Heater core bypass - vents on cool still useable? (non A/C model)

[James9100]

98% sure my heater core is leaking so I’m just gonna bypass it (looping the two hoses together) until either I can replace it or just bring it in the shop.
But I did want to make sure I could still use the vents on the coolest setting just to get some air movement inside if I don’t want the windows down.
Don’t have A/C.
Probably a dumb question, I’m assuming I can as it’s not messing with the blower motor at all but just wanted to confirm.

Also should I cap off the heater core ports just so not junk gets in there?

Thanks!

 

[MountaineerTom]

Yes, you can do that. I bypassed mine a few years back until I replaced it.

If the core is leaking, I wouldn't worry about capping them off. Where do you see leaks from? Mine leaked from the HVAC box drain on the engine side of the firewall. It had the feel and smell of Antifreeze, so I was confident it was the heater core.

 

[James9100]

Yes, you can do that. I bypassed mine a few years back until I replaced it.

Yup I’m aware I can bypass it but I wanted to confirm that I’d still be able to use my fan just for some air movement inside. Like I said I don’t see why I wouldn’t be able to but I wanted to check anyways in case someone else knows something I don’t haha.

Where do you see leaks from? Mine leaked from the HVAC box drain on the engine side of the firewall. It had the feel and smell of Antifreeze, so I was confident it was the heater core.

I am pretty sure it’s gotta be my heater core but I did say 98% sure for a reason.

The 98% sure:
1. (Faintish) smell of coolant inside
(worn drive belt? my belt doesn’t look to be in too bad of shape but it also looks original to me)

How reliable are the tensioner indicator marks?

2. Pretty sure it’s coolant leaking from my A/C condenser drain
3. Overflow tank level slowly drops

The 2% unsure:
No coolant on the passenger side carpet that I’ve been able to find

My biggest concern is the overflow level dropping. If I bypass my heater core and that quits then I know that was the issue.

 

[MountaineerTom]

Yup I’m aware I can bypass it but I wanted to confirm that I’d still be able to use my fan just for some air movement inside. Like I said I don’t see why I wouldn’t be able to but I wanted to check anyways in case someone else knows something I don’t haha.

I am pretty sure it’s gotta be my heater core but I did say 98% sure for a reason.

The 98% sure:
1. (Faintish) smell of coolant inside
(worn drive belt? my belt doesn’t look to be in too bad of shape but it also looks original to me)
View attachment 430559
How reliable are the tensioner indicator marks?
View attachment 430560
2. Pretty sure it’s coolant leaking from my A/C condenser drain
3. Overflow tank level slowly drops

The 2% unsure:
No coolant on the passenger side carpet that I’ve been able to find

My biggest concern is the overflow level dropping. If I bypass my heater core and that quits then I know that was the issue.

I meant yes, you can still run your fan.

I‘m not sure on the accuracy of the tensioner marks.

I’d say it is your heater core. Since you don’t have A/C, coolant would be the only thing available to drain out of the box.

I never had any leak in to the interior floor. I could smell it through the vents when first starting it up and getting that blast of air out of the vents.

 

[James9100]

Might have to make a new thread on this if I don’t get responses but I bypassed my heater core this weekend and started thinking about replacement.
However I am going to need heat again come October and am not sure when I’d get to it, I’d also like to get one from Performance Radiators who is currently out of stock.
So… since it doesn’t seem to be leaking too bad at this point I may end up just hooking it back up once needed, if needed.
How should I go about “maintaining” the core while it’s not in use?
Leave the excess coolant in it? Flush it out? Hook it back up and run it once in awhile?

 

[MountaineerTom]

Might have to make a new thread on this if I don’t get responses but I bypassed my heater core this weekend and started thinking about replacement.
However I am going to need heat again come October and am not sure when I’d get to it, I’d also like to get one from Performance Radiators who is currently out of stock.
So… since it doesn’t seem to be leaking too bad at this point I may end up just hooking it back up once needed, if needed.
How should I go about “maintaining” the core while it’s not in use?
Leave the excess coolant in it? Flush it out? Hook it back up and run it once in awhile?

Mine wasn't out of service as long as yours would be, but I ran some plain water through mine straight from the water hose, used some compressed air at a low setting to clear it out. You could do something like that, then find some rubber caps or something to cap the lines off with.

 

[tdrudd]

I flushed mine out to avoid dribbling coolant out for awhile, but haven't bothered capping the old one off. Figured it's only going to get replaced anyways?

Terry

 

[Link]

If you have no AC and liquid coming from the drain, you have a heater core leak. Fix it correctly and replace it. You have some time to get it done. It's not a hard job. Given your location, I assume heat is very important for you. Nothing wrong with bypassing it for a little while. I wouldn't bother plugging it since it needs to be replaced anyway.

 

[B1Toad]

Might have to make a new thread on this if I don’t get responses but I bypassed my heater core this weekend and started thinking about replacement.
However I am going to need heat again come October and am not sure when I’d get to it, I’d also like to get one from Performance Radiators who is currently out of stock.
So… since it doesn’t seem to be leaking too bad at this point I may end up just hooking it back up once needed, if needed.
How should I go about “maintaining” the core while it’s not in use?
Leave the excess coolant in it? Flush it out? Hook it back up and run it once in awhile?

I'd flush it out with water, leaving coolant sit is no good, it becomes corrosive and it's the reason most modern systems circulate a tiny bit of coolant thru the heater core all the time even when the heater control valve is off.