How to possibly prevent cylinder scoring

[Buddy]

Since the Cayman has no oil pressure gauge and expecting that the oil pump in these engines is high flow, at what engine speed when hot does the pressure relief valve tend to open so limiting the max pressure? Just wondering how high to rev before pulling away, revving above about 2,000 tends to raise eyebrows and sometimes hackles. When I had the 944 Turbo it was the method I used to quickly spool the turbo.

 

[bazhart]

Good intelligent comments and yes it would help to raise the revs after a spell at tickover and also to rev the engine in the first few gears - but not from full throttle. Baz

 

[Buddy]

Baz, In trying to find out causes, driving methods etc. Have you ever had repeat offenders? Either same car or same driver on different cars after all lot's of us keep buying Porsches. Or even are cars used in some towns with heavy traffic too many traffic lights ( haven't they all ) more prone. Low engine speeds will cause low water flow, low oil flow and lower oil pressure, all of which are undesirable. Then as you say drag race starts off the lights will compound the problem. Porsche OPCs must have had a number of these and hopefully given feedback to Porsche but it would be interesting to know if Porsche has done a lessons learnt analysis and improved whatever they think will prevent the problem. Years ago they did a development programme to optimise the water cooling to give quicker warming up, maybe they need to repeat this and their oil systems, from experience not much point asking the OPCs

 

[Laurence Gibbs]

interesting point about the reaction times for the coolant and the length of the coolant pipes to the rads. Another rear engine water cooled design , the old rear engine Skodas suffered problems allied to this. The stat would be "fooled" by the coolant being a bit cooler away from the heat soaked engine. Allowing the engine to boil away with the stat blissfully ignorant of the fact. Obviously a more obvious and drastic case than yours.

 

[Ngdexter]

My 997 is using cololant and as some milky residue around the oil cap is this scoring evidence?

 

[Rodney Naghar]

My 997 is using cololant and as some milky residue around the oil cap is this scoring evidence?

No. The milky residue is common if the car is used on lots of short journeys.

The loss of coolant is often associated with either a leaky coolant expansion tank or cap, or a 'holed' or rotten radiator.

You should start to worry worry if there is an oily residue in your coolant expansion tank

 

[Lancerlot]

As Rodney has said, the milky residue indicates moisture in the oil. It's common around the filler cap due to condensation. Long journeys will heat up the engine oil and evaporate it. However, if it is prevalent and continual, it may indicate a water to oil leakage problem, blown head gasket etc.

Cylinder bore scoring usually results in blue exhaust emissions and a sooty tailpipe one side or another.

Regards,

[font="comic sans ms,sans-serif"]Clive[/font]

 

[Ngdexter]

Hmm. Thanks. I will take a photo of the coolant expansion tank and post here when I have a moment to see if it looks normal. Ill clean the residue from the oil cap and see how long for build up to occur again. Its a weekend car at the moment which I do push when Its out. Normally its out for 10 miles or so and taken up to 6000 RPM (or a bit more) when out. Relatively new to me so just want to make sure all is well in case anything goes pop. I just used normal coolant to top up the tank. Is this OK?

 

[Lancerlot]

Water yes - preferably distilled, but Porsche use a specific long-life coolant additive so better not to mix it with others. If you're diluting it a lot, best to get the concentration checked out once the leakage problem is resolved.

Regards,

[font="comic sans ms,sans-serif"]Clive[/font]

 

[ralphmusic]

...Its a weekend car at the moment which I do push when Its out. Normally its out for 10 miles or so and taken up to 6000 RPM (or a bit more) when out...

I forget how long a 997 takes for water and oil temperature to reach normal levels but I'd think it probably is at least 10 miles to reach temperature before pushing the engine, just a thought...

 

[STiG911]

Hmm. Thanks. I will take a photo of the coolant expansion tank and post here when I have a moment to see if it looks normal. Ill clean the residue from the oil cap and see how long for build up to occur again. Its a weekend car at the moment which I do push when Its out. Normally its out for 10 miles or so and taken up to 6000 RPM (or a bit more) when out. Relatively new to me so just want to make sure all is well in case anything goes pop. I just used normal coolant to top up the tank. Is this OK?

Please tell me you mean 10 miles at least each way, not 20 miles total. By the time 10 miles has come up - particularly at this time of year - the oil has barely warmed through before you're shutting the engine down, so gunk build-up in the oil filler is not a surprise. There's also only so long you can do that until the oil can't absorb any more moisture and becomes next to useless at it's job of lubricating AND cooling (something people forget)

The oil isn't properly warm until it's at or (ideally) above 90deg. I don't even consider going above 4k rpm until this has happened, and 6k rpm is a definite no-go.

Not sure if you do this already either, but I'd consider an oil change every year regardless of service schedule. It's far cheaper and prudent to change it each year than having to fund enginer repair / replacement.

I'm pretty sure you should use only Porsche approved coolant too. IIRC it comes in pre-mixed 1 litre containers. I keep one of these and a 1 litre oil bottle in my car, just in case.

 

[Ngdexter]

Well theres no hard fast rule about the journey TBH. The engine definitely gets up to temp. and I don't hard rev until its at least showing 60 or so degs. Sometimes it gets close to 100deg. A little worried about the coolant now. Its due a service - I am in Peterborough and Cambs is a pain in the backside to get to my closest dealer (Leicester or Cambs) - also not completely sure about taking to my local independent one as I'm just not confident yet. Any good service centre recommendations would be good for minor service. Sounds like I really need a long run every once in a while.

 

[Bear911]

Officia

Well theres no hard fast rule about the journey TBH. The engine definitely gets up to temp. and I don't hard rev until its at least showing 60 or so degs. Sometimes it gets close to 100deg. A little worried about the coolant now. Its due a service - I am in Peterborough and Cambs is a pain in the backside to get to my closest dealer (Leicester or Cambs) - also not completely sure about taking to my local independent one as I'm just not confident yet. Any good service centre recommendations would be good for minor service. Sounds like I really need a long run every once in a while.

My advice is get a full major service by a Porsche centre within your area - Its due for a service so crack on and book it [s1]

Rather than going to an Indy ! - then once you get the results, item by item get them sorted. in priority order.

Then drive it more often. []

Possibly overkill, but every 6th months both the oil and filter are replaced on mine, prudent !

 

[Timbo2]

Bazhart, nice post, thank you. Do you think there could be any merit in speeding up water pump revolutions by reducing the pulley size slightly, obviously that would require a different belt.