3.4 l 996 engines reliable?

TdiRacing · 06-04-2009, 05:31 PM

I am thinking of buying a 996, but know very little about the engines. I drove one and like it a lot, but do not want to get a car without knowing more about the potential problems. Anyone have input on these water cooled engines????

i know the oil seals were an issue...and have seen a few with engine replacements..so not sure if it is wise to get or not.

Steve@Rennsport · 06-04-2009, 11:26 PM

Quote:

Originally Posted by TdiRacing

I am thinking of buying a 996, but know very little about the engines. I drove one and like it a lot, but do not want to get a car without knowing more about the potential problems. Anyone have input on these water cooled engines????

i know the oil seals were an issue...and have seen a few with engine replacements..so not sure if it is wise to get or not.

JMHO, but I would avoid these engines before 2009 as the M96 was not their best work.

The new 91A looks a LOT better.

PlayersExpress · 06-05-2009, 12:03 AM

Yes, the engines are rebuildable. They can become very costly. I would look into updating the Intermediate shaft (cost between $500-900) but will solve the main problem of engine failure in the M96 engines. The next best thing to break would be the cylinder sleeves themselves ( D-chunking) which in itself is a very rarity.

When people talk about how bad the engines are, the stigma on them is blown way out of proportion.

Less than 1% of all the M96 engines have failed prematurely because of the factory design problems. Realistically looking when Porsche built about 200,000 cars with the M96, that comes out to around 2,000 engines.. and the ones that were going to blow already have. If the car youre looking at has over 30-40k miles.. chances are ... its fine.

Look into http://www.lnengineering.com/ use the search button on here, 986F, and RT.

Cheers

TdiRacing · 06-05-2009, 09:00 PM

THanks. Was looking at the issues and they seem to be rare as far as i can tell.

BReyes · BReyes's Garage

Can't complain about my lil 99 I have had for several years now. Still runnning strong! Lots of fluid changes and I have been happy with no complaints.

Regards,

cnavarro · 06-10-2009, 04:49 AM

Yes, the engines are rebuildable, but plan on spending as much as to do an aircooled engine to do it right and address all the concern areas.

They are great cars, no questions asked. Just drive it like you stole it and enjoy the car as Porsche intended. Babying these cars are about the worst thing you can do for them.

Frequent and thorough maintenance goes a long way - start with 5k oil changes with a 5w40 oil rather than 0w40 (there are plenty of approved oils in a 5w40 if you must used a Porsche approved oil).

Looking up the service history on a car to see if it has had numerous RMS problems or hasn't had oil changes frequently are two indicators that maybe you should keep looking for another car.

TdiRacing · 06-15-2009, 06:31 PM

It is hard to find these cars with a good history. Most have had numerous owners and sold at auctions...will keep searching. I want one with a good history for sure. Looked at a few, but the engines scare me especially after having VW vanagns in the 80's...LOL the heads always leaked...

They do run nice thought.

IS the intermediate shaft issue only on the boxtser engines? Or the 3.4L as well?

cnavarro · 06-15-2009, 07:44 PM

IMS failures pertain to all vehicles with the M96 engine, including the Boxster, Cayman, and 911.

The 91A engine, with exception of carbon buildup on the intake valves requiring decarbonization servicing, looks like it will be an excellent engine.

TdiRacing · 06-16-2009, 03:53 PM

So when looking at a used car, how does one determine that there is a ISB issue or potential one? Leaking oil seal? Noise?

I am so paranoid, but really want one of these cars. I love how they drive and the engines seem great too, but the little things are really making me be cautious.

I tried finding the Excellence article that discussed these issues, but no one could get me a digital copy.

Second question is there any issues with the cooling systems? If so how to check that as well?

cnavarro · 06-16-2009, 05:27 PM

It's pretty easy to determine the condition of the IMS bearing, but it requires the transmission to come off.

I have a youtube video showing the difference between a healthy bearing and bad bearing on my website on the following page, about 1/3rd the way down:

http://www.lnengineering.com/ims.html

TdiRacing · 06-18-2009, 08:44 AM

So would one hear some noise if you were under the car listening?

I guess my question would be what mileage range to look at? Or is it just dependent on the car. Looking at the 1999-2000 model years.

How long does it take to remove the tranny and inspect that bearing? I am a competent mechanic, just curious...

Would be C2 6 speed manual...

BReyes · BReyes's Garage

You should be able to find a car without having to remove the tranny. That may be too much. Yes you will quickly know if the car makes noises. You should have luck finding a good car-really easy to get in them and negotiate for value. Walking away from lemons will be easy enough. Key may be to find a car that has already been throughly inspected. If it has your colors/accessories, you can have a PPI done on it by another tech.

How many have you gotten under and inspected for yourself just after or prior to test ride?

TdiRacing · 06-18-2009, 08:49 PM

I tried to run them hard and of course I got under there to see if there was anything leaking or weird smells, but they are low, so without jacking them up, it is difficult. I have driven about 7 cars now that were within the range and were something I would consider buying. Some I looked at and walked away because they were just ratty to begin with...

There is one that was interesting, beautiful car and ran great, but the starter spun slowly, not sure if it was battery or starter. It started every time, but was weird for sure.

Maybe I am over reacting. I know once in my possession, i will drive the hell out of it, and do track days.

I guess the main question that I have is other than checking the ECU codes and listening for noises, what else does one check? Pressure in cooling system and oil leaks i guess is the only thing???

cnavarro · 06-19-2009, 07:23 AM

I would suggest using a PIWIS to check cam timing deviation. If cam timing is off, it may indicate worn variocam tensioner pads or be early indicators of IMS problems. There is a lot that the dealership can pull from the dme which should be done with a PPI.

TdiRacing · 06-21-2009, 08:03 PM

Is that the Porsche diagnostic software? Sorry, been a away from the Porsche stuff and work mostly on VW's now, but would like to know what these mean?

PIWIS: ?

PPI: ?

Sorry for the lack of knowledge....

88911coupe · 06-22-2009, 07:55 AM

PIWIS...not sure on that one
PPI, Pre Purschase Inspection

TdiRacing · 06-23-2009, 07:01 PM

Well i found one, and will hopefully have it by next week. 38KMiles, dealer serviced all it's life with almost all records...

Will get a scan tool PIWIS or the other US based software to check things out...

Crossing my fingers on a good engine....thanks for all the feed back