Question about advices for a Porsche 996 carrera

[juankimalo]

here is a pic of the Rear main seal

 

[Doug Hillary]

Hi, Joaquin - Thanks for the Links. You are aware of course that the RMS leaking/weeping is not related to IMS issues. Leaks from the front of the engine may be! Most RMS leaks were done under Warranty (and mine was too) - it is quite a minor job! In many cases it was/is really not worth the cost of doing it for many Owners

 

[juankimalo]

Originally Posted By: Doug Hillary

Hi, Joaquin - Thanks for the Links. You are aware of course that the RMS leaking/weeping is not related to IMS issues. Leaks from the front of the engine may be! Most RMS leaks were done under Warranty (and mine was too) - it is quite a minor job! In many cases it was/is really not worth the cost of doing it for many Owners

You're right! A simple RMS is less than 30 $ but the labor increase the final bill up to more than 1000$ What I'm doing is an specialized operation. We installed the bearing without a side seal to allow the fresh oil passing through the balls. Always would be better to lubricate the bearing inside with an excellent engine oil than the bearing grease.

 

[juankimalo]

The bearing could fail due to a stud stress and besides It could begin to make a different orbital movement due to steel balls wear. Both things could happen. That's why I substitute an hybrid ceramic compound balls bearing (with the same size), which is harder and resistant to fail for more than 10 time compared to steel balls. The bearing support as you could see in the link I posted before, has 12 mm large compared to 8 mm OEM. After extracting the bearing from the IMS tube we saw that the internal grease was contaminated with wear oil, and the result is well known. That's why we decided to install the bearing with a single side seal, to allow the oil make a good lubrication task. Thanks for your reply. This thread is very interesting

Originally Posted By: Doug Hillary

Hi, Joaquin - You said this: "The bearing suffers of a lack of lubrication and finally breaks the balls..." There are many myths about the M96 engine family. Most IMS issues occurred in the EARLY engine series and Porsche did indeed replace many engines as needed under Warranty Extensive UOAs conducted in NA around 2002 did not highlight a lubricant problem and all 100 or so lubricants that were Approved and Listed remained so! This extract note from Autofarm and JZ Machtech in England tells the story. Both Organisations rebuild Porsche engines including the M96 STARTS All 996 engines have an intermediate shaft that runs the length of the underside of the block and is chain driven from the crankshaft. This, in turn, drives the twin camshafts on each bank of cylinders. At the end of this is a sprocket which turns on a bearing. The sprocket is retained by a small stud that can break, causing the bearing to fail. At first, this manifests itself as a noisy rattle, which turns into a death rattle as the cam chains come off, leading to further internal damage. Porsche changed the design of this shaft no less than four times during the life of the 996; partly to solve the bearing failure issue, and partly to reduce an annoying rattle on start-up. Later types, therefore, have a larger bearing and a different sprocket designed to mate with a special toothed chain, whereas the earlier ones drove a conventional double chain. Because of this, it is not possible to fit the later type intermediate shaft to an early engine without also using a later-type crankshaft, which will work with the toothed drive but is an expensive solution. So you have to fit another early-type shaft which may, of course fail again. However, Autofarm can modify a 997 intermediate shaft with an original-type sprocket to get around the problem. Both parties are keen to point out that the problems they’ve discussed probably affect five to ten percent of early 996 engines. In other words, there are plenty out there that are running fine. ENDS

 

[juankimalo]

Here you have lots of pics: My mechanic finished the work. My car has: - new SKF hybrid ceramic compound balls bearing/steel hub - new 12 mm bearing support F125 steel - helicopter engine special seals (the best material to seal for high temp) - OEM 3 flange end piece modified to place the new bearing support - Valvoline VR1 racing 5W50 engine oil The bearing support and the the 3 flange were made/modified by an expert lathe operator. besides we mounted the oil filter/oil filter adaptor/magnetic drain plug purchased to Raby. Link with pics: http://www.pasionporsche.com/component/c...ims-996-36.html

 

[Kevinmac]

The last time I saw the Porsche oil recommendation list, the liquid cooled engines the 5w-50 was not recommended or approved, but Mobil 1 0w-40, and Castrol Syntec 5w-40 were. L&N Engineering makes a retrofit kit for IMS bearing. Depending on single or double row te price is a little different. To do the RMS correctly you need to use the latest seal and replae the crankcase bolts with updated bolts.

 

[Doug Hillary]

Hi, Kevinmac - I believe Porsche's A40 list still includes M1 5W-50