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YOUR RESEARCH996 Possible cracked cylinder or AOS ?
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Check ironically
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Leading evidence: 'Check ironically' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check ironically' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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911uk: 1 discussions
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Hi ,
996 2002 - driven for 10 mins. Lights came on. Go to you mechanic… engine cut out. On restart , managed to park off main road. On restart, huge white cloud of smoke. Turned off. Coolant dropped but not significantly, dipstick clear. But tight oil cap ( couldn’t hear a hiss on opening ) mayonnaise on cap and in the tube. Cracked cylinder I’m thinking. Or AOS. Any info would be greatly appreciated.
@Mark gillow
that doesn’t look like a cracked cylinder at all, a combination of the engine cutting out, huge white smoke on restart and mayonnaise in the filler is very typical of an AOS failure on these.
When the AOS goes it can pull oil into the intake, cause a big smoke cloud and create excessive crankcase vacuum, which also explains the tight oil cap. I’d try removing the oil cap at idle, if it’s very hard to lift off and the engine stumbles badly that points straight at the AOS. The small coolant drop on its own isn’t enough to suggest an internal issue. I wouldn’t run it again until you’ve checked that.
It’s not been run and is awaiting an investigation. Appreciate the response. The car was sitting idle for the best part of a year, I’ve just bought it. I knew that as soon as i woke it up from hibernation that the inactivity could display quite quickly.
Thanks for the response.
Unfortunately, it’s looking like I’ve a cracked cylinder. Bad day. Made the call to Hartech. All booked in for June. I’m sticking with the 3.6 and not upgrading to the 4.1
Grant and Cameron at Hartech were so helpful. They are so good at that call. No agenda. Just honesty relating to price and process. I guess they will go through the whole car and lay it out in real terms.
The car is a keeper for us. It wasn’t a hard decision to go for a rebuild. Financially is tough though!
You've made the right call and are in the right hands. Seriously consider the capacity upgrade........it stings like f*** at first but once you get it back, will be the best bQQb job ever. Hang fire until what they find though. You can easily have a £3k variation on the bill just by other 'whilst you're in there' stuff. If a lot of that isn't needed, then the money saving (and saving on mpg) goes toward the capacity increase.
Err......yes and no. I waited till Hartech had done a full strip and diagnosis of what was required before making any decision on what to go for. If Grant hadn't had a used crank and I'd have had to buy a new one, there's no way I'd have gone for the increase. Also, if I hadn't made my own aircon pipe, that would've put another grand on the bill too. There was also some other stuff Grant & I discussed where I saved a few ££££.
But the biggest factor for me making the decision was around funding from my end of the deal - let's just say I'm a good strategic juggler when it comes to dosh and if I wasn't able to manipulate some money out of thin air, I couldn't have afforded the extra.
As a simple rule of thumb, the capacity increase will be £3k+VAT on top of not having the increase. The decision then boils down too what the standard bill comes to.
I'll give you an example of where folk can go wrong - they'll have a new clutch & flywheel, some new manifolds and back boxes, because those parts are tired and the labour is free to install them during the rebuild. Those parts come to £3k+VAT and because they chose to do that, it wipes them out for the capacity increase.
Me - I'll spend the extra dosh on a new clutch or exhaust when the time comes and I'm back on track with a maintenance fund. You can fit a new clutch 12 months later........you can't increase your capacity 12 months later for the same price.
All what was done/invoice and cost is in this post:
Thread 'Alex's 25,000th Silver Jubilee 996 Ownership Post'
14 Apr 2026
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Thought I'd put a bit of effort in to my 25,000th post on here, seeing as I've been rattling round for 12 years in the same old treasured 996 and recently ran in to 180,000 miles on the odometer. Well, what can I say - it's been an absolute dream full of nightmares and fun and everything in between, meeting some great people along the way and learning so much stuff about not only the 996 but Porsche as a whole, thanks to this wonderful place.
Some of the highs:
Multiple trips down to the French...
Alex
Replies: 20
Forum:
Porsche 911 996 (1997-2005)
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