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I have a 99 996 C4. Any instructions on how to flush and fill with new antifreeze? - Also, what type of fluid (brand, etc.) do you suggest? Thanks

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On a Carrera this is not an easy task. You must remove all the cars underbody panels and disconnect several hoses to completely drain the coolant. To refill, Porsche highly recommends uses a vacuum pull method. This method of drawing coolant in minimizes the chances of trapping air in the system (a real problem in this design). If you don't use the vacuum method you will have air trapped in the system that could take weeks to bleed out. I've seen the vacuum method done it it works very well so I highly recommend it.

Do a search here for coolant type there have been many postings on the Porsche coolant and the OEM company that makes it for Porsche.

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The proper way requires alot work removing the panels under the front of the car, removing hoses etc. Here is what I do which works fine.

There is a small plug on the back bottom of the engine (coolant plug)that can be removed with an allen wrench. Removing this screw will allow just slightly more than 2 gallons of coolant to be drained from the engine.

Procedure ( This seems very complex and time consuming, but in reality it is not. Total time is about 1 hour)

1. Remove the coolant tank cap and remove the coolant screw and allow the 2 gallons to drain from the engine. Reinstall coolant screw. Don't burn yourself. Place the bleeder valve wire in the vertical position which will open the bleeders. The valve is located next to the filler cap and will allow air to purge from the system. Fill the tank with clean warm water. Start the car and let it get to full operating temperature. Turn the heat on full to allow for full circulation of coolant. When the car gets to operating temp, let the coolant circulate for a few minutes. (tank cap on).

2. Turn off the car and repeat #1 three more times.

YOU COOLING SYSTEM IS NOW ABOUT 90% PURE WATER or about 1/2 gallon of antifreeze in 6 gallons of water. You can further reduce the percentage of antifreeze if you want by repeating #1 again, but it is overkill.

3. Repeat number 1 but this time, fill the tank with a 50/50 mix of water and coolant. You should be able to add 2 gallons to the tank. Let the coolant circulate and now you have 1.6 gallons on antifreeze in the cooling system out of a total of 6 gallons. Drain the system one more time which will remove 1/2 gallon of antifreeze. (2 gallons of mixture). Then fill the tank with 2 gallons of straight antifreeze and you are at a 50/50 mixture. Put the cap on the tank and let the engine get to operating temp, shut off and return the purge valve to closed position.

Check the tank level after driving the car and add a 50/50 mixture as necessary. Since you removed virtually all antifreeze from the system, you can use any major brand and type of coolant you choose. I use Peak.

Don't scald yourself.

You should change you coolant every 2 -3 years.

No worry about leaky hoses, broken clamps, etc.

Edited by 1999Porsche911
  • Upvote 1

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coolant tank cap and coolant screw (small plug on the back bottom of the engine)

Do you have a pic or a diagram of where these two are? Thanks for the procedure both of you. I think I will give 1999Porsche911 suggestion a try.

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Just out of general interest: Why do you want to change the coolant, considering that it's a lifetime filling and, at least according to Porsche and the coolant manufacturer, does not need to be changed?

Cheers,

Uwe

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Just out of general interest: Why do you want to change the coolant, considering that it's a lifetime filling and, at least according to Porsche and the coolant manufacturer, does not need to be changed?

Cheers,

Uwe

I only thought to do it because of postings either on this forum or other similar forums where people had stated the fluid should be exchanged about 2 to 3 years. Is that wrong?

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...

I only thought to do it because of postings either on this forum or other similar forums where people had stated the fluid should be exchanged about 2 to 3 years.  Is that wrong?

...

People say a lot of things on the internet :). The factory workshop manual states:

"Note: The engine cooling system was filled with a lifetime coolant filling at the factory. This coolant must not be mixed with or replaced by other coolants." I'm sure Loren can confirm this.

Also, if you look at the maintenance checklist available on this site you'll notice that no coolant changes are prescribed.

Cheers,

Uwe

Edited by umn

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MY996. here are the pics. You can see the allen wrench inserted in the plug. And YES, the coolant SHOULD be changed every 2 - 3 years regardless of what Porsche says. It breaks down and gets dirty just like your oil. It will also help prevent hard mineral buildup and blockage that would require more costly repairs in the future. It is a great investment of 1 hour time and $20.

post-3742-1117376310_thumb.jpg

post-3742-1117376330_thumb.jpg

Edited by 1999Porsche911

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And YES, the coolant SHOULD be changed every 2 - 3 years regardless of what Porsche says.  It breaks down and gets dirty just like your oil.

Yes, why would Porsche know ... :rolleyes:

If your coolant "gets dirty just like your oil" then you've got a major problem with your engine.

Cheers,

Uwe

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My coolant is 6 years old next month. It is neither dirty or broken down. I test it at least once a year and it has not lost any of it's cooling properties. Unless you have a leak or somehow dilute the mixture too much with water I see no reason to change it.

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My coolant is 6 years old next month. It is neither dirty or broken down. I test it at least once a year and it has not lost any of it's cooling properties. Unless you have a leak or somehow dilute the mixture too much with water I see no reason to change it.

Loren: There is no such thing as LIFETIME ANTIFREEZE, only extended life. Not only do the protectants wear out, but if you catch your coolant when you drain it, you will see quite a bit of crap in the liquid from metals and rubber that have eroded off over the years. Much of this debris over time will clog the small veins n the radiator, reducing it's cooling capacity. As time goes on, you can accumulate so much material in the veins that the only way to clear them is to reverse flush the radiator.

The protection from freezing and boiling will last considerably longer that the anti corrosion chemicals do and a tester will not identify this. As these dilute, the fluid will allow buildup in the system (especially radiator) and will reduce the efficiency of the cooling system. The fluid will eventually become caustic and actually create pitting in the metals of the system.

Antifreeze also developes and electric charge over time (as it's additive deplete) as it passes over the metal in the system. As this charge increases, it begins removing metal from the surfaces of the engine. You can measure this votage by putting one end of your multi meter in the coolant in the tank and the other end to ground. If you have ever done work on old cars that have had old coolant in them, you may have found a bolt or 2 that was actually welded to the metal componant it was securing because of sweating or a small coolant leak.

Periodic changing of the coolant will help eliminate buildup and caustic conditions and keep the system running as efficiently as possible.

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My coolant is 6 years old next month. It is neither dirty or broken down. I test it at least once a year and it has not lost any of it's cooling properties. Unless you have a leak or somehow dilute the mixture too much with water I see no reason to change it.

Ok. Let me start with this. Loren, would please tell me how you test your fluid. I will do that first. If it needs changing, I'll perform 1999Porsche911's method. :)

1999 - Thanks for your response. In case I need to change the fluid, please see the attached picture.

Are the arrows pointing to the coolant drain screw? If so, what size hex key do you have inserted in the screw. Thanks everyone for your help and suggestions.

post-454-1117385399_thumb.jpg

Edited by my996

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I use an bulb type anti freeze tester that shows you the freeze protection (in degrees) on one side and boil over protection on the other. Most good auto parts stores have these.

post-2-1117388442.jpg

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If you look at my first picture, the drain plug is centered on the car from left to right and 12 inches in from the lip of the back bumper and exactly 4 inches to the right of the end of the water hose. I use a 3/16 inch allen wrench.

Edited by 1999Porsche911

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Loren - do you know the part number to the coolant screw. I put it down somewhere and now cannot find it. :censored: Seems like I'll have to purchase a new one.

Edited by my996

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... I use a 3/16 inch allen wrench.

All German cars use fittings and fasteners that are metric. Use the correct metric size or you risk rounding out. For drain plugs like this, I use a hex key that fits my rachet so you can get good pressure on the plug and turn it cleanly.

Serious bleeding question: would you be able to park nose down on the steepest hill you can find and idle for a few minutes operating the bleeding valve?

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... I use a 3/16 inch allen wrench.

All German cars use fittings and fasteners that are metric. Use the correct metric size or you risk rounding out. For drain plugs like this, I use a hex key that fits my rachet so you can get good pressure on the plug and turn it cleanly.

Serious bleeding question: would you be able to park nose down on the steepest hill you can find and idle for a few minutes operating the bleeding valve?

I realize the bolts are metric but this plug is only lightly torqued and a 3/16 works fine. The correct metric wrench would also work.

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So I did the fast flush as described above last night and will know if it fixed my high heat issues this afternoon on the way home from work. It ran on the right edge of the zero on the 180. But now there is a red flashing light on the right side of the temp guage. Any ideas?????

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So I did the fast flush as described above last night and will know if it fixed my high heat issues this afternoon on the way home from work. It ran on the right edge of the zero on the 180. But now there is a red flashing light on the right side of the temp guage. Any ideas?????

Most likely there is too little coolant in the tank. Make sure you properly purge air from the system. It may take several fills of the tank to do so. Best way is to park the car after driving it with the nose down and the purge valve open, or drive around with the valve open.

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So I did the fast flush as described above last night and will know if it fixed my high heat issues this afternoon on the way home from work. It ran on the right edge of the zero on the 180. But now there is a red flashing light on the right side of the temp guage. Any ideas?????

Most likely there is too little coolant in the tank. Make sure you properly purge air from the system. It may take several fills of the tank to do so. Best way is to park the car after driving it with the nose down and the purge valve open, or drive around with the valve open.

Wow, lots of instructions for a simple job. First off, the blinking light is most likely caused by a bad coolant bottle. As a tech I would first pressure test the cooling system, use a mechanics mirror to look at the bottom of the bottle for leaks or at least traces. flushed cooling systems, you only do this when you have some horrible problem such as oil and coolant mix.

Second, to properly refill a cooling system, yes you must only use the vacuum fill method. The company who makes the tool is called UView (Air-Lift) and it is rebadged and sold by snap-on, matco tools, or online at toolsource.com

Anybody in L.A. area who ever needs help with this, no problem it would be nice to make new friends.

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So I did the fast flush as described above last night and will know if it fixed my high heat issues this afternoon on the way home from work. It ran on the right edge of the zero on the 180. But now there is a red flashing light on the right side of the temp guage. Any ideas?????

Most likely there is too little coolant in the tank. Make sure you properly purge air from the system. It may take several fills of the tank to do so. Best way is to park the car after driving it with the nose down and the purge valve open, or drive around with the valve open.

The proper way is to use the vacuum fill method, I never had a problems using this. the tool is made by UView and is called AirLift, snap-on or matco tools sells it under different name. any how a blinking light? I would first pressure test the cooling system and look for signs of leakage. To refill if you do it any other way its the wrong and long way.

Any body in South Bay L.A. area need help with this, no problem, Id like to help out for free.

vizcarra44

Master Tech

vizcarra44@yahoo.com

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I lost my waterpump and had to use whatever coolant was available. This happened to be Prestone that was listed as safe for all cars. Do you guys think I ought to perform this flush and refill with the Porsche type. there's no doubt I mixed them and probably have mostly the Prestone

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If you have mixed coolants (especially organic and non-organic coolants), it is wise to drain that mix out and refill with a 50-50 mix of G-12 coolant and distilled water.

There are several places you can get G-12. One is your Porsche dealership (most expensive), but you can also get it cheaper at any VW or Audi dealership, or the most economical version is getting a gallon of G-12 under the Texaco Dex-Cool brand. Dex-Cool is available at any auto parts store or Wall Mart.

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Refill with a 50-50 mix of G-12 coolant and distilled water.

There are several places you can get G-12. most economical version is getting a gallon of G-12 under the Texaco Dex-Cool brand. Dex-Cool is available at any auto parts store or Wall Mart.

What quantity of antifreeze is needed to do a complete vacuum flush? Can I just use the 50/50 mix for the entire refill process or do I need distilled water as well?

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