topping off coolant
 

How often (if ever) should I be topping off my coolant?

I drive my 98 boxster with 85k miles a few times a week for 20-30 minute runs.

The coolant light blinks every 3-4 months and I add 4-8oz of coolant or water to make the light go off.

I don't see any coolant leaking on the floor and I don't smell anything like burning coolant not do I have white smoke on startup.

It is normal to have to top off the coolant like this? From what I gather it is not. What could some potential problems be that I can check?

I am considering driving this car cross country later this summer and I want everything attended to that can break so I am planning extensive maintenance on it: AOS, coils, plugs, injectors, sensors, filters, oil.

Short answer no.
The coolant tank in the trunk are a know problem with these cars.
They get hairline cracks with age. Then they leak while under pressure.

Pull the carpet and the sub floor, everything tell you are down to steel in the trunk floor. Look for signs of coolant and coolant smell in the trunk.

A coolant pressure test to diagnose the issue would also be a good idea.
Either have a shop do it or go to Harbour Frieght and but a coolant pressure test kit.
they are around $90.00 works on any coolant system you can also test the coolant cap with them.

If you don't know when the coolant tank was last replaced, I would just replace it. They go in a very sneaky way, then strand you. Been there, done that.

Best advise I can give is check your coolant cap is the newest available with the part number ending in 04. Older caps are know to fail, some suddenly, and spilling coolant well below the pressure desired. Yours might be releasing vapour and you may never see actual liquid.

Hi buddy,
How to top off coolant: Key Steps
Step 1: Don't use your right before. ...
Step 2: Open the hood and locate the coolant reservoir. ...
Step 3: Assess the coolant level. ...
Step 4: Mix coolant and water. ...
Step 5: Top off the radiator. ...
Step 6: Top off the coolant reservoir.

This is a 986, there is no way to top off the radiator and the reservoir is in the trunk not the hood.

Since I did not see any wetness on the carpet in the trunk I figured that the coolant tank was not leaking. (I assumed that the carpet sat on the metal floor of the trunk.)

I did a little more digging and realized that there is a particle board sub-floor in the trunk. I removed the carpet and looked at that and saw that it was all swollen with- presumably- coolant.

See this picture of the particle board sub-floor that sits in the right hand (passenger) side of the trunk. It is swollen in many places.

The piece on the left is the left particle board sub-floor that sits in the left hand side of the trunk. Not swollen. The main particle board sub-floor (not shown) was not affected.

http://986forum.com/forums/uploads02...1622673407.jpg

So, yes I guess my coolant tank is leaking.

I will not go ahead and replace it.

I am also going to change the oil and plugs to make sure the coolant isn't leaking from the engine block just to be sure.

Thank you for all your help.

Yep that's why I said take out the sub floor and take it down to the metal trunk floor.
For sure and issue with the tank. Time to replace it.

Some people struggle with replacing the tank.
I didn't find it that big of a deal.
I removed the suspension triangle and went at the hoses from below.
There is lots of info on replacing it here on the forum.
Just use the search feature.