996 Thermostat + Vacuum coolant refill

Hi all, Over the weekend, I would like to replace my thermostat. I have done it it the past on e36's and e46's. But I see that everything one touches on a P-car is a bit and above in terms of complexity. The car has been fully serviced with an engine rebuild. But for this season I am going to track it and have purchased an OE equivalent Wahler low temp thermostat. A few questions; 1. By pulling just the thermostat out, what is the amount of fluid to be expected? I would like to collect as much of it as it will allow me to measure the later input quantity. 2. Any tools or tips recommended not to damage the 20 year old hose? 3. How to clean the mating surface? Many theories out there, again if it was a m50b25, would do it with a rag. :-D 4. For the vacuum tool, there is some misinformation out there. As in alot of places people say, build vacuum refill once and done . BUT this cant be so on the 996, from what I know. you need to build vacuum at least a couple of times to be sure there are no air pockets, even with a system that has some fluid like in my case. Refill. Pop the breather valve on top of the reservoir, let it heat up, add some RPM's etc. etc.. It's not just bingo bongo refill and done! Or am I the stupid one? :-D (can be). Anyways linked video under (at around 20:30) You Tube

You will likely lose half the coolant by taking out the thermostat housing and its associated hoses. Consider changing the 20 years old hoses you touch, Don't re-use the original squeeze clamps. There is little need to clean the crud, the gasket is metal and it leaves little crud. It only take one application of the AirLitt tool if you do it correctly

Quotes source post: 19276534

are you sure that it works in one go ? I mean the thermostat is closed or ? Managed to get it off during my lunch break

Fyi, a few years ago some of us tried the Wahle t-stat and it didnt operate correctly so we had to do the job agian with the LN one. Keep an eye on the temps as ours went higher then with the factory t-stat after heat soak.

Your life will be better with a vacuum fill tool and an air compressor. You can get the coolant filled without worry of air pockets and trust me, this will come in handy. My trusted tech once didn't refill properly and it was easy to fix. I will follow up with a link to a tool. Had trouble copying off borrowed Mac. Search the below on Amazon. I use the Schwaben version of this. ​​​​​​ OEMTOOLS 24444 Coolant System Refiller Kit

The Airlift tool works best when ALL the coolant is drained, the more coolant is in the system, the less effective it is ...... It is a great tool that should have been invented 40 years ago ( Pantera)...

I recently talked to a guy with manymanymany years' experience as a professional mechanic, who does not care for the vacuum fill tools. He says that getting the rear of the car up in the air and taking a bit of time to burp the system does just as well, and is easier on those 20 year old hoses. He's definitely worked on a lot of watercooled P cars so I put some credence to his words.

Quotes source post: 19276873

I've done it both ways, with vac tool and totally drained empty coolant system, and without vac tool. My anecdotal experience... With vac tool and used properly its one and done, no air full coolant charge. Although I do leave the tank bail in the up position for a few days at least and top off as/if needed. Without the vac tool takes more times and skill. One has to fill tank to middle of min/max lines and drive till at operating temp(no further) then let fully cool (maybe over nite in warm climates) to pull in needed coolant to the system and expel trapped air. Then do the same again, and maybe again, and again.... with bail up for the duration. Problem is, if you just do this once and system looks full and you think system is full, and its really got trapped air. Once it cools and sucks in coolant the tank is now low and then next morning after it cools again it could suck even more coolant out of the tank and leave it way to low, now ready to suck air into the system. 996 takes 6 gallons of coolant. With 20' of coolant piping you might be able to pour in 5 gallons. so be ready to top off a good few times after a few 'heat/full cool cycles' before any long rides. Yes you can do it fine without a vac tool, but why, when knock off good functioning vac tools are so cheap..? Or if your a pro, get the best, the airlift UView 550000 for $150... jmo

Quotes source post: 19276578

Hi there, many thanks for the heads up. I did much research on this. Wahler is the OE supplier for the tstat, on the unit itself you can see the OE numbers scratched off on the housing. With all due respect to LN, I have a unit from them and it looks quite similar even I would say identical, I would be very much surprised if they actually did more than just a rebadge and mark up as LN. Oh and yes, the t-stat opened beautifully at 71c, due to the low ambient I could not get it past 80c.

Quotes source post: 19277031

Thank you all for your support, the job is DONE! :-) Anyways I used Glysantin G30, it's directly from the chemical company BASF. I would not be surprised if they were the OE supplier to Porsche as well. G30 is the pink G12 equivalent. Ok, so I used the vacuum tool and it was dead easy, this is where I personally overthink things prior to a job and think that reading and watching videos can help. (my personal notes, so take with a grain of salt) 1. About 2 Gallons came out during the t-stat change. 2. Connected the tool. (Side note, I have a powerful 3HP hobby compressor, so there was no issue). 3. 1st go: build up the vacuum to 20 - 25 inHg (60 - 50cmHg), slowly! I was careful to slowly turn the valve otherwise it could be quite easy to go overboard. (you can hear bubbles in the process, by controlling the valve you can allow the vacuum to buildup slowly and even maintain in the range thus prolonging the air extraction). 4. Open the valve for the coolant, quickly shut off. 5. Quickly repeat step 3, as for a brief moment air could have been introduced. Again slowly build up vacuum. This means we have two gentle cycles. This would be a good moment to check if the system can hold vacuum. 6. Fill until full. disconnect. 7. Open bleeder valve. 8. Turn on the engine and after a couple of minutes, give some low RPM rev's. After 10 min once oil pressure drops more revs. 9. temp reaches 80c, thus t-stat open, last rev. Shut off. 10. Open reservoir slowly as pressure buildup (despite bleeder), or put in other words pressure would be higher. See level, in my case was a half inch above the max level. (this was last evening). 11. Just went to the garage and checked the level and it's a half inch under (pic attached). top off to full. 12. Done, drive and monitor

[QUOTE=Vect;19278407]Hi there, many thanks for the heads up. I did much research on this. Wahler is the OE supplier for the tstat, on the unit itself you can see the OE numbers scratched off on the housing. With all due respect to LN, I have a unit from them and it looks quite similar even I would say identical, I would be very much surprised if they actually did more than just a rebadge and mark up as LN. Oh and yes, the t-stat opened beautifully at 71c, due to the low ambient I could not get it past 80c. Maybe LN went back to using Whaler thermostats, back in 2019 I too had issues with the Whaler thermostat that I had just installed, I removed it and checked it against the one Jake Raby (wasn't Whaler) had recommended from L&N and it was a different design and worked correctly to this day. I believe Jake said the issue were with testing on the multiple thermostats the opening and closing that were all over the place as much as 10 degrees. I bought Whaler Tstat from a P-car parts company in KC that no longer in business, they had refused to warranty it.