Bore scoring on refurbished engine

Bore scoring on refurbished engine

Author
Discussion

AlexH997

Original Poster:

265 posts

131 months

Tuesday 21st May 2013
quotequote all
All
How many of you have had your motors suffer from bore scoring again after they've been repaired under warranty?

Does Porsche actually fix the problem or do they plaster over it.

Rockster

1,508 posts

159 months

Tuesday 21st May 2013
quotequote all
AlexH997 said:
All
How many of you have had your motors suffer from bore scoring again after they've been repaired under warranty?

Does Porsche actually fix the problem or do they plaster over it.
If Porsche deals with bore scoring as it has with other serious internal engine issues the engines are not repaired at least not at the dealer. The engine is removed and a factory supplied replacement engine (new or re-manufactured) is installed.

The removed engine is shipped back to Porsche where it may be repaired if it is deemed a good candidate for repair.

With IMS or other serious internal engine problems a few unfortunate owners experienced this twice. Once with the original engine and then again with the replacement engine. One poor soul I believe even had the 2nd replacement engine fail.

AlexH997

Original Poster:

265 posts

131 months

Tuesday 21st May 2013
quotequote all
I sent my car in cos a thought it was suing a lot of oil and pipes were dirty but they said it was ok. The advisor said it would be repaired by their technicians on site.

Luckily mine is ok but all this talk of scoring makes me wonder even if they didn't repair would they fix the cause

Trev450

6,314 posts

171 months

Tuesday 21st May 2013
quotequote all
The way I understand it is that if the engine is repaired within the dealer network, they simply replace worn/damaged parts with new equivalents thereby facilitating the potential for further future failure.

tr7v8

7,186 posts

227 months

Tuesday 21st May 2013
quotequote all
Trev450 said:
The way I understand it is that if the engine is repaired within the dealer network, they simply replace worn/damaged parts with new equivalents thereby facilitating the potential for further future failure.
Correct our Local OPC had a 997 in bits last year when TIPEC did a visit. That was for bad bore scoring on 5 & 6. They just replace the cases & relevant pistons.

spyderman8

1,748 posts

155 months

Tuesday 21st May 2013
quotequote all
Sounds very much like they repair the symptoms but don't apply a cure.

Trev450

6,314 posts

171 months

Tuesday 21st May 2013
quotequote all
spyderman8 said:
Sounds very much like they repair the symptoms but don't apply a cure.
Absolutely. You need to go to someone such as Hartech or Autofarm to limit the chances of future failure.

hartech

1,929 posts

216 months

Tuesday 21st May 2013
quotequote all
I have not seen any evidence of technical changes to a new or Porsche rebuilt engine to eliminate bore scoring - nor any changes to reduce the likelyhood.

We believe the problem is caused by the Lokasil material being particularly aggresive as it wears, the temperature between the piston and the bore too high on occasions (reducing the oil film strength and allowing too much piston face to bore pressure), the type of coating on the pistons (being too soft to resist the interference of sharp or mislodged Lokasil particles), the coolant temperature being too high and the coolant flow resulting in the top of bank 2 pistons (the thrust face) running hotter (which is the side that fails) than the bottom of bank 1 (also the thrust face) which lasts much longer.

When we rebuild engines we do offer to modify some areas that we believe contribute to the problem.

We replace liners with Nikasil plated ones (or re-round and support open deck Lokasil bores to reduce blow bye and reduce piston face temperatures). We can fit a lower temperature thermostat and we increase the coolant flow through the block to lower cylinder temperatures.

We also have an on going serious and expensive research and development programme that has been testing various cylinder bore materials, different pistons and different piston coatings. This is very time consuming as it is neccessary to cover many thousands of miles between each strip, inspection and rebuild. Results one day will be revealed when the programme has been completed.

However - despite a lot of costs, frustrations and set backs - we are getting very close to finding the answers we need to decide on the best or least expensive way forward for the next decade of rebuilding these flawed engines.

We say least expensive because replacing all the cylinders with alloy Nikasil plated cylinders (as used in Gt3's, turbos and even the older air cooled cylinders) is a permanent solution but obviously expensive and we have been trying to find a less expensive way to produce as reliable results.

Porsche didn't seem to provide anything to sort the problem out except to eventually abandon the Lokasil cylinder material and return to Alusil in Gen 2 engines (as used in the 944's and 968's etc). Boxsters up to 3.2 and 3.4 996 engines do not suffer the problem (despite also running in Lokasil) and bank one is much less vulnerable and this gives hope that there is a less expensive answer to be found.

But this leaves thousands of cars vulnerable to expensive rebuilds or replacements which we are still trying to find a less expensive permanent solution for than our reliable Nikasil replacements.


Baz

Gibbo205

3,528 posts

206 months

Tuesday 21st May 2013
quotequote all
hartech said:
I have not seen any evidence of technical changes to a new or Porsche rebuilt engine to eliminate bore scoring - nor any changes to reduce the likelyhood.

We believe the problem is caused by the Lokasil material being particularly aggresive as it wears, the temperature between the piston and the bore too high on occasions (reducing the oil film strength and allowing too much piston face to bore pressure), the type of coating on the pistons (being too soft to resist the interference of sharp or mislodged Lokasil particles), the coolant temperature being too high and the coolant flow resulting in the top of bank 2 pistons (the thrust face) running hotter (which is the side that fails) than the bottom of bank 1 (also the thrust face) which lasts much longer.

When we rebuild engines we do offer to modify some areas that we believe contribute to the problem.

We replace liners with Nikasil plated ones (or re-round and support open deck Lokasil bores to reduce blow bye and reduce piston face temperatures). We can fit a lower temperature thermostat and we increase the coolant flow through the block to lower cylinder temperatures.

We also have an on going serious and expensive research and development programme that has been testing various cylinder bore materials, different pistons and different piston coatings. This is very time consuming as it is neccessary to cover many thousands of miles between each strip, inspection and rebuild. Results one day will be revealed when the programme has been completed.

However - despite a lot of costs, frustrations and set backs - we are getting very close to finding the answers we need to decide on the best or least expensive way forward for the next decade of rebuilding these flawed engines.

We say least expensive because replacing all the cylinders with alloy Nikasil plated cylinders (as used in Gt3's, turbos and even the older air cooled cylinders) is a permanent solution but obviously expensive and we have been trying to find a less expensive way to produce as reliable results.

Porsche didn't seem to provide anything to sort the problem out except to eventually abandon the Lokasil cylinder material and return to Alusil in Gen 2 engines (as used in the 944's and 968's etc). Boxsters up to 3.2 and 3.4 996 engines do not suffer the problem (despite also running in Lokasil) and bank one is much less vulnerable and this gives hope that there is a less expensive answer to be found.

But this leaves thousands of cars vulnerable to expensive rebuilds or replacements which we are still trying to find a less expensive permanent solution for than our reliable Nikasil replacements.


Baz
I am booked in with you guys next month for low-temp stat to be fitted. I've changed over to Miller Nano oil using 10W-50 to afford greater protection as well. Like anyone here no one wants a bill for nearly £8000 to have the bores re-ligned to fix an issue which should never have been present in the first place, but then one could do this just for a month later the IMS to let go........

_Batty_

12,268 posts

249 months

Tuesday 21st May 2013
quotequote all
hartech said:
I have not seen any evidence of technical changes to a new or Porsche rebuilt engine to eliminate bore scoring - nor any changes to reduce the likelyhood.

We believe the problem is caused by the Lokasil material being particularly aggresive as it wears, the temperature between the piston and the bore too high on occasions (reducing the oil film strength and allowing too much piston face to bore pressure), the type of coating on the pistons (being too soft to resist the interference of sharp or mislodged Lokasil particles), the coolant temperature being too high and the coolant flow resulting in the top of bank 2 pistons (the thrust face) running hotter (which is the side that fails) than the bottom of bank 1 (also the thrust face) which lasts much longer.

When we rebuild engines we do offer to modify some areas that we believe contribute to the problem.

We replace liners with Nikasil plated ones (or re-round and support open deck Lokasil bores to reduce blow bye and reduce piston face temperatures). We can fit a lower temperature thermostat and we increase the coolant flow through the block to lower cylinder temperatures.

We also have an on going serious and expensive research and development programme that has been testing various cylinder bore materials, different pistons and different piston coatings. This is very time consuming as it is neccessary to cover many thousands of miles between each strip, inspection and rebuild. Results one day will be revealed when the programme has been completed.

However - despite a lot of costs, frustrations and set backs - we are getting very close to finding the answers we need to decide on the best or least expensive way forward for the next decade of rebuilding these flawed engines.

We say least expensive because replacing all the cylinders with alloy Nikasil plated cylinders (as used in Gt3's, turbos and even the older air cooled cylinders) is a permanent solution but obviously expensive and we have been trying to find a less expensive way to produce as reliable results.

Porsche didn't seem to provide anything to sort the problem out except to eventually abandon the Lokasil cylinder material and return to Alusil in Gen 2 engines (as used in the 944's and 968's etc). Boxsters up to 3.2 and 3.4 996 engines do not suffer the problem (despite also running in Lokasil) and bank one is much less vulnerable and this gives hope that there is a less expensive answer to be found.

But this leaves thousands of cars vulnerable to expensive rebuilds or replacements which we are still trying to find a less expensive permanent solution for than our reliable Nikasil replacements.


Baz
Can I just say it was a pleasure to speak to the chaps at Hartech yesterday with regards to our C4s.
We will be booking it in with you very shorty.
The last thing you want is for something like this to 'taint' the ownership of the car, as buying a car at a non opc garage always carries a risk.
But firms like Hartech offer invaluable advice, and a non Porsche route to saving the car.
Do I think it's right a performance engine should only last 55k? No. Is there anything you can do about it? No. Will be glad to get the car back in rude health with similar expenditure to the depreciation of driving a new car out a showroom.
Mr C.

Rockster

1,508 posts

159 months

Tuesday 21st May 2013
quotequote all
AlexH997 said:
I sent my car in cos a thought it was suing a lot of oil and pipes were dirty but they said it was ok. The advisor said it would be repaired by their technicians on site.

Luckily mine is ok but all this talk of scoring makes me wonder even if they didn't repair would they fix the cause
It depends upon the extent of or the seriousness of the problem.

Bore scoring involves the very foundation of the engine, the block of which the cylinders are an integral part.

It is possible to ship over a finished machined but bare block and move all the internals from the scored engine to the new block. Expensive though in terms of time.

I would believe Porsche would prefer to have this work done at the engine factory and after be able to run the engine enough to confirm it passes whatever checks/tests new (or remanufactured) engines are given.

Now I know at one time dealer techs were ok'd to fix engines with IMSB failures. I came across one such engine torn down. The tech told me that Porsche had recently given the go-ahead for repairing some engines with this problem at the dealer. The engine had to pass some preliminary inspection/partial tear down to verify it was a repair candidate. In the case of this particular engine the damage was confined to the IMS and its obviously failed bearing, and one chain tensioner rail covering.

The tech said he found no signs of any metal debris on the clean side of the engine's oiling system. The engine was torn down to its cases being split, of course, to remove/replace the IMS.

I spotted the engine - in pieces -- one day and the next day when I went back to pick up my car the 911 with the torn down engine (which I had photographed the day before) were gone. I asked the tech about this and he told me he had reassembled the engine with the new hardware, installed it in the car, road tested the car and it was on the roof awaiting customer pickup.

Magic919

14,126 posts

200 months

Tuesday 21st May 2013
quotequote all
Speaking about what happens now, in Britain, I can say they do rebuild 997 engines at the dealership. They will order new crankcases halves and then order the big end shells once the crankcases appear. Then they build in the old bits, bar anything that is a use-once item. They aim to replace just the affected pistons and reuse any undamaged ones. They will order new rings for them too.

AlexH997

Original Poster:

265 posts

131 months

Tuesday 21st May 2013
quotequote all
hartech said:
I have not seen any evidence of technical changes to a new or Porsche rebuilt engine to eliminate bore scoring - nor any changes to reduce the likelyhood.

We believe the problem is caused by the Lokasil material being particularly aggresive as it wears, the temperature between the piston and the bore too high on occasions (reducing the oil film strength and allowing too much piston face to bore pressure), the type of coating on the pistons (being too soft to resist the interference of sharp or mislodged Lokasil particles), the coolant temperature being too high and the coolant flow resulting in the top of bank 2 pistons (the thrust face) running hotter (which is the side that fails) than the bottom of bank 1 (also the thrust face) which lasts much longer.

When we rebuild engines we do offer to modify some areas that we believe contribute to the problem.

We replace liners with Nikasil plated ones (or re-round and support open deck Lokasil bores to reduce blow bye and reduce piston face temperatures). We can fit a lower temperature thermostat and we increase the coolant flow through the block to lower cylinder temperatures.

We also have an on going serious and expensive research and development programme that has been testing various cylinder bore materials, different pistons and different piston coatings. This is very time consuming as it is neccessary to cover many thousands of miles between each strip, inspection and rebuild. Results one day will be revealed when the programme has been completed.

However - despite a lot of costs, frustrations and set backs - we are getting very close to finding the answers we need to decide on the best or least expensive way forward for the next decade of rebuilding these flawed engines.

We say least expensive because replacing all the cylinders with alloy Nikasil plated cylinders (as used in Gt3's, turbos and even the older air cooled cylinders) is a permanent solution but obviously expensive and we have been trying to find a less expensive way to produce as reliable results.

Porsche didn't seem to provide anything to sort the problem out except to eventually abandon the Lokasil cylinder material and return to Alusil in Gen 2 engines (as used in the 944's and 968's etc). Boxsters up to 3.2 and 3.4 996 engines do not suffer the problem (despite also running in Lokasil) and bank one is much less vulnerable and this gives hope that there is a less expensive answer to be found.

But this leaves thousands of cars vulnerable to expensive rebuilds or replacements which we are still trying to find a less expensive permanent solution for than our reliable Nikasil replacements.


Baz
You've identified a fix but do you know what the actual problem is Is it caused by particular driving style?

My sister is looking at buying a 997.1 cab and there is one for sale which has had the engine refurbed by Porsche 1500 miles ago due to bore scoring.

She's only concerned with the colour but I'm wondering how long will the engine last before the same thing occurs, she's a crap driver anyway but is there anything she can do driving wise to stop it from happening. The car she's looking at is 2005 with 48k miles. Would it be another 8yrs and 48k miles before it happens again?

_Batty_

12,268 posts

249 months

Tuesday 21st May 2013
quotequote all
Reading from some of the past discussions (and no doubt ill be corrected) its low rev, high torque applications in high temperature situations that seems most likely to cause damage.
Think foot to the floor in 3rd @2k revs after sitting in traffic for 20mins. I believe tiptronics don't allow such low rev high torque as they drop a cog instead.
Thermal spikes occur in several places which don't help. Again it's what I recall reading and Baz/Hartech will fill you in.

AlexH997

Original Poster:

265 posts

131 months

Tuesday 21st May 2013
quotequote all
So if you're hammering the car away from standstill when the engine is warm will cause scored cylinders?

i just read about a cayman owner who had scored cylinders and owned his car from new. Never ragged or tracked it, sounded like general daily driving and he suffered with scored cylinders. Must be more to it.

doing some further searching tonight suggests cars getting from 6yrs old are all suffering in some way.

Magic919

14,126 posts

200 months

Wednesday 22nd May 2013
quotequote all
Tips suffer at least as much as manuals, if not worse. Carrera S Tip would be an ideal candidate for scoring, as would a 2006 Cayman S.

BertBert

18,955 posts

210 months

Wednesday 22nd May 2013
quotequote all
_Batty_ said:
Think foot to the floor in 3rd @2k revs after sitting in traffic for 20mins.
Well I'm guessing (or vaguely spewing up something Baz might have said in the past, but I don't think sitting in traffic for 20 mins does it. That gently warms the engine with no specific hotspots. So not the right conditions.

I think it's more likely after the engine has worked hard, has big heat soak and then hot spots where the cooling of the cylinder/piston "interface" fails.

So maybe big blat, followed by the 3rd @2k WoT activity. Just guessing!

Bert

AlexH997

Original Poster:

265 posts

131 months

Wednesday 22nd May 2013
quotequote all
Magic919 said:
Tips suffer at least as much as manuals, if not worse. Carrera S Tip would be an ideal candidate for scoring, as would a 2006 Cayman S.
You've made a statement but can you explain why you think that? What's so specific about a Carrera S Tip?

hartech

1,929 posts

216 months

Wednesday 22nd May 2013
quotequote all
Look guys this is a very complex problem with many contributory factors that is extremely difficult to prove since it takes perhaps 20 to 40K to materialise and then not in all cars. The logistics and costs to replicate such time and mileage with different conditions and monitor different solutions is beyond even Porsche (it seems) so we have to look to the people who have a lot of experience of engineering and problem solving to analyse the problem, try different solutions and make calculated educated assumptions. If they advise some driving style changes that might help it is probably worth taking on board.

The manufacturers are unlikely to reveal their conclusions (for obvious reasons).

We have researched this for about 10 years and have found satisfactory solutions. The best (Nikasil alloy liners) is quite expensive and does provide a permanent solution (although less expensive than new crankcases - which don't solve the problem).

Several contributory factors are connected to issues drivers can do nothing about. The cylinder bore material and process, the piston coating, the unbalanced coolant flow and resulting thrust face temperatures, the high running temperatures (modified by gauges that read low to stop owners worrying), the unsupported open deck cylinder (that will one day migrate oval and eventually probably crack), etc etc.

To test any one solution or improvement would require say 20 cars with that modification driven say 20 to 40K under controlled conditions with frequent strip and rebuild checks etc - and there are probably 20 or so improvements that could be tested (that’s 400 cars so far and drivers etc)- and even then you might statistically miss the issue or your test drivers may not drive the same way as the general public - all completely impossible to properly resolve.
Technically – when rebuilding an engine – we therefore cover every possible contributory factor – to eliminate it – so change the open deck design to closed deck, alter the coolant flow, lower the thermostat temperature, change the cylinder bore material etc etc.

There are some likely candidates that drivers could apply to minimise their own contribution to the problem.

Bore scoring is known historically to occur mostly at low revs and high torque. The problem started when the variable valve-lift systems increased low speed torque – so there is a clue (although other changes were made at about the same time to coolant flow balance and piston coatings). Tiptronics set of usually in 2nd and this requires more torque to get the same acceleration than a manual in 1st – so if you are going to get away quickly in a tip it would be better to flick it into 1st.

The thermostat is located at the entry to the engine so if you have been driving fast and stop for a while with the engine ticking over there is a potential for the coolant inside the engine to heat with heat soak and bubbles of air could develop that insulate the heat transfer and over heat the cylinder wall face thinning the oil and allowing the aggressive Lokasil bore material to interfere with the relatively soft piston coating and initiate a score. Setting off without too much throttle after such a stop would therefore help.

So to sum up – anything that a driver can do that might help would be worth considering and if the engine has failed it should be better (and will certainly be cheaper) to get it rebuilt by specialists that also try to eliminate some potential contributory factors rather than just the same way as it was before it failed the first time.

We have invested in excess of a 6 figure sum over several years in testing and trying alternatives (special parts and machinery, test engines and cars, piling on mileage, stripping and rebuilding them for analysis etc) and this is still on going today with different cylinder and piston materials under test and a new coolant that has a higher boiling point.
Frustratingly these all take time before it can be decided what value the modification or change contributes and if it is viable (and even then it is almost impossible to absolutely prove).

The problem is not going to go away and there are tens of thousands of cars that are vulnerable.

I still think the very best way to deal with it is to put the car under our Lifetime Maintenance Plan (if in the UK). For a typical 12K/annum 997, after the initial service check (£650 + Vat) it presently costs £79/month (+Vat) – or £948 + Vat/annum. You get all following servicing free of charge (parts and labour) a free annual MOT, most mechanical failures repaired for just the parts cost (even wear and tear items like brakes etc) and if the engine failed a rebuild with all the latest modifications for the parts and subcontract cost (around £1300 to £1500). You can transfer on sale or stop the monthly payments anytime.

If your service is due anyway that initial cost is pretty well covered and unlike the Porsche warranty – our scheme has no age or mileage limit (and it will not be long before all the models implicated fall outside the Porsche limit anyway – some already have).

The scheme has been running over 12 years without complaints or problems – to me it is a no brainer! You can forget the problems and enjoy a fabulous car to drive happy that you are already in pocket (compared to a Porsche warranty and its link to their service costs and repair limitations) and if it went wrong you get back something technically better than the original. If you are in a recovery contract (AA, RAC Green Flag etc) the car will usually be brought to us by them if it failed – best check – or we can collect.

Models mainly affected are Cayman S 3.6 and 3.8 996 and 997's. Earlier Boxster and 3.4 engines still have potential for cylinder cracks (over 3 litre engines) and IMS failures (which we also repair).

Baz



BillTheButcher

382 posts

160 months

Wednesday 22nd May 2013
quotequote all
Baz - your posts on here are some of the best I've read on any forum. Informative, well-written and intelligible to someone with minimal mechanical knowledge, i.e. me.

Thanks for taking the time to post. smile

hartech said:
I still think the very best way to deal with it is to put the car under our Lifetime Maintenance Plan (if in the UK). For a typical 12K/annum 997, after the initial service check (£650 + Vat) it presently costs £79/month (+Vat) – or £948 + Vat/annum. You get all following servicing free of charge (parts and labour) a free annual MOT, most mechanical failures repaired for just the parts cost (even wear and tear items like brakes etc) and if the engine failed a rebuild with all the latest modifications for the parts and subcontract cost (around £1300 to £1500). You can transfer on sale or stop the monthly payments anytime.
I wish Hartech was closer (you're over 200 miles away from me); I'd be on this plan without a moment's hesitation.

I can't find anyone down south who offers a similar scheme. frown