Mysterious Antifreeze Leak

[EquatorHeat00]

For 1 month now I've been losing small amounts of antifreeze, but I can never see a leak after I drive the car. (Can drive car 5 days, and level hasn't changed at all - other times leaks a little after about 2 days.) There is also never a puddle of antifreeze on the garage floor in the morning. I see no cap leak, hose leak, or thermostat housing leak.
My mixture is more on the water side then on antifreeze. (Probably like 60% water, and 40% antifreeze.)
Does antifreeze evaporate when being used if you have too much water in the system? If, so when I lose more in the future I'll just add 100% antifreeze until it evens out more.

[jdm]

No answer as far as the leak is concerned, but check the low coolant sensor, as mentioned in another post, to see if its corroded at all. If it is, just clean it up, or replace it. They're not very expensive...

Jim

[pandorasboyfriend]

antifreaze leak

I have to ask a question here, EquatorHeat00. Do you smell antifreeze at all?

[Joe 1320]

I think a cooling system pressure check is in order. This will allow you to pressurize the cooling system while it's cold, enabling you to literally crawl all over the engine and hoses to pinpoint a leak. There are a couple of other things to check:

A leak in the overflow tube or some other portion of this "sealed" system. As the fluid expands from heat, the excess goes to the overflow canister. As long as there is a complete seal, as the fluid cools and condenses, it is drawn back into the radiator. If there is any leak, this won't happen and the radiator ends up getting low.

A partially blown headgasket. I drove my T/A for several months and a thousand miles with no apparent loss of perfromance. Some days the coolant would not budge, other times it drank maybe a pint a day. It doesn't leak externally, it gets drawn into a combustion chamber where it turns to steam in the combustion event.

A cooling system pressure check should help pinpoint any leaks, both internal and external.

[EquatorHeat00]

Is it normal for the coolant to be about 2.5 inches below the cap hole on the top of the radiator, and exposing part of that medal coil inside? (When the car is COLD!)

[00 Ragtop Z]

In my experience, leaks like you describe are 1 of 2 things.

1. small pin hole in the radiator. Only leaks when the coolant is hot.

2. bad water pump bearing seal. Leak at the weep hole in the pump.

These leaks can be small enough that the coolant evaporates on the hot engine and never reaches the ground. A pressure test of the system is the easiest way to pinpoint a leak.

Doesn't matter what the mixture ratio is, you shouldn't be losing antifreeze.

On target-had exactly the same with the ragtop. look for evidence of the leak on the underside of the engine, and on the foront end parts. repalced the whole pump (it finally went bad after 100,000mles--problem was solved.

[Thomas L. Parker]

Similar problem

One of my 93's had a similar problem. Took a while to find it. Just after shut down, I looked under the hood and where the heater pipes connect to the firewall, there was the leak. It dripped straight down on the exhaust pipe and evaporated so there was no tell-tale puddle under the car.

Hope this helps,

Tom

[EquatorHeat00]

I've noticed lately at cold start up moisture in the tail pipes, but that goes away after the car warms up. (Not sure how long this had been going on, or maybe its even normal.) I heard this was normal, so its not necessarily a headgasket leak. I never have had moisture yet when it warmed up, but I'm still adding antifreeze. Its been about 4.5 months now. Oil color/consistency looks good, & antifreeze color looks good.
Could it be possible that if you add to much water, and not enough antifreeze that it could be boiling off inside thus causing it to evaporate, and showing moisture on tail pipes at cold start up. As of today when it leaks I'm going to add pure coolant to make up for the extra water, and get it closer to 50/50 mix. It probably more like 2 thirds water, 1 third coolant at this time.

In the past I was putting the coolant in just the reservoir, but now I put it in the radiator instead. I noticed that when the radiator needs more antifreeze the reservoir is still full.

[Injuneer]

I've noticed lately at cold start up moisture in the tail pipes, but that goes away after the car warms up. (Not sure how long this had been going on, or maybe its even normal.) I heard this was normal,

You do realize that when you burn gasoline, it forms water and Carbon dioxide. When the exhaust system is cold, it is completely normal for the water in the exhaust gas to condense in the piping, and drip out of the exhaust tips. That's why you have a visible white plume on cold start in very cold weather - the water vapor in the exhaust gas is condensing and becoming visible.

Could it be possible that if you add to much water, and not enough antifreeze that it could be boiling off inside thus causing it to evaporate, and showing moisture on tail pipes at cold start up.

No. The mixture of of water and ethylene glycol produces a solution with a very low vapor pressure. It does not evaporate. Additionally, your coolant system (assuming your pressure cap is working correctly) is under 18psi(g) pressure, virtually eliminating any possiblity of evaporation. The moisture in the tailpipe is normal byproduct of combustion.

As of today when it leaks I'm going to add pure coolant to make up for the extra water, and get it closer to 50/50 mix. It probably more like 2 thirds water, 1 third coolant at this time.

In the past I was putting the coolant in just the reservoir, but now I put it in the radiator instead. I noticed that when the radiator needs more antifreeze the reservoir is still full.

There is virtually no difference in the tendancy to evaporate between a 40/60 coolant/water mix and a 50/50 mix. That is NOT the cause of your problem.

You indicate the coolant level in the radiator is 2.5" below the cap level when you check it. That is not the way it should ever be. The "closed" system allows the coolant to escape from the radiator when the coolant expands from the heat, and when the coolant temperature drops and the volume contracts, the overflow tube allows the vacuum to pull the coolant back out of the reservoir and into the radiator to keep it FULL TO THE BRIM. There should NEVER be a drop in level.

As Joe pointed out, a common cause of this problem is a crack in the overflow hose to the reservoir. If it has a crack in it, it doesn't allow the vacuum in the radiator, created as the fluid cools and contracts, to pull replacement coolant out of the reservoir. The crack allows air to enter the system.

CHECK the overflow hose. Check the pressure cap to insure it can hold 18psi. Check the complete system with the pressure test as Joe outlined. It has nothing to do with visible water or vapor cloud out of the exhaust in cold weather/cold start. That is 100% NORMAL.

[Rob B (shoebox)]

I'll second the overflow pipe that goes from the radiator to the remote reservoir. I recently had to replace mine because of battery acid eating through the pipe and causing a very slow leak. A small amount of coolant would leak out under pressure conditions and then it could not replenish itself from the reservoir because of the loss of vacuum for the sealed system. Result was the level in the radiator slowly going down and only an occasional drop of coolant seen when parked for long periods. I probably would still be looking for the leak, had I not removed the battery for some other reasons and noticed the wetness underneath.
On the good side, my low coolant sensor still works.

[EquatorHeat00]

Wouldn't a bad pressure cap, and reservor tubing show up on a coolant pressure test which has already been done with no signs of leaks? Never seen a drop of coolant on the ground, or around the radiator cap area.
It does go down in the reservor area also, but I think the coolant has to be alot lower in the radiator for that too happen.
When I open the radiator cap to fill it up isn't that putting air back in the system? (I notice it bubbling, and going down some after I fill it up. Wait a little bit, and it goes a tiny bit lower then fill up a tiny bit more till it stops.

I just filled it up to the very top, so when I put the cap on it flows over, and out. If thats what you mean by the brim. I always added it not quite that high, so it wouldn't over flow. Would that be air in my system? We'll I'll see what happens when I drive it.

[Joe 1320]

Wouldn't a bad pressure cap, and reservor tubing show up on a coolant pressure test which has already been done with no signs of leaks? Never seen a drop of coolant on the ground, or around the radiator cap area.
.

Nope. The cooling sytem pressure test requires the removal of the radiator cap in order to hook up the test equipment. Not only that, the overflow tube is never under pressure as the radiator cap is what controls that. When the fluid heats it expands, it is then forced into the overflow tube and into the coolant recovery bottle. If the tube and cap are functioning properly, when the the coolant cools it condenses and creates a vacuum that pulls the fluid back out of the recovery bottle and back into the radiator. If the system is not sealed ie; the overflow tube is cracked, not properly seated and clamped or the cap is bad, the vacuum created in the radiator doesn't draw the fluid from the bottle and the coolant doesn't return to the radiator. You should see what happens if the tube gets plugged. When the coolant condenses and the tube is plugged, the radiator hoses literally get sucked flat.

think of it this way....... use a straw and drink water from a glass. Everything works fine. Put a crack or hole in the straw above the water line and you'll be hard pressed to draw the liquid up though the straw.

[EquatorHeat00]

How do you check the pressure cap for 18 psi, and how can I tell if there's a crack in the reservor hose just by looking at it?

[Joe 1320]

How do you check the pressure cap for 18 psi, and how can I tell if there's a crack in the reservor hose just by looking at it?

A test kit contains a barrel that you put the cap on one end and hook up the testor on the other. That's what is used to test the cap. The correct way to test the hose is to remove the battery first, then remove the battery tray and coolant bottle assembly. Flush it out and test the hose for a breach. Compressed air works good for this.

[Injuneer]

Wouldn't a bad pressure cap, and reservor tubing show up on a coolant pressure test which has already been done with no signs of leaks? Never seen a drop of coolant on the ground, or around the radiator cap area.
It does go down in the reservor area also, but I think the coolant has to be alot lower in the radiator for that too happen.
When I open the radiator cap to fill it up isn't that putting air back in the system? (I notice it bubbling, and going down some after I fill it up. Wait a little bit, and it goes a tiny bit lower then fill up a tiny bit more till it stops.

I just filled it up to the very top, so when I put the cap on it flows over, and out. If thats what you mean by the brim. I always added it not quite that high, so it wouldn't over flow. Would that be air in my system? We'll I'll see what happens when I drive it.

I'm really confused here, since I'm not sure what you are after. Several fairly knowledgable people have explained possible problems to you, but it seems like you are convinced you know its something else and are ignoring their advice. Why even ask?