I am trying something different on my 3800c swap. I currently have no way of filling the system other than pulling off a hose and filling there, which leaves a big air pocket. One day while wandering around the junkyard looking for other things, I happened to find a pressurized coolant reserve tank laying on the ground. It was too big for me to use, so I started looking around and found a nice sized one in a Chevy Cobalt.
The one I found laying on the ground had hoses with a T on it, so I took those. (took, bought, whatever) Now, the Cobalt tank is small, so it could be placed just about anywhere, but I was thinking it needs to be mounted high so the air can burp and the coolant can fill. That is a problem, as there isn't much room to make it high enough to not cause issues.
Notice the small hose barb on the top. In the Cobalt, this went to the head. I was going to plug it and let it go that way, but I think it is vital to proper operation of the tank. Now my question is, what is that nipple doodad on the top of the 3800 thermostat housing? At first I thought it might have something to do with preload, or a spring, but after a little searching it looks like it is nothing, maybe just an air bleed. If so, I'm going to tap it and use it to vent my coolant reserve tank. Can anyone verify that is all it is, and I can drill and tap it?
I saw one recently installed in a 3800 swap. They located it to the passenger side of the stock dogbone mount, with the cap poking up through the V shaped hole that usually has a plastic cover. They routed it to the return side of the water pump, but the one they installed had a larger hose size ( heater hose sized). I think your idea of using the bleed hole on the thermostat might be OK, but I would worry about the thermostat being closed when filling cold. Filling through the water pump side ( or maybe even one of the other ports, like tee'd into the heater hose) would allow you to fill the block without the stat being opened. Also need to consider cap pressures ( radiator vs pressurized tank). I would think one of them needs to be higher than the other, so that you have one point of "refill/burp". maybe putting a higher pressure cap on the small tank?
I was looking on Ebay for something, and found a bunch of different "fill ports" that look like they might come off motorcycles or ATV's. I as thinking of using that for my swap, if I couldn't find a pressurized bottle like you are showing.
I know that on a non-sc you can use the one from the 2.8, but usSC guys our options are limited. I know a number of people have split the hose and added a fill port. That works and all, but not my style.
I didn't think about filling when cold. I think some t-stats have a small hole in them allow a small amount of water circulation when cold, I wonder if it would be ok to drill a 1/8 hole just for air bleed purposes.
It won't be pretty where and how I mount this tank, but as long as it's functional, that's all I really care about right now. (The PO butchered this car when he did the engine swap, so it's kind of a test mule/ugly race car. What ever I learn from this will be applied to my next one.)
I'll get some pictures up when I get my phone back.
Ran into a snag, the T I bought isn't the right size for the Fiero hoses, or the Cobalt hose. (Which I already knew.) I think what I will do is pick up some 1-1/4 exhaust pipe if I can, and some 3/4 tube. I need to figure out a ring around them so the hoses won't slip off.
Filling it thru the port capped off in the lower left-hand corner of this picture works fine every time I've done a swap and it does NOT leave air pockets that create problems for burping the system...
This new fill port is connected via a hose to the lower heater hose port coming off the 3800 alternator bracket (a port which would otherwise be unused in 87-88 Fiero swaps).
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On my 3800 SC swaps I don't install the thermostat and housing until the cradle is installed and I have filled the coolant system. First I fill through the thermostat hole in the LIM until coolant comes up to the radiator cap opening. Second I fill through the hose from the thermostat housing to the radiator until the front radiator cap opening overflows a little. Third I cap the front radiator. Fourth I finish filling the block and hose and install the t-stat and housing.
No air pockets, no fancy provisions needed.
Bleed air from the air bleed and keep the expansion tank at the full cold mark.
