996 IMS, timing chain guide, transmission pinion bearing and misc items DIY project
02-06-2011, 10:51 PM
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996 IMS, timing chain guide, transmission pinion bearing and misc items DIY project
After reaching 100K miles on my 99 C4 daily driver I decided it was time to do some maintenance to keep her on the road for another 100k. My list consist of the IMS bearing update, RMS seal, replace all the plastic timing chain guide (as I have been finding plastic debris in the oil filter), air oil separator, and replace the pinion bearing in the transmission.
So Chris Walrod and I attached this job together, with Chris's transmission expertise he was a great help in getting the transmission apart and was able to replace the pinion bearing which required the removal of all the gears. Porsche went cheap on the 996 transmission, instead of using a splined shaft, they went with an interference fitted gears. Which means the gears will require a press with some force to get them off. Unfortunately to replace the pinion bearing you will have to press all the gears off in order to get to the bearing.
Besides the IMS bearing being a sealed bearing Porsche also used a sealed bearing for the pinion bearing in the transmission. So it is was just a matter of time before all the grease leaked out of the sealed bearing and the bearing eventually will burn itself out. Most people probably will not notice that their pinion bearing is bad unless you know exactly what to listen for. Basically in my case I heard a dragging whoooshing sound whenever the car was moving, almost sounded like wheel bearing. The noise was regional to the transmission area, so we knew for sure it was the pinion bearing.
Here are some pictures of the work performed.
Engine comes out much easier than a 993, there are really only 4 bolts that holds the entire engine and transmission on the car.
The hardest part of the engine removal is the removal of the A/C compressor and getting all the coolant pipes off.
I decided to keep using the clutch, pressure plate and flywheel as they were still in good shape at 100k miles.
The midrise scissor lift offered plenty of room for the engine and transmission drop and have room to store the engine underneath while it was being worked on and still allowed the Italian mistress to park inside the garage.
Here is the new air oil separator
In order to replace some of the plastic timing chain guides you will need remove the cam shafts. Of course make sure the car is locked in TDC with the pulley pin, and you will need to have all the proper cam shaft tools to lock the cam shaft and to hold them in place and the compressing tool to compress the vario cam solenoid.
Good old chop sticks method to make sure TDC on cylinder #1
The cam drive spracket will also need to be removed in order to remove the cams.
Here are the cam shafts
Lifters
Here is one of the main chain guide, there were some wear but not as bad as I thought.
These are the guides for the cam shaft chain, they were in really bad shape.
Do the same thing for cylinder 4-6, don't forget to turn the crank shaft so it is now locked TDC on cylinder 4? Can't remember, read the shop manual.
In order to replace the main chain guide on cylinder 4-6 you will need to remove the oil pump and the entire oil/coolant manifold assembly.
While I was at it I replaced the thermostat, the water pump was still good since it was replaced at 60k miles.
This is the hex drive that drives the oil pump
Extraction tool to remove the IMS bearing
New IMS bearing installed. The kit was very nice from LN engineering, I am definitely a satisfied customer.
This is the old IMS bearing, all the grease was washed out of the bearing. It was matter of time before it gives out.
Another while I am at it item, the RMS. The old one was not leaking, but why not. I did use the special RMS installation tool to make sure it was pressed in at the proper depth.
Nose cone off on the transmission
It helps to have the transmission on a engine stand to work on
Shift forks removed
Gear cluster removed from the main case
This is how badly the pinion bearing was pitted, which explains the scratchy noise I was hearing
Pitted spider gear, another common 996 transmission failure area.
New pinion bearing pressed back in, we decided to leave the seal off to allow the bearing to receive splash lubrication from the gear oil. No one really know if this would prolong the life of the pinion bearing, but I guess we will find out. Since now we know how to rebuild these they are not so bad.
At 100k miles my gears, synchros were in almost perfect condition. I expected this as I never abused my transmission by doing anything stupid.
Heating up the main tranny case to install the gear clusters
Cluster back in
The mating plate requires a special torx tool
Shift forks installed
I did upgrade the clutch fork pivot kit, cleaning the spline and upgrading the clutch fork and throw out bearing made a day and night difference on how smoothly the transmission shifts now.
All back in and runs like a champ!
So Chris Walrod and I attached this job together, with Chris's transmission expertise he was a great help in getting the transmission apart and was able to replace the pinion bearing which required the removal of all the gears. Porsche went cheap on the 996 transmission, instead of using a splined shaft, they went with an interference fitted gears. Which means the gears will require a press with some force to get them off. Unfortunately to replace the pinion bearing you will have to press all the gears off in order to get to the bearing.
Besides the IMS bearing being a sealed bearing Porsche also used a sealed bearing for the pinion bearing in the transmission. So it is was just a matter of time before all the grease leaked out of the sealed bearing and the bearing eventually will burn itself out. Most people probably will not notice that their pinion bearing is bad unless you know exactly what to listen for. Basically in my case I heard a dragging whoooshing sound whenever the car was moving, almost sounded like wheel bearing. The noise was regional to the transmission area, so we knew for sure it was the pinion bearing.
Here are some pictures of the work performed.
Engine comes out much easier than a 993, there are really only 4 bolts that holds the entire engine and transmission on the car.
The hardest part of the engine removal is the removal of the A/C compressor and getting all the coolant pipes off.
I decided to keep using the clutch, pressure plate and flywheel as they were still in good shape at 100k miles.
The midrise scissor lift offered plenty of room for the engine and transmission drop and have room to store the engine underneath while it was being worked on and still allowed the Italian mistress to park inside the garage.
Here is the new air oil separator
In order to replace some of the plastic timing chain guides you will need remove the cam shafts. Of course make sure the car is locked in TDC with the pulley pin, and you will need to have all the proper cam shaft tools to lock the cam shaft and to hold them in place and the compressing tool to compress the vario cam solenoid.
Good old chop sticks method to make sure TDC on cylinder #1
The cam drive spracket will also need to be removed in order to remove the cams.
Here are the cam shafts
Lifters
Here is one of the main chain guide, there were some wear but not as bad as I thought.
These are the guides for the cam shaft chain, they were in really bad shape.
Do the same thing for cylinder 4-6, don't forget to turn the crank shaft so it is now locked TDC on cylinder 4? Can't remember, read the shop manual.
In order to replace the main chain guide on cylinder 4-6 you will need to remove the oil pump and the entire oil/coolant manifold assembly.
While I was at it I replaced the thermostat, the water pump was still good since it was replaced at 60k miles.
This is the hex drive that drives the oil pump
Extraction tool to remove the IMS bearing
New IMS bearing installed. The kit was very nice from LN engineering, I am definitely a satisfied customer.
This is the old IMS bearing, all the grease was washed out of the bearing. It was matter of time before it gives out.
Another while I am at it item, the RMS. The old one was not leaking, but why not. I did use the special RMS installation tool to make sure it was pressed in at the proper depth.
Nose cone off on the transmission
It helps to have the transmission on a engine stand to work on
Shift forks removed
Gear cluster removed from the main case
This is how badly the pinion bearing was pitted, which explains the scratchy noise I was hearing
Pitted spider gear, another common 996 transmission failure area.
New pinion bearing pressed back in, we decided to leave the seal off to allow the bearing to receive splash lubrication from the gear oil. No one really know if this would prolong the life of the pinion bearing, but I guess we will find out. Since now we know how to rebuild these they are not so bad.
At 100k miles my gears, synchros were in almost perfect condition. I expected this as I never abused my transmission by doing anything stupid.
Heating up the main tranny case to install the gear clusters
Cluster back in
The mating plate requires a special torx tool
Shift forks installed
I did upgrade the clutch fork pivot kit, cleaning the spline and upgrading the clutch fork and throw out bearing made a day and night difference on how smoothly the transmission shifts now.
All back in and runs like a champ!
02-07-2011, 12:41 AM
#7
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Thanks guys, I lost count of the hours. I would say the cleaning and scrubbing took most of the time. The 996 is a lot easier to work on than the 993, so much more space in a very nicely engineered package. I guess when Porsche did it from scratch with the 996 they learn from all of their previous mistakes with air cool cars and applied it on the 996 design. I was very impressed with the overall 996 mechanicals after this little exercise, just wish they would not have used sealed bearings.
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02-07-2011, 10:06 AM
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The procedure outlined in the shop manual for dropping the engine is pretty detailed and simple to follow. Only tips I can offer to ease the process is to use a plastic pry tool (made for removing interior trim pieces) to pry all the rubber coolant hose, spray a little brake parts cleaner into between the rubber hose and the metal piece and work it out slowly. As for the AC compressor removal I found that if you remove the throttle body you can reach your hand in to help guide the socket to get to that angled bolt.
The plastics found in the oil filter was indeed the same plastic (color) as the ramps.
Mike, if you drive out here I would be glad to work on it for you.
The plastics found in the oil filter was indeed the same plastic (color) as the ramps.
Mike, if you drive out here I would be glad to work on it for you.
02-07-2011, 10:20 AM
#13
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Robin!
You are the man!!!!!!!!
Excellent writeup and I must say takes some of the fear factor out of DIY (some but not all for me, i need to find a bit more courage but I am getting there with articles like yours!)
Pete
You are the man!!!!!!!!
Excellent writeup and I must say takes some of the fear factor out of DIY (some but not all for me, i need to find a bit more courage but I am getting there with articles like yours!)
Pete
02-07-2011, 10:38 AM
#15
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