Ck986

I put a deposit on another car and the dealer sent me the recent major service report. The report indicates that the previous owner complained about a rattle at 1700 RPM. This is on a fairly low mileage car. The tech responded that it was typicall of the 996TT GT1/2 motor. So I did a search on the infamous rattle and it appears that it is a widespread and controversial issue. I also noticed that you guys have had lengthy oil conversations as we have had in the m96 forums (as we were once trying to figure out if the oil was causing the IMS failures). My question is do you hear this rattle at 1700 rpm or is it a sound only heard at idle. I probably only have an hour of seat time in the 996 turbo so have not heard the rattle. By the way this dealer used 5w40 oil (not sure what brand).

Also what does fuel induction cleaning consist of. It cost about $130.

Kevinmacd

First off these engines do not experience IMS failures, totally different than the regular Porsche engine. The 996tt is GT1 race derivative known as the Metzger engine true dry sump, just about bullet proof. These engines do experience a rattle from idle to about 1700 rpm. This is normal. Some say its the gear mesh some say its the oil pimp relocated to the front of the engine. Regardless, this rattle is not indicative of any failure. Some have experimented with oils to try and quite it down, and have succeeded to some extent, but in my experience it never fully goes away, and as the oil ages with use, it comes back. I use the Porsche recommended M1 oil 5w-50 since it never gets below 50 for long periods of time here, and some use the the M1 Delvac 5w-40. Both seem to do a good job. So don't get too concerned about the rattle unless it is one of a different origin other than the inherited one on the 996tt.

Macster

There are all sorts of explanations for the rattle.

My 2003 Turbo early on before I bought it -- I bought it with ~10K miles in 2009 -- was in the shop several times with rattle complaints that were due to some loose interior hardware. Judicious applications of pieces of felt cleared the noises right up.

If the noise comes from the engine/drivetrain, and if the vehicle is moving, in gear, and in a higher gear practically any application of throttle can have the car (engine? drivetrain? both?) complaining with some noise that could be described as a rattle.

My experience with my Turbo is these cars/engines do not like low RPM high load conditions. The car (engine? drivetrain?) generate a noise that to me is almost like fingernails being dragged across a blackboard.

Then there are heat shields and a number of other items that can make a noise if they are loose or touching something from being bent or installed incorrectly.

There are engine and drivetrain mounts that if they deteriorate can result in weird engine or drivetrain harmonics that can generate a noise that can be interpreted as a rattle.

You must get assurances from someone who knows these cars very well the noise is self-inflicted because of the way the car is being driven or used or arises from a loose shield or something else and is not a precursor to something going wrong in the engine or the drivetrain. For instance, the cardan shaft the bearing inside the front diff can make a noise that could be taken for a rattle depending upon how far along the bearing is in its failing.

There are a number of approved oils to use. Many are 5w-40 oils. You should verify the dealer used an approved oil. I can't imagine it not but you need to be sure.

As for fuel induction cleaning what it consists of ask the dealer who I guess offered you the service. AFIAK, there is no factory scheduled fuel induction cleaning service specified. Some dealer service departments dump in a bottle of fuel system cleaner in the fuel tank as part of the service. Whether this is needed or not depends upon how the vehicle is used. Short trips could have the injector nozzles with some deposits which can interfere with the fuel spray pattern and this can negatively affect engine performance.

A good (name brand/top tier) premium fuel (bought from a busy station to avoid getting fuel that is if not stale closer to it than fresh) has detergents that help keep the fuel system clean and using a good fuel goes a long way towards sustaining good fuel system performance. But even so it may not be sufficient if the vehicle is not driven for an occasional long drive (based on my experience something around 50 miles at highway speed).

Quadcammer

since you are so complementary about it, you may want to learn how to spell the last name of the engineer.

Ck986

This is for a car I have not seen yet. I put a deposit on it and will fly to check it out in a week. The car had a major service completed a year ago so I was able to see what was done. I had never heard of a fuel induction service, never was offered one on my Boxster so wanted to see if it was something Turbo specific. I thought you just gotta rev high to clean the fuel injectors. At least that's what I did.

The rattle is described to have come from the motor. I found the previous owners email in some service paperwork so may just send him a brief email asking about the car.

Macster

Without going into too much detail just revving the engine for a brief time with no load is not going to clean out anything but the gas tank of gasoline.

The engine will benefit some -- at least based on my experience -- from being driven at highway speeds at some steady RPM for approx. 50 miles.

After 50 miles or so at 65+mph the engines in both of my cars (and in previous cars too) perk up noticeably. This I think in part is attributable to the cleaning benefits of the detergents in the gasoline which given the amount of time the engine is run at a steady speed and at a fairly steady load give the detergents enough time to work. Not only at the injector nozzles but on the intake valves.

More cleaning can be had using Techron and this doesn't require the engine be run at a steady RPM and load for 50 miles, though this would be even more beneficial. Techron works even when the engine is cold helping to loosen/remove any deposits it comes in contact with.

There can be some benefit to with an "unknown" engine treating it to a dose or two of Techron to help bring the engine's fuel system and intake valves and combustion surfaces to a better level of cleanliness. As I have mentioned before shortly after I bought my low miles Turbo I used some Techron to remove what I believed were deposits that engine had accumulated by the previous owner's style of driving: short trips. (Based on the condition of the car I suspect half of the ~10K miles the car had on it when I bought it were accumulated backing the car out of the garage to wash the car then driving it into the garage again until the next wash day.)

Ck986

I didn't mean no load, I only drove that car between 4-7K rpm. I use to throw a bottle of techron in every other year whenever I saw a bottle at Walmart or Pep-Boys/Autozone. I am surprised they charged for an hour of labor to dump a bottle of detergent into the tank.

Kevinmacd

Quadcammer - While we are on a spelling lesson, maybe you need to learn to spell "complementary" think you meant complimentary!

Def#1 complementary adj. completing something or satisfying a lack in something.

Def#2 complimentary adj. 1. flattering; expressing praise. 2. given freely and without cost.

Think you meant Def #2

Here is an example - European Car Magazine "The 997 RS 4.0 had the last incarnation of the Metzger engine, and so a heavily tweaked version of the current 9A1 direct-injection flat-six motor takes the baton and runs with it in the 991 GT3"

If this is incorrect then there is plenty of misinformation out there! If I did not spell it correctly then I have bad info! But so what! Was this just to be argumentative?

jpflip

Kevin, I don't want to argue here but I am trying to give you information here: I just bought the book about this engineer biography and they spell it Mezger….There is also his signature inside page 25 on a letter for stopping the formula one engine production and it is spell Mezger….Sorry….

Kevinmacd

jpflip - there is plenty of mis-information out there, because a lot that I have read spells it like I have. You have something that spells it differently and probably is correct. I guess my point was why belittle something that is referenced both ways as per my example in my post of which everyone gives the credit for a great engine!
No need to be sorry!
Thanks for the insight