loss of coolant but no puddle - Resolved: Leaky Rad

I got a warning light about low coolant level while driving yesterday, and the red light blinking on the temp gauge. Arrived to work, shut off the car and forgot about it, until on my way back home I got a check coolant level warning light, after a while, and no clinking red light. Since I got the car last winter the temp gage was stable a bit over 180F, and nothing has changed since the warning messages. I checked the coolant level once the engine cooled off and noticed the low level in the tank. I must have added about 3 litres of distilled water to fill the system back up. I also realize that my tank is the updated design barring the 03 mark. I checked the level before but realized that I was tricked by a stain line between min and max, so effectively I don't know how much coolant was there since I got the car. I tried to find the source of the leak unsuccessfully, the water pump area is dry and there is no leak or puddle underneath the engine. I will take the front bumper off next to see if the leak is in the rads this weekend. Any recommendation on what to check next?

Just monitor it for now. If you have a bad cap/bleeder you may have been low for quite a while. Remove your oil cap and see if you have a bunch of "mayonnaise" in there. If that looks good, I would take the car on a long trip and see if the level changes after the car cools down. Smarter people than me will chime in. But, I wouldn't panic yet since you don't have an initial baseline to compare to.

^^^^ Good answer.

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You might want to clean between the Rads and condensers when you have the front off the car. Crap in between them can lead to corrosion. Good luck with finding the leak (If there is one).

+1 on "monitor". Also, check your cap, and if there's any "crust" around it (which means it's probably leaking) change it. I had a new cap go bad in a little over two years... What you have to remember about this cooling system is that there are lots of places for potential leaks since the coolant is routed all the way to the front of the car then returned again all the way to the back. Take a look at the diagram here: http://www.autoatlanta.com/porsche-p...section=105-05 or here: http://www.autoatlanta.com/porsche-p...section=105-10 as you can see, lots of clamps and little flexible connections, and hard lines...many of which are buried and/or difficult to access. If you really want to find the leak unequivocally - Get it up on a lift or jack stands, remove all the under-body plastics, fill it up with water, get it up to temp, and pressure test. Once you find and fix it, drain it back down and fill it back up with proper coolant. Good luck

advance auto sells a pretty good pressure tester. I used it recently on my M5 which likewise had a slow and mysterious coolant leak without so much as a smell. I never did find it, but after I replaced hoses and did a satisfactory pressure test, I quit worry about it and haven't had a problem. A really slow leak can be tough to find since it just evaporates off but the connections at the rads and the expansion tank /cap are usual suspects.

Do you have the latest 04 cap? If not I suggest that you get one. My car had a mysterious coolant loss solved by a new cap.

The cap is an 03 version, the coolant looks normal colour but the cap had a green slime underneath it.

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Hmmm... green slime! Better check the IMSB...

When my water pump started to go, coolant leaked from the impeller shaft when the engine was running; when the car was parked, no coolant escaped. If you can, get underneath the car and look for evidence of dried coolant in the areas surrounding the water pump.

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I know that you are joking, but for everyone info the IMS was changed with a LN one.

This morning I added another liter. I am hoping that this was needed because the system had some air and the shakedown run help bleeding it. Mill keep an eye on the tank now and check tonight once cooled. I�m not landing on putting the car on ramps and get under the car and remove the plastic panels underneath. Any recommendations on pressure test caps that would fit the reservoir?

Get a new cap. The latest version ends in 04. Are you adding a 50/50 mix of Porsche coolant and distilled water? The old style coolant was green colored. The new style coolant is orange in color.

Get the 04 cap, and also, if you suspect that coolant levels were low and you have air in the system, I would try to bleed that air out. If you don�t, you might have issues with temperature, blinking warning lights, etc. Distilled water should be added with the correct coolant mixture ratio.

Today I saw that you can buy a UV torch! Very handy when looking for coolant leaks as the genuine coolant has UV dye in it

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I'll translate for the 'Mericans. By "torch" he means flashlight. Don't go burnin' down the house. [I used to live in England, so I can sorta understand most of Aussie speak.]

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Hahaha thanks! Classic down under language

Mystery solved. I have a leaky radiator. I bought the car back in December from a Porsche dealership. they reconditioned the car before sales, including the major service. I guess that they never cleaned the rads as I collected a whole bucked to dirt. the leaky rad is the big one on the driver side, there are a bunch of pin holes. I guess that the general thought is to replace it, other than fix it. Any recommendations on where to get one? thanks for the moral support. I almost torched down the car

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Wops, my bad Hahaha

I suspect I have a similar issue due to a leak in that same area during winter storage. I don�t think it�s as bad as yours but curious to know the repair costs if you wouldn�t mind sharing .....

Water cooling parts including radiators here https://www.pelicanparts.com/catalog...ing-System.htm and here https://www.warehouse33auto.com/cata...Belts-Radiator

A lot of folks just replace both radiators at this point. And all new coolant as well.

I replaced both of mine this year my RHS was leaking but replaced both whilst I had the front stripped down, and the coolant drained. I found the cheapest OEM parts were on Amazon, the 2 # were AKG Radiator 99610613174 AKG Radiator 99610613174 and AKG Radiator 99610613272 AKG Radiator 99610613272 unfortunately I cant remember which was left and right. well priced from B2C Auto Parts B2C Auto Parts for $415

Thanks for the recommendations. I see that there are two part nr for the rads, 99610613151 and 99610613174. they look the same to me but I suspect that the first is for all 996, and the second one is for turbo and 4S. are those interchangeable?

The ones I listed were for a 40th AE, not sure if they are different to the standard. I guess the AE would be the sames as a 4S as they have the same front bumper

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It looks like the early ('98 - '01) radiators (99610613150/51) are quite a bit less expensive than the later ones (99610613172/74)...

Or you can get them from Gossett Porsche in Memphis - (No affiliation) I have found their prices as some of the best around.

^^ Why so cheap?

Probably because they should be cheap. They r constucted with plastic tanks and aluminum fins. I can get jeep rads 3 times the size for under $100. I upgraded mine to the csf units. More money but better cooling, construction and direct bolt in.

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Unfortunately narrow body 911 rads are 1/3 of the price of wide body ones. the cheapest I found for my C4S part nr 99610613172/74 is $350USD. My local dealership here in Canada wants $1070CAD insane.

No kidding, i know the dealer is typically the last place people source parts these days, but I've found on a number of occasions for the dealer to beat ebay pricing. I've bought tons of stuff from Perimeter Atlanta. Water pumps, thermostats, door latches, trim pieces all very very cheap. I recall a recent thread where peeps where recommending where to buy a water pump and the best price found online was $40 higher than Perimeter Atlanta, lol.