Under Pressure

95-stang · Sep 27, 2009

As the title says "under pressure".

Searched the web on this, seen a few answers but nothing thats cured the problem and i have been a bit reluctant to ask as i've tried nearly everything.
I live in the UK, so the climates pretty mild, but no matter how hot or how cool the weather is my cooling system is almost under enough pressure to almost blow a hose off, but it does'nt.
Temp runs cool i use a 180 stat and thats where it stays i have an Auto-meter gauge btw, this happened on my original motor and on the crate motor thats now in, i've tried 3 stats, 3 radiator caps, its since had a Fluidyne rad and an extra transmission cooler and new hoses.
It's had an intake upgrade, i've tried different intake gaskets fel-pro\ford racing etc, none made any difference, the spring in the bottom hose is good as is the small restrictor in the heater hose.
The heater is always good and hot occasionally there's a dribble of coolant seems to get pushed out of the radiator cap, but its the hose pressure thats high, you can barely squeeze the hoses and its not cooling well as the bottom is almost as hot as the top.
I use Ford anti-freeze and fitted a new Ford Racing [anti clock] water pump a while back [the only common denominator] its had a new belt and tensioner a while ago, there's no oil in the water, or water in the oil and it runs fine.
The fan kicks in when it should and i should add it seems to build up pressure fairly quickly.
But i cant ever remember owning any car where the hose pressure has been as much this.

I have the original water pump but its the same part number as the new one thats on. I've tried all the usual stuff and done a few hundred miles or more so i doubt its air, i've bled it umpteen times, if anyone's seen this or got any ideas i'm listening.

BlownFiveLiter · Sep 27, 2009

The system is supposed to be under pressure. Our system is rated for 15 PSI, if I recall correctly. Above that and the radiator cap is supposed to blow off the pressure. A new cap is cheap, so that would definitely be a good place to start, if the current cap is allowing antifreeze to dribble out. Also make sure the drain hose for the overflow tank has a clamp on it, and that the hose itself is not cracked or leaking around the clamp. As long as a new cap doesn't blow off the pressure, it's working as intended.

95-stang · Sep 27, 2009

I hear what your saying, but i've tried 2 new caps, [3 in total] no difference, it did'nt run like this when i first got it you could squeeze the hoses even on the hottest day after a long run.
It was so bad last year it was pushing the bottom hose almost to the point of it blowing off.
I assumed at first it was air being pushed into the system [possibly at the intake] hence swapping out intake gaskets etc, there's always a stink of anti-freeze when i arrive at the end of a trip and the fact the bottom hose is almost as hot as the top is pointing towards the fact the water is not being allowed to cool as it should. [The stat is installed the correct way btw].
I put a small clamp on the overflow pipe for that reason, some a\freeze was getting past at the neck where it pushes on, one of the new caps was one of those with a built in temp gauge, thats now full of condensation and i put the new genuine Ford one back on and again, nothing.

whitesqual · Sep 27, 2009

95-stang said:
I put a small clamp on the overflow pipe for that reason, some a\freeze was getting past at the neck where it pushes on, one of the new caps was one of those with a built in temp gauge, thats now full of condensation and i put the new genuine Ford one back on and again, nothing.

So are you saying that coolant was pushing out of the overflow hose where it goes on the nipple? That hose should not have any pressure on it, I mean it is open on the other end. There is no reason that it should be backing up there. I would check to see if there is anything blocking your vent hole on your coolant overflow reservoir or some restriction in the overflow line or in the reservoir. If there isn't I would do a compression check to help rule out a blown head gasket. You don't always get oil in the water or vice verse when they go.

Hope you get it figured out.

95-stang · Sep 27, 2009

Again the reply is appreciated, well it did this on my 55k motor, and almost immediately when the crate motor went in so i'm sure its not head gaskets, your right but if the 15lb pressure is relieved at the cap it will vent into the expansion tank as well, water is supposed to pass back and forth from the tank under expansion\contraction but its odd it does'nt blow the plastic cap off the tank, but as the pressure is "leaking" out of the cap its probably why it has'nt.
The water goes down in the tank very, very slowly over many weeks and i've put my airline through the pipe\tank just to make sure its clear.
Its whats causing the pressure thats the problem, driving me nuts in fact.

toyman · Sep 27, 2009

95-stang said:
Again the reply is appreciated, well it did this on my 55k motor, and almost immediately when the crate motor went in so i'm sure its not head gaskets, your right but if the 15lb pressure is relieved at the cap it will vent into the expansion tank as well, water is supposed to pass back and forth from the tank under expansion\contraction but its odd it does'nt blow the plastic cap off the tank, but as the pressure is "leaking" out of the cap its probably why it has'nt.
The water goes down in the tank very, very slowly over many weeks and i've put my airline through the pipe\tank just to make sure its clear.
Its whats causing the pressure thats the problem, driving me nuts in fact.

The system is designed to operate at 16 psi. Increased temp = increased pressure all other things be equal. There can be no pressure in the overflow line as that vents to atmosphere. The level in the reservoir needs to be between the cold and hot level marks. There is usually very little change in the fluid level but it's important that the reservoir not empty as that could result in air being sucked back into the system. Air pockets within the engine are quite common and sometimes take addition measures to eliminate.

If the pressure were to exceed the 16 psi cap relief value coolant from the engine would overfill the reservoir and spill to the ground. I don't see where you see this happening so it's safe to assume that the pressure is within spec (up to 16 psi).

whitesqual · Sep 27, 2009

95-stang said:
Again the reply is appreciated, well it did this on my 55k motor, and almost immediately when the crate motor went in so i'm sure its not head gaskets, your right but if the 15lb pressure is relieved at the cap it will vent into the expansion tank as well, water is supposed to pass back and forth from the tank under expansion\contraction but its odd it does'nt blow the plastic cap off the tank, but as the pressure is "leaking" out of the cap its probably why it has'nt.
The water goes down in the tank very, very slowly over many weeks and i've put my airline through the pipe\tank just to make sure its clear.
Its whats causing the pressure thats the problem, driving me nuts in fact.

Did you check the vent hole on the reservoir? If its plugged, it could be easily overlooked. When you blew air through the tank, did you do it with the cap on? I went out and played with my cap, and it fits pretty tight with 200k+ miles on the car so yours with low miles might fit tighter. Of course I have never plugged my vent hole and pressurized my tank half full of coolant to see how much pressure it takes to blow the cap off! But who knows, might take 15 or 16lbs.

The coolant system is a complete open loop once the thermostat opens, which sounds like is opening, so the only thing that can pressurize the system is heat (unless you have an obstruction, a bad thermostat, or a possibly blown head gasket) Since it has happened on two motors its probably not a head gasket. Possible but very improbable. You could have gotten three bad rad caps, again possible but very improbable.

If water gets pushed out of the rad cap on occasion and there is coolant leaking out at the nipple for the overflow, it would lead me to believe that there is some reason it is not venting properly. I would go as far as removing the tank from the car and giving it a thorough inspection/cleaning and replace the hose just for good measure.

Just some thoughts! Hope you get it figured out!

95-stang · Sep 28, 2009

Thanks i hope i get it figured too [one day].

I have the correct coolant level in the tank all i know is after a long run there and back if i check it the morning after the level has gone down a bit so the rad is drawing water back in as it should if were losing a little [which it is] it just should'nt be.
Its the extreme pressure that worries me as thats obviously the cause of the water loss, the car has'nt gone past 200 on the gauge all year even in traffic, one of the reasons i bought a Fluidyne rad was i thought the stocker might have bought it.
I know i'm going to kick my own @rse when i find out what it is.

Again, thanks for the replies.

Ok had an hour to spare today [hard when you work for yourself] so i popped the hood and took the cap off, a few drops seeped out as i removed the cap but just normal spillage.
I started it up, and after about 10 mins it started pumping a bit out the neck, then it would stay below the level of the neck for a while.
Another 5 minutes and same again it pumps a bit out and then probably once more, and about another 5-10 minutes the fans on, soon as its on the water gets drawn back down to just below the neck and there's quite a vortex going on. [Only approx times btw].
Then it seemed the fan kept it at the correct level, but as soon as it went off you got the feeling it was going to rise again and all this time there's no air bubbles.
I know in the morning the level will be down by whatever came about [about half a pint] i will top it up to just below the neck and i will be back at square one.

toyman · Sep 28, 2009

95-stang said:
Thanks i hope i get it figured too [one day].

Its the extreme pressure that worries me as thats obviously the cause of the water loss, the car has'nt gone past 200 on the gauge all year even in traffic,

What is your basis for the comment of "extreme pressure"? How was it measured? You have not described anything since the first post to indicate that the pressure is anything other than what is to be expected. Whose gauge are you referring to for the 200* reading? Can't be the stock unit as there are no numbers on the gauge.

Adam95GT · Sep 28, 2009

Totally know the answer to the question....

here

whitesqual · Sep 28, 2009

Adam95GT said:
Totally know the answer to the question....

here

lol, I knew we could count on you!

yukisho · Sep 29, 2009

Adam95GT said:
Totally know the answer to the question....

here

Well problem solved. Next question please. Lol.

95-stang · Sep 29, 2009

toyman said:
What is your basis for the comment of "extreme pressure"? How was it measured? You have not described anything since the first post to indicate that the pressure is anything other than what is to be expected. Whose gauge are you referring to for the 200* reading? Can't be the stock unit as there are no numbers on the gauge.

"and thats where it stays i have an Auto-meter gauge btw"

"It was so bad last year it was pushing the bottom hose almost to the point of it blowing off".

If you read it slightly more carefully it says above i have an Autometer gauge, which i have been told are fairly accurate and does have numbers on it.
Also above i mention the fact that its almost blown the bottom hose right off that and the fact the hoses are so pumped only Arnie could probably squeeze the damn things a little bit.

whitesqual · Sep 29, 2009

95-stang said:
Also above i mention the fact that its almost blown the bottom hose right off that and the fact the hoses are so pumped only Arnie could probably squeeze the damn things a little bit.

hmm, what about Chuck Norris?

95-stang · Sep 29, 2009

whitesqual said:
hmm, what about Chuck Norris?

Nah, too weedy.

whitesqual · Oct 5, 2009

did you figure it out????

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