They have proven themselves via the aftermarket just like the original 901 chain tensioner. LN Engineering is selling IMS kits. The PCA Panorama magazine has had tech articles where it has been suggested that all the 996's should have this performed. It was a poor design.
Porsche does sell a good number of crate engines. That you haven't had any to do may have to do with the dealers handling that plug n' play gravy boat. Shops I'm familiar with in much smaller markets than CA are swapping engines. Look up tech articles by Joel Reiser in Panorama.


FOR WHAT ITS WORTH:

http://forums.pelicanparts.com/porsc...-happened.html

PANO TECH QUESTIONS:
Engine Replacement

996, 993 | Engine

Model: 911 C4S, Year:2003, Mileage:32,000, Type of use:Street use only
Hi Joel, final update about the message I sent on July 22 about IMS failure on my 03 C4s with 32,000 miles. Engine was toast and required replacement. I wrote three earnest letters to PCNA about some goodwill (long term customer, bought/serviced by dealer), they refused. They even told me I could write as often as I liked but they would no longer respond. So I sold the car; searching for new sports car but it won't be Porsche. I'm still a little stunned about how they treated me; never even said they were sorry for my troubles.

11/13/2011 11:41:03 AM

I'm really sorry to hear that. You are not the first to report an experience like this. I will email you offline to follow up.

Joel Reiser
11/14/2011 7:54:40 AM

Engine cooling
996, 993 | Engine

Model: 911-996, Year:2003, Mileage:22,000, Type of use:Street use only
I have a '03, 911-996. I just read in the (Feb. 2011) publication of Excellence Magazine that there could be a potential failure of the coolant manifold in the 911-996 model. Have you seen this and do you know if Porsche has addressed this issue? I also read that this failure has mainly occurred on the track and fewer times on the road. Is this something I should be concerned about since I don't track my car? I just don't want to be rounding a curve and finding myself steering from the back.

12/15/2010 3:09:01 PM
I don't have February yet, but I have seen this on the 996 GT3 (street) and GT3 Cup. With the GT3, I have seen it in the street GT3, but only on cars that were tracked extensively. The water pipes were glued to the manifold pieces. After enough heat cycles and track stress they come loose and cause a large & sudden coolant leak. I was not aware of this problem on the 996 & Boxster, and the system & parts are all different. If the same technology was used, I would expect the same result. If in doubt, change it out, using the updated version. On a track GT3 I would change them every 150 hours (full-speed hours). I don't know what was done to address it for the GT3, but I can tell you the part numbers were updated, and the parts prices are quite reasonable. GT3 street and Cup use the identical parts & part numbers, as is true with the majority of the engine parts.

Joel Reiser
12/16/2010 7:29:04 AM


And finally, Jake Raby on the water pump:

The pump can fail in at least 3 ways, two of which aren't catastrophic for the pump.

1- Bearing failure: this is audible and generally is noted before the engine is driven further

2-Complete impeller failure: this can lead to a compromised engine, but usually makes enough noise and the temps climb high enough that the car is shut down and towed home safely. In this scenario the cooling system is filled with foreign object debris that can block a capillary in a cylinder head and lead to a crack.

3-Partial Impeller failure: This is the scariest of all because there are no sounds, no noises and nothing out of the ordinary. In this type of failure a small chip off an impeller blade detaches and ends up floating around in the coolant until it finds a capillary to block. When this happens the engine gains a cracked head and then gets intermix out of the blue.

Then people start misdiagnosing the issue as a heat exchanger, bad head gasket, etc and they will sometimes repair the cracked head and never even pull the damn water pump which caused the issue to begin with!!

If not caught in time the intermix contaminates the oil and kills the cylinders, then the engine is dead, like the 4 I have downstairs right now that are all here and all dead because of the damn waterpump.

What you guys need to remember is that a component doesn't have to grenade to create collateral damage that will kill the engine.

If an engine has lost an impeller, or has a chipped impeller that broken piece must be found, even if that means complete disassembly of the cooling system. If you can't find it, its probably already jammed inside a cylinder head~

We learned this while repairing heads and milling the cracks open... When finding pieces of impeller blades inside the cylinder head cooling passages one can feel pretty confident as to what the issue is and why it's occurring. We had 13 of those instances in 2010.
__________________
Jake Raby

PS: Read the line near the end of the photos: The factory KNEW these engines had issues, this isn't the same company that created the 356 and 911.

http://www.flat6innovations.com/engi...es-illustrated