94formlt1

I recently had to have my cross pipe replaced because it was leaking coolant from the fitting at the block. Getting it back from the shop, coolant was spewing out of the radiator cap, not the overflow. I tried filling up the radiator with fluid, and trying to bleed the system of air by only opening the bleed air valves, but nothing came out of the bottom one, and very little to none at all came out of the top. Before taking the car in, the temp would read slightly below 210. Now it barely comes above 160. I am new to vehicle maintaince to this degree, and I posted to a different thread for modifications (this is my first forum ever so I am still discovering how to use these) and they said that I might have air in the lines. I'm gonna try flushing and bleeding the system my self, but what is the likely hood that the cross pipe is not hooked up right, which from what I am thinking, its not letting the coolant circulate through the system. The car is not driven very much since I'm in the military and its located at my parents house for now, so access is limited. Any suggestions?

wssix99

iTrader: (5)

Is your coolant system stock?

A few first steps:
- Make sure the tube connecting the radiator neck to the overflow is not clogged and holds suction. (I hook a vaccum pump up to the hose with a clear section of tubing and see if I can pull fluid back to the clear section and hold it steady for a while under suction.)
- Your radiator cap is probably bad and its time for a new one. If it won't hold pressure properly, it will leak as you described and your overflow won't work properly. (Because the system isn't holding pressure properly.)
- I'd expect your problem to make the temperatures go up, not down. Maybe you also have a bad thermostat at the same time. I'd suggest starting with the radiator cap, see what happens, and them move on to a new thermostat if the temperatures stay low.

94formlt1

The coolant system is stock.
The coolant only overflowed once when I got the car back to the house, and hasn't done it since. I've tried filling it back up, but I don't think I'm doing it right. When I open the bleed air screw on top, with the engine on and off, no fluid comes out, so now I'm not sure how much air is in the lines. I am able to take off the bleed air screw on top and look inside and not see any fluid.
I'm going to have to check what thernostat is in the car. It was my dads before he gave it to me and he did some things to it when it was having cooling problems way back when, I think he put a 160 degree thermo in there. Plus, it's been overhauled, so I don't know if the mechanic changed it out.
Where exactly is the temp sensor located? Would it read a low temp from the coolant in the radiator even if the fluid isn't circulating?

wssix99

iTrader: (5)

That won't tell you much. The system needs to be pressurized in order to work. If your pressure cap (your radiator cap) leaks, this also causes an issue. The system should bleed itself through the overflow tank. So, put a new cap on, run it through several heat/cool down cycles and the level of fluid should be right under the cap. (As air is getting bled out of the system the level will be lower.) If you have fluid under the cap - the overflow tank is communicating with the radiator and all is well.

If your gauge read 210 before, then it was probably a stock thermostat.

On the LS1, its screwed in to a head. Not sure about the LT. It measures the coolant in the engine. (Any measurements in the radiator would be weird because that's where a temperature change happens.) If you have a low temperature, that's usually a sign that the thermostat is stuck open and you have too much coolant flow.

94formlt1

Hey thanks for the tips. I won't be able to get back to my car until this weekend. I'll definitely be checking your suggestions out. Thanks again.