Coolant tank!!!!

So, coolant been leaking for a while whenever pressure is high from hard driving. Decided to replace the tank. Renntech forum had all the instructions so thought I'd give it a go. If you follow them closely it all works out ok but is a right ***** to get the tank out of its position. C4's have the fuel filter bolted to the coolant tank and as I'm doing my 48K it's time to change that too. Remove that and its jubilee clip (helps stopping it catching on things) undo all coolant pipes and tuck out of the way, there is another fuel line that needs to be disconnected (info in renntech posting) unplug the coolant temp sensor connection and twist sensor towards engine, mine wouldn't come out as there is a pipe clip right in the way but as i move the tank a bit it dropped out. This might save you some time looking for it!!!! I dropped it 3 times in all and every time it fell down behind the coilpack heat shield, so that's where it will be if you drop it! To remove the tank I am afraid it is crypton factor, it will only come out one way and it took me 30 minutes of twisting it this way and that before it popped out leaving me none the wiser! If you drop the engine it must be easier but I've never done that before. My crack was 10mm long and would only leak at high temp and pressure, it was right in the concave bit of the molding which i guess is there to help rigidity. Looking all over the tank with a strong torch from behind, it was the only crack. It's about 2" above the bottom pipe so not totally critical level wise so i thought i'd give it ago at mending it. Polypropylene is not easy to mend by all accounts so i'll let you know when and if it starts to leak. First i used a pointed solder iron to push into each end of the crack, this will hopefully stop the stress from cracking any further. I then used the solder iron to V the crack and burn away the coolant stain in the crack. I'd bought some coolant tank putty from repairproducts.co.uk which is great stuff, first I sanded the area rough, then I heated the tank with a hairdryer and then worked the putty and pushed it into the small crack and well up around it. It gets red hot and you only have a minute to mold it before it's hard. I gave it a second go and made sure it was smeared tight to try a ensure a seal. Time will tell!! Fitting was just as hard as the removal, there really is only one way in and i still couldn't say how i did it, just that the tank was tilted left as it went in. I replaced all the spring clips with stainless jubilees which will make removing in the future easier as you need a plumbers wrench to squeeze them otherwise. Fuel filter goes in tomorrow and reconnect it all up, refill, bleed and cross fingers. I'll let you know! Hope this helps anyone with a crack problem! Steve

Fair play for going for it & getting stuck in straight away, I will have a go at doing mine next weekend, fortunately mine is the C2 so should be slightly easier. Deffinitely keep us all posted on whether it cured it or not. :thumb:

Having gone to all that trouble to get the part out, I would have bought a new tank. If the existing tank has cracked, it will probably do it again as it is a common problem on older 996's and it is 9 years old. Still, good effort on your part and instructions are always helpful :thumb: TB

Don't say that.... it was me that told Steve to attemp a repair!! The thing is, it is a weak point so a decent repair could be the way forward. I am considering using bumper repair equipment but make the plastic really thick on the weak point. Maybe I should do a recon-return service if it works well.

The weak point on mine was the V crease of the molding right on the right angle as it follows the wheel arch shape. It certainly hadn't rubbed on anything anywhere on the tank, and I checked for any other stress cracks using a strong torch shining through the polypropylene. As Lloyd says, that suggests that this is a weak point and should benefit from the reinforcement. Other than that 10mm crack the tank was perfect so to replace it for that seemed unnecessary if it could be mended, like i said time will tell. But think landfill, landfill, landfill! I know it's a contradiction in terms trying to be eco friendly and driving 3.4ltr of Bavarian Brawn but why waste if you can improve on a poor design to make it better and stop a kilo of plastic going into the ground. :mrgreen: