Knackered old Porsche with loads of miles - 996 content

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Just over 2K miles done last weekend, but this time for fun rather than work. I did my usual summer break thing of going on a Rally - which of course is a brilliant excuse to go mad in the sticker shop at work:



Some awesome kit on the trip with my nearly two decade old Porsche!


But it gave a good account of itself and arrived in the first group at nearly every check point.



Didn't even look out of place rolling around Monaco:


From Martini Porsche to Martini Audi:


It looked a bit second hand by the time we were nearly home:


And spent most of the south of France with this alarm on:


But even with that it completed the trip having used no coolant and only 200ml of oil. The rate at which it covers ground still amazes me, even with a massive power deficit to some of the cars we were with it still held it's own and was never left behind. Perhaps more impressively less than 24 hours after we got back it was in use again dropping some bits off and taking me to a meeting..... having not even opened the engine cover since we got back.

Now if only there was a large capacity bladder mod I could probably keep up with the level of endurance it has now

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CornedBeef said:

Glad to see it's all working nicely after the rebuild. You're threads claimed another victim, I put down a deposit on a red 996 this afternoon!

It didn't miss a beat!

Congratulations on your purchase, which one have you gone for? You'll have an awesome time with it, they are brilliant, brilliant things!

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stevesingo said:

Poppop,

How hot is hot? Given you have done such a thorough job of improving the cooling, I'm a little surprised TBH. Unless you have set the warning threshold lower than what most would consider hot.

"Engine Is Hot" alarm is on at 99 degrees, which is a similar temp to what most normal 996 reach idling in traffic. Considering we were moving at some speed in a 39 degree ambient I'm pretty happy with that. If the cooling system will hold it within 60 degrees of ambient at a sustained load that's pretty good!

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CornedBeef said:

A guards red aero kitted Carrera 2, 1998 with a few extras! When I get to collect in a few weeks I'll stick a thread up, I'm so bloody excited. I've wanted one since I was about 12 years old, so its kind of a dream fulfilled

Wonderful! They look so good in Guards Red! I've had mine for years and still get a bit of a thrill when I walk past it so I know exactly how you feel!

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ooid said:

I was a bit shocked to see that too though, considering the some speed maybe a little bit more than 70ish? (), it usually stays just in the middle, as long as you keep moving on open roads?

The gauge you see on the dash isn't representative of the actual coolant temp the engine is at. The zero of the 80 is about 92 degrees C and the RH edge of the zero is about 102 degrees C actual coolant temp. The high speed fans don't even click in until this point on the standard ECU calibration. It's not unusual for standard cars with air-con to see 104 degrees in traffic. In high 30 degree ambients the standard two rad cars are fairly close to the limit of their cooling ability.

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Frogmella said:

Sir PPBB, this thread has been one of the most enjoyable and inspirational I have had the pleasure to read on these forums, thanks!

Quick pick of your brains, I live in Florida so my 997 sits in mid-high 30c temps for half of the year. Would you say it would be wise to install an extra rad? I appreciate we are talking about 2 different generations of car here but I would love to draw upon your knowledge.

For the most part no but that is with a pinch of salt. If the car isn't overheating in traffic as is then adding the centre rad won't help or make much of a difference as it has no fans on it. The centre rad is really for cooling during periods of high load at speed e.g. fast motorway cruising or circuit use. However the centre rad does help get the bulk temp of the coolant down MUCH quicker once you are moving again so in that respect it can be very useful.

The most important thing is to make sure the fans are working, rads are in good order and clear of debris and if you so desire you can fit a low temp thermostat which whilst won't help the maximum temperature achieved in traffic it will reduce the starting temperature so on average reduce the overall coolant temperature average.

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ooid said:

Cheers. I've always heard they got near left side of the 0 in higher ambients, but never actually heard of that high while cruising at fairly good speed. Were you able to check in evo what was the oil temperature in that moment?

Put simply you have about 150KW going into the coolant system at 130mph cruise, the oil is cooled via a water oil heat exchanger so the coolant system has this additional heat to lose as well. In a 20 degree ambient on my car this gives a stable coolant temperature of 80 - 84 degrees or so, in a near 40 degree ambient it gives 95 - 99 degrees. Not a lot you can do about that as it's a function of ambient air temperature and heat transfer for a given surface area of radiator. What I can say from experience is that a standard car would be another 10 degrees up on this. At this the oil temp is around 120 degrees C which shows just how efficent the little heat exchanger is.

The ideal point for cooling is around 80mph as this gives the best air speed through the rad ducts for the amount of power being used and therefore heat the cooling system has to deal with. At this in a 20 degree ambient all cars in good health should run on the thermostat temperature.

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JS1500 said:

Interesting stuff.
My 996 overheated on the way to and from getting some new tyres fitted at the weekend. Believe it is the driver's side radiator leaking...but fans didn't seem to be coming on...requires investigation! Wondered about the possibility of fitting a centre rad too...

Did it actually overheat in terms of boiling over and steam or did it just show high on the gauge/start flashing the red light at you?

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BrotherMouzone said:

PPBB,

My 3.4 C2 has had a FVD sump fitted (actually after reading one of your threads at the other forum helped with my decision); on track day do you add additional oil or just top up to the 'max' level?

I am going to take my car to Thruxton and it's got many long high speed sweeping corners (110mph+), hence my question.

Thanks.

Just top up to the max level, due to the sump being deeper the max on the dipstick is now +0.6L or so more than the standard max on the dipstick...... if that makes sense?

Mine has been on Thruxton with no issues however keep an eye on your oil pressure gauge on the first couple of laps and if you see it sinking during long corners then don't continue to push on or you will have issues, depending on your engine setup, number of scav pumps etc. you can have issues with clearing the oil back to the sump.

Having said that if you are on road tyres you are extremely unlikely to have any sort of issue

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JS1500 said:

On the way there the light started flashing just before I reached my destination. Just as I parked up it began pishing coolant from the driver's side radiator. KwikFit said the radiator had a hole (genius) and they couldn't do anything about it so put my new tyres on and topped up the coolant. Car had been sitting cooling for three hours so thought the six miles home would be ok...but half a mile from home the light started blinking again and I saw a wisp of steam in the mirror. Boiled over and rad unsurprisingly still leaking. Pulled over, let it cool, topped up with water and got it home. Ordered a new rad.
Think the fan might be buggered too...

If the rad is holed enough that the cooling system can't hold pressure then it's very likely to boil over unfortunately. The flashing light is coolant level low, solid is an overheat so it's likely a combination of loosing quite a bit of coolant + no system pressure is what caused it rather than the actual engine temps getting silly high.

Change both rads if you are doing one, it's easier to do them all at once and they are fairly cheap things so it's not worth getting all the front end apart to change just the one unless the other is fairly fresh. If they've never been done it's likely they have rotted from debris stuck between the air-con rads and the coolant rads.

If you switch the air con on and the low speeds fans don't activate then it is likely the fan resistors have died. The high speed will still work but not the low. Suitable resistors are available from RS for a lot less than Porsche

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eltax91 said:

Any chance of engine damage/issues if it gets hot like this and spits its coolant out?

Usually no, the head gaskets/head sealing on the M96 is pretty robust. Later cars with plastic coated pistons will be more prone to damaging the coating and therefore having bore scoring issues some time later than early ferrous coated piston cars though. They can briefly do 120 degrees if they aren't put under load without much issue.

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I've done a few odd jobs over the bank holiday weekend. Firstly the car is due front wheel bearings so I've made a start building up some spare uprights ready to swap on. I want to make a few mods to these for strength so not done yet but at least one is dipped, crack tested and assembled with a new bearing:



The hub was also dipped, crack tested and checked for excessive run out before being pressed (or pulled more accurately) into the bearing.



I also got round to fitting the OMP wheel I ordered quite a while ago. Red is definitely a better match for a Porsche interior than yellow!



The OMP horn push was a bit OTT though but a bit of carbon solved that:



Has made a very positive difference to the seating position as it's a good 55mm further towards the driver than the original wheel was. If nothing else it's a good stand in whilst I get the original wheel re-trimmed and draw up a spacer to move that a bit further out.

It will need discs shortly too, I would like to go to floating discs on the front but when the OE Porsche 997 350MM Turbo disc can be had for around £120 it's hard to justify it. Either way 60K miles from less than £250 quid of brake discs is pretty good going

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Dammit said:

I like the idea of the wheel being closer to me, how tall are you PPBB?

As Paul says a smidge over 6ft. I have quite long legs though which means I find in order to get the leg position I need to heel and toe comfortably I end up with the seat fairly upright. The new wheel has really helped as I can tip the seat back a little more obviously it's a small thing as I've managed to do a quarter of a million miles with the old wheel and not exactly suffered but it's always nice to tweak the fit a little

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CornedBeef said:

PPBB, finally picked up my red 996 over the weekend! Absolutely over the moon with it and spent the whole weekend driving nowhere in particular.

Mines a 1998, so I know I've got the dual row IMS - do I benefit from the ferrous coated cylinder liners?

Yes you do, although it's the pistons which are ferrous coated rather than the liners. The pistons in all 996 have an anti scuff coating on the skirts. On the early cars this was a ferrous coating which was originally designed to work in Alusil and Lokasil bores, due to the nasty chemical shiz involved with getting this on the skirts and the general cost down on the later 996 this was changed to a plastic coating - which doesn't survive any where near as well and arguably whilst not the "cause" of bore scoring in a technical sense is part of the reason why later engines die of bore scoring. My 3.4 had got hot a lot of times, been launched hard after sitting and generally abused (i.e. I did all the things you aren't supposed to do) and yet had absolutely no scoring at 500K KMs.

Enjoy the new purchase. They really are a great thing!

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Spitfires said:

This is a truly epic thread about a truly epic car, and has been a massive contributing factor to my bothering to sign up to PH.

The level of engineering on this car and your knowledge is staggering (and to be expected given your job I presume) and I salute you for taking the time to post.

Thank you - I never really gave the car a second thought as it has developed over quite a lot of time to the point it is at today. When something wore out we just made a better "thing" and a lot of the big things are just a by product of what I have been doing with it. It was only when several people told me I really should share it that it twigged it probably was quite a cool thing

I'm amazed by the response it has got and really enjoy sharing bits about it. It really is a pleasure

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Sa Calobra said:

What's the total mileage tally now?

12,700...... on the new motor - which isn't bad since the end of April but I'm not using it enough this year to be honest, it's managed a couple of two thousand mile weekends though, can't have it getting lazy! 320K something in total now but I'm not going to make it past 350K before the year is out I don't think.

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Beautiful car! They look so good in guards red!

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nsa said:

What rate ARBs are you using please? I picked up some H&R 26/23mm ones for half price and I'm a bit concerned they are going to be too stiff. I won't fit them until I have upgraded the rest of the suspension.

I also bought my 996 based in part on this thread and Richard's Project Leichtbau over on 911uk.

Mine are 25/24mm which I think are about right for my car but my dampers have much firmer compression damping and a higher spring rate than a standard car so you would run a thicker bar on a softer damper/spring combination to get the same effect. I'd be tempted to give them a try to be honest, I suspect they'll work pretty well, especially if yours is on standard rather than sports/M030 suspension.

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As I mentioned above the car is due wheel bearings so it's apart at the moment, the wheel bearing has failed in a fairly normal way but not at a particularly high mileage:



As you can see it has lost it's grease due to a failed seal and as a result got very hot, you can see the bluing from the heat in some areas. The other side is fine so on the new uprights I have fitted the same spec of bearing as these and I will see if I have another failure, hopefully it is just a one off!

The new uprights are now built up ready to go on, I have carbon wrapped the outer face of the steering arm and outer face of the damper arm on these as both areas I have experienced some cracking on. The 996 uprights are hollow cast aluminum which is great for weight but they do seem prone to cracking from the top of the caliper boss across the damper arm. This may be just because on my car they experience much more load as the suspension is much stiffer and the angle the damper runs at a little more extreme than standard as my top mounts move the pickup point. To help prevent this I took a hint from Renault and their 2009 gearbox which was a thin wall Ti casting with carbon wrap on the high load areas (between the rocker posts etc.) Carbon wrapping boosts the stiffness of a thin wall casting significantly and as such reduces flex which can cause cracking, the effect of carbon wrapping in terms of stiffness increase is far more than just the stiffness of the thin layer of carbon itself, because of how it is bonded for the casting to flex it must pull apart the many hundreds if not thousands of bonds in the carbon to do so. It's a quick and easy fix for this sort of thing as well as a viable repair for small cracking/fatigue failures in castings as the crack can be stop drilled etiher end then over wrapped with carbon.

It's nothing fancy on my uprights, just a wet lay of four layers of 2/2 twill, the uprights surface is keyed using an abrasive wheel in opposing directions to provide a well keyed surface as this is key to providing useful structural reinforcement. Here's one curing:



Then roughly dressed:

It doesn't need to be pretty as it'll never really be seen.

Both uprights built up ready to go back on:


I've upgraded the original caliper mounts to use a Ti stud as the caliper fixing rather than a cap head as the cap heads corrode in situ making them a pain to remove and meaning the brackets are only really two or three use before the threads fail on removal of the mounting bolt. As an M12 K-Nut is the same OD as an M12 cap head the calipers require no modification to work with this setup. In hindsight the design of these is a bit of a cock up as it would have been better to make the bracket deeper at the ends where the caliper mounting bolt holes are located so the threaded hole was blind rather than open which in turn would have stopped road debris etc. getting to the rear of the bolt and causing it to corrode..... although I suppose solving it with Titanium is more flash than simply making them from a bigger billet and a bit heavier


This saves about 5 grams over a cap head

Also fitted new wheel speed sensors:

As life is too short to try to salvage them out of the old uprights to reuse

I'm going to do front drive shaft service whilst it's apart and fit a new set of track rod ends as whilst neither are due for a while I don't want to take it apart in another 15K miles to do them so they can get an early service and the front should be good for another 50K miles

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I've had a productive morning solving an ongoing problem with the car. The rear undertray will not stay put at sustained high speed, it always finds some way to make a bid for freedom, either by cracking allowing it to drop into the airflow under the car enough to shred it or by pushing the plastic nuts off. So I've made a bit of a motorsport bodge to fix it, I've carbon fibre'd it;

It's not a pretty piece but then as it's under the car it doesn't need to be. To put some stiffness and strength into it which will hopefully stop it getting a flap on or cracking I've laminated two layers of 2x2 twill onto a new rear undertray. This has increased the stiffness hugely whilst still alowing it the bit of flex required to fit it, it should also completely stop it cracking and it's not really added any significant amount of weight either:

Setting having been cooked off with a hot air gun - circuit style :


Set:


Flapped over to take the high spots off - it's a wet lay onto a component so it is never going to aesthetically pleasing but if it stops it falling off I'll be happy!:


To solve the plastic nuts issue I've cut a proper thread into the studs which the plastic nuts originally fitted onto and drilled out and riv nutted the bracket which hangs off the gearbox mount. This will allow me to nut and bolt the undertray on with M5 K-Nuts and penny washers. In theory it shouldn't be able to get off then regardless but we'll see.

The theory for why it keeps getting off is the car runs a much lower ride height than a standard Carrera along with no front splitter and as such the air speed under the car is higher. The 996 Turbo runs a different rear undertray with some air take ups in it and the 997 extends the undertray back to the rear cross member covering the gearbox entirely - that might be a future mod!