building lots of pressure in my cooling system

Posted by: msu_johnny

building lots of pressure in my cooling system - 03/25/09 09:42 PM

i'm having a problem with my 99 grand marquis. I was over heating and thought it was my fan, checked that it's working, then thought it was my thermostat, replaced that still having a problem, over the winter i had no heat at times made me think that it was the themostat so replaced that now i'm still over heating and i'm building so much pressure in the cooling system it's blowing the fluid back out the cap of the over flow tank. any ideas?
Posted by: msu_johnny

trying to find good price on intake manifold - 03/25/09 09:48 PM

if it wasn't enough that my grand marquis is down and i can't figure out what's wrong with that, my 2000 crown vic is down now too, found that i have a crack in my intake manifold, i patched it to get it running again with high pressure high heat epoxy. don't know how long this will last though any one have experience how long this will last? I know it will have to be replaced anyway just trying to get an idea of when i might expect to HAVE to change it out. anyone know where i can get a good used one or a really good price on a new one. found some on ebay for around $200, hoping i didn't have to spend that much
Posted by: gDMJoe

Re: building lots of pressure in my cooling system - 03/26/09 10:09 AM

 Quote:
msu_johnny ... 99 grand marquis

Overheating + cooling system pressure build-up sometimes indicate a head gasket problem. *Though a pressure and/or combustion-gas test should be done on the cooling system.

Do you have oil in the coolant ?

Do you have anti-freeze in the oil ?

Alternative ... Air pocket in the cooling system.

Regarding the no-heat ... Plugged heater core and/or air pocket in the cooling system | blend-door issue (?).

Posted by: Timmn1

Re: trying to find good price on intake manifold - 03/26/09 10:39 AM

The time I tried patching a crack in the intake manifold with epoxy, it lasted all of maybe 15 minutes.

As far as picking up a good used one, just about any junk yard should have at least one Crown Vic/Grand Marquis/Towncar with a good intake. The U-Pull-It yard by me has many of them.
Posted by: Big_Bad_Joe

Re: building lots of pressure in my cooling system - 03/26/09 12:03 PM

Pressure is from the heat.... temps must be very high. Does it got hot real quick?

Did the heat in the car stop first or did it stop after the overheating?

Could be a collapsing hose... or could be a water pump

check the hoses and make sure they are not really weak ....

any leaks?

Radiator cap check that too as it will suck air if it is not sealing correctly
Posted by: brack86svo

Re: building lots of pressure in my cooling system - 03/26/09 01:02 PM

Your best bet would be to get a hold of a pressure tester and put it on the reservoir. Start the car up from cold and if the pressure shoots right up you have a cold compression leak. That could be a head gasket.

If you have a cracked head, the compression might not get into the cooling system till the engine warms up and everything starts expanding.

You can also look in the reservoir for any signs of foreign material, this can be a sign of exhaust gases.

Don't rule out the air pocket, and it probably wouldn't hurt to pull the water pump and check it out.
Posted by: TheShadow

Re: building lots of pressure in my cooling system - 03/26/09 02:27 PM

A '97 CV had similar problems with cooling system. Bad thermostat, mostly clogged radiator, failing water pump, lots of hot running (not necessarily "boiling-over" overheating), and always max pressure in the cooling system. Then started running poorly - missing, rough idle. Did a compression check and coolant spat out of cylinder #1. Replaced the head - it had a crack that was going from the combustion chamber to the cooling jacket.

Do a compression check and be ready for some bad news.

Edit: Also make sure the heater core is not plugged up.

Posted by: msu_johnny

Re: building lots of pressure in my cooling system - 03/26/09 04:50 PM

as far as oil in the antifreeze or antifreeze in the oil i'm not noticing any of that and have check for it several times.

as for a pressure test on the reservoir they are telling me the pressure is getting so high that they can't even do that.

as for how fast it heats up, you start it up, let the oil get to the top of the engine then put it in gear and drive 120 yards from the pole barn to the garage and the temp bars are lighting up one after the other quickly.

didn't think about the air pocket though or the water pump, i'll check those too.

if anyone has anymore ideas i'd be grateful to hear them, thanks for the help thus far.
Posted by: gord_bolton

Re: building lots of pressure in my cooling system - 03/26/09 05:02 PM

Your first tip off to being low on coolant may be the lack of heat from the heater. Looking at the reservoir may be misleading because you may have a huge air buble inside the engine.

Fill through the thermostat housing or heater hose.

You will need to pressure test to see if the system holds pressure and to detect leaks.
Posted by: Big_Bad_Joe

Re: building lots of pressure in my cooling system - 03/26/09 05:22 PM

 Originally Posted By: msu_johnny
as far as oil in the antifreeze or antifreeze in the oil i'm not noticing any of that and have check for it several times.

as for a pressure test on the reservoir they are telling me the pressure is getting so high that they can't even do that.

as for how fast it heats up, you start it up, let the oil get to the top of the engine then put it in gear and drive 120 yards from the pole barn to the garage and the temp bars are lighting up one after the other quickly.

didn't think about the air pocket though or the water pump, i'll check those too.

if anyone has anymore ideas i'd be grateful to hear them, thanks for the help thus far.


i would say the water pump crapped out completely.. no circulation
basic tea kettle
Posted by: TheShadow

Re: building lots of pressure in my cooling system - 03/26/09 05:39 PM

Compression test!!! Compression test!!!

Before you spend any more money on parts.

I had no coolant in the oil. The rings' seal was so good that I got 250+ lbs. of compression on the failed cylinder! I don't think a cooling system pressure tester (@ 16 lbs.) can go quite that high.