Finally getting around to bypassing the leaky heater core. Got 2 5/8" brass elbows, connected them together with a brass coupling nut,to get a "U" shaped connection to connect the 5/8" and 3/4" hoses together. Couldn't locate a 3/4" elbow. Just wanted to get some opinions if this should work until I can get the heater core replaced. Thanks in advance...

On my 64 bypassing the heater core raised the running temperature 10-15 degrees depending on the outside temp. Engine and radiator are original. I didn't think it would make that much difference but it did, especially in stop and go traffic.

------------------
OrrieG
64 Malibu HT Survivor
Gold Member #171

Just did the same thing. Only I did mine to limit the amount of heat let off into the cab. No AC in the south isn't too grand.

I bypassed mine at the engine. i.e. the hoses are still in tact to the heater core. I just stuffed them along the fender and connected the two ends.

The engine just goes straight from the water pump to the block. I also put ina 160 thermostat. No heat issues here.

------------------
have now>>>>> am building
SB350>>>>BB396 w/nitrous
TH350>>>>TH400 (haven't bought it yet...)
shooting for low 12s in 1/4
college student budget!

Old trick I used is to carry 2 bolts in my tool box, a 5/8 and a 3/4. Remove the hoses from the heater core, plug the lines with the bolts and clamp them tight.

I still have the bolts in my tool box, never know when a heater core could start to leak...

If the heater core is bypassed, what kind of precautions should be taken to prevent overheating. New thermostat, etc...? Or is this not a big concern?

To bypass it, just take the 3/4 hose off the core, the 5/8 hose off the engine, then loop the 3/4 hose from the engine back to the engine(to the 5/8 connector).
This allows coolant to circulate and plugs the "holes".
Overheating should not be an issue - never has with my cars anyway. http://www.chevelles.com/forum/biggrin.gif

------------------
Gotta have a Chevy !In Durham N.C.
Make it look the way you like it, forget what the other guys say! http://www.chevelles.com/forum/biggrin.gif

[This message has been edited by 283v8 (edited 03-20-2000).]

Funny this comes up, as I just had to bypass mine a couple days ago due to core leak. I just put a 3/4 nipple fitting on the water pump and ran a hose from there to where the other hose would go coming out of the core. Seems to circulate fine. Haven't hooked up water temp gauge yet so don't know how it's doing temp-wise.

Tony
'68 Chevelle 400

One of the hoses, cant remember now, either the 3/4 or 5/8 runs through a device that looks like an "EGR" valve and is mounted on the inner fender well. Looks like is has a small vaccum tube coming off of it also. Not sure what this is. Can it be taken out of the equation?

------------------
D Smith
ALABAMA
1970 Chevelle 350

That "little" valve does exactly what we are talking about, it bypasses the coolant circulation to the heater core when the A/C is on high for maximum efficientcy. That is a vacuum line, and it connects to the dashboard heater/A/C controls, when the A/C is put on "MAX", a vacuum is applied via the little hose and sucks in a plunger in the HOT WATER SHUT-OFF valve and stops coolant circulation.

If you want to TOTALLY by-pass the heater core like the original question states, don't leave any of this stuff connected. Connect the hose that enters the water shut-off valve and the hose that leaves the heater core itself together--everything will be totally by-passed. http://www.chevelles.com/forum/smile.gif

How imperative is it to take the valve out of the path? I cut the hose so that the valve is still in the path. Should I go back and redo this, or would it be fine with the valve still in use? Thanks...

------------------
D Smith
ALABAMA
1970 Chevelle 350

Nothing to worry about. Just so you're not sending coolant to the leaky heater core. I've had to plug or bypass several over the years because of hoses busting on the highway. The first time all I had was a pair of pliers and I found a stick on the side of the road to use for a plug. Just clamped both hoses on the stick until I got home.

------------------
http://www.geocities.com/MotorCity/Strip/4523/ElkyPage.html

Chad Landry
TC Member #643
'68 El Camino