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the question for me is: do only *crazy* people only own these ? are do these particular cars make people *crazy*.
Both apply, when an engine or rebuilt engine can run 20k, it certainly doesn’t give a warm feeling when the coolant tubes blow out or the chain rattles against the case. It certainly isn’t making the engine better, it’s definitely a better engine than the normally aspirated one.
the question for me is: do only *crazy* people only own these ? are do these particular cars make people *crazy*.
Both apply, when an engine or rebuilt engine can run 20k, it certainly doesn’t give a warm feeling when the coolant tubes blow out or the chain rattles against the case. It certainly isn’t making the engine better, it’s definitely a better engine than the normally aspirated one.
The chains are not contacting the case at all. They slide over composite plastic rails that are part of the chain tensioner. These plastic rails are specifically designed for this.
At start up and if the engine has sat some time the chain tensioners have lost any oil pressure that forces the tensioner rail tight up against the chain so the rails may not be even up against the chains. As soon as the engine spins the chains are a bit loose and the slack side -- which is the side the tensioner pushes against -- drags along the tensioner rail a bit before sufficient oil pressure develops to push the tensioner hard against the chain which when this happens tends to reduce the noise. At the same time the chain gets wet wtih oil which also tends to quiet the chain noise.
Cam chain drives are inherently noisy. They have the benefit though of not needing any service unlike rubber timing belts that need periodic replacement.
It doesn't help the Turbo engine is located very close to the cabin and is rather exposed so any engine noise has a better chance of being heard. And most owners have other vehicles which have either rubber timing belt engines or engines with much more sound deadening around/over them. The Turbo is a bit raw compared to other passenger vehicles.
The initial startup noise is of no real consequence.
I am not a fan of pulling the fuel pump fuse and cranking the engine some in an attempt to lube the engine at cold start. The starter spins the engine very slowly, maybe around 75 RPMs. This is quite fast enough as normally the engine fires right up -- all it takes is just one cylinder to have a full power stroke which can happen in just a few revs -- and then the engine controller takes the engine up to over 1K. I have to also point out Porsche and this is true of all engines with which I have any experience do not delay engine start any to let the engine crank some to lube the engine before actual engine start. IF this had any benefit at all I think it would be common.
Anyhow, the initial rise in engine RPMs is done on purpose. One is gear driven oil pumps are rather inefficient at low speeds. This also means they may not self prime at too low a speed. The engine controller "racing" the engine RPMs up to just over 1K is to ensure the oil pump primes and to get oil flowing to the vital areas ASAP. Also, RPMs are needed to form the oil film/wedge from the residual oil in the main and rod bearings.
Slow cranking risks the oil pump may not prime or be slower to prime. Oil flow and pressure build up are slower to occur. Additionally the slow cranking may not result in the formation of the oil film/wedge but instead work to force this residual oil out the bearing. Then when the fuse is plugged back in and the engine is started and RPMs shoot up this may occur with the bearings "dry".
The best advice I can offer is do not run the oil too long. My experience with both my Boxster and Turbo is at around 5K miles the engine is a bit noisier at start up -- all other things being equal -- and a bit noisier at hot idle. The engine is a bit more likely to smoke at cold start too.
Keep the oil level up near the max level.
Run the proper viscosity of oil for where you live and drive. Remember Porsche calls for 0w-40 if temperatures are cold (-25C). Frankly I'd run 0w-40 even if temperatures stay well above -25C.
For some owners where ambient temperatures are mild there is an approved 5w-50 oil which offers a bit more protection at high temperatures. Where i live and drive it doesn't get that cold but can get plenty hot so I switched to 5w-50 year round. However, I did not notice any real change in the hot idle oil pressure. The 5w-50 oil is not *thicker* it only offers slightly better HTHS numbers.
And just start the engine with all fuses in place.
Porsche techs told me for cars that are not used regularly they recommend the use of Swepco 502 oil improver. This contains 200ppm of moly which is an anti-wear additive. (BTW, the factory recommended oil I use in my Dodge Challenger Hellcat engine, Pennzoil 0w-40 Ultra Platinum, contains around 230ppm of moly.)
The techs said this Swepco additive tended to quiet (some) cold engine start noise and offered some extra protection against wear. (I note both my Boxster and Turbo racked up some pretty big miles without this additive and suffered no signs of any engine wear so it is not like the factory oil is not up the to the task of protecting the engine.)
Because of the oil capacity of the Turbo and Boxster engines -- both over 9 quarts total -- I used two bottles of Swepco 502 per engine. The engines were a bit (not much but a bit) quieter at cold engine start and at other times. But I can't come right out and say using the Swepco was worth it. Also I note Porsche advises against using any oil additive, so there's that.
But I put this Swepco thing out there for you to consider.
The chains are not contacting the case at all. They slide over composite plastic rails that are part of the chain tensioner. These plastic rails are specifically designed for this.
At start up and if the engine has sat some time the chain tensioners have lost any oil pressure that forces the tensioner rail tight up against the chain so the rails may not be even up against the chains. As soon as the engine spins the chains are a bit loose and the slack side -- which is the side the tensioner pushes against -- drags along the tensioner rail a bit before sufficient oil pressure develops to push the tensioner hard against the chain which when this happens tends to reduce the noise. At the same time the chain gets wet wtih oil which also tends to quiet the chain noise.
Cam chain drives are inherently noisy. They have the benefit though of not needing any service unlike rubber timing belts that need periodic replacement.
It doesn't help the Turbo engine is located very close to the cabin and is rather exposed so any engine noise has a better chance of being heard. And most owners have other vehicles which have either rubber timing belt engines or engines with much more sound deadening around/over them. The Turbo is a bit raw compared to other passenger vehicles.
The initial startup noise is of no real consequence.
It’s a shame they didn’t design the noise straight from the factory. Funny none of the Mercedes chains I have make any noise similar to this engine, even after sitting for months. My 997 doesn’t make the noise, I certainly don’t miss the sound.
i abhor the oil starved chain rattle startup noise that occurs primarily in summer months when even 5/50 is nowhere to be heard/found until oil pressure is reached.
Thank you Dock but I forgot to specify I have a 997 TT not a 996 It seems that I have the same noise when I go for days without starting, but maybe not the same fuse box?
You should have a fuse diagram on the inside of the fuse box cover. My guess is that the fuse box in the 997 Turbo is in the same location as it is in the 996 Turbo. Check your owner's manual or just take a look inside the car.
Yes the fuse box is on the left I will try to find the right position of the fuel pump fuse
Thank you.
I just finished reading the post and some owners leave the rattle on cold starts ... not sure what's right or wrong ...
01-16-2019, 11:21 AM
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