bypass hose

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brian6pac

brian6pac

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I have blocked off the water pump bypass hose on a couple of my small blocks and I was wondering how may people do it and what you think of it, is it better!
 
I had no bypass hose but I also had nowhere to hook up a heater .

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I removed mine after the second hose split at high RPM, one was a dayco and the other a gates. When the thermostat closes the pressure spikes. I have no heater in my 67. My daily driver still has heat.
 
I didn't think the thermostat ever completely closed once at it's operating temperature?
 
Isn’t there a higher chance of cavitating the pump when the thermostat is closed?
 
The bypass hose allows water to circulate thru the engine when the thermostat is closed. No bypass, the coolant stagnates, and can/will cause localized hotspots, esp in aluminum heads. Funny, a new post show a person drilling and modifying an intake manifold and therm housing, for more circulation, and you guys stopping circulation..
 
When I removed my bypass hose I also tossed the thermostat, installed an adjustable thermoswitch for the electric fan and have no cooling issues. Blowing a bypass hose at WOT is not an option for me.
 
Yea I forgot to mention that I was also running a restricter plate (no thermostat) and blocking off the bypass
No heater also.
 
With no thermostat and a restrictor, no bypass hose... with a thermostat, then yes bypass hose needed...
 
diymirage said:
where do your breather hoses go?
Click to expand...
They go to aspirator valves that are attached to the headers at the collectors. There are pipes welded in the collectors at a 45 degree angle. This is an evac system for the crank case. It is sold as a kit which creates a vacuum under the pistons. No positive crank case pressure at all.
 
Oldmanmopar said:
They go to aspirator valves that are attached to the headers at the collectors. There are pipes welded in the collectors at a 45 degree angle. This is an evac system for the crank case. It is sold as a kit which creates a vacuum under the pistons. No positive crank case pressure at all.
Click to expand...
I wonder if that would help with a certain engine I have which has a lot of blowby
 
It won't help to restore compression but it would definitely keep the oil from under the hood. The breathers have built in baffles that help stop the oil from being sucked out

I had a preacher that we built a chevy motor for. He came back after a years of driving and racing. It had a miss. The hood cable was broke for over a year and he never looked under the hood. When we got the hood open I found the one valve cover dead loose. Two out of the four bolts were gone. I couldn't believe the motor was as dry as it was. The evac system actually kept the covers sucked down. I tried lifting them while holding the throttle open I couldn't believe the the suction it had.

From then on I was a believer in this system. This is used on big cam race motors that have no vacuum for a PCV but I wouldn't see why it wouldn't work on a street motor. It may smoke But it may not. I never tried to relieve blow by but it doesn't sound like a bad idea. Why suck the oil through the intake with the PCV and gunk up the valves when you can just suck it out with the exhaust

In the back ground on this pic you can see the aspirator on the tube welded in the collector

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mderoy340 said:
When I removed my bypass hose I also tossed the thermostat, installed an adjustable thermoswitch for the electric fan and have no cooling issues. Blowing a bypass hose at WOT is not an option for me.
Click to expand...

Do you run an Electric water pump or belt driven on the 67 ?
How did you plug the large water pump bypass port if OEM style belt driven pump?
 
Bypass hose is just what it says - bypasses the radiator when the thermostat is closed. Gets the engine to come up to operating temperature quickly while allowing the coolant to circulate. No circulation means no warm coolant flowing at the stat and can cause hot spots and boiling coolant before the stat opens.

No stat or an open restricter - remove the bypass so all the coolant flows through the radiator. Stat - you need the bypass.
 
One more time;
the thermostat sets the MINIMUM coolant temp.
The efficiency of the system sets the max.

The minimum is supposed to be around the rating of your stat. When you start your cold engine, minute by minute, the temp increases, and eventually gets to the set-point. Then the stat begins to open. When it does, often the cold water from the rad will cause a brief hiccup in the stat and if your gauge is fast enough, you can catch it.
But the temperature will continue to go past the set-point, and if your system is down on efficiency, especially at idle, the temp will continue to rise until it finds equilibrium, even tho the stat is wide open.
So by now, you are itching to go so you put it into gear. This slows the engine reducing efficiency, cuz you are still not moving; and so, the coolant temp continues to rise. Finally you begin motoring away, the rpm comes up, the fan is spinning and the pump is pumping; efficiency is on the rise and the temp falls TOWARDS the minimum. If it should happen that your system is exceptionally efficient,and the coolant temp falls below the minimum, then the stat will begin close. Few systems will do that unless your stat set-point is quite high.
Any time the stat is closed, coolant will be forced back into the pump for a second trip thru the block. Some of it can be diverted into the heating system.
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In my engine the bypass is severely restricted, and the cab-heater is my bypass. This is my back-up radiator in case the main system can't keep up.
After I installed the Milodon hi-flo pump/ thermostatically-controlled, 7-blade all-steel, factory fan; the cab-heater safety back-up, has never been needed; so I put valves in the lines, and shut the heater off for the summer. Now the restricted bypass, makes sure my alloy heads come up to temp in a reasonable period of time.
But the fail-safe is still there, all I have to do is open the valves.
I run a hi-Flo Milodon stat rated at 195. The coolant runs a rock-solid 205 to 207, measured at the stat-house by IR gun; no matter what the circumstances, cuz that Ford pick-up fan-clutch is flippin' wonder.
 
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