RE: the engine cost... $15-20k isn't all that insane by comparison to other modern engines - an LS7 crate motor is $17k and makes similar power per liter to the Porsche. 315HP for 219 cu vs 550HP for 427 cu.
It is only insane in terms of depreciation... when you can buy a running 996 for less than an engine rebuild.
Reading this thread makes me think that this could be a very reasonable repair for someone with the tools/time/skills to DIY it. Water under the bridge at this point - but still - I wouldn't be afraid of buying one of these if I could spend some time building my confidence (and special tools collection) that I could tear it down myself.
If I were in Boxhead's shoes - I'd have to really, really love the car to not just have a DIY party with friends to throw a junkyard motor with a 1yr salvage warranty in it and move it along to the next guy ASAP.
The problem is the amount of time it takes to effect the repair - the current estimate for the work at the shop is around the 60h mark by people who know what they're doing. The car is my DD so I can't futz about with the engine for a month or two to take it apart and fix it up, and that's assuming I'm willing to buy the necessary tools.
I thought about throwing a motor in and selling it on, the problem is that even throwing a junkyard motor in is something like 20h worth of work with no guarantee that said motor is any good. That way I'd still be upside down on the car when selling it, just about 2k-3k less with a motor that's an unknown quantity.
Trust me, I thought about this long and hard...
A well built 911 engine can last 10 to 15 years easy.
My dad has built a number of motors for the earlier cars up to '88 that have been tracked and driven regularly. If taken care of they last as long as any other motor.
My brother's 69 911s, has just had the motor pulled out due to low pressure when warm. This engine was built close to 20 years ago. Basic specs were 2.7 litres, fairly low compression, I think 9.5 :1 or less, and it was always well maintained.
Don't let the costs scare you. I bet if you wanted to run a well prepared LS-1 motor the costs would be very similar.
Well, these are aircooled engines though - plenty of experience with those, but so far there seems to be less experience with high mileage on M96s.
Oh, and we just broke the $10k mark. Shop strongly recommended new rod bearings - they warned me about that, so it wasn't entirely unexpected. Still awaiting a photo, but supposedly the chain guide for the chain running between the crank and the IMS was in really bad shape. Another "just about caught this in time" thing.
Giant Purple Snorklewacker wrote: RE: the engine cost... $15-20k isn't all that insane by comparison to other modern engines - an LS7 crate motor is $17k and makes similar power per liter to the Porsche. 315HP for 219 cu vs 550HP for 427 cu. It is only insane in terms of depreciation... when you can buy a running 996 for less than an engine rebuild.
My motor costs were for us building the motor... only specialty items were farmed out. (very minimal.)
I dont see 20h to replace the motor. granted not as much wiring but it takes us 2hours to drop the motor in dad's 1983... tons of practice etc...
20 hours of book time sounds completely normal. Last engine job i remember doing as a tech was 23hr to replace an engine in a dodge ram which probably had 'less access issues'.
So what is it about a porsche engine that makes it expensive other than the fact that it's apparently falling apart at what i would probably consider 'low miles'? Just ludicrous parts prices?
The parts prices aren't too bad - out of the $10k, it's a little over $3k for parts.
Even the aircooled engines take quite a while to strip down, but are easy in comparison to the watercooled ones. The M96 is a huge pain to strip down to level the shop is going (basically down to the crank cradle, which is going to be left alone as they reckon the crank & crank bearings are good for 300k-400k miles) and that's where the majority of the labour time is going. You can rebuild multiple domestic V8s or Miata engines in the same amount of time, and we're not even doing a proper rebuild here, just a refresh.
To me this is looking like Porsche likes to leave little Easter Eggs in their engines - keep in mind that we have to go through all this effort because you can't get at the IMS chain guide otherwise. So in essence, all this work is being done to replace a factory part with an uprated $300 part. Most, if not all of the other chain guide as fairly easily accessible in comparison.
Alldata shows 26hr to get to the IMS bearing which would include getting to those guides i'm guessing. $100/hr would be $2600. Is the shop super expensive on labor rate?
Engine overhaul with auto and AC is 32hrs.
Not trying to pick this apart with any particular agenda, I'm just curious. I've written up a LOT of tickets as an estimator for Manheim auctions so i'm intimately familiar with determining total cost, I just dont have a lot of detail on what all is being done/included.
You can get the IMS bearing pulled out without stripping down the engine to the crank cradle, which is what the shop is currently doing.
Pulling the engine out to address the IMS bearing (btw, the shop I use will pull the transmission instead of pulling the engine for the IMS bearing, which is much cheaper) allows to access most of the chain guides and tensioners so if only the cam chains were affected, we wouldn't be in so deep and the 26h are more than realistic.
Unfortunately it turns out the pad on the chain guide/tensioner for the crank to IMS chain can't be accessed without an (almost) full strip down. If the 32h you quote for the overhaul is ex engine removal, then we're pretty much in the same ballpark - 32h for a 996 engine overhaul including engine removal sounds way too low, I've seen 40h quoted for a strip down and build up multiple times excluding engine removal.
The hourly labor rate is a little higher - IIRC they're more around the $120 mark - but in line with what the non-Ferrari specialists around here charge.
Gotcha. My rough figures look a lot like yours now.
For the record i dont think it's out of line based on my experience. I've done engines in old-ish vehicles that were $8k tickets and were nothing near the amount of work or requiring any specialty anything.
Still, this whole thing makes it look like 996s should be even cheaper than they are.
so yesterday I was at the Motorsports Expo in charlotte. INS engineering was there selling a few things, one of which was a kit for 996's to repair/replace the IMS bearing...Supposedly a better than factory repair with no need for being done again... They had some really nice stuff there.
The good news keep on coming - the last batch of parts were inspected and we're getting closer to having the engine go back together. Apart from a little hiccup.
The heads came back from the machine shop, they're in good condition, checked out and can be used as is. Oil pump is also good, so that can go back as is.
The little hiccup? One of the two sprockets on the intermediate shaft is severely worn. Oh, and they're non-replaceable so we're currently on the hunt for a good used shaft as a new one is, err, a tad expensive...
Yeah, so the news still isn't too good on the engine front.
Small block Chevy time. http://www.renegadehybrids.com/911/911.html
No it isn't.
If it makes you feel even better, in his dark days, my Dad paid to have a Super Stock engine built for him. It was near 14K and it lasted six passes. Not seasons, passes. So, like 60 seconds.
That's the crapshoot. Could have just as easily been trouble-free for many thousands of miles. 20/20 hindsight makes the 996 TT look like a reasonable option. I have no room to criticize since I have more than my share of scruffy p cars. Good on ya for giving it a go and being realistic on what could go wrong.
Thanks for calming my urge to have a 911 as my only car.
For anyone interested, spend some time here - http://flat6innovations.com/ - click on the "Featured Technical Artilces" if you want a sense of what the potential problem areas are on these M96/M97 motors, and what it takes to fix them. PCA estimates are that less than 5% of the motors end up with a failed IMS - but, of course, if it's yours....
Youtube has some great vids (one 6 parter) that shows what's involved rebuilding one of these. Extremely labor intensive - specially when you see what's involved getting the pistons/wrist pin clips installed when the 'second' cylinder section goes on. Not easy.
It was reading this that caused me to look '09 and newer for my Cayman to move beyond this engine series.
To the OP - hope they get it back and working correctly soon, so you can get back to enjoying it. It is a unique and VERY enjoyable powerplant.
Any chance you could pick the mechanics brains about the failures? Are these a sure thing and something to work into the cost of owning the car? Are there better replacements or is this going to be a 120k service interval item?
I'm not terribly concerned about the IMS at this point. It's a very well known issue and the fixes seem solid. Pretty easy to calculate into the purchase/ownership price.
In reply to mazdeuce:
I already am 
. They kinda have seen this movie before and so far suggest that the likely cause of what they're seeing is adherence to or stretching the official Porsche service intervals and then driving around with contaminated oil for too long, causing the accelerated wear at least on the chain guides. They suggest that the problem shouldn't reoccur for another 200k if I keep on top of the oil changes.
Pretty much everybody seems to agree that the Porsche oil change intervals are too long and it's much better for the engine oil to be changed every 5k miles from a longevity perspective.
In reply to oldtin:
Yeah, with hindsight I would've been better off to sell the Evo first and then buy a 996TT as a replacement. However without knowing if the ergonomics of a 996 would work OK for me, that would've been an even bigger albatross around my neck if it hadn't worked out...
The IMS, guides, updated AOS, D-chunking of the cylinder liners and water pump failures (plastic bits break off and block coolant paths = overheating) are well known problem areas on the M96/M97 engines. If you're going inside one to fix something big, and you're planning on keeping the car -- all of them should be addressed. The AOS can be addressed with the motor in the car, but it's much easier with the motor out. I use a 6-month/5k (which first) mile interval for changes on mine. And if you're tracking the car, the Joe Gibbs DT40 synthetic oil for any hard use.
It's already got a new waterpump and the AOS will be changed out as part of this work "while we're in there". We're pretty much addressing all the known trouble spots while trying to avoid having this mushroom into a complete rebuild.
BoxheadTim wrote: In reply to oldtin: Yeah, with hindsight I would've been better off to sell the Evo first and then buy a 996TT as a replacement.
Are you suggesting the TT is more reliable? Or just more awesome (obvious)?
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