Porsche Cayenne – Under Intake Engine Coolant Leak

Vehicle Details: 2004 Porsche Cayenne S. –  75,000 miles

Technician: Brad

Initial Condition:

  • Overheating
  • Coolant Leakage – Down the back of the engine
  • Towed in

Diagnostic Process:

Performed pressure cooling system tests – confirmed coolant leakage down the back of the engine.

Double-checked other cooling system components to make sure this was the correct repair.

NOTE:  This is a common / known problem on the first generation (9PA) Cayenne.  It only affected the V8 engines.  When the problem first came to light the repair was much worse:  to replace the coolant pipes required removal of the engine to get the rear cross-over coolant flange/pipe out.  This made the repair very costly in labor.  Porsche later updated the parts so that the pipes could be replaced with the engine in-chassis.  The materials were updated as well – from plastic to aluminum.

Repair Process:

Generally the work is straight forward:

Start with removal of the airbox and air snorkel tubing.

Cayenne V8 intake

Cayenne V8 intake

Remove intake manifold:

Cayenne V8 intake removed

Cayenne V8 intake removed

Remove coolant pipes, note  that there is a grouping of three on the top and a lager single pipe underneath.

Cayenne - old plastic coolant pipe under intake

Cayenne – old plastic coolant pipe under intake

To remove the lower pipe you will have to cut it.  This is why, when repairing this the old way, the engine had to be removed – there is no ‘collapsing’ of the pipe so they can fit with the engine in-chassis.

NOTE – we stuff shop rags into the intake ports of the engine to ensure nothing accidentally falls into the engine!

Cayenne V8 with under intake coolant pipes removed.

Cayenne V8 with under intake coolant pipes removed.

Here’s a close-up of the back

coolant cross over pipe and hoses - rear of engine

coolant cross over pipe and hoses – rear of engine

Here was the actually leak – hard to see but if you look at the mirror in the middle of the picture you can see the coolant

Lower pipe leak

Lower pipe leak

Here is the leak in the lower pipe (pipe removed).  NOTE this leak / crack in the pipe is much (much!) smaller than they typically are when we do this repair

Lower coolant pipe - crack in plastic

Lower coolant pipe – crack in plastic

Here’s the new / updated parts.  NOTE how the larger pipe is now shorter and Porsche have provided a short rubber hose.  This change in design is what allows the repair to be done in-chassis (saving very large amounts of labor).

updated coolant pipes (aluminum)

updated coolant pipes (aluminum)

This is a little closer look at the lower three-piece pipe

updated lower pipe design

updated lower pipe design

Going back together – here’s the pipes installed.

new coolant pipes intalled

new coolant pipes intalled

close up of collapsible / three-piece lower pipe installed.

close up of collapsible / three-piece lower pipe installed.

Conclusion:

After re-assembly we pressure test the system and get the engine up to temps / ensure there are no other leaks and the repair should out-last the rest of the vehicle.  NOTE sometimes this coolant leak can also damage the torque converter seal (!) – this is usually the case when a LOT of coolant has washed down the back of the engine.  BUT if the vehicle develops a transmission leak shortly after this ‘event’ that is likely what happened.  This leak or defect has given the Cayenne a bit of a bad reputation but we advise to consider it in context:  the is a top-end performance SUV that is otherwise a blast to own and drive.  We see this repair occasionally but it’s not an epidemic.  Let other people think it’s a huge problem and then buy yourself a cool V8 Cayenne for a good price – reduced because of everyone’s fear of this problem!