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996 Complete Coolant Flush DIY


I did not see a 996 coolant flush with pics so heres my contribution. My car is a 2003 C4S 6 speed and should be similar to all NA 996's as far as coolant flush is concerned (Tips have 3rd radiator). I decided to replace the coolant because I had no idea how long it had been in my nine year old car. It was the yellow color so I assume it was the correct type for the time but who knows. For refill I chose Pentosin Pentofrost even though its a little pricey at @$45 per gallon. Make sure you buy th

 

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Only comment on your procedure would be to let the car sit under vacuum for at least 5 min. before commencing the system fill. Reason for waiting is that holding that car under vacuum (The vacuum level on the gauge should remain unchanged during this wait) will show if there are any leaks in the system before the often expensive coolant goes in.

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Nice write up.

You forgot one critical step which is to bleed the heater core loop while you are bleeding the entire system.

To bleed the heater core loop simply turn the ignition on and turn the heater on hi with the fans on low.

A few other tips while you are refilling:

Keep the rear end of the car jacked higher than the front, and gravity will aid the fill, although not required.

To get every last drop out of the system you can disconnect and remove the radiators and heater core and let them drain for several hours. Optionally, you can also hook up a shop vacuum attachment on "blow setting" and blow out the large coolant lines that run the length of the car to evacuate all remaining coolant from them (they have steep angles and so they can trap a lot of coolant regardless of what angle you put the car at). Coolant is caustic, so do be careful if you try this method.

It is a good idea to run the car with the bleeder valve open for a few days (with blips over 5krpm) to ensure the system is totally bled.

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JFP, for some reason the Airlift guide said 20 or 30 seconds (not sure which). I did wait a little longer until I was sure. I can edit that part if allowed.

logray, I did mention the heater on HI and did this on mine. Maybe I need to clarify that part. I just wasnt sure if it helped or not. Your right, it is very difficult to get all the coolant out. I drained the rads from the bottom hose too but still missed @1 gallon somewhere but not sure. No indication of air in system so far.

I was curious if anyone else measured the exact amount they were able to get out without a more extensive disassemble of the system. If I change the water pump and T-stat soon, I will do it again and measure more carefully.

Edited by krazyk
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The longer dwell time under vacuum is purely a “belt and suspenders” method to test for any possible leaks; it is the perfect time to do it, especially if you had taken various parts of the cooling system apart.

It is nearly impossible to get all of the coolant out of these cars; there are just too many spots in the system where it can be trapped. On average, using the standard service procedures, you probably get 80-90% out at best. For car where we are forced to get everything out (e.g.: those that have suffered an intermix), we use an external pump system to force water or water/cleaner mixtures through the system for several cycles to push out the contaminated coolant before refilling.

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OK, I feel better knowing 80% to 90% is normal. I thought the same about pumping through the system but thankfully I didnt have intermix it felt it might be overkill for a regular maint. flush. Thanks for the tips. I have some others to post including a complete PS fluid flush I have never seen done before, so hopefully it will be approved. Thanks again. This forum is a gold mine for the DIY guys or those willing to learn.

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  • 1 month later...
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According Porsche is a periodic refresh not required, only for major operations to the engine or replacing radiators and pipes = large coolant loss, it will be done. You are of course free if you wish, and maybe better, to replace the coolant after several years.

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According Porsche is a periodic refresh not required, only for major operations to the engine or replacing radiators and pipes = large coolant loss, it will be done. You are of course free if you wish, and maybe better, to replace the coolant after several years.

While Porsche does not set a time period for changing out the coolant, over the years we have observed that eventually the coolant will show signs of degradation (change in system pH, rising freeze point, development of cloudiness, etc.). This does not occur at any specific time (we have seen it in five year old cars, and had others go past 8 years with no problems). Being observant would seem more important than a calendar.

As the M96 also is also well known for its composite impeller related issues, most cars are probably going to have their system opened to replace the water pump well before the coolant begins to fade.

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2000 carrera2 w/56k miles. Is the antifreeze brand in the DIY tutorial recommended for my car? I'm a little low and need to bring level up to the MIN mark. No leaks or overheating. Is there a generic brand that can be bought at car store? Also, since I'm going to add a little bit, mix 50-50? and, use distilled water?

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Moondoggy:

If you are just "a little low" you can get by with just adding distilled water. A quart or so will not make an appreciable difference in the mixture.

The question of whether to use only Porsche coolant or not is a much more difficult question to answer as Porsche has gone to great lengths to protect that little profit center.

There are lots of threads discussing the type of coolant to be used and just as many opinions.

Regards, Maurice.

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2000 carrera2 w/56k miles. Is the antifreeze brand in the DIY tutorial recommended for my car? I'm a little low and need to bring level up to the MIN mark. No leaks or overheating. Is there a generic brand that can be bought at car store? Also, since I'm going to add a little bit, mix 50-50? and, use distilled water?

Here is a fairly detailed DIY from the DIY archive at the top of the page, the author chose to use an aftermarket coolant, but it would still be the same for a 50/50 OEM coolant/distilled water mix............

http://www.renntech.org/forums/tutorials/article/301-996-complete-coolant-flush-diy/

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Thanks Maurice and JFP for quick replies and yes, I read the DIY. I didn't know if the pentosin pentofrost G12 was porsche or after market. And, since appears I need less than a quart, will do the distilled water. Good info again.

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Pentosin is after market, Porsche has theirs compounded to their specific OEM specs. There has been much speculation over exactly what it is, but as it is readily available, works very well, but has a reputation for not being overly compatible with some aftermarket coolants, you would need to be cautious about mixing. As a fresh batch of OEM coolant premixed with distilled water lasts for many years in a clean system, we stay with what we know works,

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Thought I read somewhere to check coolant level cold and that's when I have the low reading. Checked it hot this time but found level where it's supposed to be, so no distilled needed afterall. Appears I jumped the gun. Thanks again.

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