[Infinite Monkeys]

Hi,
I have a transplanted, 1993 Chevy 5.7L TBI motor from a Buick Roadmaster. I can't figure out where one of the heater hose port is. I can see one near the TB unit on the passenger side, on the intake manifold, but don't know where the other might be. Any help would be greatly appreciated.
Thanks

[nine4gmc]

on a 93-94 truck, there is one hose coming from the back passenger side intake by distributor and the other comes from under the filler neck on the radiator. 95 has a port on top of the water pump instead of the radiator port.

[Infinite Monkeys]

Thanks,
I don't have the stock radiator so I had no idea of that port. Guess I'll have to figure out how to put in a port some where in the system.
Maybe I can fit the 95 pump on the motor and make it easy.
Thanks again

[oldbogie]

Originally Posted by Infinite Monkeys

Hi,
I have a transplanted, 1993 Chevy 5.7L TBI motor from a Buick Roadmaster. I can't figure out where one of the heater hose port is. I can see one near the TB unit on the passenger side, on the intake manifold, but don't know where the other might be. Any help would be greatly appreciated.
Thanks

These ports move around on different installations, basically there is only 2 things going on:

1) a hose picks up pump pressurized coolant ahead of the thermostat which obstructs the return of coolant to the radiator when closed. Usually this is either from the rear of the intake manifold on the passenger (right) side. It can also be from the coolant return ports at the front of the intake manifold before the thermostat.

2) a hose returns coolant to the intake side of the pump (low pressure side). This depending on model and year can be a fitting on the pump, or a return to the suction side tank of the radiator, or a tee fitting in the suction hose feeding the pump from the radiator.

The whole point is to provide a coolant bypass when the thermostat is closed to prevent hot-spot boiling usually around the exhaust seats and spark plugs when there is not yet general circulation; to prevent pump cavitation that would occur with a stall condition when there is no circulation from the radiator; and lastly to provide early cabin heat. AC installations usually include a 3 way valve that shuts off circulation through the heater core when the AC is on but provides a route so the normal bypass circulation occurs. The SBC also includes a bypass drilling on the right side from the head into the block and into the pump suction side, this is to balance right to left side flow as the pump favors flowing to the right side of the block a little bit. It is not intended to function as a closed thermostat bypass being too small for that.

Bogie

[Infinite Monkeys]

Hi Bogie,
Thanks for that extremely informative reply. You saved me from making a big mistake. Since I am not going to put in a heater for now, I was going to block off the manifold port and just run the upper and lower radiator hoses. I did not realize that the coolant needed to circulate before the thermostat opens.
Another question is: what direction does the coolant flow when the thermostat opens. Does it go into the engine from the top of the radiator, or out.
Thanks again

[oldbogie]

Originally Posted by Infinite Monkeys

Hi Bogie,
Thanks for that extremely informative reply. You saved me from making a big mistake. Since I am not going to put in a heater for now, I was going to block off the manifold port and just run the upper and lower radiator hoses. I did not realize that the coolant needed to circulate before the thermostat opens.
Another question is: what direction does the coolant flow when the thermostat opens. Does it go into the engine from the top of the radiator, or out.
Thanks again

It comes from the bottom to the pump typically into the block, up to the heads with return collected at the front using the intake manifold as a location to put the passages. The manifold houses the thermostat and return fitting which then sends the return coolant to the upper radiator connection.

While this description covers a great many engines including the SBC not all are configured like this. The early Chrysler Hemi's followed this basic scheme but the return was separate from the intake manifold and external using a fitting on the passenger side and a hose to connect to a bolt on thermostat housing on the drivers side with the radiator return from there. The 1990's LT1 and LT4 with reversed cooling puts the coolant into the head first then to the block and uses a complicated mixing system that adds just enough cold coolant to the hot to maintain a very tight operating temp. The new LS engines also use this system. At GM reverse cooling came out on the Pontiac engine in 1955 and was used through 1959 production. The system proved to be troublesome in service this being a period of transition trying to get the motoring public to adapt the use of glycol coolants instead of straight water, or water mixed with a dissolveable oil (water pump lubricant). the other problem was steam formation in the heads above the rear combustion chambers which was not solved till the LT1/4 with nothing more than a small bleed tube from the rear to front of the heads then connected to the pump's suction side. There are, also, many other coolant routing schemes both by the factories and by the racing community.

Bogie

[nine4gmc]

i just learned something, Thanks!

[Infinite Monkeys]

Thanks again Bogie.
For what it's worth, I put the 1995 pump with the heater hose port on it and it fit just fine. Right now I have the manifold and the water pump ports hooked together till I get around to putting in a heater.

Thanks

[oldbogie]

Originally Posted by Infinite Monkeys

Thanks again Bogie.
For what it's worth, I put the 1995 pump with the heater hose port on it and it fit just fine. Right now I have the manifold and the water pump ports hooked together till I get around to putting in a heater.

Thanks

As long as you're aware that a 1995 is a reverse (counter clockwise) rotation pump and only works with a factory serpentine belt system or an aftermarket that runs the belt under the pump pulley like the OEM does. If you're using older V-belts or an aftermaket serpentine that goes over the pump pulley, then you need the older clockwise rotation pump. Same goes for fan if it's being turned by the pump.

It just never stops coming at you with these things anymore.

I'm getting out of here for the night, we're running a dyno simulation and the damn program keeps locking up, I just don't want to mess with it any more.

Bogie

[Infinite Monkeys]

Another good point, also one I did not take into consideration before putting it in. Luckily, I am running the factory, serpentine belt, reverse rotation on the pump.
Lucked out that time.