Cooling system not building pressure

Falcons Talon · 10-08-2002, 05:08 PM

I just got my car back from having the oil pump changed and as I was driving home(20 minutes), the car started gradually heating up. I immediately thought it was just the factory gauge the way it was just creeping up, but the overflow tank was getting overflowed. I cooled it off and refilled the water system thinking it may have been an air pocket. After another 20 minute drive, it did the same thing. It wasn't the thermostat because water was flowing freely. I decided to redo the cooling system. I had the 3 row radiator lined out, changed all the hoses just in case they were collapsing, changed the water pump just in case the impeller was corroded, and while I had the motor apart upgraded to a '95 alternator(thanks for all the wring guides). I also had the air con recharged and after driving all over town for over an hour, the gauge went up a little more than 1/4, but never went over 1/2. When I checked to make sure that nothing was leaking, I noticed no pressure in the hoses but no overflow either. I changed the radiator cap just in case as well. When I took it for another drive, it still didn't build pressure. . All parts are torqued down and I'm not losing water. I checked to see if there was water in the oil and it's clean as well. Is this normal, and if not, is this a problem? I haven't even put on the Black Magic Fan. I'm just using the regular fan clutch with the stock fan.

PKRWUD · 10-08-2002, 09:30 PM

First off, your initial problem was due to a defective cap, or one that wasn't rated high enough.

As far as building pressure, if you aren't, and you'r gauge isn't pegged, then the t-stat isn't closing.

You should have a 192 degree t-stat, and your upper hose should become firm withing 10 minutes of idling. When it becomes firm, it means that the t-stat has opened. If it never becomes firm, yet the temp gauge doesn't peg, then something is obstructing the t-stat from closing completely.

Take care,
~Chris

Falcons Talon · 10-11-2002, 10:45 AM

Being a little burnt out on being on and under my car, I went down to AZ and borrowed the coolant sytem pressure tester. I pumped her up to 17 and listended for leaks. Pressure was good with no visible or audible leaks so I jiggled the upper radiator hose and it hissed at the radiator. I took off the hose and noticed that the radiator inlet was no a perfectly round, but actually a little mishapen. I tightened down the clamp on an unbent portion, repressurized, jiggled, and voila. I thought I was slick. Then I drive her the 20 minutes back to work in 90 deg sunny weather w/ the AC on and it didn't heat up at all. I stop to put gas and popped the hood to feel the pressure in the hoses...NO PRESSURE! God I hate working on the thermostat. Two bolts and no room to work...

Thanks PK

Falcons Talon · 10-11-2002, 11:31 AM

Just out of curiosity...wouldn't the sytem still build pressure with the thermostat stuck open?

dragstang86 · 10-11-2002, 11:37 PM

It wont produce any pressure until there is heat in the system unless you are leaking compression into the coolant because of a blown head gasket, cracked head or cylinder wall, etc.. but that isnt the case so ill stop rambling. My car also has run really cold ever since i got it and Im sure its the thermostat i just havnt had the time to mess with it.

Falcons Talon · 10-12-2002, 09:29 AM

Hey, it's building good pressure...

maybe the thermo got "unstuck", or maybe it's cooling TOO well??? Whatever the case...I'm no longer overheating. Thanks to EVERYONE for yur help and advice...

10-08-2002, 05:08 PM	#1
Falcons Talon T.P.M. President Join Date: May 2002 Location: Brownsville Posts: 265	Cooling system not building pressure I just got my car back from having the oil pump changed and as I was driving home(20 minutes), the car started gradually heating up. I immediately thought it was just the factory gauge the way it was just creeping up, but the overflow tank was getting overflowed. I cooled it off and refilled the water system thinking it may have been an air pocket. After another 20 minute drive, it did the same thing. It wasn't the thermostat because water was flowing freely. I decided to redo the cooling system. I had the 3 row radiator lined out, changed all the hoses just in case they were collapsing, changed the water pump just in case the impeller was corroded, and while I had the motor apart upgraded to a '95 alternator(thanks for all the wring guides). I also had the air con recharged and after driving all over town for over an hour, the gauge went up a little more than 1/4, but never went over 1/2. When I checked to make sure that nothing was leaking, I noticed no pressure in the hoses but no overflow either. I changed the radiator cap just in case as well. When I took it for another drive, it still didn't build pressure. . All parts are torqued down and I'm not losing water. I checked to see if there was water in the oil and it's clean as well. Is this normal, and if not, is this a problem? I haven't even put on the Black Magic Fan. I'm just using the regular fan clutch with the stock fan.

10-08-2002, 09:30 PM	#2
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	First off, your initial problem was due to a defective cap, or one that wasn't rated high enough. As far as building pressure, if you aren't, and you'r gauge isn't pegged, then the t-stat isn't closing. You should have a 192 degree t-stat, and your upper hose should become firm withing 10 minutes of idling. When it becomes firm, it means that the t-stat has opened. If it never becomes firm, yet the temp gauge doesn't peg, then something is obstructing the t-stat from closing completely. Take care, ~Chris __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
NEED HELP!!, cooling system problem	TRICK_5_0	Windsor Power	2	08-21-2003 10:02 AM
How to completely drain a 5.0's cooling system???	Italianstanger	Windsor Power	1	07-13-2002 11:18 AM
how about a revese flow cooling system?	nitrousjunkie	Windsor Power	2	04-01-2002 12:45 AM
How to clean cooling system???	Fostang	Windsor Power	1	07-15-2001 06:13 AM
Cooling System problems	1973Mach1	Classic Mustangs	7	06-25-1999 10:33 PM

10-11-2002, 10:45 AM	#3
Falcons Talon T.P.M. President Join Date: May 2002 Location: Brownsville Posts: 265	Being a little burnt out on being on and under my car, I went down to AZ and borrowed the coolant sytem pressure tester. I pumped her up to 17 and listended for leaks. Pressure was good with no visible or audible leaks so I jiggled the upper radiator hose and it hissed at the radiator. I took off the hose and noticed that the radiator inlet was no a perfectly round, but actually a little mishapen. I tightened down the clamp on an unbent portion, repressurized, jiggled, and voila. I thought I was slick. Then I drive her the 20 minutes back to work in 90 deg sunny weather w/ the AC on and it didn't heat up at all. I stop to put gas and popped the hood to feel the pressure in the hoses...NO PRESSURE! God I hate working on the thermostat. Two bolts and no room to work... Thanks PK

10-11-2002, 11:31 AM	#4
Falcons Talon T.P.M. President Join Date: May 2002 Location: Brownsville Posts: 265	Just out of curiosity...wouldn't the sytem still build pressure with the thermostat stuck open?

10-11-2002, 11:37 PM	#5
dragstang86 Registered Member Join Date: Sep 2002 Location: baltimore, md Posts: 220	It wont produce any pressure until there is heat in the system unless you are leaking compression into the coolant because of a blown head gasket, cracked head or cylinder wall, etc.. but that isnt the case so ill stop rambling. My car also has run really cold ever since i got it and Im sure its the thermostat i just havnt had the time to mess with it.

10-12-2002, 09:29 AM	#6
Falcons Talon T.P.M. President Join Date: May 2002 Location: Brownsville Posts: 265	Hey, it's building good pressure... maybe the thermo got "unstuck", or maybe it's cooling TOO well??? Whatever the case...I'm no longer overheating. Thanks to EVERYONE for yur help and advice...