Quick question draining coolant

Hopefully this is simple to answer. I'm replacing my water pump and draining coolant from the plug. The process is very slow so I opened the reservoir to allow air to speed up the process. However, all the writeuwri never mentioned this. When I replace the coolant (man there is a lot of coolant--need a massive bucket) will the bleeder valve be sufficient to evacuate all the air? Why is it never mentioned to take the cover off the resevoir in the write-ups?

Not really, it is very difficult to get all the air out of the system. You will need something like a UView Air Lift or a similar vacuum system to do it right. You can find these on Amazon and other sources.

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I disagree. I've bled my coolant several times and had no problem purging air by just opening the valve on the reservoir and running the engine at various RPM. Pelican Parts has a nice write-up on this that works great. It's an easy DIY requiring no special tools. https://www.pelicanparts.com/techarticles/Porsche-996-997-Carrera/29-WATER-Coolant_Flush/29-WATER-Coolant_Flush.htm

Thank you! I'm still busy with the water pump and the engine bracket. I have fabspeed exhaust and it's too close to remove a couple of the exhaust bracket bolts. I'll get it eventually, just taking my time and learning all I can about the engine.

While you can do it without the special tools, but it is much more fool proof with an airlift. Also much quicker with zero re-do. The trick is to drain the whole car from everywhere and there is a lot of coolant in that car.

Just read the Pelican article and it has a lot of info on the composition of coolant, additives, etc. And you could certainly use their method for draining and filling the system, But an Airlift is much simpler, faster, easier and more foolproof. And it allows you to test the system with the vacuum it creates. So for the $120 or so it costs it will save you hours of time. And if you are going to change your coolant every year or two (I do) it will save you those hours again and again. So if you value your time get one IMHO.

Follow THESE instructions! https://rennlist.com/forums/996-forum/737700-simple-3-step-complete-coolant-drain-updated-w-refill-procedure-water-pump-tips.html

I did mine without the UView and have had no problems, but it is on my list of things to buy for the next time.

Be careful removing the bolts from the water pump. There are different lengths for the bolts. What I did was place the new water pump on the floor and as I removed bolts I put them in the corresponding holes on the new water pump.

I used a cheaper version of the UVIEW from amazon: Amazon Amazon Will never do the old method again after that. Nice to do a vaccum test on the system as well. Although, it's worth noting the vacuum does not help with missing hose clamps (for those that are reinstalling an engine) that will blow off when the system gets to pressure. Ask me how I know...

Been busy at work and haven't had a lot of time to work on the car. I tried briefly to remove the fabspeed x exhaust (a necessity for removing mounting bracket and gaining the space to remove water pump) but the bolts are so rusty, I'm waiting for a PB blaster miracle. However, I've never seen PB blaster work so more than likely will revert to heat and a few snapped bolts (already snapped one off a clamp). I plan on swapping the aos as well and I've heard that dropping the engine an inch is the way to go? Also, my desire to save money got the best of me and ai bought an aftermarket cheaper AOS... hopefully that works; but I'm a little nervous. These cars are pushed to the limits and require quality parts NOT made in China, but since the aos is mostly plastic I'm crossing my fingers.

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I have a fabspeed exhaust and recently replaced my water pump. I will admit i am a mechanic and did this at work while on a lift. But i did not have to lower the engine nor remove any part of the exhaust. Just loosen the bracket. If your doing it on the ground with jack stand i can see how it would be easier but it is not needed to remove the exhaust itself. Their is a youtube video that is the actual service manual. It is a very good representation of what needs to be done. Not to say it will just fall out and be easy. But if done per the manual it really isn't that bad to do.

You probably won't heed my opinion, but, the AOS is a total PITA job....one that I never hope to do again with the engine in the car. Do not skimp on the AOS . It is an important engine component. It is very difficult to get a new one in. Get an OE Porsche AOS. You must understand that a knockoff AOS is not going to be equivalent to a Porsche part. Porsche does have quality standards for parts supplied from vendors to be used on Porsche cars.

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The part is my biggest concern-- I will get the OE. When you replaced yours did you lower the engine? If so, by how much? I'm thinking I will lower it by just an inch or two for more clearance.

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Thanks for the confidence boost! I am no mechanic but enjoy taking things apart. I do most of my own work on cars and after every job, even the ones while in process I thought I dug myself into a hole, I've always looked back and thought that, wasn't so difficult. Yes, snapped bolts and rust and space can make jobs more time consuming, but in the end it all boils down to "left Loosey, righty tight."

The biggest problem that you "might" face is the small coolant passages in the heads... if any air is stuck in them you WILL create a hot spot and that will cause some damage that eventually will lead to a cracked head or worse. 95+ times out of 100 you will never need to worry about this happening.... but with the cost of the damage verses the cheap cost of the tool its definitely worth it! PS two radiator car is about 5 gallons of mix... three radiator cars come in at 6 gallons of mix! PSS if you are in the Chicago land area send me a PM and ill give you my address... we can flush and refill your car in no time since I have the tool!

No hijack here, but OP says he's replacing thermostat when doing water pump. Is this necessary or recommended? Do they wear or fail often? Doing my WP tomorrow and not replacing thermostat and this post got me to rethinking it. Was going to but I'm not going with the low temp version, sticking with stock. Thanks.

they are cheap and simple to do while you are there so its best to do it to avoid having to go through all the hassle again, with that said i dont think they fail often

HIGHLY RECOMMENDED. The thermostat goes thru thousand of cycles through out the years and it can get stuck open or closed. It's cheap insurance to replace at the same time. Not to mention the time, money and aggravation to do it at a later time in the event it fails soon after water pump replacement. Normally as a tech i would agree to go with the OE temp stat. However Porsche has had and does have issues with certain spots in the engine potentially getting hotter than expected before the OE temp stat opens which can cause severe damage. The low temp stat does not in effect keep the engine colder. It just opens earlier preventing the hot spots from forming. My car has the low temp LN Engineering t-stat. It only runs a few degrees cooler on the highway and normal temps in traffic. The question shouldn't be why should i change the t-stat, rather why not?

I did the 3-step coolant flush today. Only got 5 & a quarter gallons out, no spills. So I decided to refill (used the Uview) with just distilled water to flush again. Once filled, I ran the car for 15 minutes to get the thermostat to open and mix the distilled water thru. Right at 15 minutes the temp flight started flashing and the digital temp gauge (in the hidden menu) read 97 celsius. Shut it down immediately. Wondering why the light started flashing? Tonight I'm draining the distilled water (let it cool down) and replacing the water pump & thermostat and refilling.

Quick follow-up. Water pump has taken longer than expected due to fabspeed x exhaust in the way. I had to remove the cats and the bolts were rusted so badly I broke everyone on the clamps. The bolts holding the cat to the exhaust manifold some broke (desired outcome) while others stripped and I had to cut them off. My cutting tool is slow and the angle was disastrous, so it took a very long time. Anyway, water pump is finally out and getting ready to out in the new one. Question on the most difficult bolt to the lower right (from rear looking to front), that took me forever to get out. Wasn't difficult but could only manage 1/8 turn. I got it out from the top of engine but not sure the best way putting it back in. Any suggestions? I wonder if it would help to loosen the two mounting bolts from underneath and just lower the engine so that bolt can be reached easier from under the car rather than above?

Water pump back on but I did NOT replace thermostat, need to order the part first. However, it should be an easy job in the future since 95% of my time was dealing with the exhaust. For those who have the fabspeed x exhaust: on mine, there is not enough room between the exhaust mounting bracket BOLT and the pipe from catalytic converter in order to remove the mounting bolts and the exhaust bracket. I had to remove the cats first, then it was easy. All the bolts on my exhaust we're severely rusted and most snapped while the painful others stripped; all were presoaked with PB Blaster for 24hours to no effect (as always). The bolts that stripped you have two options: drill and or cut. I cut them off with a small air-powered cutting tool that takes about 30mn to cut through a small M6-M8 bolt. I had to be careful cutting so you don't also hit other exhaust parts. I replaced all bolts at the hardware store. The ***KEY*** is reassembly. Fabspeed should have provided this and I will call to pet them know: you need to cut half of the threads off the mounting bolts that hold the exhaust bracket to the engine bracket. This will allow just enough room to remove these bolts without having to remove the cats in the future. *KEY* When the time comes to replace thermostat, other than costing additional coolant (which I want to flush again anyway) it shouldn't take much time at all. Lastly, regarding the water pump bolt on far-right. If you're having trouble here is the number one tip with these engines. You HAVE to have a 1/4" flat head drive to work on these engines. You might think, well 3/8" is pretty close, but I promise you that unless you have a 1/4" drive along with extensions, you will encounter headache after headache on these engines.