Hey, all. I've finally got my car running again but I'm having some trouble with cooling issues. I've been using Shoebox's site to fill but I have a specific question. It says to open both bleed screws when filling. When I do this, I can get a stream of coolant at the thermostat housing bleed screw but I can't get a stream at my heater hose bleed screw before the radiator can't take anymore coolant. Do I potentially have a blockage somewhere? Or am I interpreting the instructions incorrectly? They're very straight forward.

Some history:
A couple years ago, I spent some time working on it to get to it running. I ended up going through a full drain and flush procedure. Once complete, I installed a new radiator and mine was OE and gunked up pretty bad, a new water pump and seal, and a new thermostat. I ended up with some opti issues so it ended up sitting for another year. Last year, I got the opti taken care of and everything back together but I ended up with some cooling issues and coolant loss. I found a pin hole in the heater hose so I decided to just go through and replace all the rad hoses and heater hoses. It didn't quite take care of my issue. This year, I pressure tested and found it's not holding. I tested the system for hydrocarbons and it passed so I don't think it's an internal leak. I just replaced my coolant reservoir and hose with pipe yesterday and went through to top off procedure in hopes of it being the final piece of the puzzle and ended up boiling coolant and overflowing out of the coolant reservoir. I also didn't hear my fans kick on. The only parts that haven't been replaced is the steam pipe and the heater core. I've not yet drained my oil too see if coolant has made its way into the pan but I check the dip stick often. The level of the oil has maintained but my old coolant reservoir definitely has coolant last the hot mark when cold when I checked yesterday.

 

What year is the car? The hose routing for the steam pipe is different 93/94 vs. 95-97.

When you were flushing the cooling system, did you flush the heater core? Common for them to plug up.

Have you replaced the radiator cap, or at least checked the cap for holding 18 PSI?

Are you sure you have the steam vent line and the overflow line connected correctly at the radiator? Swap them accidentally and you'll pour coolant into the reservoir.

Did you check the overflow hose for cracks? If the hose has breaks, the radiator vacuum (which develops as the system cools down and the coolant contracts) can't pull the needed coolant out of the reservoir to refill the radiator with the coolant that “overflowed” as the system heated up and the coolant expanded.

 

It is a 95 with a 96 engine, not sure where my sig went. What should I check with my steam pipe? I just stuck a mirror back there while it was running and don't see any leaks. It's routed to the passenger side with the steam vent hose attached to it from the radiator, I do have the TB bypass done.

Yes, I flushed the heater core, though I have noticed the infamous sweet smell when running my heat in the past. I actually have the passenger side apart to check for a leak in the heater core but am not able to find anything.

I checked the cap and it holds but I actually just installed a new AC Delco cap since I never liked how the metal Motorad fit. I checked the AC Delco I just bought prior to installing it.

The steam vent and overflow are correct. I've been all over these forums these past weeks so that is one of the first things I checked.

I did not check the overflow hose I just installed as it is brand new. I had to get a new reservoir since my battery tray tab was broken so I went ahead and picked up a new overflow hose/pipe also. I was actually thinking the overflow hose might be my problem since my original one looks pretty rough, though I can't see a hole/crack in it either.

I do have a few standard hose clamps as opposed to the clamp style that require the tool or pliers to install. Is it possible they are not strong enough to get a proper seal?

 

Shoebox has the radiator and heater hose diagrams. 95-97 the steam pipe is routed to the throttle body first, then to the radiator. 93/94 route it directly to the radiator. Since you’ve done the TB coolant bypass, it in effect is routed directly to the radiator.

93/94:

http://shbox.com/1/93-94_hoses.jpg

http://shbox.com/1/heater_hoses_93-94.jpg

95-97:

http://shbox.com/1/95-97_hoses.jpg

http://shbox.com/1/heater_hoses.jpg

Outside the box - the flow restrictor in the line from the pump to the core could be plugged.

When you indicate the fans do not run, is the coolant reaching 226°F.

As far as the hose clamps, shouldn’t be a difference, but obvious places to look when doing the pressure test and the pressure is dropping.

I shouldn’t have asked about the overflow line. Overlooked that it was new in your post.

If the coolant boiled when you went to refill, just means the coolant/water mix was such that the release of pressure allowed it to boil. But if you were topping it and it boiled and overflowed with the cap on, that's kinda classic symptom of a head gasket problem. But your HC test would seem to rule that out.