Bypassing heater question
Thread Starter
Drifting
Joined: Oct 2004
Posts: 1,259
Likes: 7
From: Ontario
Bypassing heater question
I just installed a new heater core and the new one leaks!!! It is not the hoses, it's leaking into the interior. I am not going throught this again, going to bypass it. Question, do I have to keep a short hose between the intake and waterpump heater connections, or can I seal them off completly with plugs? I have a small block.
Pro
Joined: Nov 2004
Posts: 659
Likes: 0
From: Flower Mound Texas
That'll make you say a few choice words. I just replaced mine, too. The first heater core I bought didn't fit right, but I got a refund. Second one fit better and fortunately doesn't leak. Before I replaced the heater core, there was a hose from the water pump to the intake manifold, but I do recall a thread on this forum where others said this was optional.
Safety Car
Joined: Jun 2004
Posts: 4,652
Likes: 80
From: Lakeland Florida
That is too bad. To think of all the work that you did, and then find out that it is leaking. That would really upset me.
I have read on this topic about people doing a bench test on the heater core to see if it leaks BEFORE putting it into the car.
My question is.....how do you bench test the core before putting it in? Do you hook it up to the engine with long heater hoses, and leave the core outside of the car? That would mean doing this before tearing up the inside of the car.
kdf
I have read on this topic about people doing a bench test on the heater core to see if it leaks BEFORE putting it into the car.
My question is.....how do you bench test the core before putting it in? Do you hook it up to the engine with long heater hoses, and leave the core outside of the car? That would mean doing this before tearing up the inside of the car.
kdf
Racer
Joined: Dec 2003
Posts: 275
Likes: 6
From: NY
New heater core leaks
I changed mine out last year. Read the posts about testing AFTER replacing. Scared me a bunch to think it would be no good. But I bought my heater core and radiator from a local radiator shop. There aren't too many of them left. They press. checked both cores before they gave them to me.
Melting Slicks
Joined: Oct 2004
Posts: 2,662
Likes: 8
From: Knoxville Tennessee
You can do which ever is easiest. Plugging both connections shouldn't cause the water pump to cavitate. When you turn the heater off the valve stops the flow of water to the heater core which is what you would be doing if you plug both places. I know of many people, including myself, that have installed ballcock valves on both lines so that residual heat from the engine can't work its way back to the heater core with no ill effects to the pump or the system. Sorry about your leaking core.
Bernie
Bernie
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
Originally Posted by kdf1986
That is too bad. To think of all the work that you did, and then find out that it is leaking. That would really upset me.
I have read on this topic about people doing a bench test on the heater core to see if it leaks BEFORE putting it into the car.
My question is.....how do you bench test the core before putting it in? Do you hook it up to the engine with long heater hoses, and leave the core outside of the car? That would mean doing this before tearing up the inside of the car.
kdf
I have read on this topic about people doing a bench test on the heater core to see if it leaks BEFORE putting it into the car.
My question is.....how do you bench test the core before putting it in? Do you hook it up to the engine with long heater hoses, and leave the core outside of the car? That would mean doing this before tearing up the inside of the car.
kdf
Instructor
Joined: Jul 2004
Posts: 106
Likes: 0
From: Brandon Mississippi
Originally Posted by carguy4sure
I just installed a new heater core and the new one leaks!!! It is not the hoses, it's leaking into the interior. I am not going throught this again, going to bypass it. Question, do I have to keep a short hose between the intake and waterpump heater connections, or can I seal them off completly with plugs? I have a small block.
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Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
after reading all the warnings posted here before, when I replaced the wifes heater core (1973 w/AC) I placed the replacement in a bucket of water and pressurized it with my air compressor... looking for air bubbles.
I don't know how thorough this test is, but the replacement core didn't leak any air bubbles during the test, and didn't leak after installing in the car either.
I don't know how thorough this test is, but the replacement core didn't leak any air bubbles during the test, and didn't leak after installing in the car either.
Melting Slicks
Joined: Oct 2004
Posts: 2,662
Likes: 8
From: Knoxville Tennessee
When two shut off valves are installed, one on each hose it stops water flow and heat transfer just as if you plugged both ends with pipe plugs; period. The water pump will not cavitate either way you do it. When the thermostat is closed allowing the rad. to cool the water mixture the water pump doesn't stop pumping for that time; it merely tries to pump water unsuccessfully until the thermostat allows it to do so. This isn't rocket science and whether you stop the flow at the source or ten inches away the same thing happens; fluid stops flowing at the source, just as if it were plugged there. Again, its your car and either way will be fine. Go to corvettefaq.com for more on this if you want to research it further. Happy vetting!!!!
Bernie
Bernie
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
Originally Posted by Mike Mercury
after reading all the warnings posted here before, when I replaced the wifes heater core (1973 w/AC) I placed the replacement in a bucket of water and pressurized it with my air compressor... looking for air bubbles.
I don't know how thorough this test is, but the replacement core didn't leak any air bubbles during the test, and didn't leak after installing in the car either.
I don't know how thorough this test is, but the replacement core didn't leak any air bubbles during the test, and didn't leak after installing in the car either.
i like this idea even more then mine..air submegerd in water will certainly show off any leaks....how did you cap of the ends and make an air hose fitting? ....the bike tire is easy with the schrader valve already in it....
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
I have an air gun nozzle with a big rubber tip that sealed into one end. The other end I capped off with my utility sinks rubber stopper (holloow on underneath side) - using a hose clamp around it.
It was a little ackward, but I felt confident I had proven enough
that it was safe to install.
It was a little ackward, but I felt confident I had proven enough
that it was safe to install.
Drifting
Joined: Sep 2001
Posts: 1,427
Likes: 1
From: Boxford Mass
Originally Posted by BerniesVette
When two shut off valves are installed, one on each hose it stops water flow and heat transfer just as if you plugged both ends with pipe plugs; period. The water pump will not cavitate either way you do it. When the thermostat is closed allowing the rad. to cool the water mixture the water pump doesn't stop pumping for that time; it merely tries to pump water unsuccessfully until the thermostat allows it to do so. This isn't rocket science and whether you stop the flow at the source or ten inches away the same thing happens; fluid stops flowing at the source, just as if it were plugged there. Again, its your car and either way will be fine. Go to corvettefaq.com for more on this if you want to research it further. Happy vetting!!!!
Bernie
Bernie
Given the option of plugs vs hose loop, I choose plugs. Its easier. The hose loop option works but you'll need to handle the change in hose size.
Le Mans Master
Joined: Jan 2003
Posts: 6,575
Likes: 1
From: Tuttle OK
Cruise-In VIII Veteran
Originally Posted by Jack71
I agree this is the best long term solution because its nice to shut off the water flow in the summer.
Given the option of plugs vs hose loop, I choose plugs. Its easier. The hose loop option works but you'll need to handle the change in hose size.
Given the option of plugs vs hose loop, I choose plugs. Its easier. The hose loop option works but you'll need to handle the change in hose size.
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
When two shut off valves are installed, one on each hose it stops water flow and heat transfer just as if you plugged both ends with pipe plugs; period.
What does adding a second valve accomplish or cure (or are we strictly talking about complete core bypass)?
Le Mans Master
Joined: Aug 2003
Posts: 7,720
Likes: 12
From: Chattanooga TN
Originally Posted by Mike Mercury
after reading all the warnings posted here before, when I replaced the wifes heater core (1973 w/AC) I placed the replacement in a bucket of water and pressurized it with my air compressor... looking for air bubbles.
I don't know how thorough this test is, but the replacement core didn't leak any air bubbles during the test, and didn't leak after installing in the car either.
I don't know how thorough this test is, but the replacement core didn't leak any air bubbles during the test, and didn't leak after installing in the car either.
You want to be careful with this. The core is not designed to hold 100 psi. You probably don't want to exceed 20-25 psi. I liked the bicycle tire idea. Pressurize it and submerge that in water might be the best idea.
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
Originally Posted by Mike Mercury
I
What does adding a second valve accomplish or cure (or are we strictly talking about complete core bypass)?
What does adding a second valve accomplish or cure (or are we strictly talking about complete core bypass)?
even with my shut off valve clsoed i still get some heat through the heater core from the transfer of heat through the water in the other line....i think the area you live in dictates how much you need to stop all water flow.....the hotter it gets where you are the more ways you look to stop the heat flow...for a couple of day this summer i didn't even drive the car during the day because it was just too hot....
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
even with my shut off valve clsoed i still get some heat through the heater core from the transfer of heat through the water in the other line....
during the middle of the last summer is when I installed the vacuum operated valve. So I got a good before/after comparison (especially since the 1973 is the wifes car and I get to be the passenger).
It did make a huge difference. Enough that I can probably let it go as is. My wife only likes to drive the 1973 with the T-Tops off - so I'm sure that's helping with the slight amount of heat that may still be seeping through.
Last edited by Mike Mercury; Dec 31, 2004 at 12:36 PM.