Bypassed the Heater Core

[steve665]

I have a 1979 Eldorado with the 350 Olds engine. I only use it as a collector

car. Local summer car shows, etc. I bypassed the heater core today

because it allowed some heat into the car all the time, even with the

temp control all the way on cold and the system turned off. Seals in the

HVAC box probably a bit compromised by the years.

So here's my question. With the hose from the water pump rerouted to

the engine block which now allows full flow all the time from the water

pump to the engine block, will that compromise the cooling system at

the margin and possibly cause the engine to overheat in the future unless

the flow in that hose is throttled down by crimping the hose or installing

a valve to reduce flow?

[Ranger]

Just connect the two heater hoses at the firewall together. That should not affect anything.

[JohnnyG]

Connecting the two hoses together would simulate a condition where the heater was on all the time. No big deal, but if you really thought about it, the heater core would always provide some kind of restriction, so this situation doesn't really represent a "normal operating condition" for coolant system flow.

The opposite is also true. Just blocking off both hoses would simulate a condition where (IF) there is a water valve which closes off the flow to the heater core entirely.

Does the car have any kind of water flow shutoff control to the heater core? Some designs in different engines do. If so, I'd opt for blocking the hoses, which might provide greater flow through the rad if it were ever needed.

Sorry if it sounds like I'm thinking this thing to death, but the thought processes of people at work who must justify their cubicles must be rubbing off on me.

Either way would probably work forever.

[steve665]

Does the car have any kind of water flow shutoff control to the heater core?

Some designs in different engines do. If so, I'd opt for blocking the hoses,

which might provide greater flow through the rad if it were ever needed.

Yes, there is a vacuum operated water flow shutoff control which I eliminated

when I bypassed the heater core. Thus on a very hot day when the

thermostat is wide open the flow to the radiator would be reduced by

whatever amount the water pump is sending in a circle from the front of the

engine to the back, around and around as if the heater was calling for

maximum heat....itself a cooling radiator that is no longer in the loop.

So I agree with you that I should take steps to crimp the bypass hose or

block it to a minimal flow to avoid reducing flow to the radiator that the

water pump is designed to produce. I'm not comfortable with blocking

the flow through the bypass hose 100% though.

[lothos]

nice looking car

[coolnesss]

I've bypassed the heater core several times with GM V-8's over the years, and haven't ever had a problem in Southern California, where the temps can get into the 90's alot.

Unless the temp gauge shows some increase in temperature, I wouldn't worry about it.

One of the after-market car gadget companies sells an adapter to stick in each end of each cooling hose - 3/4" to 5/8" if memory serves.. It's straight through, and doesn't have any reduction in flow. I doubt that they'd manufacture it that way if it caused a problem.

[steve665]

I've bypassed the heater core several times with GM V-8's over the years, and haven't ever had a problem in Southern California, where the temps can get into the 90's alot.

Unless the temp gauge shows some increase in temperature, I wouldn't worry about it.

One of the after-market car gadget companies sells an adapter to stick in each end of each cooling hose - 3/4" to 5/8" if memory serves.. It's straight through, and doesn't have any reduction in flow. I doubt that they'd manufacture it that way if it caused a problem.

I've bypassed the heater core on numeros old cars through the years too, with no

problem. But they each had a temperature gauge I could keep an eye on. The '79

Eldorado just has an idiot light. I probably shouldn't obsess about this. I'm in

Northern Michigan. Summer temperatures are moderate.