Frozenrabit

Hello all!
Have an issue come up that has to do with three things combined.
My Cayenne is:
Overheating between 65 and 75 miles per hour
Hearing the trans doing hard shifting noises during this time
A cardian shaft "type" of banging but more towards the engine
Shifting is out of sorts

Now, I will say I have michelin on the fronts and continentals on the back. "Didnt want the michelins but had to at the time".

I have had Porsche proper and now an idependent shop check for cardian, fuel pump, trans visual and oil and nothing is out of place. I have seen on some forums that it could be the fact I have two diffrent brand tires, even if there the same size. I am probably heading to the tire shop tomorrow to make them all the same brand.
Any other ideas I should look for?
Thanks in advance!

wrinkledpants

Ned to know what year and type of Cayenne. How many miles?

What makes you think it's overheating? Needle moving off the 180 mark, or is it pushing into the red? Does your trans *only* shift hard when the engine is hot? Or is it hard shifting at all other times, too?

You shouldn't have two different sets of tires on the car. Has nothing to do with the shifting, and everything to do with the transfer case. It's something you can get away with on an Audi since torsen is just an open diff, but you really need all the rolling diameters to be the same on the Cayenne. You'll put unnecessary where on the transfer case.

Frozenrabit

Hello!

Thanks for the response! Car specifics
2006 cayenne s titanium
146000 miles
I plan on keeping it forever, laugh!

The needle at first was moving to the 200 + mark, but I brought it into the indy shop and they tested it inhouse and had it go as high as 220 at about a rev of 3 to 4 or around freeway speed of 65 to 75 on freeway. They just changed engine fluids also at this time.
At idle afterwards it took a good couple of minutes before returning to the normal 180.

Another suggestion by the Porsche Dealer was it could be the awd part of the trans that is partial engaging and dragging on the engine. I dont know what to think about that, I do not know enough about awd trans to test for this. I did take it on some dirt and engage the awd move around a bit and then unengaged it and still have the same issue.

I found a road force tire center near by that is ordering me the tires now and will do a road force balance on all tires then an all wheel alignment this morning. Then I will have on it four continental 4x4 contact 255 55 R18.
At the very least the specs will be right and if this continues I will have this off my checklist of possibilities.

After that I will entertain any thoughts on this matter from everyone!

Thanks again!

Frozenrabit

Sorry, just saw the question about the shifting.

The trans is shifting hard around 65 to 75 miles per hour. Almost feels likes its loose, I turn off the psm to tighten it up. But when its not overheating at lower speeds its fine. The alignment does feel off at this speed too, and it has only done this since we changed the rear tires. Continental to Continatal same type just new.

wrinkledpants

FWIW - the needle will move around between 180 and 220. If you have the AC on, it should stay closer to 180 since both fans will come on. But, the Cayenne doesn't have a viscous fan attached to a belt that is always turning. So, if you run it on econ, or with the HVAC turned off, there won't be any fans running until the engine temp hits 200 degrees or so, then they'll come. The thermostat doesn't fully open until 220 degrees. So, any engine temp between 180 and the next mark on the gauge is normal operating temp.

If I'm doing a long climb in the mountains, or it's especially hot out (95+ degrees), it won't be uncommon for me to see the engine temp around 200 degrees, especially on a hot climb in the mountains where I might hit 220 degrees. All normal.

At your mileage, though, the water pump may be showing some wear. You might consider having it replaced. It's a pretty simple job, all things considered. If you're car isn't going past the first mark on the coolant gauge after 180, then I would assume your thermostat is working fine. You might also want to consider replacing your coolant reservoir cap, too. If they don't hold the same pressure, it can reduce the system pressure enough that the water pump could cavitate a bit.

Have you ever had the trans fluid changed, or any of the driveline fluids changed?

Frozenrabit

Hello!

I have driven this car since 2012 across country up hills through valleys etc loaded with lugage and family with this never happening before. But I suppose it could be age also, and fluids need to be done more often.

Yes all line drive fluids were changed at 90k. I was thinking of changing then at 180k again, you think I should do sooner?

Water pump was changed at 120 k.
Cardian was replaced at 90 k also.

Thanks!

wrinkledpants

I'd try the reservoir cap. Aside from a failing thermostat, I'm out of ideas on the engine temp.

You may be due for a valve body on the transmission if it's shifting hard and the fluid is somewhat recent. You may also take a look at the bottom of the trans. The bell housing has a small hole, and if there is trans fluid coming out - you might have a failing input shaft seal resulting in low on trans fluid. That's all I have for you.

mtnrat

I was thinking the valve body as well. Do a search on that. Wrinkledpants make a good suggestion to look at the hole in the btm of the bell housing to see if any tranny fluid is leaking out.

Frozenrabit

Hello,

Thanks for the ideas and thoughts on this. The tires are on and had everything balanced and aligned. The clanging around and bad shifting have stoped. It is running smooth.

The trans was looked at a Porsche Indy dealer here in Riverside Ca. and he did say he checked the trans for leaks and saw nothing. he is highly recomended through pca so I am trusting hime with this one.
So one problem down.

The temperature is still wonky though. So thermostate and cap are next on the list.
Ill let you know what happens!