Year: 2004
Engine: 3800 NA

Random 3800 swap question: I have relocated my alternator and removed the factory bracket. Now I have the two open ports (intake lower, water pump). I know I need to put a plug in them, and they measure out at 1 inch and 7/8 inch. I have read that I need to get some freeze plugs to put in them.

My question is are both of these ports supply, in other words, do they both push out coolant, or did one pull in coolant and the other push? If so, which one did what?

I know others have done this, but I just want to understand the mechanical process here.

Also, does anyone make/sell the modified Fiero thermostat housing that has the port for the heater core hose? I see them for sale from time to time, but I can’t remember if someone sells them.

Thanks for any help.

Rob

We usually sell them without the heater hose port. But, we can definitely make you one with it still attached

They are $70 shipped. We do need a core and they come powder coated

Here is one without the port



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3.4TDC/4.9l/3800(SC) Swap kits and parts

F23 Transmission Kits

Big Brake Adapters

Polish and Powder Coating

True dual equal length 3800 Headers

[This message has been edited by FriendOfYours (edited 10-01-2012).]

Thanks. And of course, the one with the heater outlet has the outlet below the thermostat right? Just want to be sure im asking for the correct thing. i'm still trying to build my knowledge base for the 3800 swap. I filled my brain with all the 3.4 DOHC stuff and now have to learn a whole new swap.

Rob

That is correct

The port in the lower intake manifold supplies water to the heater core and it returns to the water pump.

On later Fieros the return line is built into the lower radiator hose, so you need only to run the hose from the intake manifold and plug the water pump inlet.

On earlier Fieros you would have to run both lines.

[This message has been edited by MRose (edited 10-01-2012).]

quote Originally posted by MRose: The port in the lower intake manifold supplies water to the heater core and it returns to the water pump. On later Fieros the return line is built into the lower radiator hose, so you need only to run the hose from the intake manifold and plug the water pump inlet. On earlier Fieros you would have to run both lines.

From what I have read I have two options. I have an 88GT so the heater core return line is plumbed into the engine coolant line at the pass side near the cradle bolt. The feed line has to come from either the lower intake manifold or from the modified thermostat housing. If I used the lower intake manifold, I'd have to tap the manifold and then install a 7/8" bung into it. If I use the thermostat housing, I have to plug the manifold and run the line off a small bung welded into the housing.

If I have this right, either one will work, both have possible issues and i'm not sure which is easier.

I have not found the 1" and 7/8" plugs at any of my local parts stores, and I'm going to have to google search for them and buy them online. I have found a 7/8" bung to install into the manifold, but I have never used a tap before, and I don't know if I want to "practice" on the aluminum manifold. I guess I could take it to someone and have them tap/weld it in place. Its not like i'm ever going to put the motor back into a Grand Prix.

If I get the modified thermostat housing I "kill two birds with one stone". I get the coolant "high fill point" along with the heater core supply.

If anyone has had a bad experiance with any of this, please let me know.

Rob

If you use the outlet in the t-stat housing you still have to tap and plug the manifold, only to end up with a longer heater hose.

I was able to tap the water pump and manifold with the motor in the car. The water pump is just a tad large so you don't get the best threads.

I JB welded a brass plug into the water pump and JB welded a pipe bushing into the manifold to adapt to a smaller size, then inserted a brass hose barb into the bushing.

No need for a nip on the housing for an 88. Just cap the water pump heater fitting and run your single heater hose from the one next to it that goes into the LIM