The Bartender

I have an odd issue happening with my '99 Boxster. It would appear that I have a coolant leak. Got it in October 2012, the light for low coolant started to flash intermittently around January, got the coolant topped up during an oil change in February, issue cropped up again.

So I had some other work to do at the mechanic, left the Boxster there for a couple of weeks but it didn't leak at all. They had it up on the hoist, ran the car - nothing.

I put cardboard under the car and coolant does seem to leak from time to time, but not much and not consistently. When I start the car, the light on the dashboard will flash but let's say I go grocery shopping and park the car there, when I get back to the car, the light will be off. So the levels are fluctuating.

I can't really peg what it is. My parking spot is on an incline, so my car is usually parked in reverse, which means the car is declined down and to the left a bit. Could that have something to do with it? When parked flat, it's fine but on a decline/incline, the liquid pools? Any ideas?

The coolant container is fine - otherwise there would be a big mess in the trunk. Just had the cap replaced as it appeared the last one was faulty.

Has anyone else come across this situation? Leak is by the back right tire. Any help is appreciated.

zedcat

If the leak is near the right rear I would still suspect the coolant tank. My 04 S started to drip from the lower right rear diagonal suspension brace- just drips leaking leaving a small patch overnight. I didn't have any warning lights though and there was no leakage in the rear trunk. Anyway, replaced the tank and that was it.

Macster

Second zedcat's opinion.

Coolant tank.

If you want drive the car around until it is nice and hot. Leave the A/C off.

Pull the car into a parking place that is easily accessible by a tow (flat bed) truck.

Bring rpms up to 1500 or so and hold until you hear the radiator fans come on. Shut off the engine.

Get out of the car.

Wait. At a safe distance from the car.

When the how coolant comes gushing out of the split tank call the tow truck and have the car brought into a shop and the tank replaced and the cooling system properly refilled with fresh antifreeze and distilled water.

While the car is in the air the water pump should be inspected. If there is a large stain of dried residue on the pump housing, if the belt has a sharp edge if with the belt removed the pump has any play have the pump replaced at the same time.

The Bartender

Thanks for your response.

I was told by the mechanic leaks are hard to find - that maybe it's the thermometer or something else related to the coolant.

Does that make sense? Both of you seem to think that it's the container - is there an easy way to test to see if that's the issue? The mechanic ran a pressure test on the coolant line and couldn't find the problem.

Macster

There's a poor man's pressure test.

Be sure the cooling system is topped up. You can use distilled water.

Drive the car around plenty to get it fully up to temperature. Be sure the A/C is off. This keeps the radiator fans off until the coolant temperature gets to 212F.

Once you are sure the engine is fully up to temperature and has been for some time -- ideally you have heard/felt the radiator fans come on/go off at least once -- then back home (where I like to point out the car is easy to get to by a tow truck operator) raise rpms to 1500 and hold until the radiator fans come on.

Then shut off the engine.

With the rear trunk lid open just walk around the car. You might first smell anti-freeze but given what you have posted you'll probably be treated to a gush of hot coolant to the ground as the tank split opens from the pressure helped by the heat which has softened tank some.

Be aware if the tank - or any other part of the cooling system is suspect -- if it lets go you do not want to have your hands or face near by. The coolant is boiling hot and under some pressure. A bad scalding can be had and believe me you do not want to be scalded.

If the tank does let go, make that if anything let's go, a hose or a water pump seal, or a radiator weakened by corrosion, when the car is on the rack be sure to inspect other areas for signs of other leaks. Remember: There are always 2 leaks, unless there is just one or 3 or more.

extanker

take it to a shop that knows how to use the dye and light test

Macster

The problem is the pressure test is often (always?) done cold. It takes a pretty good leak to leak cold.

But with everything nice and hot and soft...leaks are often pretty obvious. The problem of course is no one wants to open the cap to the hot coolant tank its pressure.

Thus the poor man's coolant leak test. Get the engine coolant nice and hot then shut off the engine. The residual heat will raise the temperature of the coolant which is now of course not flowing through the radiators and at the same time raise its pressure.

Granted dye can help in some cases if the leak is still not obvious. A pinhole leak for instance. Even so the leak has to be on an exposed surface at least one that can light up when the light is shined upon it.

My '96 Mustang created a saucer sized spot of coolant on the ground. The leak was a pinhole leak that was found on the back side of the radiator but not from any wetness but from the lighter color spot the tech rightly diagnosed as the leak point. But had the leak been hidden behind the fan shroud, or coming from an inside surface in amongst the radiator fins...

extanker

.......THAT KNOWS HOW TO......