Well, I've now eliminated the heater core from my car. My question is ... can the 2 lines (water pump & intake), that normally cycle coolant through the heater core, can I just put pipe plugs in them ... Or, should these still circulate coolant with a hose between the two?

Thanks, Neal

Plug them. But then make sure you are either running the bypass hose between the water pump and the intake or plug that as well and drill a couple little holes in the T-stat.

So, it's also OK to plug the hose going from the water pump to the intake manifold? That would be cool. No issues with cooling problems that way? Basically would just have the 2 radiator hoses for the whole coolant circulation.
Thanks, Neal

I would maintain at least one of these connections, either the heater circuit or the intake to water pump bypass. These provide some circulation when the thermostat is closed to you get even warm up without localized hot spots in the engine.

My vote is to leave the hose from intake to water pump.

My vote is to leave the hose from intake to water pump.
Well, that's good ... cause, as of about 3 days ago, there is no more heater core!! Firewall is el-smootho:-)

No, I do get what you're saying ... could someone illustrate better how the coolant routing actually goes with this? Is the water pump to intake, just a very large bypass? How's it interact with the rest of the cooling flow?

Thanks, Neal

You can plug both as said above. Just drill 2 1/8" holes in your T-stat to keep a little fluid circulating before it opens.

This is my engine. No heater core, no bypass. Just 2 1/8" holes in T-stat.
http://i52.photobucket.com/albums/g34/Brettd85/DSCN0818.jpg

the little hose from the pump to the intake does the exact same thing as the hose to the heater core does. i'd leave it, if only because the GM powertrain engineers spent a lot of time and money getting it right, and they put that there for a reason. sure, a couple of holes in the t-stat would do the same thing, but why question the guys that designed it in the first place?

This is another case where many things work... but some things just work better.

If you read around on the Stewart site they advocate (read that also as "sell") 3 3/8" holes in a high flow thermostat. This amounts to about 0.33 sq. in. of flow area.

Those 2 much smaller 1/8" holes only provide 0.025 sq. in. of flow area. That does not accomplish much besides allowing air bubbles to pass. That is only 7% of the area on the Stewart thermostats BTW.

The OEM bypass design used 2 hoses of about 1/2" diameter for a 0.40 sq. in. flow area. This is what GM engineers found to be optimal as far as circulating coolant through the BBC and achieving an even warm up without localized hot spots. You might argue that the heater hose size was driven more by heat delivery requirements for the passengers, and you might be correct. Nonetheless, if less was required, they likely would have used a smaller hose at least on the bypass.

It is interesting that the Stewart setup comes fairly close in flow area to the OEM design.

If you wonder why it is important to have even heating of the engine components and avoid hot spots, it is to maximize engine life. The parts in an engine fit optimally with all parts at operating temperature. Make parts colder or hotter and the fit degrades as those part expand and contract. If the fit gets tighter it can lead to additional wear as the parts rub and wear from fitting too tightly. Loose is not much better. So do you want your engine to last 50k miles or 100k miles?

The downside to removing the bypass in favor of the thermostat "leak" is it prolongs engine warmup as now all the coolant in the radiator and it's hoses must also be warmed up. Worse still the radiator will be cooling the not yet warmed coolant delaying warm up even further. In cold conditions the coolant may never get warmed to normal operating temperatures at all. Again operating at temperates below normal will increase engine wear.

One last question: what affect will it have on the power used driving the water pump if the water is unable to circulate/move? Might it require more power and thus increase fuel consumption? (yeah, yeah, I know... who cares with a BBC) ;)