Mister Quickie

and a design that did not have an imsb was rolled out?
I'd rather not upgrade an ims then have to do it again in 75k miles

scottiemac

Yes.

dasams

That is correct that the 9A1 engine does not have an IMS bearing.

Mre21

This is one of the reasons that I chose to dive into p-car ownership with a 997.2. I'm hoping there isn't any Achilles heel that shows up during my tenure! 3 years in and so far, so good!

Mister Quickie

Thank you

Bruce In Philly

Actually, the 9A1 introduced in 2009 doesn't have an intermediate shaft at all, hence no need for a bearing. The shafts in the past (Metzger engine) had a plain bearing on each end (force fed oil, no *****). The M96/97 engines used a plain bearing on one end and a "lifetime" sealed ball bearing in the other. The lifetime bearing is the one that fails.

Peace
Bruce in Philly

Mister Quickie

Thinking of trading up to a 996 NA but would one be able to determine via visual inspection on the outside (assuming the car is raised up) if the bearing upgrade has been performed? or is the only way to start taking stuff apart?

PVKPorsche

No visual inspection will show that so if you buy the car from the person that had the repair done, that will be one they make sure to tell you about. If the car has been traded then hopefully there is some record of that service, otherwise you really wont know. I bought my 05 997 and had all of the records. They had done the RMS and the clutch but not the IMS. So I did the IMS first thing just to be relieved.

If you look at 996s, then as the saying goes, make sure it has good service history or you buy from the original owner that can tell you what they did or didnt do.

Mister Quickie

Debating whether to get an early model with an IMS (read cheaper) and pay $5k for the upgrading bearing or wait (read save) and get an MY 2009 but my decision hinges on if:

a) Having an IMS in the first place a design flaw and the beefier bearing simply mitigates a flawed system, or
b) Having an IMS is fine, the problem is in the bearing that was never made durable enough.

I'm leaning towards "a)" since the beefier bearings have a lifespan of 75k miles before recommended replacement.

Would like to get opinions on this pls

nk215

IMS is not $5K. It’s a $2.5K job.

If you get a 997.1 early model for cheap then get the “IMS solution”. It’s a plan bearing and lasts forever.

There’s more to a 997.2 engine than just IMS bearing. You get better cooling, better MPG and more power. Maintenance tasks are also easier in the .2 such as oil and belt change. Beside the engine, there are significant differences in other areas as well.

it's (b). The bearing is just bad. Porsche moved from sleeve bearing to double row bearing to thinner single row bearing to thicker single row bearing designs.

Sleeve bearings don't fail (turbo model). Double row bearings are also solid, you don't hear about IMS bearing failure for models in 1999 to 2000 time frame.

Starting in 2001, they switched to a smaller single row bearing and that's when the problem started. In 2006, they switched to a larger single row bearing and the problem was significantly reduced.

Philster

Somewhere by 2006, the IMSB was upgraded. Seemed to really eliminate the problem. Bore scoring is what keeps the engine builders backed up and busy post 2006 -- not the IMSB at all.

When the IMSB was upgraded, for people still (wrongly) convinced they needed an IMS solution, the bad news is that the effort to replace the larger bearing requires twice as much work, with the engine needing to be removed and split. When from a modest/large job to a ''You gotta be kidding me. It needs that much work to replace the bigger/newer one?" kind of job.

.

Mister Quickie

This is helpful, thank you

cringely

If the IMS was replaced, be sure that it was properly done. When I bought my 2002 Carrera, I had the bearing replaced with a L&N bearing. However, no L&N sticker was present when I took delivery of the car.
20,000 miles later, the IMS failed. The moral of this story is, if you are having the IMS replaced, be sure that it was done properly and used the correct parts.
See https://rennlist.com/forums/996-foru...wn-engine.html for the gory details—including what Ahsai (the Reenlist member who bought the 996 from me as a roller) has done so far.

andy92782

If there's one longer-term risk with a 997.2 it's probably carbon build-up on the intake valves due to DFI. So far it seems like Porsche did a pretty good job of minimizing this on the 9A1 but I suspect it's only a matter of time before we see this become more of an issue.

My '07 335i had this problem. I paid the dealer $700 to media blast the intake valves clean to cure the misfires and restore performance. My guess is a similar job on a 997.2 would be two or three times that cost. Even still, this would cost a lot less to remedy than a nuked engine due to IMSB failure.

Flat6 Innovations

Porsche used an IMS assembly starting with the 547/1 engine in the early 50s. Every flat 6 Mezger ever built also had an IMS. There's nothing wrong with an IMS, and it has very important roles in the function of the engine, especially since it slows chain surface speeds, and reduces loads.

Nothing wrong with an IMS, everything wrong with using a sealed deep grove ball bearing to support it.