Loss of Coolant

[LocoDriver]

'99 Boxster / 3.4 engine / 147K

Drove to a meeting. Everything OK. Parked car. About an hour later, came out to find coolant under the car. Assumed cracked coolant tank (it had been replaced under warranty years ago). Coolant tank in trunk was empty but no water in the trunk as I had expected. Filled up the tank with water and saw it draining out under back third of the car (NOT in the trunk or just by the right rear wheel).

Drove it home (about 25 minutes) and, although the temp came up quite a bit, it did not get close to overheating but, of course, the water level light was flashing as the tank was empty.

Undid all the trunk carpeting and found no coolant in the trunk. Put the car up on my QuickJack (highly recommended, BTW) and don't see anything obvious to indicate where the water was coming from. Filled up the coolant tank and nothing is leaking out! I have not yet pulled out the panel behind the seats to get to the front of the engine.

I'm assuming that the leak is engine and/or coolant temp related, so the next step is to start the engine while on the QuickJack and, hopefully, find the leak. Before I do that, I'd like some thoughts from the group. (my thought: possibly related to thermostat or water pump?) The fact that the engine wasn't running (though probably still warm) when I initially filled the tank and watched the water drain out sorta leave me stymied,

--- Tom

[Rob175]

Hoses, hose connections and water pump would be my starting points. I doubt it would be a thermostat issue but if it turns out to be the water pump then I'd change out the thermostat too....but my guess is a hose or hose connection. Hoses are under pressure when the system heats up and even a small crack, cut , slice etc can release a lot of coolant in a very short time.

Hoses and clamps....i bet.

[Gilles]

Pretty sure that once you have the engine running and up to operating temperature, you would be able to find the source of the leak.

[Luckyman01]

My car overheated and puked coolant, cleaning the radiators solved cooling issues

[theiceman]

could be the hoses that attach to the coolant tank,, that is the most rearward connection. I think if it were water pump or thermostat he would see it , but we will see..

BTW i bought a quickjack last week, so glad you find it useful, which blocks do you use for the Boxster? do you just put them under the square reinforcements underneath the car ??

[blue62]

This is what coolant system pressure testers are for.
Harbor freight has them for around $90.00.
They have adapters to fit just about any system on any car.

[LocoDriver]

OK, the mystery coolant leak saga continues. As I said in my first post, I saw no apparent place where the coolant was leaking, I filled up the coolant tank and opened the bleeder valve on the tank and, with me in the car on my QuickJack, I brought the car up to normal operating temperature at 2500 RPM with an occasional blip to 5000 RPM to bleed off any trapped air in the system. Ran it for about a minute at idle, then shut it down. When I got out of the car, there was a coolant puddle once again and the tank was empty but, again, I couldn't discern where the water was coming from.

So I decided to start taking things apart. Removed all the lines from the tank to the plastic distributing panel on the firewall in the trunk, and was ready to start the nasty task of removing the corresponding hoses in the engine compartment. My son stopped by so we decided to put the hoses back on, refill the tank again, and with him in the car on the QuickJack, proceeded to bring the car up to normal temp once again (and again with some blips). I had removed the left rear wheel to get a different angle when the leak started.

NO LEAK!!! Coolant tank remained full, car stayed a normal temp. The rain around here finally stopped, so this morning I put almost everything back together (kept bleed vale open though) and took the car out for a drive. Fully 30 minutes, normal operating temp and NO LEAK!

Luckyman: Radiators are clear of debris and car doesn't run hot.

Iceman: My car is lowered so I can only use the shorter blocks and I do place them to mate with the normal jacking blocks on the car. I do recommend the hack on YouTube to allow the QuickJack to roll much easier (https://www.youtube.com/watch?v=k0DQoEQrHmk).

Blue62: I seriously thought about this but $95 is a little much for what (I hope) would be a one-time use.

I'm stumped!

--- Tom

[Rob175]

Where abouts was the most recent "puddle" located under the car?...Front, rear, middle, left or right?

(Front left or right could be a problem with a radiator or connection)
(Middle left or right could be connections, hoses, thermostat and water pump)
(Rear (behind the rear wheels) left or right could be expansion tank or the hoses there)

BTW....I don't think that running the car on a jack for a few minutes is the best way to get the system up to temp.....driving is best then pull over in a level parking lot or your garage and observe until the system gets cooler.

[Gilles]

If you have an Autozone nearby, they have 'tools for rent' (free), get a coolant pressure tester and you can pressurize the system and find the leak.

[theiceman]

my guess is when you removed and reattached the hoses, you fixed your leak.

[LocoDriver]

I hate it when problems "fix" themselves. I did "rent" a pressure tester from a local parts store (free loaner) and pumped it up to 19 psi. It held steady with no apparent leaks for 20 minutes.So maybe my removing and replacing the hoses somehow cured the leak. I'll drive it around a bit more (if it ever stops raining again!) and see what happens. Thanks for all the suggestions.

--- Tom