haulinkraut

I posted in the IMS noise thread about these questions, but I thought it would be better to post in it's own thread so the IMS thread doesn't get anymore hijacked than it already is. I just get annoyed by hearing part of an engine failure story and in the meanwhile nobody seems to clarify all of the details so that the enthusiast like us will be aware of our engines and how to threat them. Kevin is a wealth of knowledge with these engines and has helped quite alot and I have followed his advise about oil to a T. Maybe he and the other knowledgable people here could share what they know about these issues for the better of the community? And also to have it all in one thread so that people don't have to spend alot of time searching threads. And in the effort of keeping everyone in the loop I just thought we could lay all the cards on the table with the noises this engine makes and the risks of said noises. And also to discuss actual failure areas and their causes as well. What I would like to see cleared up about this engine is:

Variocam Tappet FailureAre variocam lifters failing due quality issues or are these engines seeing unusual use or stress to cause it like overrevs, incorrect oil, incorrect oil change intervals etc? How common is the issue? Prevenetative measures? Solution?

Variocam Sealing Ring FailureCauses lack of Variocam tappet actuation. Signs of failure? How common? Preventative measures? Solution?

Cam Chain BreakingIs this caused by overrevs or money shifts? Signs of failure is engine misfiring and shutting down. DO NOT TRY TO RESTART ENGINE!!! Preventitive measures? Solution?

Engine rattleIs the noise that 95% of these engines have normal? Is it safe? What could be expected with running the engine with this issue un-resolved? Is the damage worth the cost of tearing an engine apart to chase it? At what point should the issues be something to worry about? How do you determine the difference between a normal chain noise and an IMS issue? Prevenetative measures? Solution?

IMS FailuresWhat are the issues with the shaft that causes the noise(as in gear lash or loose/worn woodruff key for IMS gear)? What causes these issues(overrevs or quality issue with part)? How to identify this issue? What are the long term risks of running an engine with these issues? Is it worth chasing this noise or issue if your car is not making metal or needing a tear down for other issues? Prevenetative measures? Solution?

It just seems hopeless and discouraging to think that any engine may be failing early regardless of treatment or mod levels. I can't buy that these engines are just falling apart without outside influences such as use, wear and maintenance either. Or are some of these design flaws? And I know other people feel the same way and want answers.

Also, here are some 996TT engine issue threads for reference. They discuss some common issues and some rare issues. This of the stuff that has already been discussed to some degree:
https://rennlist.com/forums/996-turb...-bouncing.html

https://rennlist.com/forums/996-turb...ode-p1325.html

https://rennlist.com/forums/996-turb...il-filter.html

https://rennlist.com/forums/996-turb...nd-engine.html

https://rennlist.com/forums/996-turb...ace-track.html

Edit: Added cam chain failure and separated variocam issues for better clarification.

jpflip

Joel (2001) , vario cam failure of the cam support metal seal ring at 24,000 miles....Porsche doc (2001) , same problem at 90,000 miles. And you got T2 (2003) with almost 300,000 miles without any issue and Pierre (2001) from Switzerland did in the first two years over 87, 000 miles + he track his car without any major issue...How can we pin point the problem ????? But, "haulinkraut", it is a good suggestion for, I hope, a long discussion.

haulinkraut

Well, the causes for most these issues are known by the people tearing them down for repair evaluation.

Land Jet

There is also the coolant manifold insert blow outs.

No matter how advanced these engines get they are still machines and as such are prone to metal fatigue and failure. There has never been a machine that didn't break down sooner or later.

haulinkraut

I am referring mainly to the issues requiring engine tear down. But the coolant fitting insert is a great thought. We know this is a glue issue and is a fix requiring an engine pull.

Dock

haulinkraut - I applaud your attempt to nail things down a little better.

I think though that before any attempt is made to come up with takeaways from any engine/transmission noises or failures it is important to first establish two things to the best of our ability; First, has the engine and/or transmission been modified (and to what level), and second, what kind of treatment has the car been exposed to. With regard to the first point, I think most bets are off in establishing any takeaways if the engine/transmission has been modified, and with regard to the second point, its establishment will be very difficult if the Turbo is not a one owner car.

haulinkraut

As far as causes on all three issues I was referring to things such as oil contamination/breakdown, oil starvation, incorrect oil viscosity/weight, overrevs etc. This may be of course accelerated by mods, horsepower levels and use such as track events and such. An engine builder can usually look at a failed engine and narrow down the failed component that caused the issue and determinate what happened. This data will have to be plugged into what we know about how the car was treated. But Kevin or other experienced builders have opened enough of these engines up to tell if one particular component is wearing faster than it is supposed to. And chances are the accelerated wear is associated to a root cause that can be identified. This isn't to be able to say that you will need an engine rebuild at XX amount of miles. Just to identify the issues and causes.

The point stands that when you push an engine that makes as much HP per liter as this car and use it for track and race duties you will experience more wear. This is even more so when you add more HP and more track events. This is why race teams rebuild their engines as often as they do.

SSST

I'll be interested to follow this thread as I am very new to Porsche.

One observation though. If you go to Bimmerfest and start reading about the famous HPFP problem on the 335 you wouldn't touch one with a ten foot pole. The telling symptom is long starts.

I have a 335 with 32k miles and it had about half dozen long starts at the 10k mile point. I never did anything about it and they went away. The car runs great.

Some people are going to have problems, especially if they push the engineering limits with mods and tracking them. However, the 996 rates as one of the most reliable cars on the road. They are high performance machines but sometimes they break.

haulinkraut

One thing to consider about the BMW 335 and these engines is that not everyone spends a ton of time listening to their engines and some people don't really register little things like long starts little rattles or ticks. In the end you can around and worry all day or you can drive your car. Their are not many problems on a stock or chipped engine that will cause your engine to just grenade unless you don't change your oil, run crap gas and oil or never drive your car. The never drive your car part5 is important because the oil tends to drain completely off your intake valve tappets. Especially if you run thin 0w oils. A well driven engine is a well oiled engine.

Kevin

Haulin, you should seperate the vario-cam sealing ring issue vs the intake tappet failures. Two different failures. However, both failures can exist in the same engine. You can have rings that are wearing on bank one and failed inlet tappets on the other. Timing chain breakage is another failure.

What some of you are failing to grasp is that MOST folks will not post there experiences. Put another way, it's alot easier for someone to email there concerns vs posting on this forum. I have a customer that is shipping his car across the US for a intake tappet failure right now. He reads the forum but does not post. This is more common than one can imagine. There is NO smoking gun. Why are the chains just breaking. There are 4 engines documented that just failed. 3 of the 4 engine were STOCK..

At this point in time it's hard to pinpoint the cause of events that will give us failed tappets, or vario cam failures, or chains breaking. I have a opinion that because the oil change interval gets stretch out close to 10K miles and the reduction/modification of oil/metal additives> we have acce,erated wear.

I receive on average 15 emails a week from owners and buyer that have video and sound clip of there engines. There is no scale to dictate and predict a failure. I have made the recommendations to CHECK your own oil filter. If you have metal in it, it is getting past the oil pump screen and it does go thru the oil pump. The common theme to alot of these engine failures is a PACKED oil filter. I do have a oil filter that I will try to post a picture of that is packed with metal.

There is a period of time between a little metal in the filter and ALOT of metal in the filter. I don't know the timeframe.. But if one notices the metal, AND decides to change there oil sooner> the outcome should be better, with a extension of more miles. Seeing a little metal in the oil filter does NOT warrant a engine tear down. However, it does require a evaluation of the oil change schedule, and possibly a change in oil.

I have taken apart 4 engines that had the IMS rattle. There was no smoking gun in the failure. However, don't discount what I just said > all of the engine had chain wear, sprocket wear with teeth missing, and woodruff key wear. One early mileage X50 engine showed wear but no major component FAILURE. This changed when stripped the components off the crankshaft. The keyway was slotted.

Edit: It's sad for those owners that have had a major engine failure. Some have had bone stock engines. They have had factory service schedules and have lost there engine out of warranty. These guys do exist.

Dock

None of the engines you've seen with one or more of these issues had oil change mileage intervals that were lower than "close to 10k miles"?

haulinkraut

Well first off, thanks for your input! Based on what you have seen do you suspect the engines that you have seen with difficult to explain failures to have unusual oil change intervals or other oil related issues? Do you see any connections with high mileage turbos with these variocam and cam chain issues verses lower mileage cars? I have been doing 3k mile oil changes with M1 5w40 Turbo diesel because I don't want these issues.

Dock

I consider information with regard to how the problem cars were driven to also be of high interest.

Kevin

Dock, why "none" > they weren't engines owned or serviced by me. Most were engines that failed where no history was given for previous service records. 2nd and 3rd owner cars.

I would offer my stats that 30% of these failures had engine outputs greater than your standard flash. And we aren't talking about engine failures from rods breaking and exiting the block.

Haulin, most of the failures come after 20K.. The very first tappet failure that I seen was back in 2005 with a 2003 X50 car. A cylinder head was replaced with two banks of tappets ( covered under warranty) the car was under 35K Doing a 3K oil change interval is the best that you can do > very reasonable.

Dock

Then that causes me to have some trouble squaring this comment you made in a post above ...