LT1 Coolant Pressure Problem

[LuvMyF8LWS6]

For some reason, there is a lot of pressure building up and making my radiator hose more than double in size! To get the car home, a normal 20 min trip from East Brunswick to Monroe, I had to stop 4 times and bleed the pressure out so it didn't go KAMBOOOOM! Which included going to Lowes (was at Kohls on Rt 18) and buy an 88 cent flat head! hahahaha

I loosen the radiator cap, and now no pressure is building up obviously. I had the radiator flushed and bled. Ever since, it's just holding onto pressure.

Any thoughts? BTW, it's my 1996 Trans Am.

[LTb1ow]

Did you bleed it correctly?

[LuvMyF8LWS6]

The first time, yes. But to get it home, I just opened a bleeder up just so I didn't die in the parking lot lol

[LTb1ow]

What was your coolant temp? Did it run hotter than normal?

[LuvMyF8LWS6]

No, all temps are running fine. I don't even have the thermostat in the car anymore, so it's constantly running thru.

[LTb1ow]

No thermo is bad news but I don't know whether that would cause your problem.

Is the cap the right one for the car?

Are the hoses stock?

[LuvMyF8LWS6]

it's holding the pressure with or without the thermostat, so thats not causing it.

The cap and hoses are what came on the car when I got it 2 years ago. They appear stock. The only thing I've done up front is put on a new intake, MAF, and Opti. The car ran fine after all that. It's like my car decided since it's perfect convertible weather, I'm going to purposely cause you problems.

[LTb1ow]

No the radiator cap.

[sweetbmxrider]

if you just had the radiator flushed, i would try bleeding the cooling system a couple more times letting it cool down completely each time. no other service was done? no hoses replaced?

[LuvMyF8LWS6]

I would assume the cap is the right one since it worked fine the last 2 years. I dont know if they go bad like a gas cap?

No hoses were replaced on the cooling system.

I was thinking of bleeding the entire system again, but wanted to know if there was any common LT1 issues before I did anything else.

[LTb1ow]

Well pressure in coolant is either a lot of air (likely with the LT1 without a thermo) or head gasket problem.

I would bleed the system very well, and or throw a thermo in there too...

[sweetbmxrider]

if the system was just serviced and wasn't properly bled or allowed to reach operating temp, this situation could easily arise.

[LuvMyF8LWS6]

It was bled properly, but should I do it again, maybe a few times? I don't think it's a BHG because I am not losing any coolant (except for what I am bleeding out)

[LTb1ow]

Well something is pressurizing the system....

[LuvMyF8LWS6]

Yes, that's what I'm trying to figure out. But hopefully it just needs some more bleeding.

[LTb1ow]

How long has the system been without a thermo?

[LuvMyF8LWS6]

Like I said earlier, it did this before AND after I took it out. I don't run thermostats during the summer on my older cars because they like to get too hot when sitting idle. The car didn't have it in last summer either.

[BonzoHansen]

As mentioned, start by buying a new rad cap. Put a t-stat back in it, no t-stat is incorrect (I'm not even going into why on that anymore). Bleed it again. Report back. If the hoses are getting stretched like that I'd seriously consider new ones.

[Pampered-Z]

Keep bleeding the system, it's not that uncommon to have to do it 3-4 times before you get all air out. But normally that will cause the engine to run hot if there are air pockets. You should also will notice your coolant level dropping slightly as even if you don't bleed it the air will eventually work itself out.

But with the type of pressure your seeing I would start by just replacing the rad cap. The LT1s run a bit high on the pressure, but 18-20 PSI the coolant should be pushing out past the cap way before the pressure would start expanding the hoses. I would also recommend going right to GM for the cap.

Check the overflow tank, if it's not full then the rad cap is probably your issue.

I would also replace those hoses.

[Triple-A]

I had problem bleeding my LT1 before. what helped me is, I fill the block trough thermostat hole. then put the stat back in and finish filling it normally and bleeding it.

Sounds like rad. cap.
I wouldn't trust thous houses after that stretch.. but that just me paranoid.

If its getting too hot for you, why don't you get 160 stat and/or SLP manual fan switch?
After I did 160 stat, water wetter and tune for 160'... after that I never used my fan switch.