Trouble Reseating the Coolant Expansion Tank

Greetings: I recently had a coolant leak and a track down (one?) possible source to the coolant pressure release valve (that thing was blowing serious bubbles when I pressure tested it). Anyway, I replaced the entire valve assembly without having to lower the engine, drain the coolant, etc. I only had to remove some parts (air intake, emissions thingy) and slide the tank out a bit (with some modest effort). Got the new assembly on, no more bubbles. The problem is I can't get the damned tank back into place, fully; its almost as if there is an obstruction on the back (nearest the driver's side rear fender) but, having looked at schematics, there shouldn't be anything there. I suppose it could be the teeth that attach the tank to the ceiling guide (and that would be a very Porsche problem). Any experience and/or suggestions? thank you!

I have not had to replace my tank or the part you are referring to, but I gather from others that you may have better access if you lower the engine a little by unscrewing the nuts that hold it to the motor mounts.

Before you drop the engine, double check the clearance back there—it's almost always something small snagged behind the tank. Grab a mirror and a flashlight and look down the driver’s side fender wall. The coolant level sensor harness, small vacuum lines, and the SAI hose love to slip behind the tank and wedge it tight. Also check the bottom drain nipple, and take a look at the slide bracket to make sure a chunk of old plastic or debris isn't jamming the track. A little soapy water or silicone spray on those plastic rails helps it slide home a lot easier, too. Usually it's just a pinned hose stopping it dead. Another guy on RennTech had this exact issue and fought it until he found a line hung up behind the tank: https://www.renntech.org/topic/47119...lant-tank-diy/ If everything is completely clear and it still won't seat, don't force it. You don't have to pull the motor—just support the engine with a jack and a block of wood, back off the two 18mm motor mount nuts, and lower it an inch or so. That extra bit of wiggle room makes lining up the slide bracket way less of a headache.

I appreciate all the advice. In the end I stepped away, gave it 24 hours to think about its actions, and returned to the task an hour or so ago. This time? Success. The only thing I can think of that is different is that it had been a full 24 hours since the car was last driven. Yesterday when I was first attempting the coolant was still a bit warm. Second, I just really focused on twisting the rear towards the engine while pushing up and out and then maintaining it perfectly level and pushing back in. It may be rubber chicken, but I would definitely advise that anyone finding this thread make sure the coolant - and likely, more importantly, the tank - is cold.

It's a black magic thing with these tanks. I've done the job 3 times. It will absolutely refuse to go in and then when it's ready, it just slides in with no effort.