Alxx Nova

When I got the car the coolant level was a little low. About an inch down from "Min". I added some up to the middle range and it went back down to the same point the next day. so filled it again and now it has stayed in the middle range for a week.

Since the first day I noticed a mist of coolant on the trunk lid inside the dark circle (see picture). I thought it might have been the cap so I wrapped a paper towel around the cap and drive it for two days and it was dry. Yet still mist of coolant on trunk lid in circle area.

So is this the sign of a tank leaking or is it normal to have this little bit of moisture on the trunk lid?

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Alex
2001 Boxster S
1989 944 n/a
2008 Passat 2.0 T

Macster

It is not normal to have any moisture under the trunk lid.

If the trick with the paper towel has any validity then the cap is not the problem. The next source would be the tank. Well, the tank or the air bleeder valve on top of the tank.

If you want remove the oil filler tube cap, the coolant cap (when engine cold!), the dipstick then take something and lift up an edge of the basin's floor and lift the whole thing out. This exposes the top of the tank and the bleeder valve.

Put the oil filler tube cap back on the oil filler tube to avoid getting anything in that tube.

Look for signs of coolant leakage. If if there is a leak though you may not see much of a sign since the leak at this point is not coolant but water vapor that carries little anti-freeze.

For a long time -- months maybe longer -- I've smelled a bit of anti-freeze around the back of my 02 Boxster. Cap was replaced some months, maybe 12 or more, back with a new cap. The original cap started leaking. Moisture/condensation under rear trunk lid, around the rubber seal was in evidence. Oh, and coolant level dropped enough to cause coolant warning light to flash.

After replacing the cap the level stayed good.

And remained good right up to the instant -- about a week or more ago -- when I allowed the car to get good and hot one mild day to get the coolant hot enough to cause both fans to come on. When the coolant temperature reached 212F degs. I heard at least one fan come on. I got out of the car and checked the driver's side and found no air being pulled into the radiator duct opening and no air being exhausted. Checked the other side and felt air being drawn and and blown out as expected.

About this time I noticed a trail of what looked like water that traced the route my car took when I backed it into its parking space. I checked the fluid was not water, but coolant. Had that slick oily feel.

As I was walking to rear of car to check coolant level noticed coolant dripping from just ahead of passenger rear wheel. Coolant tank had cracked.

Sure enough after I had the tank replaced the tech handed me the old one and at the bottom of the tank in a molded crevice the tank had split.

Oh, the non-functioning fan was traced to a bad low speed resistor.

My WAG is your car's coolant tank has a crack that hasn't yet developed into a leak but regardless this needs looking into.

I didn't do it, but perhaps it will be something for you do, and that is to get safely under the car with the engine and cooling system nice and hot -- hot enough the radiator fans are running -- then shut off the engine and keep an eye on the tank from under the car and on the top of the exposed tank from above the car.

Be careful if you're under the car hot coolant if there is a leak doesn't fall on you, get in your eyes. Stay a bit off to one side.

With everything cold you can use a bright flash light to look at the under side of the coolant tank to see if you can spot any signs of coolant leaking.

Sincerely,

Macster.

mdkelly1

My experience (hairline crack in coolant tank) was similar to Macster's. Normal driving in cool weather, there was no sign of leak. After being parked overnight from hard driving in hot weather, it usually resulted in a "low coolant" light (and loss of fluid in tank to below min).

You might also check under and around the mat in the trunk for evidence of coolant. That's where mine was. The coolant smell tends to stay with the car for a long time as well.

Alxx Nova

Thanks for the tips. I'm going to check it out today. Also got a tip from a Porsche tech. Wipe down the plastic tank really well and if it's cracked you'll see a dark line where the crack is.

How far down below the Min mark did it go before the "low level" warning light came on?
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Alex
2001 Boxster S
1989 944 n/a
2008 Passat 2.0 T

mdkelly1

It wasn't much (.5 inch maybe) below "min" before the coolant light came on. When the car was shut off for a while and later restarted, the light wouldn't come on until the car had been driven for sometime.

Hope you find the problem.