Whole lotta pressure... what gives?

CornerCarvin67 · May 23, 2005

I recently blew my upper radiator hose. I replaced it the next day. I'm currently running around 90% water.. 10% antifreeze. I was planning on replacing the lower hose soon and then get it back to a 50-50 mixture. But at the moment I'm noticing a massive amount of pressure building up in the cooling system for an unknown reason. The car is not running hot though. The factory gauge seems to be right at normal. But when I get home after a little spirited driving the front end of the car sounds like its tea pot ready to blow. I installed a overflow tank about a month ago and ran the hose from the port off the radiator neck to the connection point on the overflow tank. Is there a special radiator cap I need to complete this kit? Of course I don't dare touch the cap when hot... but it's definetly bubbling out from under the cap and spouting a bit of antifreeze on top of the radiator. The overflow tank has a valve at the bottom that you can throw to release whatever pressure or fluid manually. I put an empty water bottle under it and threw the valve. It literally spit bubbles of fluid into the bottle. I'm not sure what's happening. What could be happening?

Is the water to antifreeze mixture too high that the water tends to have a lower boiling point and thus creating all this pressure? Like I said.. the car isn't running hot I don't believe.

Maybe there's a radiator problem of some kind? Should I flush the radiator?

The thermostat is a year old...

Could it be the radiator cap??

Umm, let's see... I'm not sure what else it could be.

Please give your opinions... THANKS!!!

geostang351 · May 23, 2005

I personally think the antifreeze ratio is too one sided. It is antifreeze but as you said it also controls boiling temp. What about maybe the thermostat is put in backwards?

69 Capecod · May 23, 2005

the boiling is the cause of the pressure for sure. Is the cooling fan running right and I would flush the radiator and get back to a 50/50 mix.

69 Capecod · May 23, 2005

I didnt think of that good point is the thermostat backwards?

67coupestang · May 23, 2005

is this a plastic overflow? squeeze it and see if its full of pressure. did you replace the radiator cap? the cap acutally controls boil over more than the mix i think. water has a higher boiling point at greater pressures. i.e. when the cap is holding it in. sounds like its almost wide open and your getting condensed steam shooting out the overflow valve. I know that mix is a little skewed though. and antifreeze does raise the boiling point, im not saying that, but i think the cap is more of a key player

brianj5600 · May 23, 2005

He said the temp is normal, so it is not boiling to make pressure. I would look at the spark plugs. If there is 1 or 2 really clean ones, it could be a head gasket or even worse a cracked head or block. I hope I'm wrong but it could be serious. Also check the oil for overfull or milky color.

CornerCarvin67 · May 23, 2005

Okay... I believe the thermostat is correct. I put it in last summer and did not have any of these issues. The overflow tank is just a plain aluminum version from Summit. The fan hasn't changed since I've owned the car for five plus years. I have not replaced the cap.... although I just bought one from Napa on the way home. Haven't tried it yet. Is it possible it could just be the cap? Or maybe just the mixture? I checked the oil... it's not overfull and it's normal color (thank goodness). I'm not seeing any other abnormal leaks anywhere either. I did not check the plugs. I guess what I should do is flush the radiator and fill it back up with a 50-50 mix, along with the new radiator cap, and see what happens. If I really was unlucky and I had something cracked... what other tell tale signs would I look for? Man I sure hope that's not the case.... my car could end up sitting for a couple years waiting for the money needed for that kind of fix...

65ShelbyClone · May 23, 2005

I believe there is this stuff you can get that reacts with combustion residues in the coolant for the purpose of diagnosing a blown head gasket. Another way is to start the car(cold) with the rad cap off and let it come up to temp. If your coolant has lots of tiny little bubbles, it could be from combustion pressure getting into the system. See if the new cap works first, though.

CornerCarvin67 · May 24, 2005

Hello again... well talking to a friend here at work and he informed me that to make
sure of the "dip stick test" that I should run the car a bit to make sure that last nights
reading wasn't just a result of the oil being settled. (the oil looked good last night).

Maybe I don't really have enough fluid in the system. Too much air could be a factor.

Well here's my plan of attack... take a look and let me know what you think.

1)I replaced my upper rad hose when I blew it a few weeks ago.... I don't know if the
hose just went bad or if the fan finally possibly nicked it. I don't have a shroud and
I never bothered moving the hose further away when I knew it was close. So I'm
going to drop the system and replace the lower hose right away also.

2)The thermostat is less than a year old... and I'm sure is working just fine. So I'll
leave that alone... later in my plan I'll be able to notice if it's working just by letting
the car warm up and then watch to see if it opens by watching the inside of the
radiator flow.

3)I picked up a new radiator cap. I'll put that on.

4)I'll be putting in a fresh new mix of 50/50 fluid.

5)I'll fill the rad... leave the cap off... and start the car. Let it get up to temp and then
continue filling it. At this time I can watch for... and pray.... that I don't see any tiny
bubbles that could possibly indicate a crack or leak on the engine.

6)During this operation I'll watch the temp gauge and see if it gets hot. Like I noted
originally... .the cars temperature seems to be normal. At this time I can also
check the dip stick and see if it's milky or any other bad signs.

Hopefully this will all turn out to be some kind of voodoo and I'll inadvertently fix the
problem by going thru the steps above.

Cars... gotta love em...

jikelly · May 24, 2005

Good luck. I'll keep my fingers crossed for you.

CornerCarvin67 · May 24, 2005

Thanks... now if we all get together and pray....

The more I think about it... the more I think that I just need to properly fill the system back up. Fill it while it's running and the thermostat is doing its job. The car isn't running hot... it just has alot of pressure.

At least that's the "glass is half full" part of me talking...

jikelly said:
Good luck. I'll keep my fingers crossed for you.

84convertablegt · May 24, 2005

also, i had a similar issue. i didnt have any coolant in the oil though. but i could smell coolant in the exhaust on the side that was blown. this was on a supercharged car though, and it only acted up under boost. sometimes you can smell coolant in the exhaust. also, the upper hose felt like it was going to burst it was so full and the car was running hot. do u really know if the car is running hot though? the factory gauge and sender is no way to tell. you need to get a good gauge and sender on there to be sure. i hope for you its not a head gasket, but it sure looks like it could be

CornerCarvin67 · May 24, 2005

Well I'll check the stick again... and I'll watch for the bubbles when filling the radiator. I did smell some coolant for awhile on the car... but then again if you recall from my original post... I blew coolant all over the entire car when I blew that upper radiator hose. I think the smell has since gone away. I guess I just need to start on it and figure it out. It makes sitting here at work very difficult wondering if my car is broke bad or if it's a simple fix. It's gonna be a long day....

grego37 · May 24, 2005

I dont think it's your mixture.
100% water is proven to be the best coolant, but use an additive for lube and to fight corrosion. (Unless you live where it gets cold and you need the anti freeze.)

1) pressure test your system with a pressure tester, you can also pressure test your cap.

2) when your car is hot, and the therm should be open , take off radiator cap and see if the water/coolant is flowing, if its flowing your therm is good , at this time top it off.

check out "stewart components" for any cooling issues. great website and tech help.

my guess is:
Thermostat
radiator cap
or an internal problem (hopefully not)
good luck

jikelly · May 24, 2005

grego37 said:
2) when your car is hot, and the therm should be open , take off radiator cap

Um, be really careful with that. In fact leave the cap off and start the engine and watch for flow when the temp comes up and the thermostat opens. I think you were already planing to do that actually.

I made the mistake of opening the cap on my stang once. Boy did that smart.

stangbuilder66 · May 24, 2005

I am a rookie to all this so sorry if I sound stupid, but could it be that you just have air trapped in the system? I am currently rebuilding my first 302 for my stang, but I have driven fords and worked on them all my life (all 26 years of it LOL). The I-6 300 is the engine I know best..so that is all I can draw from. On my truck I blew the radiator hose once, the a/c clutch caught it once and burned a hole in it. When I replaced it I had the same problem as you sorta. I kept getting overflow into the tank, the thing was running hot and I couldn't figure it out. I thought I had a restricted radiator maybe, but it ended up I had air trapped in the upper end of the system. I still am not sure what exactly happened, but before doing expensive repairs I drained the entire system, flushed it all out and then refilled with the car running and thermostat open to make sure as it filled up it pushed all the air out. On the truck I got one of those inline fillers that goes in the heater hose line so water was filling from the intake side of the water pump. Doubt you would want to put one on a mustang (they are pretty ugly under a clean hood), but that could be your problem. I also know that on the V6 they ran in the 1994 model mustang the thermostat neck had a plug for just this problem. When refilling you could pull that plug and it would let air bleed out as you filled through the radiator.

Again I am probably way off and there are guys laughing right now because I was filling the system wrong, but figured it might help to put my experience out there, see if it helps any.

Good luck

CornerCarvin67 · May 24, 2005

No not at all.. I thank you for your feedback. I'm hoping you're right!

And yes I do have one of those in line filler connections. Maybe I'll utilize it.

Thanks everyone....

stangbuilder66 said:
I am a rookie to all this so sorry if I sound stupid, but could it be that you just have air trapped in the system? I am currently rebuilding my first 302 for my stang, but I have driven fords and worked on them all my life (all 26 years of it LOL). The I-6 300 is the engine I know best..so that is all I can draw from. On my truck I blew the radiator hose once, the a/c clutch caught it once and burned a hole in it. When I replaced it I had the same problem as you sorta. I kept getting overflow into the tank, the thing was running hot and I couldn't figure it out. I thought I had a restricted radiator maybe, but it ended up I had air trapped in the upper end of the system. I still am not sure what exactly happened, but before doing expensive repairs I drained the entire system, flushed it all out and then refilled with the car running and thermostat open to make sure as it filled up it pushed all the air out. On the truck I got one of those inline fillers that goes in the heater hose line so water was filling from the intake side of the water pump. Doubt you would want to put one on a mustang (they are pretty ugly under a clean hood), but that could be your problem. I also know that on the V6 they ran in the 1994 model mustang the thermostat neck had a plug for just this problem. When refilling you could pull that plug and it would let air bleed out as you filled through the radiator.

Again I am probably way off and there are guys laughing right now because I was filling the system wrong, but figured it might help to put my experience out there, see if it helps any.

Good luck

pabear89 · May 24, 2005

Just another thought, Did you turn on your heater to purge the air out of it after the upper hose blew?

And depending on the size of your Rad, it may be closing the themostat when it is trying to reach operating temp.
The rush of coolant inward will close it down till it regains the right temp to open.

Leaky head gasket will purge the coolant each time you run the engine and shut it off, air pumped into the cooling syatem will find a way out usally thru the cap.

PB

krash kendall · May 24, 2005

The cap you need for an overflow has a gasket that continues up the side of the plunger portion to maintain a seal when the spring is compressed under pressure so the coolant flows into the catch can instead of out the top of the spout. This also allows it to suck the coolant back into the system when the engine cools down. A 14lb. cap should do the job.

CornerCarvin67 · May 24, 2005

First... I eliminated my heater system last year. Don't need it. So yet another possibility leading to me having air in my system.

I have a radiator cap that on my desk in front of me that I believe is for the overflow system. At least that's what the guy said to use for the closed system that I'm now running. I couldn't find a pic to post. It's basically got two rubber gaskets. One big spring.. and one smaller spring that you can't see attached to a little round metal plate at the very end of the assembly. Geez it's hard to explain...

I hope that's a good enough description.

Krash... I have an idea of what your describing... but have never seen one. Possible you could post a pic?

Pabear.. I'm sorry you've lost me on some of what you said. I ain't too smart in this area...

Whole lotta pressure... what gives?

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