cruising along at 45 or 50 MPH?

[camaro1969]

thanks todd.

@greg, as most users have mentioned, 225 is just too hot, i am aiming for under 200 at any given time (whether in traffic or whether driving).

I am using my autometer gauge to monitor my temperature.

I havent used an infrared gun to test inlet and outlet temps, I can and will after I put the water pump back on. At that time i will compare the gauge to gun.

The gauge is near the thermostat, in the front of the engine on the manifold.

Stay im at 220-225 while sitting for a few minutes, when i start driving it will start going down eventually to around 210-220, will not go below 200 what so ever.

At cruising speed, gauge reads around 200-215. I am at 180 for only about 5 minutes or so, even when cruising, and then will go up to 200+ where it will stay for remainder of the drive.

Temp outside when is 15 degree's celsius or more.

thanks for the help.

[GregWeld]

My guess is your gauge is off by 20* -- and your cruising at 180 -- and traffic has it up to 190 - which would be normal - although like Todd said - your electric fan should hold the temp + or - 10 degrees... and should be able to kick on at a stop and then cycle.

Keep us posted.

[Che70velle]

The temp never coming down below 200 while cruising rules out the fan, but as stated above, you can't always trust the gauge.
If your radiator is the correct size, and relatively clean on the inside, and assuming the gauge is accurate, then either the water pump isn't doing its job, or the thermostat is malfunctioning.
You run a lot of rpm while cruising?

[Vegas69]

I agree that it should run cooler than 200 down the freeway unless you are turning some rpms or you have a 195 tstat. It's to early to rule out the fan for low speed operation in my opinion.

[camaro1969]

not pushing RPM too high, keeping it pretty conservative when driving it. I have a feeling its the china brand water pump stuck on there. The tstat is few months old, i can replace it with a new one. Running 180, should i run a higher or lower temp tstat?

i have ordered a thermo gun, should have the car back together and running temp results shortly.

thanks for the advice, keep you updated soon.

[Vince@Meanstreets]

keep the 180...I think Todd might be on to something. What kinda fan again? Size? Does it have one of those closed up shrouds? What else is infront of the radiator?

I would definatly double check the temp with an infrared. I have seen a few 15 20 degrees off.

while you have the infrared out, check the radiator for cold spots. That would indicate a plugged radiator row.

[GregWeld]

I agree that it should run cooler than 200 down the freeway unless you are turning some rpms or you have a 195 tstat. It's to early to rule out the fan for low speed operation in my opinion.



The fact that it's NOT CLIMBING at freeway speeds (and there shouldn't be any fan on at freeway speeds) is why I'm thinking his temp gauge may be off be as much as 20*


But to your point Todd - and it's a good one - the fan should also be capable of keeping the car near the thermostats rated temp if the cooling system itself is in good order. If not - then the fan(s) need to be looked at.

So with that in mind --- WHAT IS CONTROLLING THE FAN(S)?? Do you have a separate fan switch? Is it electronic etc?

[Sieg]

Radiator cap and coolant recovery system condition?

[camaro1969]

keep the 180...I think Todd might be on to something. What kinda fan again? Size? Does it have one of those closed up shrouds? What else is infront of the radiator?

I would definatly double check the temp with an infrared. I have seen a few 15 20 degrees off.

while you have the infrared out, check the radiator for cold spots. That would indicate a plugged radiator row.

The fan sucks quite of bit of air from the outside. The shroud is build on to the radiator, see image. The fan housing measures 17 inches.

When the temp gun comes, i will preform a list of checks.

http://i361.photobucket.com/albums/oo52/camaro_1969/DSC00144_zpse334eb2c.jpg

[camaro1969]

The fact that it's NOT CLIMBING at freeway speeds (and there shouldn't be any fan on at freeway speeds) is why I'm thinking his temp gauge may be off be as much as 20*


But to your point Todd - and it's a good one - the fan should also be capable of keeping the car near the thermostats rated temp if the cooling system itself is in good order. If not - then the fan(s) need to be looked at.

So with that in mind --- WHAT IS CONTROLLING THE FAN(S)?? Do you have a separate fan switch? Is it electronic etc?

Fan is running once car is started.

[camaro1969]

Radiator cap and coolant recovery system condition?

13 psi becool rad cap.

I have an aluminum canister recovery system in place, new condition, rubber hose is also new condition.

[Vince@Meanstreets]

The fan sucks quite of bit of air from the outside. The shroud is build on to the radiator, see image. The fan housing measures 17 inches.

When the temp gun comes, i will preform a list of checks.

http://i361.photobucket.com/albums/oo52/camaro_1969/DSC00144_zpse334eb2c.jpg

I have always had air flow issues with that type of shroud. As designed you a reducing through radiator air flow by at least 50% with the single fan. Add a trans cooler and AC condensor and it's going to be tough to keep the engine cool.
If you look at high end shrouds they have a number of rubber flaps to increase air flow at speed. Sitting still your fan should be running at temp.

[Vince@Meanstreets]

http://i88.photobucket.com/albums/k183/jackmagic1/Shrouds.jpg

Not saying its the cause of your problem but it is a contributer.

[GregWeld]

Plenty of fan!


Okay --- if the fan is RUNNING all the time -- it's going to cause blockage at cruising speeds when it's not needed at all....


A simple fan switch and relay -- such as this, or similar, would be all that is needed to add fan control. It simply shorts to GROUND when the temp reaches "X" -- you can buy these in various temp ranges.


http://www.summitracing.com/parts/sum-890017/overview/


Do you have Air Conditioning?? If so then it gets a little more complicated and you'd need a Trinary switch in the A/C system.


Stupid question -- but you said the thermostat is "new".... but hopefully it's not installed upside down? Did you have this issue and is that why a replacement thermostat??


ASSume the system was "Burped".... i.e., after filling -- the cap was left off the radiator -- until it opened and you could see hot water circulating in the radiator. Sometimes this can create a mess if you fill it too full as there can be air trapped and when the thermostat opens you get a big belch of water out of the radiator... so I always leave it low -- and add water after it's run a bit and the burping is all done.



Next up -- is -- once you get 'er back together -- measure at the thermostat housing. Also at the inlet hose and outlet hose. Also a couple places around the head to check for hot spots. You should have at least a 20* DROP in temp from the top of the radiator where the hot water comes in = to the bottom where it re-enters the pump. That will check for adequate flow in the radiator.

THEN after you've ruled out a cooling system malfunction --- LET'S DISCUSS where your timing and timing curve is set -- and give us some details about that and the motor -- aluminum heads or not - big cam or not - initial timing - total timing - and springs used to set the curve -- then is it vacuum advance or not and has that been checked to see how much advance that's pulling in. And at what vacuum is it adding curve.

Do you have a dial back timing light??

[Vince@Meanstreets]

I would not put that pump back on. Get a quality pump with a anti cavitation plate impeller design. They work much better.

[camaro1969]

Plenty of fan!


Okay --- if the fan is RUNNING all the time -- it's going to cause blockage at cruising speeds when it's not needed at all....


A simple fan switch and relay -- such as this, or similar, would be all that is needed to add fan control. It simply shorts to GROUND when the temp reaches "X" -- you can buy these in various temp ranges.


http://www.summitracing.com/parts/sum-890017/overview/


Do you have Air Conditioning?? If so then it gets a little more complicated and you'd need a Trinary switch in the A/C system.


Stupid question -- but you said the thermostat is "new".... but hopefully it's not installed upside down? Did you have this issue and is that why a replacement thermostat??


ASSume the system was "Burped".... i.e., after filling -- the cap was left off the radiator -- until it opened and you could see hot water circulating in the radiator. Sometimes this can create a mess if you fill it too full as there can be air trapped and when the thermostat opens you get a big belch of water out of the radiator... so I always leave it low -- and add water after it's run a bit and the burping is all done.



Next up -- is -- once you get 'er back together -- measure at the thermostat housing. Also at the inlet hose and outlet hose. Also a couple places around the head to check for hot spots. You should have at least a 20* DROP in temp from the top of the radiator where the hot water comes in = to the bottom where it re-enters the pump. That will check for adequate flow in the radiator.

THEN after you've ruled out a cooling system malfunction --- LET'S DISCUSS where your timing and timing curve is set -- and give us some details about that and the motor -- aluminum heads or not - big cam or not - initial timing - total timing - and springs used to set the curve -- then is it vacuum advance or not and has that been checked to see how much advance that's pulling in. And at what vacuum is it adding curve.

Do you have a dial back timing light??

When it is running all the time, isnt that how the original set up was back in the day, when the fan was attached to the water pump pulley? I have a temp switch, never bother to install because having the fan running at all times didnt seem like a bad idea.

no AC on the car.

Thermostat was installed correctly. I ran no thermostat for about a month a few years ago, then installed one to manage problem with overheating, and then recent put a new one in since i was still getting over heating issue.

I am not putting the old water pump back on. I bought an AC Delco water pump and will be replacing with that. I will then burb the system when i put new fluid/water in the car.

i will be putting the pump back on the car either today or tomorrow. I will check timing after I have done the above. I do not have a dial back timing gun, that isnt to say I cannot get one. Is there any on Amazon that i can get? (i have amazon credit, figure i use it :thumbsup: )

[camaro1969]

I would not put that pump back on. Get a quality pump with a anti cavitation plate impeller design. They work much better.

Replacing with AC Delco #252 592

http://www.autopartswarehouse.com/sku/AC_Delco/Water_Pump/AC252-592.html

[Vince@Meanstreets]

When it is running all the time, isnt that how the original set up was back in the day, when the fan was attached to the water pump pulley? I have a temp switch, never bother to install because having the fan running at all times didnt seem like a bad idea.

no AC on the car.

Thermostat was installed correctly. I ran no thermostat for about a month a few years ago, then installed one to manage problem with overheating, and then recent put a new one in since i was still getting over heating issue.

I am not putting the old water pump back on. I bought an AC Delco water pump and will be replacing with that. I will then burb the system when i put new fluid/water in the car.

i will be putting the pump back on the car either today or tomorrow. I will check timing after I have done the above. I do not have a dial back timing gun, that isnt to say I cannot get one. Is there any on Amazon that i can get? (i have amazon credit, figure i use it :thumbsup: )

One of the purposes of an electric fan is to run and cool as needed. As Greg states it running at speed causes air turbulence that can impede air flow through the rows and fins at cruise speed.


Water pump I would recommend within that price range. SUM-312449. At summit racing.com

[GregWeld]

I own this timing light...



http://www.amazon.com/INNOVA-5568-Pro-Timing-Light-Tool/dp/B000EVU8J8/ref=sr_1_2?s=automotive&ie=UTF8&qid=1401662045&sr=1-2&keywords=dial+back+timing+light



It gives me RPMS... timing - Dial back - voltage.... Kinda handy depending on what you're working on.

We can walk you thru how to plot your TOTAL TIMING -- how to build a rough timing curve -- and of course most know how to set initial. It's the curve and the total that are important...

[Vegas69]

If that is a knock off fan it may be really under powered. If that is the case, I could see it impeding your high speed operation along with your low speed problem. I agree with these guys, put it back together with a good pump and verify your temps before you go much further.

[GregWeld]

Depending on how it's wired - it might not even be getting full voltage. I bought a '37 Ford out of Bakersfield from a guy - and he said "yeah it will overheat if I sit at a stop light too long".... got the POS home and the wiring was so poor - the fan was seeing 10 Volts... Put a proper relay and some proper gauge wiring and it was FINE...

[camaro1969]

Vince - Thanks, the Summit one and the AC Delco one are pretty much identical. I will be putting the AC Delco on today.

Greg - Thanks, Id like to walk through the timing when i get to that step.

Todd - A lot of guys from another forum are saying to cut my shroud off since its stopping airflow. I should be going back to a fan mounted to the water pump pulley. As well, talking about adding rubber louvers. I will be mounting my water pump today, should be getting my temp and timing light this weekend.

Greg - I will check what volt i am getting to the fan and report back.

[GregWeld]

Vince - Thanks, the Summit one and the AC Delco one are pretty much identical. I will be putting the AC Delco on today.

Greg - Thanks, Id like to walk through the timing when i get to that step.

Todd - A lot of guys from another forum are saying to cut my shroud off since its stopping airflow. I should be going back to a fan mounted to the water pump pulley. As well, talking about adding rubber louvers. I will be mounting my water pump today, should be getting my temp and timing light this weekend.

Greg - I will check what volt i am getting to the fan and report back.





Personally I don't think you're "overheating" --- so I wouldn't do anything to the shroud or fan etc until you've got those temps double checked. I know you know that - but stating this for others as many people read this stuff.....

[camaro1969]

Personally I don't think you're "overheating" --- so I wouldn't do anything to the shroud or fan etc until you've got those temps double checked. I know you know that - but stating this for others as many people read this stuff.....

of course!

[dale68z]

That I know of, all of the reverse rotation pumps have metric threads on the 4 pulley attachment bolts.

[camaro1969]

update:

Received my infared temp gun, and measuring at the temp sending on manifold, 150-160 at idle for the first 5 minutes or so. At this point, my outlet hose is cold, and inlet hose is hot. At 180, the thermosat opens and the outlet measure around 6 degrees higher than the inlet.

Drove the car for about 10 mins, let it idle for another 5 minutes, reached 210, and sits at 210. If i turn the car off, the car does not cycle its water, and temps were record at around 215-220 while off, it cools down to about 180 after 10-15 mins.

Btw the gauge reads the same as my temp gun.

Should be getting timing gun in the next few days, will measure the timing to see whether i am too adv or reta., or neither.

[Vince@Meanstreets]

update:

Received my infared temp gun, and measuring at the temp sending on manifold, 150-160 at idle for the first 5 minutes or so. At this point, my outlet hose is cold, and inlet hose is hot. At 180, the thermosat opens and the outlet measure around 6 degrees higher than the inlet.

Drove the car for about 10 mins, let it idle for another 5 minutes, reached 210, and sits at 210. If i turn the car off, the car does not cycle its water, and temps were record at around 215-220 while off, it cools down to about 180 after 10-15 mins.

Btw the gauge reads the same as my temp gun.

Should be getting timing gun in the next few days, will measure the timing to see whether i am too adv or reta., or neither.

looks normal... temp will rise with no flow.

Is this with your fan on constant? Should be more than a 6 degree drop through the radiator.

[GregWeld]

looks normal... temp will rise with no flow.

Is this with your fan on constant? Should be more than a 6 degree drop through the radiator.




EXACTLY -- should be a 20* drop in temp from inlet to outlet....


I've PM'd him how to plot a timing curve... We need those numbers - initial - and then 500 rpm increments -- and then total advance and at what rpm is his maximum advance at. That info will help with whether it's a cooling system or timing is messed up which can add a lot of heat and decrease performance.


I'll be on the road for the next couple weeks so maybe you guys will have to take over trying to help him solve this issue..

[camaro1969]

looks normal... temp will rise with no flow.

Is this with your fan on constant? Should be more than a 6 degree drop through the radiator.

fan is on constant at this point.

[camaro1969]

EXACTLY -- should be a 20* drop in temp from inlet to outlet....


I've PM'd him how to plot a timing curve... We need those numbers - initial - and then 500 rpm increments -- and then total advance and at what rpm is his maximum advance at. That info will help with whether it's a cooling system or timing is messed up which can add a lot of heat and decrease performance.


I'll be on the road for the next couple weeks so maybe you guys will have to take over trying to help him solve this issue..

definitely not 20* difference.

I will report back the timing in the next few days.

Thanks Greg for ur help to this point, chat when u return.

[GregWeld]

BTW --- The temp gun is a great inexpensive tool to have -- and can be used for many things! Like Brake bias and header temps and all manor of stuff.


The key test there is that the gauge is accurate. Now we can use the temp gun to isolate or read the temps in various places to get a picture for what the issue is.

Make sure not to use these guns on chrome or polished pieces -- they don't get as good of a reading on those surfaces.

Many times -- I'll just read right off the fins of a radiator... just point the gun at an angle so it gets a good look at the surface you're trying to measure. It's also helpful to read near the exhaust ports of the head... the sides of the block etc.

[GregWeld]

Just to be sure --- have you had the radiator cap OFF when the car is cold ----- and then let the motor come up to temp --- and watch the water flow when the thermostat opens up??


You always have to be careful doing this - because sometimes they'll "burp" hot coolant..... but sometimes that's the problem! They have air trapped in the system that needs to get the hell out of there!


It's also useful information for you to see the water flow and now it's going the right way and has some pretty good movement to it.

If your cap is on the driver side tank -- where is your upper hose? Assuming the bottom (suction) hose is on the passenger bottom...

With this arrangement - water should be coming into the tank from the upper hose.

[GregWeld]

And -- as long as I'm writing a book on cooling...


Is your bottom (suction side) hose reinforced?? It should have a spring inside of it to keep the hose open... they can be sucked almost closed at cruising speeds if they're not internally supported. Lots of guys just chuck the spring --- dumb move guys! These pumps move a LOT of water volume... you'd be shocked how much suction they can create.

All the fans in the world won't help you if the hose is collapsing....

You should be able to reach down and squeeze the hose to check for the spring.

You can also visually inspect the hose with the car running and have somebody rev the car up and watch to see if the hose is trying to suck in on itself.

[camaro1969]

BTW --- The temp gun is a great inexpensive tool to have -- and can be used for many things! Like Brake bias and header temps and all manor of stuff.


The key test there is that the gauge is accurate. Now we can use the temp gun to isolate or read the temps in various places to get a picture for what the issue is.

Make sure not to use these guns on chrome or polished pieces -- they don't get as good of a reading on those surfaces.

Many times -- I'll just read right off the fins of a radiator... just point the gun at an angle so it gets a good look at the surface you're trying to measure. It's also helpful to read near the exhaust ports of the head... the sides of the block etc.

Trust me i was checking the temp of almost everything lol. The rad reads different all throughout, nothing more than a 20* difference.

the headers get extremely hot, upwards of 200*f +.

[camaro1969]

Just to be sure --- have you had the radiator cap OFF when the car is cold ----- and then let the motor come up to temp --- and watch the water flow when the thermostat opens up??


You always have to be careful doing this - because sometimes they'll "burp" hot coolant..... but sometimes that's the problem! They have air trapped in the system that needs to get the hell out of there!


It's also useful information for you to see the water flow and now it's going the right way and has some pretty good movement to it.

If your cap is on the driver side tank -- where is your upper hose? Assuming the bottom (suction) hose is on the passenger bottom...

With this arrangement - water should be coming into the tank from the upper hose.

I did have the rad cap off the first time, at around 150-160, the water started to flow out of the rad, made a mess, i stayed clear. After it overflows, should i be replacing the water that over flowed? Feel like if i let the water keep flowing the rad would eventually become empty.

Cap is on the passenger side, hose from the thermostat housing goes to a driver side of the rad

[camaro1969]

And -- as long as I'm writing a book on cooling...


Is your bottom (suction side) hose reinforced?? It should have a spring inside of it to keep the hose open... they can be sucked almost closed at cruising speeds if they're not internally supported. Lots of guys just chuck the spring --- dumb move guys! These pumps move a LOT of water volume... you'd be shocked how much suction they can create.

All the fans in the world won't help you if the hose is collapsing....

You should be able to reach down and squeeze the hose to check for the spring.

You can also visually inspect the hose with the car running and have somebody rev the car up and watch to see if the hose is trying to suck in on itself.

I dont believe there is a spring. I havent squeeze it while running. It is shaped perfectly to connect my rad to the water pump. I can try to see if there is a spring today.

I have not seen it collapse on itself

[Vince@Meanstreets]

I did have the rad cap off the first time, at around 150-160, the water started to flow out of the rad, made a mess, i stayed clear. After it overflows, should i be replacing the water that over flowed? Feel like if i let the water keep flowing the rad would eventually become empty.

Cap is on the passenger side, hose from the thermostat housing goes to a driver side of the rad

should have a catch can that will return fluid to he system during cool down. i like to use this on on everything. http://www.classicindustries.com/nova/parts/551448.html
tucks into the fender area.

I use my temp gun for everything. Rotor temp, tire temp, misfire detection, belt slip detection, electrical shorts or malfunctioning components...shoot it into my ear for an excuse to go home.

[GregWeld]

I did have the rad cap off the first time, at around 150-160, the water started to flow out of the rad, made a mess, i stayed clear. After it overflows, should i be replacing the water that over flowed? Feel like if i let the water keep flowing the rad would eventually become empty.

Cap is on the passenger side, hose from the thermostat housing goes to a driver side of the rad



So once the water burped out of there -- and made a mess -- it should STOP doing that after it's initial puke....


Then -- YES -- you should top off the radiator - using only distilled water or a mix of distilled water and the proper anti freeze (for aluminum radiators!)... when the engine is NOT running... these big crossflow radiators should only be filled til there is about 6" of free space in the tank. Sometimes you'll need a flashlight to look in.... leave some space! Water expands - and these big radiators need some room for expansion.... If you fill them to within a couple inches of the cap -- they'll puke out!

You might find that if you haven't topped off the radiator since you puked some coolant - that is your trouble right there....

[Vegas69]

I agree, you need to let it burp and make a big mess and then let it continue to purge minor pockets after the tstat opens. It can be topped off when all air is out and at full operating temp. A proper overflow/return will keep it from making a mess unless you get it really hot like Vince mentioned.

Sounds like your sensor may have been in an air pocket.

[camaro1969]

should have a catch can that will return fluid to he system during cool down. i like to use this on on everything. http://www.classicindustries.com/nova/parts/551448.html
tucks into the fender area.

I use my temp gun for everything. Rotor temp, tire temp, misfire detection, belt slip detection, electrical shorts or malfunctioning components...shoot it into my ear for an excuse to go home.

I have a catch can.

And yeah same, been using it for everything. I will start using it more when the car is on the road.

[camaro1969]

I agree, you need to let it burp and make a big mess and then let it continue to purge minor pockets after the tstat opens. It can be topped off when all air is out and at full operating temp. A proper overflow/return will keep it from making a mess unless you get it really hot like Vince mentioned.

Sounds like your sensor may have been in an air pocket.

Sounds good. I will let it burp fully.

[Vince@Meanstreets]

I have a catch can.

And yeah same, been using it for everything. I will start using it more when the car is on the road.

is it a return type? hose to top or bottom of tank?

[camaro1969]

is it a return type? hose to top or bottom of tank?

Sure is.

Small hose goes from the top of rad by the cap down to the overflow tank.

[Vince@Meanstreets]

Sure is.

Small hose goes from the top of rad by the cap down to the overflow tank.

but does it feed from the bottom of that overflow tank?

[camaro1969]

but does it feed from the bottom of that overflow tank?

Yes because water levels in the catch can go up and down