Be interested in hearing how that epoxy holds up. We've been having the same sort of discussion on the same pipes over on rennlist - on the 958 series (up to around 2014 when they put bolted on-flanged pipes in place of the glued in one.) Our consensus was JBWeld makes some specific high-temperature epoxy - that is good up to 500F, unlikely in that location to ever get that hot, but some epoxies are removed by heating them, so.. wonder what the temperature rating for golf-club epoxy is?

There are those of us who owned various BMW's and became masters at JBWelding the crappola plastic cooling parts they now are plagued with.

Here's the thread over on Rennlist: https://rennlist.com/forums/cayenne-...pipe-glue.html

Several of us are thinking about doing preemptive reinforcing of the pipe junctions with an external bead of JBWeld. It appears that removing the throttle body might provide the clearance needed without the need of removing the entire intake plenum. Mebbe.

 

I did think about the temperature but then I know that the golf clubs get extremely hot at time sitting in the sun and in the trunk of cars. If the epoxy fails, then it's time to get the TIG welder out and just weld the tubes to the housing, permanent fix. I'll just have to be careful of the temperature so the casting doesn't warp

 

One of the things I noticed was the inside of the housing was so smooth, it seemed it was machined for o-rings, not glue. When the pipes came out the glue was really stuck to the pipes, but none on housing. I hope my roughing the surface solves the problem. tubes/pipes are a rather loose fit.

 

You took the seal off the thermostat and slid this one into it's place? This ring seals the back side of the thermostat. With a front and back seal the area between the two seals only mixes when the thermostat opens. Is your cooling system functioning correctly?

I'm in the middle of replacing this ring. I had to make a tool to extract it, and surprise!, I have to make a tool to insert it. I'll continue making that tool but...

Does anyone know if there's a tool already to extract and/or press this ring/seal in?

Also, this lubricant, Kluberplus Grease 10 (p/n 000 043 205 93), does anyone know what it's actually for?
I read it was for conditioning the seals, but I'm wondering if it needs to be used on the barrel of the thermostat to allow it to slide freely as it opens and closes, thus ensuring proper functioning. Pelican's DIY only says to use it for the front seal of thermostat and the intake socket.

Sorry for the questions, but this episode in ownership has taken a lot of time to figure out what is not working properly and I'm now down to a single seal (which was not missing but I'm replacing just in case it was worn out after 100k miles).

 

Yes, I took the seal off the old thermostat just to check the pressed in seal in the thermostat housing. That is when I found out I did not need to replace the seal. The part of the thermostat that slides does seal against the purple seal on the thermostat.

I just used a Dow-Corning silicone lube on the o-rings. One thing I noticed was the original and new o-rings in the intake socket were twisted... therefore I removed the o-rings from the new socket coated with silicone lube and re-installed... they maintained their shape and the thermostat and intake socket pressed into place nicely.

I also had indication the rear tube might have been leaking, so I replaced those o-rings with https://www.mcmaster.com/#1295n555/=1bqmjcx

NOTE: when installing the intake manifold pay close attention to the vacuum line in the back with the 90 degree elbow... if it comes loose during installation, it will throw code P0455 ..... I found out the hard way...



I've got about 100 miles on the Cayenne now and no repeat of P2181 WooHoo! So far, the epoxied pipes are solid, only time will tell.

 

OK, well, thanks for posting all of that. I finished up the work today. New seal is in. No change in the problem. The Cayenne warms up to temperature at idle fine. But when I turn the fan on blast and turn the cabin heat to HI the coolant temp drops far below 180. Outside air temp 50 degrees F.

I'm out of ideas, and even this last one was iffy because when I pulled the thermostat out I could see the old seal was still there and it looked ok, but maybe... yeah, that didn't work.

I'm a new owner of this vehicle and there was work done to the front of it from an accident. This leaves the possibility that the hvac water pump was fiddled with in the fender. I haven't looked at this.

* I can tell you the coolant sensor is good with relative certainty since the old one and new one were no different.
* I can tell you the thermostat is almost certainly fine because I've tried two new ones and the result was the same as the old one. One note about this - old is OEM, new is aftermarket, both thrown in a pot of water, heated slowly, and they started opening at the same temp, maxed at the same temp.
* I changed the gasket/seal in the housing, again, no change.

Does anyone have any ideas? Could the HVAC be involved? Is there a hose crossed in that setup? The excessive cooling also happens when the HVAC is off and travelling at highway speeds in lower temperatures. Break even point where this isn't an issue is around 70 degrees. So my choice are to fix it, or move to the deep south.

 

So how long did it take you guys to do the replacement?

 

Very helpful thread - I just completed this job. Not too bad. I ended up using two clamps around the spring of the thermostat and then used a large bar to lever against the harmonic balancer. The thermostat and socket slid out easily. Good luck.