Heater Bypass

[contraption22]

When eliminating the heater, is it better to have a bypass hose or simply block off the coolant flow through the heater circuit?

Is if it is better to have some path for water to circulate, in order to make sure there is a good flow of coolant when the thermostat is closed. Perhaps a restrictor in line? Thoughts?

Thanks.

[4 l-bodies]

Mike,
I would definitely have a bypass hose installed. Otherwise it will have too dramatic of temp swing when thermostat opens. Waterpump needs to do it's thing moving coolant whether thermostat is open or not. It also greatly reduces hot spots if coolant is constantly moving throughout system.
Todd

[Pat]

Wouldn't putting a series of holes in the t-stat accomplish the same thing?

[tryingbe]

Route a hose from the bottom of the thermostat to the waterpump, heater core bypassed.

[contraption22]

Mike,
I would definitely have a bypass hose installed. Otherwise it will have too dramatic of temp swing when thermostat opens. Waterpump needs to do it's thing moving coolant whether thermostat is open or not. It also greatly reduces hot spots if coolant is constantly moving throughout system.
Todd

Makes sense.

Wouldn't putting a series of holes in the t-stat accomplish the same thing?

Also makes sense.

Route a hose from the bottom of the thermostat to the waterpump, heater core bypassed.

I'd be concerned that an unrestricted bypass would allow too much coolant to bypass the radiator.

[Pat]

On my 8v motor that I've been running at GRM the last few years, I ran a 3/16" unrestricted line from the drivers side of the head to the low pressure side of the water pump and have a hole drilled in the thermostat. That motor has been amazingly reliable given the abuse it gets.

Without the dedicated bypass line, I would think a few extra holes would keep enough coolant moving past the Tstat would work fine.

[4 l-bodies]

I'd be concerned that an unrestricted bypass would allow too much coolant to bypass the radiator.

Mike,
That is exactly what the factory did. One bypass is the heater core. Virtually no coolant restriction unless it is clogged/plugged up. On AC equipped cars the recirulation valve stops flow of coolant through core and emulates exactly what Harry and I posted. What Harry suggests is all good with zero drawbacks (except no heat/defrost lol). I've done it countless times on Turbo Mopars, street rods, etc. The only thing your bypassing is the radiator. Doing it this way keeps coolant moving rapidly through motor and allows it to quickly come up to temperature allowing thermostat to open and STAY open.
Punching multiple holes through thermostat will just delay thermostat opening causing longer warm up period. To few holes (restriction) and waterpump just cavitates and vehicle gets hot spots and runs hot. Too large of bypass and vehicle will take forever to come up the temperature if bypassed coolant is allowed to flow through radiator (thereby cooling it).
A vehicle with a clogged or plugged up heatercore many times will run hotter than normal. That is because of the cavitation the waterpump is seeing because the bypass has been compromised. You can get wild temperature swings when the thermostat is opening and closing. Same thing could happen with no bypass.
Todd

[tryingbe]

I'd be concerned that an unrestricted bypass would allow too much coolant to bypass the radiator.

Nope, not a issue running a hose from bottom of the thermostat to the water pump.

I did run into an issue when I blocked the bypass completely both at the thermostat and the watepump. From a cold start, the cylinder head will warm up FAST, but head will run into 220-230F for a bit before the thermostat will open and temperature back down to 170F then stabilizes.

You have to realized, I live in AZ with 110-120F summers. If there is a cooling issue, AZ people will find it before anyone else.


So far, I have found, TII radiator are junk for cooling, even when it is brand new. Stock radiator fans are also junk. Go for aftermarket universal radiator and a fan from Volvo 940/960. A/C system works better with later a/c compressor, aftermarket universal condenser, custom made hoses, etc.


I've gone from this,



To this. So I can have my a/c working and car not over heat in the summer.

[contraption22]

Cool thank you all.

[cordes]

On my 8v motor that I've been running at GRM the last few years, I ran a 3/16" unrestricted line from the drivers side of the head to the low pressure side of the water pump and have a hole drilled in the thermostat. That motor has been amazingly reliable given the abuse it gets.

Without the dedicated bypass line, I would think a few extra holes would keep enough coolant moving past the Tstat would work fine.

An aspect to that reliability may be the fact that you're taking it off the end of the head. Shadow has had great results with that, and RJ138 with the experimental Omni has actually logged a decrease in knock after doing the coolant mod with it going out the side of the head and back into the pump housing.

[contraption22]

I am looking at this on the 2.4 engine, which i am not sure would have the same coolant stagnation problems as the 2.2.

My setup is requiring a custom coolant outlet/thermostat housing, so I was wondering if a provision for the coolant bypass should be part of it's design.

[cordes]

My mistake. I think the concept would remain the same for the bypass.