ok so i was wondering if there is a way to use the stock set up on the coolant lines that come out right under the alternator. i was reading around and it seems that no one seems to use this set up. it seems like everyone's just blocking off holes. this is just really confusing me. can anyone help clearify what really needs done here? i'm getting really close to finishing the swap and i have the engine in the car and everything. i'd really like to be able to solve this without having to take the whole engine back out of the car again.

Might I suggest you search the archives. Pleanty of people use the "stock setup" that comes on the 3800 in their swaps. I'm one of those people.

The main reason why people delete this bracket from the 3800 in their swaps is so they can run a conventional dog-bone mount in that location on the engine; because they are using conventional type Fiero mounts on the engine. I don't do that in my auto trans swaps; so I don't need a dog-bone. But in the latest manual trans 3800 swaps I have done, I have created a dog-bone mounting bracket that bolts directly to the 99-up 3800 alternator mounting bracket. In auto swaps, I leave the bracket on there and usually mount the ignition coil in that location.








As you know the stock 3800 alternator bracket has pass-thru passages for both the heater supply and return lines. When I do engine swaps into 87-88 Fieros, the heater return line from the heater core already dumps into the passenger side coolant tube. So there is no need to run the return all the way up to this bracket on the engine. Instead what I do is use that (return) port coming off the bracket to connect to a port that I mount next to the strut tower which serves as the NEW coolant fill port (see below). This elimintates the need to use the bulky Fiero T-stat housing on the 3800. The heater supply line coming off this bracket connects to the stock heater supply line in the Fiero. Pretty straightforward.



Something else important to note. The alternator bracket that comes on these 3800 Series 2 and 3 engines also contains the bypass circuit for the cooling system. This is designed to prevent excessive coolant pressure from building in the engine (via the water pump) when the thermostat is closed IN CASE the heater core system becomes plugged. It also serves to reduce pressure in the heater core circuit in normally operating systems. If you remove the stock alternator bracket from the 3800 and do not build in a bypass circuit externally; if you have a restriction form in the heater core system, excessive pressure can build up from water pump operation during periods when the t-stat is closed that can result in blowing out the heater core or related hoses/lines.

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5+ years on this same swap -- NO engine or transmission failures...

Custom GM OBD1 & OBD2 Tuning | Engine Conversions & more | www.gmtuners.com

I used this setup, Everything is stock, The weird curved hose I got from autozone both runs into my fieros stock coolant locations

I used them to. I took the factory straight hose connections cut them at an angle and welded them back together to make them into 90 deg. elbows to attach the coolant lines to.

What about the age old trick of drilling an 1/8" hole or smaller, in the flat part of the thermostat and use that as a bypass?

Sorry butt in here but I have a related question. What if your heater supply line is on the firewall and not running back by the dog bone? Also who makes or where do you buy the heater hoses for the engine compartment? My 87's have what look to be high pressure fittings on the them. I have looked around and do not see any listings for these unless I missed something.

Thanks for any advice.

[This message has been edited by ca420 (edited 03-17-2009).]

420 in your first picture that's where I hacked my tubes (next to the holding bracket but giving me enough length to attach rubber heater hose and clamps) and then I ran heater hose up to the dogbone area. I think it was just 5/8" and 3/4" regular autozone heater hose.

[This message has been edited by Bubbajuju (edited 03-17-2009).]

quote Originally posted by RumbleB: What about the age old trick of drilling an 1/8" hole or smaller, in the flat part of the thermostat and use that as a bypass?

Drilling holes in the T-stat usually results in it taking longer for your engine to reach normal operating temperature. People living in areas where the car will have to be driven in cold climates probably won't like the affects. It is not good on the engine either. Most of your engine wear occurs while the engine is operating before it is fully warmed up.