Just the usual, 996 engine rebuild

Just the usual, 996 engine rebuild

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sm34uk

Original Poster:

135 posts

149 months

Sunday 8th November 2015
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Two weekends ago, started up the car, huge cloud of smoke the day before it's MOT. Obviously no point in going for the test, the fact that the road was engulfed with a smoke haze akin to downtown Beirut pointed to the fact that it was unlikely to pass the emissions element! Luckily, the mechanic I use for the girlfriend's car happens to build Subaru race engines so was more than happy to give it a go to at least try and diagnose the problem. So, for a few days last week, in-between other work, he took out the engine and gearbox and began to strip it down.

AOS looked fine so that was discounted and a visual inspection of the cylinder heads showed up nothing either. So there was nothing else for it but to split the case. The only thing that was awry was a split seal on one of the pistons. Have the sent the case away to check for ovalisation but visually it looked fine and the bores perfect. Happy in that all the worse case scenarios seem to have been avoided but a bit gutted that one seal is going to, in all likelihood, end up costing about £3000. I am now on the shopping list of parts to make it worthwhile on the labour front. This poses a few questions as to what exactly I should replace so all help or suggestions appreciated please:

Clutch plate and clutch bearing
Low temperature thermostat
Complete Seal and gasket kit
RMS seal if not included in above
IMS bearing - thoughts on supplier? European Parts Solution via Design 911 or LN Engineering?
Air and Oil Separator
All three timing chains
Full service kit, including Spark plugs

Anything else glaringly obvious I have missed?

Thanks in advance, Rich


mollytherocker

14,365 posts

208 months

Sunday 8th November 2015
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Its likely that the bores will be oval to a degree. I wouldnt be putting the engine back without the Hartech style liner conversion.

jamesx19

26 posts

191 months

Sunday 8th November 2015
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Hi Rich,

What age and mileage is the car? 3.4 or 3.6?

Any excuse to rebuild an M96 with a light weight flywheel, balanced together with the crank and new clutch (sprung plate). Maybe some forged con rods? ARP big end fasteners? New engine and gearbox rubber mounts?

Could end up making it all a bit noisy though.

Jim

sm34uk

Original Poster:

135 posts

149 months

Sunday 8th November 2015
quotequote all
Thanks for the replies, it's a 2002 model 3.6 but has done 172,000 miles (106,000 done by me on the motorways of the UK) so the Hartech route makes it all a bit uneconomical if I'm honest. That is likely to push the bill nearer to the value of the car and luckily for me, the missus is of a view that it and the Karmann Ghia need to go to get a newer 911! Unfortunately I have missed the boat in terms of a GT3 etc but still plenty of nice motors around.

mollytherocker

14,365 posts

208 months

Sunday 8th November 2015
quotequote all
sm34uk said:
Thanks for the replies, it's a 2002 model 3.6 but has done 172,000 miles (106,000 done by me on the motorways of the UK) so the Hartech route makes it all a bit uneconomical if I'm honest. That is likely to push the bill nearer to the value of the car and luckily for me, the missus is of a view that it and the Karmann Ghia need to go to get a newer 911! Unfortunately I have missed the boat in terms of a GT3 etc but still plenty of nice motors around.
Its a quandary that many owners have found themselves in.

My view, and its just my view, is that if you are keeping the car, you should do it properly so that you can forget the engine and enjoy the car to its full.

Imagine spending your 3k then you have more issues in a couple of years and end up having to do it all properly!

Good luck with whatever you do.

BertBert

18,953 posts

210 months

Sunday 8th November 2015
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What's a split seal?

sm34uk

Original Poster:

135 posts

149 months

Monday 9th November 2015
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Thanks MTR but the missus has seen a blue 997 and whilst maybe not this particular car, it will be a 997 in blue!

Not sure if oil seal is the right terminology Bert but on the piston, there is a lip and sitting underneath the lip is a seal and it was this, on one cylinder only, that a piece had separated. Hope that helps, may even try and take a photo this week.

m444ttb

3,160 posts

228 months

Monday 9th November 2015
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mollytherocker said:
Its a quandary that many owners have found themselves in.

My view, and its just my view, is that if you are keeping the car, you should do it properly so that you can forget the engine and enjoy the car to its full.

Imagine spending your 3k then you have more issues in a couple of years and end up having to do it all properly!

Good luck with whatever you do.
Exactly my opinion and why my car is residing at Hartech at the moment to have the full works of:
- Basic engine rebuild
- 6x new nikasil lined ali cylinders
- 6x re-coated pistons
- New IMS + beainr & spindle (997 spec)
- Crank bearing set
- Timing chain set
- Cylinder heads overhaul

My engine is suffering some terrible oil usage and can, if not used for 10 days or so, produce quite the blue haze on cold start. Hartech's initial boroscope says there's nothing wrong so likely some piston rings failing.

Moosh

1,122 posts

220 months

Monday 9th November 2015
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sm34uk said:
Two weekends ago, started up the car, huge cloud of smoke the day before it's MOT.
Did the smoke continue when you drove off or did it stop?

sm34uk

Original Poster:

135 posts

149 months

Monday 9th November 2015
quotequote all
Moosh said:
Did the smoke continue when you drove off or did it stop?
It stopped after a minute or so, initial thought was head gasket and it was burning off water but this was definitely oil based smoke. No coolant contamination in the oil, no fragments in the oil when we drained it off and nothing on the sump plug/strainer.

Moosh

1,122 posts

220 months

Monday 9th November 2015
quotequote all
sm34uk said:
It stopped after a minute or so, initial thought was head gasket and it was burning off water but this was definitely oil based smoke. No coolant contamination in the oil, no fragments in the oil when we drained it off and nothing on the sump plug/strainer.
after the smoke stopped did run okay

sm34uk

Original Poster:

135 posts

149 months

Monday 9th November 2015
quotequote all
Moosh said:
after the smoke stopped did run okay
Yes, although I only went 20 mph back from the garage but seemed fine; wasn't hunting or misfiring and no loss of power that I could detect but I didn't floor it. No warning gauges and temperature was it's usual self

sm34uk

Original Poster:

135 posts

149 months

Sunday 15th November 2015
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Great news over the weekend, absolutely nothing wrong with the engine casing, no delamination of the bores and ovalisation is absolutely minimal. Cylinder heads also had a clean bill of health, no cracks or warping so a skim and the valves need to be re-seated. Final bill is going to be a few thousand due to the likes of the new IMS, RMS, AOS, clutch plate, clutch bearing and timing chains etc. All in all, a fair amount of relief. Did take on board the view of sending it to Hartech but really can't justify that economically with the mileage it has. Just glad it's not off for scrap. Both engineering shops are happy to provide reports of their findings for peace of mind.

Tap450

44 posts

102 months

Sunday 15th November 2015
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sm34uk said:
Great news over the weekend, absolutely nothing wrong with the engine casing, no delamination of the bores and ovalisation is absolutely minimal. Cylinder heads also had a clean bill of health, no cracks or warping so a skim and the valves need to be re-seated. Final bill is going to be a few thousand due to the likes of the new IMS, RMS, AOS, clutch plate, clutch bearing and timing chains etc. All in all, a fair amount of relief. Did take on board the view of sending it to Hartech but really can't justify that economically with the mileage it has. Just glad it's not off for scrap. Both engineering shops are happy to provide reports of their findings for peace of mind.
Might sound silly but are you sure it's not just abit of oil sat in the bore? Has it been using any oil? The flat engines do smoke on start up some times when there's oil in the notes from were it's been stood?

sm34uk

Original Poster:

135 posts

149 months

Sunday 15th November 2015
quotequote all
Tap450 said:
Might sound silly but are you sure it's not just abit of oil sat in the bore? Has it been using any oil? The flat engines do smoke on start up some times when there's oil in the notes from were it's been stood?
The only thing that found was a piston ring/seal that had split; everything else has passed the check! Not sure how much one is, but it's resulted in a large bill but could have been a whole lot worse!


Wozy68

5,387 posts

169 months

Sunday 15th November 2015
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Tap450 said:
Might sound silly but are you sure it's not just abit of oil sat in the bore? Has it been using any oil? The flat engines do smoke on start up some times when there's oil in the notes from were it's been stood?
This is what I thought, I have a friend with a perfectly driveable MOTable 2005 Cayman and it does absolutely the same thing, smokes like a gud un for around a minute when not started for a week or so.

Are you sure you are not spending money for moneys sake?

sm34uk

Original Poster:

135 posts

149 months

Sunday 15th November 2015
quotequote all
Definitely sure, there is smoke and there is something akin to a pall of smoke from a live firing range! Anyway, bit too late now as it's in a million pieces in the garage awaiting a shopping list of parts... The seals and gaskets from Euro Car Parts are £464 before anything else.

Tap450

44 posts

102 months

Sunday 15th November 2015
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To be honest I would only strip the engine if it's got piston slap or using a lot of oil and the bores are scored I'd just keep topping it up otherwise

c4sman

758 posts

153 months

Monday 16th November 2015
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This thread kinda supports my theory that all m96 owners are not crazy as their engines are not all about to implode. 172k miles on a high performance engine sounds pretty good to me and even now the problem is not catastrophic. Sorry that the OP is having to shell out but sounds as if you've had your monies worth.

griffter

3,981 posts

254 months

Monday 16th November 2015
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I'm amazed a broken piston ring hasn't wrecked the bore, but if you've caught it in time, you did the right thing and it's money well spent.