What's the theory behind removing the rear IMSB seal?

[j_beede]

Most experts agree that the those of us with MY05 cars cannot know whether we have the small single row IMSB or the large, inaccessible IMSB--without a visual inspection (i.e drop the trans).

 

If I knew that I had a replaceable IMSB bearing I would spend the money on the plain bearing "Solution" in a flash.

 

When the clutch eventually gets done and I (probably) find out that I have the larger bearing, the suggestion is to remove (or distort) the rear IMSB seal. I don't recall anyone describing how this helps. With no pressure fed oil supply what value does removing the rear seal have?

[Ahsai]

When the engine is runnng, the oil can splash onto the balls of the bearing lubricating them. The hot oil vapor will do the same.

Edited June 5, 2015 by Ahsai

[j_beede]

I must be confused about which IMSB seal is the rear IMSB seal... Since the seal of interest is described as removable I assumed it to be the seal on the clutch side of the IMSB. I don't picture oil splashing in that area. If the seal of interest is the seal on the shaft side of the bearing how would the seal be removed?

[Ahsai]

Yes, the seal on the flywheel side. The oil can splash in the small gap between IMS sprocket and the IMSB flange (between the caramel and yellow arrows).

[Ahsai]

You can see the gap being exaggerated in this diagram.

http://forums.pelicanparts.com/boxster-cayman-forum/757877-direct-oil-injection-13.html#post7885594

[Ahsai]

Even better cad diagrams here.

http://www.cheetahonline.com/technical-articles/installing-an-ims-retrofit-upgrade/

[JFP in PA]

I must be confused about which IMSB seal is the rear IMSB seal... Since the seal of interest is described as removable I assumed it to be the seal on the clutch side of the IMSB. I don't picture oil splashing in that area. If the seal of interest is the seal on the shaft side of the bearing how would the seal be removed?

 

To remove the seal, you need to go through all the steps required to do an IMS retrofit (eninge locked at TDC, cams locked, tensioners removed, etc.), and then simply use a tool like a dental pick to pop the seal out:

 

[j_beede]

Sounds like a bigger job than I expected. I am trying to grasp the value this modification would add. I am thinking that removing the seal might permit some level of inspection of the IMSB. Perhaps multiple oil analyses before and after seal removal could support the claim that the bearing gets better lubrication after seal removal... 

[JFP in PA]

Sounds like a bigger job than I expected. I am trying to grasp the value this modification would add. I am thinking that removing the seal might permit some level of inspection of the IMSB. Perhaps multiple oil analyses before and after seal removal could support the claim that the bearing gets better lubrication after seal removal... 

 

The value is simple: I am unaware of anyone running without the seal having an IMS failure.

[Jager]

 

Sounds like a bigger job than I expected. I am trying to grasp the value this modification would add. I am thinking that removing the seal might permit some level of inspection of the IMSB. Perhaps multiple oil analyses before and after seal removal could support the claim that the bearing gets better lubrication after seal removal... 

 

The value is simple: I am unaware of anyone running without the seal having an IMS failure.

 

How many IMS bearings, with the seal in-place, failures are you aware of (997's with large bearing)?

[JFP in PA]

 

 

Sounds like a bigger job than I expected. I am trying to grasp the value this modification would add. I am thinking that removing the seal might permit some level of inspection of the IMSB. Perhaps multiple oil analyses before and after seal removal could support the claim that the bearing gets better lubrication after seal removal... 

 

The value is simple: I am unaware of anyone running without the seal having an IMS failure.

 

How many IMS bearings, with the seal in-place, failures are you aware of (997's with large bearing)?

 

 

Only a couple, but both were definitely an IMS failure.

[Jager]

 

 

 

Sounds like a bigger job than I expected. I am trying to grasp the value this modification would add. I am thinking that removing the seal might permit some level of inspection of the IMSB. Perhaps multiple oil analyses before and after seal removal could support the claim that the bearing gets better lubrication after seal removal... 

 

The value is simple: I am unaware of anyone running without the seal having an IMS failure.

 

How many IMS bearings, with the seal in-place, failures are you aware of (997's with large bearing)?

 

 

Only a couple, but both were definitely an IMS failure.

 

As you may or may not know, I now own a 997 4S along with the 986 Jӓgermobile (now over 280,000 miles on original motor). I will definitely pull the IMS seal on my first clutch job on the 997. Thanks for the data.

[Hilux2400]

 

 

 

 

Sounds like a bigger job than I expected. I am trying to grasp the value this modification would add. I am thinking that removing the seal might permit some level of inspection of the IMSB. Perhaps multiple oil analyses before and after seal removal could support the claim that the bearing gets better lubrication after seal removal... 

 

The value is simple: I am unaware of anyone running without the seal having an IMS failure.

 

How many IMS bearings, with the seal in-place, failures are you aware of (997's with large bearing)?

 

 

Only a couple, but both were definitely an IMS failure.

 

As you may or may not know, I now own a 997 4S along with the 986 Jӓgermobile (now over 280,000 miles on original motor). I will definitely pull the IMS seal on my first clutch job on the 997. Thanks for the data.

 

 

 

 

 

 

 

Sounds like a bigger job than I expected. I am trying to grasp the value this modification would add. I am thinking that removing the seal might permit some level of inspection of the IMSB. Perhaps multiple oil analyses before and after seal removal could support the claim that the bearing gets better lubrication after seal removal... 

 

The value is simple: I am unaware of anyone running without the seal having an IMS failure.

 

How many IMS bearings, with the seal in-place, failures are you aware of (997's with large bearing)?

 

 

Only a couple, but both were definitely an IMS failure.

 

As you may or may not know, I now own a 997 4S along with the 986 Jӓgermobile (now over 280,000 miles on original motor). I will definitely pull the IMS seal on my first clutch job on the 997. Thanks for the data.

 

I can't figure out how you would do that on a 997, or late 996, with the larger bearing as this bearing can only be accessed from the engine side and not from the clutch side. There is no oil  source on the clutch side.  The oil source comes from the sump side.  

 

I have asked this question before as I have a 996 which had a Porsche replacement engine in late 2005.  I have been unable to determine from the engine number the precise type of bearing, but owing to the lateness of the refit I think it's probably the bigger bearing of the style in 997 cars. 

 

I can see from the engine geometry that removing the inner seal from the "big" bearing engine would allow the bearing to gain splash lubrication from the chain drive next to it.  Does this later type bearing have an inner seal?  It is my understanding that access to this inner seal, if it is present, can only be achieved with the IMS removed.  I have been told that It is not possible to gain access to the inner seal by just removing the sump cover.   

 

Is the reason for the success of these later bearings that they don't have an oil seal from standard and are therefore adequately lubricated from the start? 

[j_beede]

Read replies #4-7 above

[Hilux2400]

Read replies #4-7 above

OK thanks.  I just thought that as this later bearing cannot be withdrawn from the flywheel side there would be insufficient space on the flywheel side to gain access to the seal. 

 

I still find it hard to believe that against the history of pre 2004 failures that the manufacturers would insert a limited life sealed bearing here, when an unsealed bearing could have an adequate splash lubrication source from the sump.

[JFP in PA]

Here is the flywheel side view of the oversized IMS, waiting to have its rear seal removed, there is plenty of room to get at it:

 

 

All OEM IMS bearings have inner and outer seals to retain the grease they were packed with.  As most have already had the grease washed away, you simply pop the rear seal off to allow access for engine oil.

 

All cars built after 2006 (until 2009) carry this style bearing, as do many of the 2005 cars.  There is no way of telling in the 2005 cars which bearing is in the engine, you have to take it apart and look.

[Hilux2400]

Great picture - thanks JFP.

[Uwon]

With reference to oil getting at the larger non-removable IMSB, see post #48 in

http://www.renntech.org/forums/topic/43715-clutch-aos-water-pump-thermostat-diy-questions/page-3?hl=uwon

Hope this helps.

Johan

[Hilux2400]

With reference to oil getting at the larger non-removable IMSB, see post #48 in

http://www.renntech.org/forums/topic/43715-clutch-aos-water-pump-thermostat-diy-questions/page-3?hl=uwon

Hope this helps.

Johan

What I hadn't realised until reading your post and the Pelican Forum thread linked above (cross section through sump) is that the bottom part of the IMS bearing sits within the engine oil.  Therefore, oil washing and pickup will always occur with a full sump.  This will be even more the case if the car is often parked front down or under braking.   

[JFP in PA]

 

With reference to oil getting at the larger non-removable IMSB, see post #48 in

http://www.renntech.org/forums/topic/43715-clutch-aos-water-pump-thermostat-diy-questions/page-3?hl=uwon

Hope this helps.

Johan

What I hadn't realised until reading your post and the Pelican Forum thread linked above (cross section through sump) is that the bottom part of the IMS bearing sits within the engine oil.  Therefore, oil washing and pickup will always occur with a full sump.  This will be even more the case if the car is often parked front down or under braking.   

 

 

When the engine is running, there is an oil "mist" everywhere inside the sump and cam chains areas, which is more than enough lubrication for the IMS. 

[Uwon]

^^^Yes, you are spot on! Not much elevation difference between the IMSB and the shallow sump.

Just reinforces that the oil level should always be right up to the top (one bar down is not acceptable to me) as extra insurance. And 5w40 of course.

Johan