i smell..oh a bad heater core..newbie question

[thfonz98]

yes i smell that great smell of coolant in my passanger side of my 91 k5. ive read how fun it will be to change.

my newbie question is: does the core only have coolant running to it when the heater is turned on...i presume that to be true but this is a busy weekend for me and its about 50-50 that ill ge tthis done.

steps(basically):
1. drain a good amount of coolant from my radiator
2. remove hoses from core(keep them high)
3. take off glove box..maybe remove dash just to make easier(i removed it this last week to install new speakers)
4. remove heater box...detach cables...remove all the &*^% bolts/screws
5. (more swearing here) install core
6. reattach hoses
7. run engine with raidiator cap off(filling as necessary) till it warms up to allow air to escape and fill, cap off the radiator and fill coolant through the extra resivior thing that is used for collant level.

i know of the write up i was just making sure of the basic steps(being a total newb and all)

 

[HarryH3]

There is no heater valve on our rigs. Water runs through the heater core 100% of the time (unless you add one, like I did, to keep the extra heat out of the cab in the summer).

 

[monster man]

all that the "heater" switch does is opena door in the heater/ AC box to allow the hot air into your fan system


I've done this three (3) times , the fourth I am adding a bypass valve. I would add a bypass valve NOW, you can get the fittings at Home Depot or similar, and will help save your core by not running coolant through it except when needed (though it may make your engine run a little hotter in summer).
the bypass valve will essentially look like an "H" with a handle on the two top parts of the H, when you turn the switches off it will just route the coolant in a "U" bypassing the core altogether

I've modified your steps a little:

steps(basically):
"drain a good amount of coolant from my radiator"
skip this step. I would get rubber line clamps and crimp off the two hoses going to the core, remove them (you will probably need to cut them iff they've been on there for a while, and set aside, or add your valve now

3. take off glove box.. don't need to remove dash, but you need to remove
the heater vents under the dash

4. remove heater box...detach cables...remove all the &*^% bolts/screws

if you have a/c it's even more fun, as that is all one large box and you have to take it all off for better access

* add step, drop out inner fender, this provides much better access to some of the bolts you need to remove on firewall

5. (more swearing here) install core
6. reattach hoses
7. run engine with raidiator cap off(filling as necessary) till it warms up to allow air to escape and fill, cap off the radiator and fill coolant through the extra resivior thing that is used for collant level.

 

[Russell]

Its not that bad of a job. I did the heatercore in my 74 in about 30 minutes.

Just drop the pass side inner-fender, undo the bolts that hold the firewall peice on, then undo the few bolts under the dash, slide it all out, undo 2 screws that hold the heatercore in, slide the new one in, and put it back on. Only other thing I had to undo was the heater cables, and all they took was a screw, then they slid right off without any trouble at all. You may want to pull your dashpad, I found that to make it quite a bit easier to see what is going on, in addition to your glovebox door.

This is all assuming you don't have AC, that could complicate things

 

[thfonz98]

i have a/c yippy![/sarcasm]

probably geterdone today(anti rain dance)

 

[thfonz98]

took 5 hours(worked on it from 12-6 but the engine was hot at 12pm) so i d.'ed around for about an hour, worked on it, then had a problem getting the heating box taken apart to get the core out and went to my friend's shop and had him show me how it comes out.