Porsche C4S water pump replacement tech question and parts list

Hi everyone, Im thinking about replacing the water pump and thermostat on my 996 C4S 02'. This work will be more a preventive maintenance then anything else as I have no leaks, no pump noise or anything that lead me to think of a possible failure but the car is now at 150000kms and I think it would'nt hurt if I change theses components. The system has been flushed and fluid replaced in 2017 by the previous owner. Im not tracking the car but do some spirtited driving (Who doesnt..) I watched some good step by step tutorials available here on the forum and on Youtube. I understand the points of getting a plastic empeller and a low temp. thermostat which is what I will get. There is a couple points Im not confortable with or still have a doubt. 1- It seems that I need to loosen the engine carrier plate while supporting the engine. For what I can understand I just have to support the weight of the engine, undo the bolts and move the plate back a little bit to make room to take out the pump. When I did the engine mount it was really important to do one at a time, even with the engine supported just to make sure it would'nt move out of alignment. Im now wondering why the entire engine carrier plate can be unbolted without risk of misaligment. 2- 50% of people seems to use gasket sealant on each gaskets... Im not agaist the idea if it can prevent leaks but I would'nt want part of that stuff in the system. what is your opinion on this? 3- Using a vacuum tool to refill the system... I think I get how it works. It create a vacuum in the system and the new coolant is sucked in leaving no air bubbles. I guess you can hook-up the tool, set a vacuum setpoint and come back like an hour after and see if the vacuum is still the same? Just to make sure your system has no leaks or is there another method method to check for leaks before refilling? 4- Torque on the water pump bolts. If I remember correctly the setting is 7 ft-lbs but I dont see alot of room to be able to put a torque wrench in there. Is there enough room or what is the technique you are using. 5- I will probably go for new water hoses clips if I change the hoses.. Should I upgrade to a better model or new stock ones will do it just fine? ----------------------------------------------------------- I prepared a part list just to make sure I have everything before attempting the job and I would like advises from you guys just to make everything is correct: -Uview Airlift 55000 tool or similar tool -Water Pump 99610601151 -Gasket water pump 99610634051 -Bolts water pump x5 90037801309 -Bolts water pump x2 90037817709 -Gasket thermostat 99610632650 -Bolt cover thermostat x4 90037803009 -Thermostat LNE, Motorad, Wahler 160deg (Havent decided yet) -Coolant fluid from Porsche, ROWE, Pentosin -Coolant plug 90021900701 -Coolant plug Gasket 90012314430 The rest of the list is for parts I would like to change while Im there. Oil sump coolant gasket: -Bottom: Gasket 99610631651 + bolts (x4) 90037803009 Top: gasket 99610632150 + Bolts (x2) 90037803009 I would like to change a few hoses... Here's a picture of my car with the hoses I would like to change if they are easily accessible with the engine still in place. Can someone provide the parts numbers as I am a little bit lost with the different versions... I think the 90deg hose on the extreme right is: Water hose 99610623356 But Im not 100% sure. as for the 2 others.. the one from the pump and the thermostat I have no clue as the technical drawings leave alot of interpretation. I also dont know if they are easy to swap out.. Let say that they look brittle so if I can change them while the system is empty I will. So if you ever think Im missing something please let me know! Thanks for your time Hugo

Hey Hugo, When I did mine, I had the cats off, so I just removed the carrier plate completely. Made the job extremely easy as everything is exposed. I think if I was to do it again, I'd remove the cats again to avoid all the aggravation everyone talks about. No issues with alignment, the carrier plate doesn't have much movement once all the bolts are in place, even loose. I installed gasket dry and haven't had any leaks, I believe this is the way it is suggested in the Porsche manual. Yes, when you use a vacuum system, if it holds pressure (or vacuum in this case), it should be leak free. As I don't intend on doing this multiple times per year, I picked up my vacuum system from Princess Auto significantly cheaper than Uview. All my hoses and clamps were good so I reused.

https://www.pelicanparts.com/techart...eplacement.htm Also recently did mine with cats off. metal gasket goes on dry. Coolant come in both forms, 5 gallons needed if doing a complete flush. Follow Ahsais write up and you should be fine... https://rennlist.com/forums/996-foru...pump-tips.html

Don't sweat it. It is not the hardest thing you will have to do on your car. 1. There is not a problem with both engine mounts off. They will come back just fine. 2. Pentosin concentrated coolant is what I use. Buy 3 or 4 1.5L bottle. Each bottle makes one gallon of coolant. 3. I would be very surprised if you could get ALL the old coolant out. The last time I did this, the car only took back 3 gallons of coolant 4. The metal gasket goes on dry. 5. The torque spec is low. This is where an experience hand is needed without a torque wrench. You don't want to ruin the thread. 6. Buy the hoses from a dealer. One of those hoses is actually a hose assembly with a bunch of hoses tucked in together. It will be more expensive buying from a dealer but you will get the right parts, and you drive a Porsche right? It costs. There is plus and minus with either metal impeller or plastic impeller. Metal impeller grinds the case if the bearing is bad. Plastic impeller breaks off and sends pieces everywhere. The way to avoid all problem is to change the water pump every 60K miles before it breaks. Treat it as preventive maintenance, which is what you are doing now. Best of luck

Get the Pierburg pump. It's impeller is a composite with some sort of metal blend that withstands breaking of the fins like the old ones.

Thanks for your advises guys. I will probably end-up using Pentosin coolant as it is easily available and correctly priced. as for parts Im really interrested in the LNE kit that come with a Pierburg pump, LNE thermostat, gasket and bolts https://lnengineering.com/products/m...riven-csp.html Price for price I think it worth it as I would have to order all parts from different sources and end-up spending potential savings on shipping fees. i will do all the math but I think I found exactly what I need at the right price.

^ good price for what you get. I wish I went that route a few weeks ago!

I did this a couple of months ago and still feel it was the most unpleasant job I have done on the car. Check you bolts on your cats, if they are rusted you may have issues removing. May be worth using a block of timber to keep the space between the block and the carrier. Makes it easier to get the pump in and out. Some bolts can be torque wrenched some not. consider doing the third radiator now since you�re draining some coolant. good luck and enjoy.

That LNE kit is a good kit for a good price.

For the space to get the pump out I think I will take off bumper, cats and engine support plate. All my exhaust hardware is brand new so Im confortable removing everything and re-use the hardware. With the labor saved I think I will invest in a nice support table for the engine which will make the job alot easier.. More time consuming yes but alot easier. Picture from a fellow member found while doing my research thanks!

Hi guys Just a quick update. I have been able to figure out the P/N for the different hoses I would like to change for new hen changing the water pump. Waterpump 3 ways hose: 996-106-850-06 + 996-106-851-03 Thermostat housing to hard coolant line: 99610683204 90deg water hose from oil pump side: 996 106 233 56 Top side of the oil pump 996 106 831 01 So Im wondering how to disconnect the one from the top side of the oil pump from the picture above. I understand the clip side but Im wondering if the other side can be done with the engine in? Same thing for Thermostat housing to hard coolant line: 99610683204 Anyone have changed this hose with the engine in and can share his experience? Thanks Hugo

If you can see and touch them then yes they can be done. Spring clamp tool is a must. Channel lock pliers work fine if you have the room.

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Spring clamp tool ordered! Thanks Bill Can you explain me how to disconnect the hose that has no clamp on one end? Also what do you think about vacuum refill system? It seems to be easy to use and refill the coolant without air bubbles but Im concerned about hoses getting collapsed. Thanks Hugo

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I sent you a link to Pelicans Technical section, did you not explore it? It's right here, see figure 10 at the bottom https://www.pelicanparts.com/techart...eplacement.htm

Just did mine this weekend. The compressor trick at 10psi blowing coolant out the thermostat worked really well. I replaced the 90 degree hose on right too. A little coolant cane out with air and the thermo reconnected. A must is a 10mm wrench that has a bend to get at wp 10mm bolt on right side towards the middle. I was able to torque all but top left bolt.i should have done when engine carrier loose. That black line that blocks the wp from sliding down needed a little wrestling to get out too. Good luck.

Just to make a little update I finally got all the parts needed for the water pump replacement and 4 water hoses for a C4S 2002. 90012314430 coolant drain plug washer 90021900701 Coolant drain plug 996 106 233 56 90deg hose oil pump side bottom 996-106-850-05 water pump 3 ways water hose 996 106 832 04 return pipe thermostat 997-106-831-03 coolant hose oil pump side top (the old PN for the following part is not available anymore and require a new flange) 997 106 216 00 flange 996 106 321 50 gasket 2x 997 106 802 03 clips 2x 900 378 030 09 bolts 996-106-447-04 coolant expension tank cap it might help someone looking for theses parts. The numbers are accurate as of today.

Hi! Im working on my water pump project and I been able to gather most parts. Im still wondering if I should re-use the old constant tension clamps, go with stainless steel worm type hose clamps or use new constant tension type hoses clamps. I dont have the size needed for each hoses I want to replace but I will get them when needed. So what is your favorite solution for replacing hoses clamps? thanks!

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I've done to bottom one (the one on the right/passenger side just below the air-box). 1) Jack up the rear of the car. 2) Remove the air-box. 3) Set up a large clean pan/bucket under hose connections to catch coolant (I think you'll get around a gallon of coolant coming out of the connections). 3) Remove clamps, pull hose ends off the end fixtures. 4) Make sure the connections are clean (scotch-brite) so as not to develop any leaks later. 5) Put you clamps onto the hose so the screws are situated in a way the accommodates tightening/loosening when installed (if you've ever done it wrong, you know what I'm talking about). 6) Re-install the hose making sure it's fully seated on the connections, then position and tighten clamps. 7) Re-fill coolant (you can filter and re-use the stuff that drained out, or just use new - but make sure it's the same type that was in there before. DONT mix different types of coolant - ie. green/pink). 8) Pop the bale up on the Coolant Tank bleeder valve and keep an eye on the coolant level - make sure you replace all the coolant that drained out. This is exactly how I did mine, and I never developed any air bubbles or other problems with the system - it was stable after a day or so (I probably topped it off once or twice with a few ounces of coolant). Good luck

Thank you sir I appreciate your input and take that in note for when I begin the work.

How difficult is it to remove the cats? I'll be removing my mufflers as well (for spark plug/coil packs), but I'm assuming there's not much more to do once those are off? Also, isn't the LNE low temp thermostat just the Motorad one?

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Hi Depends on the hardware conditions... Cats are submitted to high temp. so if you add humidity the bolts and nuts rust and ''weld'' together. Mine were easily out with the right tools. I had another set of cats ready and instead of re-using pressed-in bolts like the OEM we drilled them out and use SS bolts and nuts for future dissasembly. I suggest you to replace each and every bolts you can after the dissasembly. As for the LNE thermostat no its not just like the Motorad one which are set to 180deg opening temp. The LNE is made for 160deg opening temp. but I think (Please correct me if Im wrong) it is manufactured by Motorad especially for LNE.

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They're not difficult to remove per se' just make sure you have plenty of the proper hardware to replace what you make have to break to remove. Depending on when they were last removed and, if copious amounts of high heat anti-seize was used the chances of them actually unscrewing is iffy at best. From what I've read, the LNE low temp thermostat is one that they specifically developed for the M96...

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No. Our low temp thermostat is made by Motorad but it is not the same part sold by Motorad. We use a thermostat from another application that we modify.

Hi Just a quick update. I will start the water pump and hose replacement next week. Everything is ready except I dont have new clamps. I have the part numbers for each clamps I would like to change following this technical drawing: 2x 2- 99951234802 hose clamp 49 X 12 19- 99951255201 hose clamp 28 X 12 20- 99951255101 hose clamp 36 X 12 21- 99951255101 hose clamp 29 X 12 22- 99951255400 hose clamp 14 X 12 2x 25- 99951266909 hose clamp 53 X 12 28- 99951255201 hose clamp 27 X 12 30- 99951255101 hose clamp 25 x 12 many PN are duplicated but are separated in the parts listing. I was under the impression the PN would refer to contant tension clamps but if I search theses PN most refer to German worm gear hose clamps.. I guess the worm gear style are more easier to work with but not in every situation. I have found this site who has pretty much all desired size for metric constant tension clamps. https://www.belmetric.com/constant-t...frt362jsa1mds0 if you had the choice worm clamps or constant tension? I have the right tool to the deal with constant tension..

I just did all 29 or so hoses in my car. 99% of the spring clamps were changed to the worm drive style. I just used a nut driver style screw driver and just tightened by hand. Not a single leak. I bought the correct clamps from autoatlantas drawings.

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Correct - it will remove the remaining coolant through the vacuum. Then it will suck all the air out and at that point if it holds vacuum in the green part of the gauge then refill the system. If there is vacuum there is no leak. Don't think it needs an hour maybe a few minutes - thats the best way to check for leaks.

Thank you guys. I decided to order both type of clamps. Since I can use them for other jobs and the price was correct I will decide which model is best suited when installing.

I recently did this job so I can share my experience. Did you install aftermarket motor mounts? I have Rennline semi-solid motor mounts and I found that they made it impossible to slide the engine carrier back to make enough room. I had to loosen both motor mounts from underneath in order to move the engine carrier. Not a big deal, but just something to be aware of. When I torqued them back up I made sure they were oriented properly (just checked visually from below that the engine carrier was flush with the motor mount. If the little square orientation block was out of it's rectangular recess then it would NOT be flush). I did NOT use sealant. No leaks. I did NOT use the vacuum tool. I found it wasn't a big deal to refill to cooling system. Immediately after the job I got maybe a gallon and a half of coolant in, ran the car for a bit to let the thermostat open up. Once it cooled down I was able to add maybe another gallon. Drove around for a bit with the burper valve open then added maybe another quarter to half gallon. Really wasn't a big deal. The tool looks slick but for how little I would be using it I didn't think it was worth while. It's SUPER important to torque all the bolts correctly. You don't want to crush the gasket too much (causing a leak), or worse, damage the block. I bought new bolts to ensure they would screw in properly with no corrosion. I did NOT use thread locker on them. The correct torque value is indeed 7 lbs-ft. I found a small 1/4" drive torque wrench worked well, with a fairly long (maybe 5") extension and a U-joint. With these tools it is possible to unscrew all the bolts and to get them back in carefully (turning the 10mm socket attached with U-joint and extension) by hand to screw them back in, then torquing them with the torque wrench. There is one bolt near the bottom of the water pump that looks like it's one of the water pump bolts - it's not. Be careful not to take this one out as well. I didn't bother changing any of the hoses or clamps. No problem with leaks. I think the hose clamp tool is a great idea. I struggled with pliers to deal with the hose clamps and wish I had this tool. It's a frustrating job but be patient and you can do it. Make sure you unbolt the three bolts holding the hard cooling line on the driver's side so you can push it down to get the water pump in and out. I'm quite an amateur (had never done anything like this before), and I'm super slow and apprehensive, triple checking everything as I work. Changing the water pump and thermostat took me 8 hours. Knowing what I know now (having to loosen the motor mounts, and dropping that hard coolant line, and also the tricks with the U-joint and extension to handle the bolts) I think I could do it a lot faster - maybe 3 or 4 hours. I also found that I had to experiment a little bit with where to place my jack and wooden board to support the engine to lift it equally on both sides. If you lift it too much on one side the studs at the back will bind on the engine carrier on one side while being loose on the other side. A bit of patience and you can find the sweet spot where it lifts equally on both sides and allows the carrier to slide back on it's studs. I guess one more thing I should mention, since you're also in Canada. I ordered my thermostat and water pump from germanparts.ca. Was cheaper than sourcing it through a dealership, and probably a lot cheaper and faster than getting it from somewhere in the states (no duty, brokerage, hold up at customs, etc). I will definitely be using them for parts in the future if they have anything I need!

Hi thanks again for all your advises. Im in the middle of the job and Im now cleaning old gasket. Im trying to make a clean surface without using any other tool than a plastic scrapper and light scotch brite. So now Im wondering how clean it should be!! My reference is the t-stat housing as I have a spare on hand and decided to practice my cleaning skills.. is this good enough? That's basicly what I can do without using an air tool with pad. If I touch the surface I can't feel anything but it still look kinda dirty. If I bring the engine part that clean should I expect any problem? thanks Hugo

There should be no sealant so u r only cleaning the oxidation. The staining is from the metal gasket so i would not worry about it. If its smooth to the touch u r good to go.

Perfect thank you!

Just want to thank you all for your help!!! Your descriptions based on hands-on experience were really usefull. Finished the job today, filled coolant back using Uview while following Ashai procedure and it work wonders approx. 17lts out 17lts in. However I decided to verify the "strenght" of the new hose and squeeze them by hand. I can hear a slight water sound, like water is moving...How is it possible if the system is full? I dont see any change in the expansion tank level while squeezing the hoses. I didnt try to start the car yet as I had some other work to do on the car but I plan giving the first try tommorrow with durametric plugged in to monitor the coolant temp. Anything else I can do? Leaving the expansion bleeder valve open maybe? Coolant level is at max mark in the expansion tank but I have few liters ready in case of. On a side note the job in itself was not too bad. I decided to do it with the engine carrier on. I only had an issue with 2 of the 7 water pump bolt. The first longest bolt, the one easily accessible was stuck.. On the engine core side they decided that the thread would go through which allow dirt dust water and more to go in there.... I had to heat it carefully, let it soak in lubricant and unscrew it a little bit at a time but I manage to save the threads. I didnt use thread locker or anti seize on the WP bolts but I would like to bloc the end of the threaded hole with someting. Probably a blob of anti seize in the hole will do the trick. Second challenge was the bolt on the bottom right corner of the WP.... I tried to torque it down with the smallest torque wrench I found and a swivel extension but I was not feeling any precision there so I decided to do it by hand. After a vacuum test of a few mins it holds vaccum perfectly so I decided to fill the system, and no leak so far. I wonder if heat cycles and pressure in the system will affect this. Theold pump was in very good condition and was previously changed. I had no record of it so I had to verify anyway. The impeller was in good condition, the bearing was still good. Im pretty sure the expansion tank was also replaced. There is no way the tank would look like this after 18 years and 151000kms. So its still goid and diesnt leak. Ill replace it in 4 to 5 years when Ill redo the pump. Thanks again! Hugo

I just remember what's stated in the Uview manual. Some car may required a second vacuum pull. Im mostly convinced that there is still some air trapped somewhere. Not much but Im sure there is some. That water noise I can ear when pressing on the hose make me believe that there is some air pockets. I dont want to damage the engine, I know there is atleast 17 lts went in but I dont think its suffisent is air pockets are present. Should I try to draw a small vacuum with the Uview and see what happen? Could it get rid of the kast air bubbles? Im sure some coolant will be drained out but I can catch and re-use it easily.

Just drive the car. U r way over thinking this and u wont hurt the car. It will force any air to the resi after a few heat cycles. Just keep an eye on it and top off as needed.

Open the bleeder valve bale it's the black thing with the metal clip on it. Lift it in the up position drive around then close it. Lifting the bale just forces it to vent otherwise it lifts by itself.

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Exactly what I told myself before reading your post. On the other side I changed few components and there was room for mistakes as it was my first experience with a car cooling system. Im used to change the water, pumps, rads and bleed system on kart engines like my KZ and ICA engines but never did anything similar to a car.. Tonight I went for a ride with Durametric plugged in and the bleeder valve open. After briging the engine to running temp I stopped and couldnt see any change in the coolant level. Restarted, did a good run while reaching 5000rpms here and there and left the bleeder valve open. On the cooldown about 750ml went in. No hose bursted, no leak, temp was between 81 to 85 deg C all time, no abnormal noise. Job done. I guess we are allowed to be proud of ourself sometimes! Im proud of me there. Thanks for your help guys.

Sending u an attaboy with slap in the back .

Replacing my water pump soon... can anyone help identify these hoses? Located right next to the oil filter on a 996 911.

#27 and 33 heater hoses, i think. Be careful as they changed for different car options. http://www.autoatlanta.com/porsche-p...-05�ion=105-05