Carrera 4S PPI Number 4 - Bore score!

[Robertb]

The question is if your car is displaying no symptoms of bore scoring then why go poking round in the bores and worrying yourself unnecessarily?

Worry about it when symptoms are presented.

In any case, as an engine's mileage increases, all sorts of components could benefit from a refresh and upgrade, this is true of any high-performance engine.

I will cross that bridge if and when I come to it, and it will be an opportunity to enhance my treasured car.

For less than the price of a leggy Gen 2 or Turbo I could have bought my car, enjoyed it for 5 yrs, paid for a Hartech rebuild (maybe even a 3.9) and sent it to CoG for a suspension refresh.

 

[deMort]

For my point .. i think bore score on a 996 is rare .. but to be fair i dont scope that many and i have a hunch you can have score but it lasts for far longer than a 997 without showing any symptoms ... in fact i'm pretty sure of it .

I think Baz is the man to ask for this question as my knowledge is limited .

 

[millby]

I have spoken to two dealers, one a Porsche specialist, another that occasionally deals in them.

Both suggested that they will avoid the 997.1 due to bore scoring issues affecting a 'high proportion' of cars, and not worth the risk and reputation of getting one wrong, but otherwise the 996 (.1 &.2) are reasonably safe bets.

To clarify the issues above usual car buying DD (servicing/condition) for the 996.1/.2

IMS - can this be inspected to see if it is likely to fail? Or do you just upgrade it when the opportunity arises (clutch change) as a matter of precaution? Or leave it, if the car has passed say 60,000 miles?

RMS - only replace if their is an obvious issue (oil leak), minor issue if it is leaking though

Bore score - effectively engine degradation, so likely to happen on all engines in time, but more prone in the 997.1? Not catastrophic if identified (opposed to IMS failure which is), and can be 'lived' with even if it is there?

I'm wary of dealer advice vs forum advice, and keep swaying from the 996 being a good proposition, to a time bomb...?!

PS. I've decided to focus on the 996 C4S, as the early 3.4s are not ULEZ compliant, which would affect me daily post 2021 (expanding ULEZ area)

 

[Jackzi]

@millby: I think the consensus is that a 997.1 3.8 is more likely to suffer from bore score. (IMS is as much of a worry on cars that are up to model year 06)

And, as Iain points out, the symptoms of scoring tend to be more pronounced and obvious to see than in a 996.

That's actually a very interesting point, as the car I had inspected had only a very slight puff of smoke from the left side tailpipe on a cold start and no deposits around the pipe itself. So it could have been any number of things.

I'm relatively certain the owner didn't know as he had no reason to suspect it. And I wouldn't go poking round the bores either if it was mine :hand:

Even though my (non-car) friends think I'm mad after so many failed inspections, I still believe in the 996.

I still believe there are good ones out there. And I find the C4S has more character than a 997.1. It's turning out to be a hunt for a unicorn for me, but I'm undeterred, I'll find one :lol:

(anyone got one for sale?)

 

[deMort]

Ok .. a few questions from millby

Imho and as a Porsche mechanic for 15 years ..

997 can and do suffer from bore score .. an 05 plate has the same ims bearing as a 996 so the worst of both worlds i'm afraid .

The percentage of failures for both of these problems ...

Porsche put it at 5% or less .. is that true .. i can't say .. i can say i don't see that many with the sheer volume of work i do on these cars .

996 and bore score is rare .. it takes or indeed seems to take far longer to show problems than a 997 .. with 997 being more prone to this .. again .. 5% of cars built can suffer from this .

car dealerships wil paint a darker picture .. they get caught with one car and it's an expensive bill for them .. so they say they dont touch them .. they aint Porsche specialists period .


06 onwards and its very rare for an ims to fail .. i've not seen it but i believe Hartech have .

RMS can leak .. its a seal .. many seals can leak ... look for oil on the bottom of the bell housing ... it needs to be forming a drip or dripping on the floor to be a problem .. damp and its fine ... dripping on the floor being a problem btw .

Any make of car out there has its own issues and Porsche are no different .. the down side is if it does happen then its an expensive bill .. it doesn't happen overnight though .. a scope check on any car will soon tell if its going that way .

 

[millby]

Thanks both, very informative.

I am looking at an 996 C4S, which sounds like I need to be wary of bore scoring, but unlikely to suffer. The risk is with the IMS.

Will a pre purchase inspection give any sort of conclusion on whether the IMS is likely to fail?

And what is the current favoured solution (and approximate cost) to remedy the IMS, whether on the basis of an inspection advising so, or for peace of mind.

 

[maldren]

As the owner of a 996 3.6 with 100k on the clock, my current thoughts are:
1. IMS failure unlikely.
2. Bore score possible but I should get plenty of warning from oil use/smoke and it's repairable although expensive.
3. Bottom end wear. This seems to be the biggest risk with possible catastrophic failure without a warning.

Item 3 seems the real risk but gets relatively little coverage apart from Baz's excellent advice.

 

[Robert SausageTrousers]

I wonder what the percentage of wrongly diagnosed bore-scored cars is, given the recent thread where a PPI from a well regarded specialist threw up scored bores which apparently turned out to be fine.

 

[Griffter]

I wonder what the percentage of wrongly diagnosed bore-scored cars is, given the recent thread where a PPI from a well regarded specialist threw up scored bores which apparently turned out to be fine.

PPIs have their place, but someone doing a PPI is going to want to cover their back. It's a bit like advisories at MOTs. Sometimes they're a genuinely useful heads up, sometimes the tester's being a bit overzealous and they're nothing to worry about.
I've never had a PPI but I guess if you're being paid to find something, you'd better find something!

 

[Robert SausageTrousers]

Yet a lot of the 'evidence' we have that bore scoring is an issue comes from PPI's, this thread alone highlights huge percentages of apparently bore scored cars where the owner is oblivious to any problems ~ if the diagnosis in the other thread was wrong then what's to say that lots of other PPI'd cars are being wrongly diagnosed?

 

[Jackzi]

There could well be loads of wrong diagnoses, for sure.

And the simple fact that people may be looking for signs of scoring knowing the cars are afflicted, rather than checking to see if everything is OK can lead to that.

In my case, even a non-mechanic like me could see very obvious signs of deep grooves in the cylinders. Then I sent the pics to various specialists and engine rebuilders, who all independently confirmed the diagnosis.

Sure, a PPI isn't exactly a 'gentle' look. But from my point of view (and that of a few people I have used for them) if a PPI comes back with very little to say, then it's more than worth the money spent.

You can also generally tell if a tester has been overzealous in the way they write the report and how they prioritise things (I'm not all that bothered if the cigar lighter isn't there).

In the best cases (thanks Iain), the tester will walk you around the car and show you exactly what they're talking about. That's where I've learned a lot.

 

[alpinaman]

I had a C4S many years ago and also had a C2 cab and C4 coupe...

They are getting old now,and apart from the obvious engine malodies there is plenty more to go wrong and maintain.


Do you need 4 seats?

Would a 981 Cayman do the job for you,much newer and seem pretty bombproof,they are very nice to drive and maintenance costs are pretty low in Porsche terms.
You wont be suprised to hear i now have a 981 and find it fantastic,forget the people that say "its not a 911 though"...

Just a thought...

 

[bazhart]

Apart from a very small number of the last 3.4 996's all the pistons fitted were made by KS (who also made the Lokasil blocks) and had a hard iron coating so will probably not score. The cylinders however gradually go oval and may crack or "D" chunk one day.

The last 3.4 996's, all Cayman S 3.6 and 3.8 engines have plastic coated pistons and a different size and content of silicon in the bores that resist ovality longer (good) but lead to scoring sooner (bad).

Most crankshafts around 100K have worn through some patches of white metal on the big ends and be partly running on the steel backing.

A full Hartech rebuild is not cheap but still competitively priced and reliable but we also have excellent results from engines built to a lower spec where owners cannot afford the full monty (as revealed many times on here).

Much more technical explanations available to all soon.

When we have finished demonstrating our oversized engine options we will have a number of cars available that have had full rebuilds but covered anything up to around 5K that we will be selling (so we can move on to testing newer products and rebuild options for the next models). These may prove an option worth considering.

Baz

 

[Jackzi]

When we have finished demonstrating our oversized engine options we will have a number of cars available that have had full rebuilds but covered anything up to around 5K that we will be selling (so we can move on to testing newer products and rebuild options for the next models). These may prove an option worth considering.

That sounds very interesting indeed Baz...