marton

Hi,

Last monday, my heater would not work - I called into my local independent Porsche specialist and he quickly noticed there was little water in the cooling system. It took around 1.5 gallons to refill. It was around 3 or 4 weeks after the regular service where he filled the system and fitted a new radiator cap so I must have lost the water over a short period.
Strange thing is he could not find any trace of any water leak. He said that usually with a water leak you get a lot of white residue somewhere in the engine compartment.
I added some more water to the expansion tank so I could just reach the water with my finger. Now, after 5 days and about 250 miles driving I did not need to add any more water. Also went back to the Porsche specialist and he still can't find any sign of a leak.

I (& specialist) have checked items 1, 2, 6 and 7 in the enclosed list (thank you Adrian from UK for this list).

Anybodyelse have any other good ideas, suggestions?

Regards, Marton

1. Cracked expansion tank or incorrect/ broken radiator cap
2. Water pump not working correctly (noisy) or seal leaking
3. Faulty thermostat (rare) or on S4's thermostat housing leaking
4. Blocked or leaking radiator. (clean & reverse flush if old antifreeze)
5. Viscous coupling or electric fan, not operating properly
6. Head gasket failure (check oil, and filler cap for milky deposit)
7. Leaking hoses (check small hose and valve behind air filter assembly )

Greg86andahalf

Marton,

The first thing that comes to mind is that shouldn't you have a coolant level light on the dash for low coolant warning? Did it signal you to the problem?

Second, was the replacement cap original Porsche?

Since you are saying water, are you using straight water? I'm wondering what the actual water/coolant mix (%) is?

If the system was filled with the heat off, it would come up short when the heat was activated. This would not account for 1 1/2 gallons, but could this have happened?

You can burp air out of a newly filled system and make room for roughly over a quart more collant. This can be done my repeatedly squeazing the lower hose while car is running. I do it with the cap loose. Was it burped, or filled with the car on a slope (nose high), heat on ?

Greg

marton

Hi Greg,

Yes I am using a antifreeze/Water mix, quite a high % as it gets cold here in Switzerland in Winter.

Before the problem last Monday, I did not lose any coolant.

I did not get any warning light about loss of coolant although there is a light comes on when I switch the engine on but it goes when I start up, like all the other warning lights (except the barke light which requires the brakes to be applied before it goes).

Good question about the radiator cap - is it original Porsche? I will check.

So Monday to Friday, I did not lose any water from the cooling system
although I did about 250 miles in varied traffic - some autobahn,
some traffic jams.

Over the weekend, the water level in the expansion tank fell over an
inch. I did not do much mileage over the weekend and nothing extreme
like driving fast or sitting in a traffic jam. Only thing different
was it was hot here and the airconditioning was full on. I don't
think there is any link to the a/c? Maybe a heat transfer somewhere
that is boiling the water away? But nothing to see on the temp gauge.

Puzzled 81s

WallyP

The percentage of antifreeze in the coolant typically should be 50%, and never more than 67%. More than that actually degrades the performance - higer freezing point, lower boiling point, less heat transfer.


The coolant that you are losing has to be goning somewhere. Some possibilities:

Blowing out of the system by the pressure cap. Put a small can on the drain hose and see if you catch any coolant.

Leaking to the outside somewhere - look for any traces of coolant under or behind the engine and radiator.

Leaking into the intake tract, and going thru the engine. Bad news. Check the exhaust for excessive moisture, white vapor, and a sweetish smell of antifreeze. (Some moisture and vapor is normal.)

Leaking into the oil - bad news. Check the oil and make certain that the oil level is not increasing, and that there is no sign of white gunk. If so, take immediate action.

Leaking into the automatic transmission fluid - bad news. Check the transmission fluid level - if it is too high, take immediate action.

Ethylene glycol (antifreeze) destroys the lubricating properties of oil or tansmission fluid, and will cause catastrophic failure.

Steve Cattaneo

Marton,
When your Porsche specialist checked the block and radiator did he add dye to the coolant and pressurized the system, if not that is the best way to find a leak.

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Randy V

If you verify you don't have a breach into the trans cooling loop, my guess is that it was not properly filled during the original service.

The engine must be run up to operating temp to open the thermostat to fill the engine block, with the heater at the hot position, blower on high to permit filling of the heater core, followed by 'burping' the lower radiator hose to remove entrapped air.

Repair or replace that low coolant level warning sensor.