3.1 Heater Hose Question

[KlingonFiero]

The engine is from a 1992 Buick Regal.

I have been through the whole forum, couldn't find the info I need.

First, I just want to confirm that the heater hose coming from the Water pump housing is the outlet TO the Heater Core / Radiator .

The heater core return goes to the thermostat housing.

Is the above correct???

Also, the heater hose goes through the TB, yes?
I can just delete that section, Right?

Thanks!

[KlingonFiero]

I took a close look at a 3.1 in a car at the junkyard today.
Looks to me like maybe the WaterPump is the outlet FROM the Heater Core / Radiator.

Can someone confirm this?

Thanks!

[3100 MPFI]

The lines under the throttle body can be bypassed to each other so that it is not hooked up to the throttle body at all. I can't really remember the heater core lines, but it seems to me that the BOTTOM one on the heater core (on my 1990 STE 3.1 MPFI) is hooked up to the line over the water pump, and the top heater core one is hooked up to the one going over to the thermostat housing.

I then bypassed the throttle body so that it is not longer connected.

I can try to take some pics tomorrow, if you think that will help.

[KlingonFiero]

Thanks for th eoffer, but pics probably wouldn't help. I am installing this in a Fiero

I just need confirmation of the coolant flow.

Is it from the Rad to the waterpump? So the water pump is sucking it from the radiator (when the thermostat is open, of course).

Thanks!

[3100 MPFI]

Is it from the Rad to the waterpump? So the water pump is sucking it from the radiator (when the thermostat is open, of course).

Thanks!

In my car (1988 Cutlass Supreme W-body with a swapped in 3100 SFI which is the same cooling system as the 3.1 MPFI) the water pump pulls in the coolant from the radiator (on the passenger side), and then when the thermostat opens (drivers side), it flows back into the radiator.

As for how the heater lines do, I am not 100% certain, but my twisted logic in the way I think seems that the waterpump would be PULLING from heater core. I don't know if this is true, since I have not really had to think about this.

I also am not willing to pull one of my heater core lines, and start the car just to see if water comes out, or not. LOL

Check your PM's

[KlingonFiero]

In my car (1988 Cutlass Supreme W-body with a swapped in 3100 SFI which is the same cooling system as the 3.1 MPFI) the water pump pulls in the coolant from the radiator (on the passenger side), and then when the thermostat opens (drivers side), it flows back into the radiator.

Excellent, Just what I neded to know!!!
P.S - I am going to assume that the heater lines are the same...

I also am not willing to pull one of my heater core lines, and start the car just to see if water comes out, or not. LOL

Check your PM's

Come On, you know you want to burp the cooling system!

And,
PM replied too.

[3100 MPFI]

If I MUST do that for you, it will have to wait until I am finished with the OBD2 conversion in my 1988 Cutlass Supreme. I have the engine out of it right now, and it iwll be about 2 weeks before it goes back in.

[Guest]

Coolant flow is always OUT of the water pump. there is only one inlet to the water pump and that is from the rad.

Yes, the heater hose connected to the LIM is the return from the heater core.

[CNCguy]

Sorry to disagree with you Raven but the heater core return is to the water pump. If you look at where the heater hose connection is located, you will see that it is on the inlet/suction side of the water pump. Even the RWD 60V6s are this way but it is deceptive due to the pumps routing of the inlet passage. It makes sense that the cooled water from the heater core would enter at the same place as the cooled water from the radiator.

GM trucks are a little different since they dump the heater return into the outlet end of the radiator. I assume this is to get the transmission to the proper temp quicker but does make for a slower warm up for the heater. Even though it is somewhat different, it still returns to the heater outlet to the inlet side of the water pump.