Tom M

I dropped off my car for the AH08 recall the other day and while sitting in the dealer intake area notice it was dripping coolant. After it was there for 4 days they finally got around to looking at it and said the water pump needs to be replaced and that I should do the thermostat at the same time since it would be open. Total price would be ~$1300.00. Ouch. Good thing I've got a loaner Macan as they still haven't gotten to the AH08 recall and probably won't for a couple of more days. Just hoping they get done before the weekend so I can do the replacement.

I've ordered the water pump and thermostat along with gaskets from Suncoast. I'll pick up some coolant locally to top things off. Including shipping it'll come to around $510 and around 3 hours of my time. I plan to replace the serpentine belt while I'm there since I'm unsure how many miles this one has on it even though it looks good.

I'm assuming that I can pretty much follow the same instructions for doing the R&R on the 957 since I can't find anything specifically for the 958.

deilenberger

Probably. You may want to read up some of the threads on the pipes loosening up in the thermostat housing and causing leaks. Since your Cayenne is a 2011 V8 of some sort - chances are this has never been addressed. People have drilled and pinned the pipes in place. I would think a bead of JB Weld around the junction of the pipe and the housing would secure it adequately. Or just replace the housing, it doesn't appear to be frighteningly expensive. A quick google on the PN - Porsche Atlanta seems to be the low price leader at $310.. https://www.porscheatlantaperimeterp...810608002.html

Worth reading: https://rennlist.com/forums/cayenne-...pipe-glue.html

Tom M

Thanks for the reminder. I've been keeping an eye on that thread as well as some of the older ones that referenced the same or similar issues with glued in pipes working loose and resulting in catastrophic coolant loss.

I do plan to at least look at the housing to see if there's been any movement and being proactive with a bit of JB Weld doesn't seem like it would hurt anything that's for sure. I am a bit reluctant to replace the whole thing if things look OK though as $300 give or take is a bit steep to do it "just because." Hope I don't wind up regretting that decision once I actually have the car back and can take a look at things first hand. Based on the feedback from the dealer I know that the pipe working loose is not currently the cause of the leak as they did visually inspect things in order to determine the cause of the coolant winding up on the ground.

ScootCherHienie

I can tell you that JB Weld will last around 15-16 years in a "plugging a potential coolant leak" duty. Back in the 1970s, I did an intake manifold swap on a smog-era engine using an intake manifold from a pre-smog car. That left a water passage in the cylinder head "open" so it had to be plugged some way (the smoged engine's intake manifold had hot water circulate around the runners). I made a plug about half an inch thick with layers of fiberglass impregnated with JB Weld. Poked it into the unwanted water outlet in the cylinder head (after cleaning, roughing, and cutting an angled groove into the cylinder head so the epoxy/glass mix would have something to "bite" into for grip to keep from being blown out at 220 degrees F or more. That plug stayed in there for 15 or 16 years after I put it in there. The person who owned it after me had the plug blow out, followed by total loss of coolant, fortunately not far from home. I'd done that so long ago, I had completely forgotten about it when I sold the car. As soon as I saw the open hole in the cylinder head below the intake manifold, I immediately remembered that somewhat-but-not-much-better-than-redneck fix. This is what happens when car punks don't have access to shop tools so they can fabricate a small 3/16-inch thick aluminum plate with a couple of bolt holes so it can be bolted to the cylinder head for a fix that should at least double the life of the JB Weld/fiberglass fix.

Eskimo1

That's awesome.

Tom M

Subscribed to AllDataDIY and it seems that Porsche specs a grease (000-043-205-93) for the thermostat seals. Don't feel like paying $25 for a couple of drops of something I'll hopefully only need once so wondering what's a safe alternative or if it's actually needed when installing the new thermostat.

Cosmo Kramer

^^ I've read that the techs just wipe some coolant on them and put them in.

Tom M

This makes the most sense.

Tom M

I've started the removal portion but won't be able to finish until sometime after Monday as UPS screwed up the guaranteed Friday delivery again. Plus, they won't deliver it on Saturday as it's not listed as a Saturday delivery. Makes perfect sense - not.

I've got the serpentine belt off and the tensioner pulley/roller is lightly grooved. For the 955/957 they list that as a separate item from the bracket but on the 958 it's listed as a single assembly. Wondering if there's a specific replacement part for just the roller portion as there's no real reason to replace the entire unit. It seems like the earlier part would be a direct replacement. Alternatively, is there really any reason to replace it at all as the bearings on it and the other idlers sound and feel just fine. If no real reason to replace then I'll just throw on the new serpentine belt once the water pump finally shows up and is installed.

ScootCherHienie

If the roller surface is metal, it should be fine if the bearing is still good. If the roller and surface are any type of plastic or composite material, you get more into a gray area about how to deal with wear of the roller. If the plastic is shiny, generally those types of plastic would be more likely to need to be replaced if there is visible wear. If it is a composite material with a dull finish, it is probably FRP (fiberglass reinforced plastic) or CFRP (carbon fiber reinforced plastic) and generally the plastic will be a thermoplastic that can deal with the heat in the engine compartment. Those materials are stronger and can handle a little wear without worry.

trendy996

Tom M

Based on the carfax the selling dealer I bought it from a few years back replaced a leaky plastic fitting prior to the sale so I'm thinking (hoping?) I'm good there.

As far as all the other bits I do have new gaskets and o-rings for the t-stat and water pump. The valve covers got new gaskets as part of the AH08 recall which was just done. I opted to the do water pump & t-stat as the water pump failed on the intake drive at the dealer for the AH08 recall. They wanted close to $1300 for the pair + labor. I'm also replacing the serpentine belt as I don't know how many miles are actually on it other than the 40K I've put on, but since I'm there figured I should even though the one that came off looks very good. The old belt will serve as a spare - as will the t-stat that's coming out. Figure I'm saving about $800 over what the dealer was going to charge.

Tom M

Finally finished after my parts kept getting delayed by UPS and the Post Office.

I replace the water pump, thermostat and serpentine belt and I figure I saved $700-$800 over what the dealer wanted even with needing to buy a couple of items such as an e-socket set to remove the water pump. I also bought an airlift system for the coolant. I probably could have gotten by w/o it but this made sure I didn't need to mess with trapped air and also confirmed no leaks. The old thermostat and serpentine belt will be kept as spares though I doubt they'll ever be needed.

One of the best purchases I've made recently was this light from Harbor Freight for $19.99 as it made working in the engine bay relatively easy and also works great for under the vehicle.