Mysterious Coolant Loss

[SVTtripleblack]

For the last year I have been having a slow coolant leak and both the Ford dealer and I can't find out where it's coming from. It seems to be only leaking when the car is turned on and there is pressure in the system. At first the leak was only occuring in the winter and it wouldn't leak at all in the spring fall and summer, but now it's happening in the winter as well. It's been pressure tested three times, had the plugs inspected, and been inpected by me. I can see some coolant on the bottom of the radiator, and other places under the car but it's so little of anything that I think it is just being sprayed around when the fan kicks on? Anyone else with this problem on a 94-95 stang or cobra? Any suggestions appreciated.

 

[steede302]

My leak turned out ot be the freeze plugs on the firewall end of the heads,

Probably not ur prob, but I just wanted to share.

:SNSign:

 

[Bosko5.0]

make sure the hose clamps are tight. also the plastic ends might be leaking.

Get the car up to temp the start wiggle the hoses, check for leaks.

 

[toyman]

For the last year I have been having a slow coolant leak and both the Ford dealer and I can't find out where it's coming from. It seems to be only leaking when the car is turned on and there is pressure in the system. At first the leak was only occuring in the winter and it wouldn't leak at all in the spring fall and summer, but now it's happening in the winter as well. It's been pressure tested three times, had the plugs inspected, and been inpected by me. I can see some coolant on the bottom of the radiator, and other places under the car but it's so little of anything that I think it is just being sprayed around when the fan kicks on? Anyone else with this problem on a 94-95 stang or cobra? Any suggestions appreciated.

Are you saying that the pressure tests didn't show a leaking down of pressure? Or are you saying that it failed the pressure tests but you can't find the source of the leak? Was the pressure test done with a hot/warm or cold engine? Should be cold.

If there is coolant at the radiator base then the source has to be the radiator (physical damage, seam/weld failure, hose clamp(s)) or from a crack in the expansion/overflow tank which would not show up in a pressure test).

A loss anywhere else in the system (frost plugs, heater core, hoses, etc) will result in a loss of pressure over time. A very small leak may require that the system remain under pressure during the test for a couple of hours to be detected.

 

[SVTtripleblack]

The car passed all three of the pressure tests with no signs of leaks. They even ran the car for quite some some and said they couldn't get the car to drink any coolant. I believe the tests were done in colder weather for the exeption of one. I do see a tiny bit of coolant under the radiator shroud but I have also seen a couple small drops elsewhere like even on my CAI tube. This is why it is hard to spot because I think it is being sprayed from the source of the leak. I check the coolant and oil everytime before I drive the car and I only put about 4,000 mi on a year. I do this of course while the engine is cool. Sometimes the coolant is full and sometimes it has dropped a few inches below the full line. I don't understand why it leaks sometimes and other times it doesn't.

 

[5.0_GT_kid]

Sounds to me like a leak in the overflow bottle, as I am having the same problem right now. That would explain why it did not show up on a pressure test and the physical location of the drip.

I'd pull the overflow tank our and see if that is the problem.

 

[SVTtripleblack]

Thanks, I have considered this to be the problem before, but I thought if it was cracked it would at least leak a few drops of coolant the entire week that I have it parked. I have to remember though that the car is 13 years old now and plastic pieces don't hold up forever. I usually only drive it on the weekends and it never leaks coolant while sitting. I will try to give it a shot. Are there any other overflow tanks on the market for our cars that would hold up better than the stock piece?

 

[BlackVert]

i had a similar problem a couple of years ago. coolant was getting low even though there was no sign of a leak. if i remember what my mechanic said correctly, he said that our radiators develop a slow leak somewhere near the stopcock (i don't remember exactly what he said leaks). he also said it tends do leak more in the winter than in the summer (again, i don't rememeber why). he replaced my radiator with a new one, and the problem was fixed.

 

[Blackened302]

used to have the same problem--thought it was the overflow tank, but as soon as i replaced the stock radiator w/ the mishimoto, the leak went away.

 

[SVTtripleblack]

Thanks for the info. I will probably end up replacing the overflow with a canton aluminum piece. That way I will know it won't leak again. I have a feeling my problem is in the radiator and will probably upgrade that as well. How are those Japanese Mishimoto radiators? I've seen some for good prices on Ebay.

 

[earleys94gt]

I'd agree with the overflow tank.

I don't this for sure, but I have heard of some clearance issues with the Canton overflow tanks and Fluidyne rads. Not sure about Mishimoto's.

Maybe someone else can confirm/deny this.

 

[scorpion95]

IMHO the stock OEM radiator will cool just fine and it can be had for around 100 bucks from Napa. Just a thought to save you some cash.

 

[ford302redneck]

I had the same thing happen.

Had a tiny, I mean TINY pin hole, in the radiator. That wasn't even a year old yet.

It would only leak when the water got warm. Pass couple pressure tests good.

Just get your car hot one day, and start looking.

 

[SVTtripleblack]

I just ordered a Mishimoto rad for $200 shipped. I am almost positive this is the problem judging by where I see the coolant. I am sick of adding coolant every weekend and I'm getting to the point where I'm just going to upgrade the system untill the problem is resolved. I have heard mostly good things about these rads, so even though it is such a Japanese product, I will give it a shot. Not that it isn't bad to be Japanese, and they do make some reliable cars and products, but it is going on a Mustang. If anyone has picks of their radiator install, or some key steps to follow please give me some advice. It seems like a straightforward install and I like to do my own work if I can, but experience always helps. Thanks

 

[WHITE94COBRA]

!00% agree, check your radiator cap for proper pressure, as this will either let it build too much pressure or too little, thus either blowing come coolant out of the overflow, or letting it overflow prematurely.

Sounds to me like a leak in the overflow bottle, as I am having the same problem right now. That would explain why it did not show up on a pressure test and the physical location of the drip.

I'd pull the overflow tank our and see if that is the problem.