Goodness of replacement engines?

[pfbz]

Coming up to speed on 996's for a purchase (currently have an '82 911 SC). In my price range, it will likely be a '99-01, which I realize are the most potentially problematic, especially with the IMS bearings and rear main seals.

I see quite a few cars with replacement engines, presumably through a Porsche dealership with a new or remanufactured engine.

How good are these replacement engines? Are the bearing and seal issues resolved or improved on these replacements, or the exact same issues but another roll of the dice plus a mileage reset?

Ideally, a 2001 911 C4 cab that is well priced, reasonable mileage, cosmetically outstanding, PCA/Pelican member owned, perfectly maintained, and LN IMS bearing upgraded would drop in my lap, but not so far

So I'm weighing my options on buying an original-engined non-upgraded or replacement engined car....

Any wisdom?

[occb2]

I'll tell you. I went through all the same problems. I ended up searching and searching. You can do two things. One. Buy a 996 turbo, gt2 or gt3. All of them have no IMS problems because they don't have one.

All 996 and 997 have the same problem with the IMS. Early 996 have cracking head issues.

People say the a 2002 and up 996 have less issues with the IMS and RMS. Not true. My best friend owns a porsche repair shop and I can tell you that its just not true.

Other thing is that the IMS and RMS issue are over rated. Not all of the 996 have the problem.

I ended up getting almost the car you are describing. A 2002 996 C4 Cab. It had a bit more miles on it than I wanted. Around 94,000 on the car. The thing was that the IMS had been done and the engine was upgraded by LNM with new piston and cylinders to a 3.8 under 15,000 miles with new clutch and light weight fly wheel.

I could have got a 2001 for 23ish. The 2002 with all the upgrades came out to around 28 but let me tell you, that it is the best porsche I have ever owned. Faster than my 930. Also its the best of both worlds. It came with a factory hard top. Let me tell you I thought I would hate it, thinking that there was going to be tons of wind noise. Not at all. Very nice. I've only driven the car for about 3000 to 4000 miles and it does have a few things that I don't like, the flywheel rattles at a light with the clutch out. I was told it was what I have to deal with due to the light weight flywheel and that they all do that. The convertible top micro switch works when it wants. To solve that when the top is coming up I have to put a pencil in the switch and all problems solved.

All in all that is it. You will enjoy a 996. Don't stress yourself over the IMS and RMS. Get a PPI from a good shop and you will save yourself $ in the long run.

My next thing is a 996 turbo. I've been searching for them and they are very reasonably priced. They are going from high 30's to $50,000. Wife won't let me have two of them so we will see. Good luck and again I have seen 996 and 997 that have high miles with the orig. IMS and RMS. I have seen 996 and 997 with 30,000 miles with blown IMS.

Also in answer to your question. Like I said my friend owns an independent porsche shop. He replaced a 3.4 with a factory 3.6 replacement. Brand new from Porsche. The owner put around 30,000 miles and the IMS blew on that one. No method to the madness.

Get a car and get the LNM update. Every time you do a clutch get a new one. You should be fine.

Robert

[KNS]

Check any service history for water pump replacement, another weak spot for these engines.
Plan for it after purchase if it hasn't been done (not too expensive or difficult DIY).

[BYprodriver]

Originally Posted by pfbz

Coming up to speed on 996's for a purchase (currently have an '82 911 SC). In my price range, it will likely be a '99-01, which I realize are the most potentially problematic, especially with the IMS bearings and rear main seals.

I see quite a few cars with replacement engines, presumably through a Porsche dealership with a new or remanufactured engine.

How good are these replacement engines? Are the bearing and seal issues resolved or improved on these replacements, or the exact same issues but another roll of the dice plus a mileage reset?

Ideally, a 2001 911 C4 cab that is well priced, reasonable mileage, cosmetically outstanding, PCA/Pelican member owned, perfectly maintained, and LN IMS bearing upgraded would drop in my lap, but not so far

So I'm weighing my options on buying an original-engined non-upgraded or replacement engined car....

Any wisdom?

In My Informed Opinion IMIO there are 3 different categories of watercooled 911's & engines.
98-01 996 3.4 these engines are the most problematic because of the thin cylinders & thus should include leakdown & compression tests as part of the PPI.
02-04 996 3.6 this is the sweet spot of 911s IMO do the PPI then LN IMSB & you are
05-08 997 3.6 & 3.8 these engines have several upgrades BUTT require complete engine disassembly to replace the "somewhat improved" IMSB with the LN upgrade!
Any engine remanufactured by Porsche & installed by a authorized dealer incorporates all the latest upgraded parts & has a 2 year warranty, so if it was rebuilt 2005 or later it has the bigger IMSB & 997 RMS, any engine rebuilt prior to 2004 has the easily replaceable IMSB & leaky RMS.

[pfbz]

Originally Posted by BYprodriver

In My Informed Opinion IMIO there are 3 different categories of watercooled 911's & engines.
98-01 996 3.4 these engines are the most problematic because of the thin cylinders & thus should include leakdown & compression tests as part of the PPI.
02-04 996 3.6 this is the sweet spot of 911s IMO do the PPI then LN IMSB & you are
05-08 997 3.6 & 3.8 these engines have several upgrades BUTT require complete engine disassembly to replace the "somewhat improved" IMSB with the LN upgrade!
Any engine remanufactured by Porsche & installed by a authorized dealer incorporates all the latest upgraded parts & has a 2 year warranty, so if it was rebuilt 2005 or later it has the bigger IMSB & 997 RMS, any engine rebuilt prior to 2004 has the easily replaceable IMSB & leaky RMS.

Exactly the kind of info I was looking for. Thanks!

Tell me if I have this correct...

Years & IMS/RMS Issues:

• 1999-2001. 3.4L engine. Potential issues with RMS (rear main seal), IMS (intermediate main shaft) bearing, AND thin cylinder walls. IMSB can be upgraded to LN (ln engineering) version if you get to it before it fails.
  
  
• 2002-2004. 3.6L engine. Same issues with RMS and IMSB as earlier models. Cylinder wall issue resolved. Also upgradable IMSB
  
  
• 2005-2008. Both 3.6L and 3.8L engines. Improved RMS, improved IMSB, BUT IMSB no longer replaceable without an engine teardown.

Factory replacements & upgrades:

• Engines replaced after 2005 will have improved RMS and improved (but non-replaceable) IMSB.
  
  
• Engines replaced after 2002 will have original 3.4L thinwall engine, or improved 3.6L engine?

What about single row vs. double row IMS bearings? Are both replaceable without teardown? Is there a cutoff date when they switched? Is one notably better than the other?

[BYprodriver]

Originally Posted by pfbz

Exactly the kind of info I was looking for. Thanks!

Tell me if I have this correct...

Years & IMS/RMS Issues:

• 1999-2001. 3.4L engine. Potential issues with RMS (rear main seal), IMS (intermediate main shaft) bearing, AND thin cylinder walls. IMSB can be upgraded to LN (ln engineering) version if you get to it before it fails.
  
  
• 2002-2004. 3.6L engine. Same issues with RMS and IMSB as earlier models. Cylinder wall issue resolved. Also upgradable IMSB
  
  
• 2005-2008. Both 3.6L and 3.8L engines. Improved RMS, improved IMSB, BUT IMSB no longer replaceable without an engine teardown.

Factory replacements & upgrades:

• Engines replaced after 2005 will have improved RMS and improved (but non-replaceable) IMSB.
  
  
  
• Engines replaced after 2002 will have original 3.4L thinwall engine, or improved 3.6L engine?

What about single row vs. double row IMS bearings? Are both replaceable without teardown? Is there a cutoff date when they switched? Is one notably better than the other?

You are correct. Porsche only accepts a like engine for core charge. So 3.4 for a 3.4 & 3.6 for a 3.6 the 2 engines use Different DME computers so you have to stay with the same engine design unless you change the DME also.

All IMSBs 1998-2004 are replaceable without engine disassembly until the changeover to the final version in early 2005 requiring a visual inspection of the IMSB to verify which was used. The original double row is the best, changed to single row during 2001.

[Luxter]

Originally Posted by occb2

.... Like I said my friend owns an independent porsche shop. He replaced a 3.4 with a factory 3.6 replacement. Brand new from Porsche. The owner put around 30,000 miles and the IMS blew on that one....

It appears that the common denominator in this case is the same owner.
Mhmmm.... Makes you think.

[occb2]

Luxster I agree. He admits he is hard on the car but still. It is a Porsche. It should be able to take a beating. I love the 996 and agree that the 3.6 with updated IMS is the sweet spot. Now bump it to a 3.8 and put a euro spec suspension. That is a very fun car.

[eastbay]

I bought a car with a replacement motor and it went about 35k before the IMS went and I put in the LN replacement, so far so good.

[dennish]

Originally Posted by eastbay

I bought a car with a replacement motor and it went about 35k before the IMS went and I put in the LN replacement, so far so good.

Did you lose your motor?

[pfbz]

Great info... Now I'm thinking more about 996 Turbo's. The pricing on them seems to be sitting in a very sweet spot. Super clean, low mileage or mid mileage 996 Turbo's seem to be available in the $38K-$44K range. A bit more than I wanted to budget for an early 996, but way more car.

I'd like to become better informed on the 996 turbo engines. Can somebody give me a rundown? I've seen some scattered info scattered, but I'm sure I don't have the full picture. Can someone verify or provide a more complete explanation?

• All 996 turbo's have 3.6L engines.
• The block is not the same as the non-turbo 996 3.6L?
• There is no IMS bearing in turbo 3.6's?
• The turbo block is based on the earlier air-cooled 993 block instead of the new design found in non-turbo 996's?

Some questions:

• Are the Turbo 996 engines inherently more reliable than non-Turbo's due to their design?
• Are there RMS issues with 996 Turbo engines?
• Are there other significant 'issues' with 996 Turbo's that I need to learn about?

[KNS]

I've considered the 996 turbo as well but it will cost a bit more to operate. Replacement parts, radiators, brakes, etc are significantly more expensive than a regular 996.

You're not buying parts for a $38,000 car but for $120,000 car.

[eastbay]

Originally Posted by eastbay

I bought a car with a replacement motor and it went about 35k before the IMS went and I put in the LN replacement, so far so good.

Originally Posted by dennish

Did you lose your motor?

Did not lose the motor, it gave plenty of warning with a big oil leak. IMS cover was finger tight when I took it apart. Car runs better and smoother than ever with the new LN bearing.

Would have put in a Pelican kit if it would have been available.

This is no different than the crappy chain tensioners in the air cooled motors, something to always look out for. Just like Chevy can never get water pumps right on any motor, Porsche has had unreliable timing systems for 40 years on multiple engines.