Boxster 2.5 Engines
Discussion
The youngest 2.5 Boxster will be 21-22 years old and so regardless of things like IMS and bore scoring (both of which are a bit of a non-issue on the 2.5), there are a myriad of other things at this age which could write off an engine (general wear and tear being one). Obviously it's luck of the draw but worth remembering.
I had a 2.5 boxster and apart from coil packs and a labda sensor, it will incredibly reliable. It only died due to a head on meeting with a German winnebago driving on the wrong side of the road...
I had a 2.5 boxster and apart from coil packs and a labda sensor, it will incredibly reliable. It only died due to a head on meeting with a German winnebago driving on the wrong side of the road...
A very brief history covering most of the points raised above.
2.5's will not bore score (without some other major fault like no coolant etc and then they will seize) because the pistons were the original hard iron coated variety that the manufacturers "KS" said were essential for Lokasil to work - and they were right.
We have also never seen a standard N/A one that has cracked or "D" chunked the cylinders (because they were thicker and had much more coolant surrounding them).
The original double row IMS - if it is still going - will probably now keep going.
Great little cars.
Problems generally started when some of the first double row IMS bearings did fail early and the single row replacements were not as strong. Both types suffered from being screened from oil by a cheap seal that once the grease had seeped out might or might not be worn enough to allow a small amount of fresh oil in to keep it lubricated.
A longer stroke crankshaft (but same bore and overall cylinder height and coolant capacity) worked OK with the 2.7 and a bigger bore for the 3.2 was accompanied by a new inner casting keeping the thick cylinder walls and are reliable enough.
The 996 3.4 started the rot because the additional 3mm increase in bore diameter was not done with a similar increase in the O/D - so while the forces pushing against the cylinder wall increased - its stiffness reduced together with the space for coolant (never a good idea).
Cylinders flexed too much and eventually metal fatigued and cracked or "D" chunked.
When the 3.6 increased the stroke (again without increasing the cylinder O/D - possibly to try and maintain enough coolant?) the mix of Lokasil was changed by increasing the amount of silicon grit and its size slightly - to strengthen it - so cylinders flexed less and lasted much longer but by a real stroke of very bad luck - at about the same time hard iron coated pistons process for the cast piston coating was outlawed for H & S reasons in Europe (and dropped by KS) and substituted by plastic coated Mahle pistons of typical Mahle forged variety (the change from cast to forged not being a factor in reliability just a preference of each manufacturer - the salient issue being the change in piston coating that accompanied it).
The screen printed plastic piston coating process was not as secure and the original electroplated hard iron so didn't resist the little gritty bits of silicon that eventually break free from the matrix and damage the plastic coating. The piston face and the bore causing bore scoring. So at the same time that the cracking was greatly improved the scoring emerged as a new issue.
The larger IMS bearing made that problem acceptably reliable (although still shielded by a seal) and during this history Porsche went from almost bankrupt to become the most profitable car manufacturer - kind of paints an overall picture - doesn't it.
If they do need repairing - with Nikasil alloy cylinders replacing Lokasil, the larger IMS bearing, improved coolant flow etc and stabilising the cylinders at the top - rebuilt engines by us largely eradicated the weak spots and allowed us to go on to make increased capacity versions that are proving extremely popular.
Baz
2.5's will not bore score (without some other major fault like no coolant etc and then they will seize) because the pistons were the original hard iron coated variety that the manufacturers "KS" said were essential for Lokasil to work - and they were right.
We have also never seen a standard N/A one that has cracked or "D" chunked the cylinders (because they were thicker and had much more coolant surrounding them).
The original double row IMS - if it is still going - will probably now keep going.
Great little cars.
Problems generally started when some of the first double row IMS bearings did fail early and the single row replacements were not as strong. Both types suffered from being screened from oil by a cheap seal that once the grease had seeped out might or might not be worn enough to allow a small amount of fresh oil in to keep it lubricated.
A longer stroke crankshaft (but same bore and overall cylinder height and coolant capacity) worked OK with the 2.7 and a bigger bore for the 3.2 was accompanied by a new inner casting keeping the thick cylinder walls and are reliable enough.
The 996 3.4 started the rot because the additional 3mm increase in bore diameter was not done with a similar increase in the O/D - so while the forces pushing against the cylinder wall increased - its stiffness reduced together with the space for coolant (never a good idea).
Cylinders flexed too much and eventually metal fatigued and cracked or "D" chunked.
When the 3.6 increased the stroke (again without increasing the cylinder O/D - possibly to try and maintain enough coolant?) the mix of Lokasil was changed by increasing the amount of silicon grit and its size slightly - to strengthen it - so cylinders flexed less and lasted much longer but by a real stroke of very bad luck - at about the same time hard iron coated pistons process for the cast piston coating was outlawed for H & S reasons in Europe (and dropped by KS) and substituted by plastic coated Mahle pistons of typical Mahle forged variety (the change from cast to forged not being a factor in reliability just a preference of each manufacturer - the salient issue being the change in piston coating that accompanied it).
The screen printed plastic piston coating process was not as secure and the original electroplated hard iron so didn't resist the little gritty bits of silicon that eventually break free from the matrix and damage the plastic coating. The piston face and the bore causing bore scoring. So at the same time that the cracking was greatly improved the scoring emerged as a new issue.
The larger IMS bearing made that problem acceptably reliable (although still shielded by a seal) and during this history Porsche went from almost bankrupt to become the most profitable car manufacturer - kind of paints an overall picture - doesn't it.
If they do need repairing - with Nikasil alloy cylinders replacing Lokasil, the larger IMS bearing, improved coolant flow etc and stabilising the cylinders at the top - rebuilt engines by us largely eradicated the weak spots and allowed us to go on to make increased capacity versions that are proving extremely popular.
Baz
Edited by hartech on Saturday 10th April 10:30
Baz great post. Not looking just yet, but as a drop the car off then pick it up when finished, what is a ballpark figure for that work on a 986? Mine is on 120k and runs well, but has a weeping RMS and at some point will need major engine work as I intent to keep it for many more years (my first Porsche and had it for almost 5 years).
We are working on a few videos to expose the causes behind common failures (that many others misinform about) and this will include the RMS. We do have info on it in a long report available FOC from admin@hartech.org but briefly.
Due to the need to make an engine casting mould that will survive the huge casting pressures needed for Lokasil to work - the hole that the RMS fits in is not machined at the same time as the holes for the crankshaft and as a result is usually off centre by a few thousandths of an inch.
The off centre distortion of the RMS allowed weeping which Porsche supplied a different seal for that has a centre devoid of a soring (to tension it onto the crank journal) but instead which is strong enough to remain at the right diameter and allow itself to distort the supporting seal structure off centre so the seal now runs in line with the crankshaft journal.
If you still have the original seal then a change to the new one might be all you need to do.
If and when you need a new clutch, taking the IMS seal off in situ may be all you need to prolong the life of that bearing as well.
Using a good quality oil - slightly thicker in viscosity than the manual states for newer tighter engines and changed more often - may also preserve the life of the engine even longer.
There could be an argument with a 2.5 that it might turn out cheaper to await a failure that needs the engine rebuilding than doing it too soon. It is a bit of a lottery but for the 2.5 on average that should be a much higher mileage than you are presently on. For a 3.2 - still probably higher mileage - but for a 3.4 and bigger - failures occur much sooner and often involve the need to replace many more parts and leaving it too late can cost more than a timely pre-emptive rebuild. So for them - if - like you - the car is a keeper - it can be more cost effective to choose a time and date to rebuild it - save up for it and get it done before too many new parts are required (particularly the crankshaft).
Depending on how the car has been abused or not - for 3.4's upwards these mileages usually start around 80 to 100K and to encourage owners to consider that we introduced our capacity conversions so for little extra cost they get back not only a car that will last but is also nicer to drive, less strained (unless used always flat out) and that is more economical (due to better thermal efficiency at the typical driving revs and throttle openings most drivers use on public roads).
Bu it is is a lottery and the newer the model the more of a lottery it becomes. Although there was always a variation in the distribution of hard silicon grit in Lokasil (which all the cylinder have in these models) the higher the power and smaller the coolant space - the more prone they are to causing problems while the plastic piston coating on later engines (there to protect the piston and bore when the gritty particles escape the cylinder surface) can also wear off prematurely, peel off or pick off in patches after which the alloy piston surface has no protection against damage. So if a later engine had really good cylinders and piston coatings and the car was normally driven and well maintained it might last over 180K or more before having problems. If on the other hand it had poor silicon distribution in the Lokasil bores, poor piston coating and was driven abusively by some owners - they have been known to fail at around 30 to 40K.
The main issue therefore with your 2.5 will be the IMS bearing and if it has lasted this long that may just keep going for a lot longer yet.
Plenty more about all this in our free report together with pictures (if you have the time and patience to read through it) on the 4 main problems with these engines and hopefully a more reader friendly version following with our videos currently being made.
Baz
Due to the need to make an engine casting mould that will survive the huge casting pressures needed for Lokasil to work - the hole that the RMS fits in is not machined at the same time as the holes for the crankshaft and as a result is usually off centre by a few thousandths of an inch.
The off centre distortion of the RMS allowed weeping which Porsche supplied a different seal for that has a centre devoid of a soring (to tension it onto the crank journal) but instead which is strong enough to remain at the right diameter and allow itself to distort the supporting seal structure off centre so the seal now runs in line with the crankshaft journal.
If you still have the original seal then a change to the new one might be all you need to do.
If and when you need a new clutch, taking the IMS seal off in situ may be all you need to prolong the life of that bearing as well.
Using a good quality oil - slightly thicker in viscosity than the manual states for newer tighter engines and changed more often - may also preserve the life of the engine even longer.
There could be an argument with a 2.5 that it might turn out cheaper to await a failure that needs the engine rebuilding than doing it too soon. It is a bit of a lottery but for the 2.5 on average that should be a much higher mileage than you are presently on. For a 3.2 - still probably higher mileage - but for a 3.4 and bigger - failures occur much sooner and often involve the need to replace many more parts and leaving it too late can cost more than a timely pre-emptive rebuild. So for them - if - like you - the car is a keeper - it can be more cost effective to choose a time and date to rebuild it - save up for it and get it done before too many new parts are required (particularly the crankshaft).
Depending on how the car has been abused or not - for 3.4's upwards these mileages usually start around 80 to 100K and to encourage owners to consider that we introduced our capacity conversions so for little extra cost they get back not only a car that will last but is also nicer to drive, less strained (unless used always flat out) and that is more economical (due to better thermal efficiency at the typical driving revs and throttle openings most drivers use on public roads).
Bu it is is a lottery and the newer the model the more of a lottery it becomes. Although there was always a variation in the distribution of hard silicon grit in Lokasil (which all the cylinder have in these models) the higher the power and smaller the coolant space - the more prone they are to causing problems while the plastic piston coating on later engines (there to protect the piston and bore when the gritty particles escape the cylinder surface) can also wear off prematurely, peel off or pick off in patches after which the alloy piston surface has no protection against damage. So if a later engine had really good cylinders and piston coatings and the car was normally driven and well maintained it might last over 180K or more before having problems. If on the other hand it had poor silicon distribution in the Lokasil bores, poor piston coating and was driven abusively by some owners - they have been known to fail at around 30 to 40K.
The main issue therefore with your 2.5 will be the IMS bearing and if it has lasted this long that may just keep going for a lot longer yet.
Plenty more about all this in our free report together with pictures (if you have the time and patience to read through it) on the 4 main problems with these engines and hopefully a more reader friendly version following with our videos currently being made.
Baz
Another great reply - thanks Baz.
Mine is a 2001 2.7 and one of the last with the stronger IMS bearing according to the VIN check. I will keep driving it until it needs some major work - anything where the gearbox or engine needs to be dropped (clutch, IMS or other major work) will likely result in me going for a big upgrade/rebuild.
I have a thread running on here with the mods so far, but distant future plans include a larger engine. Being a 2001 with the electronic throttle there are plenty of 911 engines that are compatible, but these are expensive and would still need work to ensure it is in good health. Enlarging and tuning the 2.7 could be an interesting alternative and probably cheaper...
Mine is a 2001 2.7 and one of the last with the stronger IMS bearing according to the VIN check. I will keep driving it until it needs some major work - anything where the gearbox or engine needs to be dropped (clutch, IMS or other major work) will likely result in me going for a big upgrade/rebuild.
I have a thread running on here with the mods so far, but distant future plans include a larger engine. Being a 2001 with the electronic throttle there are plenty of 911 engines that are compatible, but these are expensive and would still need work to ensure it is in good health. Enlarging and tuning the 2.7 could be an interesting alternative and probably cheaper...
DanG355 said:
Another great reply - thanks Baz.
Enlarging and tuning the 2.7 could be an interesting alternative and probably cheaper...
Would think your best option would be a used 3.2 if you could source one reliably. You could spend an awful lot of money for something little or even no more effective.Enlarging and tuning the 2.7 could be an interesting alternative and probably cheaper...
Possibly, but a decent 3.2 engine is £3k and then you’d want it checked over and serviced and still need it fitting and possibly some modification to mate it to the 5 speed 2.7 gearbox. Then it would be 260ish bhp rather than 220bhp for a 2001 2.7. I wonder what m £5k would achieve if spent on rebuilding and upping the capacity on the original 2.7 - if it could be done?
Hi Baz,
How about the "cracked cylinder head" issue, a.k.a "Milkshake" situation in the oil... I always assumed this is mostly MY2000 models on 2.7 and 3.2, as probably only saw one 2.5 with rebuilt-engine due to this.
- Actually, the 2.5 I saw, rebuilt by you guys many moons ago.. It was brilliant by the way, still going strong"
How about the "cracked cylinder head" issue, a.k.a "Milkshake" situation in the oil... I always assumed this is mostly MY2000 models on 2.7 and 3.2, as probably only saw one 2.5 with rebuilt-engine due to this.
- Actually, the 2.5 I saw, rebuilt by you guys many moons ago.. It was brilliant by the way, still going strong"
DanG355 said:
Possibly, but a decent 3.2 engine is £3k and then you’d want it checked over and serviced and still need it fitting and possibly some modification to mate it to the 5 speed 2.7 gearbox. Then it would be 260ish bhp rather than 220bhp for a 2001 2.7. I wonder what m £5k would achieve if spent on rebuilding and upping the capacity on the original 2.7 - if it could be done?
Pretty sure the 3.2 hooks up to the 5-speed box fine. No mods needs.Actually increasing the capacity of the 2.7 would be comfortably in excess of £10k at all the engine builders I am aware of. I seriously considered sourcing a gen 1 3.4 Cayman with a scored engine (very similar engine in most relevant regards) with a view to a rebuild with increased capacity and it was around £15k including VAT. Without naming names that was not the most expensive option (which would have been £20k plus), though I thought it the best.
You may prove me wrong, but would be totally amazed if you could find someone to rebuild a 2.7 properly and with increased capacity for anything even close to £5k. £5k only gets the most basic of internal repairs and rebuild. A quick and dirty resleeving of a cylinder or two with steel rather than something nice like Nikasil plus gaskets and maybe crank shells if you're lucky is all £5k will buy you, if even that, at the rebuilders I'd be happy to use. If you can get mates rates or know of some unusually cheap but still decent quality outfit that will charge far less than the market norm, well, I suppose fair enough!
(All numbers inc VAT)
£20k!! Blimey - suddenly those second hand 911 engines at £6k to £8k don't look such bad value... My thoughts were that if they are rebuilding an engine they could use different parts to increase capacity or at least tune for more power, but it sounds like you have researched this more thoroughly than me and those sort of costs would definitely be prohibitively high.
The good news is that according to Pelican Parts, a 2001 Boxster is very flexible in the engines it is able to accept from the Porsche range.
The good news is that according to Pelican Parts, a 2001 Boxster is very flexible in the engines it is able to accept from the Porsche range.
Even the most very basic of rebuilds is £5k plus at all the places I would consider using (obviously can't comment on every shop in the land).
The absolute easiest way to increase capacity, would be a stroker crank, but the cranks are a few thousand-plus second hand from what I understand. I'm not an expert in rebuilding, but I would think you may well need to replace the rods and pistons, hone the cylinders etc for that most simple approach.
The cylinders are integrated into the block and from what I understand are not amenable to simply boring out (open deck, thin walls, wrong materials etc), so you'd need to machine the block to take new liners. Here in 2021, this is all very expensive.
Which is why I think a 3.2 is your best option. It's a pretty reliable version of the M96 lump. Honestly, given 986 values, I think better yet would simply be sell the 2.7 (remove any expensive aftermarket parts first if relevant) and buy the 3.2. Will be the most painless and cost effective route.
The absolute easiest way to increase capacity, would be a stroker crank, but the cranks are a few thousand-plus second hand from what I understand. I'm not an expert in rebuilding, but I would think you may well need to replace the rods and pistons, hone the cylinders etc for that most simple approach.
The cylinders are integrated into the block and from what I understand are not amenable to simply boring out (open deck, thin walls, wrong materials etc), so you'd need to machine the block to take new liners. Here in 2021, this is all very expensive.
Which is why I think a 3.2 is your best option. It's a pretty reliable version of the M96 lump. Honestly, given 986 values, I think better yet would simply be sell the 2.7 (remove any expensive aftermarket parts first if relevant) and buy the 3.2. Will be the most painless and cost effective route.
F6C said:
You may prove me wrong, but would be totally amazed if you could find someone to rebuild a 2.7 properly and with increased capacity for anything even close to £5k. £5k only gets the most basic of internal repairs and rebuild
(All numbers inc VAT)
Yup, you are not wrong. My old 2.7 had an engine rebuilt back in 2015. it costed 5k (with 1 year warranty). Back in time, re-conditioned engines were around 3.5k with 6 months warranty. I think it would cost more than 6k now, with basic rebuilding, for any further modifications you would need to spend more £££, which is to be honest pointless. (All numbers inc VAT)
I'm a little late on this thread, but my early 1999 986 2.5 has been a great little car and very solid and reliable (aside from a current niggling hot start issue which is likely sensor related) and drives beautifully. For that year, no worries with IMS.
I test drove a 2008 987 Cayman 2.7 gen1 last night and felt a preference for my 986 (not that the Cayman isn't lovely) which was interesting. I prefer the sound of the 986 too. The Cayman would be an addition, not a swap.
I test drove a 2008 987 Cayman 2.7 gen1 last night and felt a preference for my 986 (not that the Cayman isn't lovely) which was interesting. I prefer the sound of the 986 too. The Cayman would be an addition, not a swap.
Gassing Station | Boxster/Cayman | Top of Page | What's New | My Stuff