Update on Low Temperature Thermostat Tests - Page 2 - 911/Carrera GT - PistonHeads UK

It is several years since we last conducted the engine running temperature tests that resulted in the provision of the "low temperature thermostat" and we thought we should revisit the tests to be sure our advice provided since is still valid and to check several questions that readers have asked since about how to minimise the risk of bore scoring. Our original tests were carried out at this time of year and we know that in the Summer the temperatures are a little higher and the difference between std and our low temperature thermostat is slightly reduced by about 2 degrees. In a standard 3.8 997 (with no Hartech machining mods to the coolant flow in the blocks i.e. as your standard car would be) but with 6 temperature sensors fitted to the engine and simply with first a standard and then a Hartech Low Temperature Thermostat we have just conducted back to back tests on the same day, routes and speeds etc and recorded temperatures driving, stationary, after ticking over for 2 and 5 minutes, switched off and on again after 5 and 30 minutes and at town and fast road speeds with the following results. (1) Despite the temperatures recorded varying from 79 to 104 the dash board temperature gauge read 80 for every reading - confirming that the instrument in our test car has a buffer zone of about 25 degrees during which it does not change nor reflect what is going on in the engine or the coolant. This may lead to some who have fitted such a thermostat to question if it was doing its job! which it probably will be (and certainly will be if it is one of ours) . (2) With the standard thermostat - on average the thrust side of bank 2 ran 5 degrees hotter than the thrust side of bank 1 @ 93 and 98 respectively. In contrast- with the Hartech thermostat - the difference was only 1.6 degrees @ 83.8 and 85.4 and this shows that the thrust side of bank 2 is now running cooler than the original thrust side of bank 1 (where we do not experience bore scoring failures). (3) The oil temperature was on average 9.9 degrees cooler with the Hartech Thermostat (100 and 90.1). (4) Whether driving slowly in traffic or fast on an open road the temperature differences between bank 1 and bank 2 were not significantly high (because at slow speeds there is little temperature generated anyway and at high speeds both the engine revs and air speed through the radiator are higher and overall cooling very efficient). (5) The major difference was obvious when the car was either stopped but running on tickover for a few minutes or stopped for a few minutes with the engine switched off and started again. In both cases bank 2 thrust side increased temperatures much higher than bank 1 (because the contra-flow works on bank 1 and maintains a more even temperature gradient inside the engine whereas bank 2 exists with a higher temperature range that soaks out when the coolant flow reduces or is stopped) . On tickover or with the engine stopped - the oil around the piston in bank 1 and bank 2 would naturally gravitate to the bottom this would leave the piston in bank 2 thrust side (the top) with less oil on the thrust face for a restart and much hotter and thinner to resist the high torque loads possible driving off again - while bank 1 piston would be cooler and carry more oil on its thrust face (the bottom) for the re-start. This confirms our advice to drive off modestly after a period stopped at say lights or for a brief engine "off and on" stop before opening the engine up again. It also confirms that high speed driving at higher revs should not be a problem (as it has not been also in our race car engines). (6) With both thermostats bank 2 cylinder head ran slightly cooler than bank 1 (96.7 to 98.1 std and 87.2 to 89.2 Hartech). (7) The engine under test is fitted with pistons with yet another pair of different coatings and when it is stripped for the first time to check wear rates - we will modify the coolant flow to reproduce our usual rebuild changes and test out the results of those again too. (8) In general the fact that the thermostat is fitted on engine entry did not de-stabilise the temperatures but of course resulted in much higher internal running temperatures and thinner oil film strength than was the case when thermostats were fitted to the outlet. Assuming the same thermostat was fitted either before or after the cylinder block - the difference in internal cylinder temperatures would be about 8 or 10 degrees. The fact that the std thermostat is rated higher than those tradditionally used in more conventional engine coolant flow layouts would also mean that the internal engine temperatures std are probably in the region of 10 to 15 degrees hotter than they used to be (and all to assist the emission reductions required to export cars to major outlets). Similarly with the more traditional layout the higher internal coolant temperatures were maintained the same as the engine usage was increased through faster more aggressive driving whereas with the thermostat on the inlet - as the engine is worked harder - so too does the internal temperature range increase. I am not sure if it is an advantage to use a thicker oil if a lower temperature thermostat has been fitted (as the running temperature reductions will inevitably result in the same oil holding a higher viscosity) but personally - once any new parts have been run in - I still think an upgrade (as Wizard proclaims( is a benefit likely to extend the engines life). It must be remembered that fitting a low temperature thermostat will not repair any existing wear rates that might have worn down the piston coasting somewhat already and therefore although running the engine at a cooler temperature may have avoided bore scoring all together if adopted when the car was new - with scored bores on bank 2 having occurred @ 9000 miles (but more usually about 30 to 60K) and as yet no evidence of scoring on bank 1 even up to 100K - it does seem that the temperature difference between the banks is what promotes early bank 2 failures and therefore although reducing those temperatures in bank 2 should extend piston life significantly, it is impossible to establish how worn they may already be at the time of fitting the low temperature thermostat and therefore being unable to predict how long the benefit will last for afterwards. Although the low temperature thermostat is a low cost way of improving reliability - we are still working on hopefully even better solutions both for retro-fitting new designed parts to existing cars and during rebuilds. While fitting 6 Nikasil cylinders removes the problem all together - it is still expensive and so despite trying several different coatings unsuccessfully to date - we are still working on finding a reliable piston coating that may enable us to overbore scored cylinders that combined with changing the coolant and cylinder block temperatures - may eventually reduce rebuild costs with much improved long term reliability to "Nikasil" levels. Finally I am not sure why there seems to be some form of competition to demonstrate where readers obtained their own lower temperature thermostats from and at what price - ours is just £35 + Vat and these test results only apply to our thermostat and do not necessarily apply to any others. Have a great New Year - and "KEEP COOL" Baz

A very interesting read once again, Baz, and reinforces my decision to have fitted one of your low temperature thermostats to my gen 1 987.

Great feedback, thanks for that Baz, really interesting. Mine is a genuine Hartech one..........

Thank you Baz. Grant is currently rebuilding my engine and I note the low temp th. Is part of the new parts. Looking forward to getting it back!

hartech said: Finally I am not sure why there seems to be some form of competition to demonstrate where readers obtained their own lower temperature thermostats from and at what price - ours is just £35 + Vat and these test results only apply to our thermostat and do not necessarily apply to any others. Baz - I was looking at fitting a low temp thermostat to my 3.6 996 in the new year with my next service - your website says £42 + vat...should I be asking for a PH discount to get the thermostat for £35 + vat. Cheers

Scores are usually too deep to hone out and there will usually be damage to the crystal structure of the remaining silicon bits making them more likely to fail as well - so in most cases a new liner is necessary. Sometimes light polish marks can be re-honed to increase oil retention and run in new pistons and rings - but each case has to be analysed and then the best recommendations made to the customer - usually with some alternatives for them to consider. The price will be £35 plus packaging and Vat but I will speak with the guys back at work when we return to clear up any anomalies. Baz

I know you guys do a lot of testing but without wanting to start an argument why would one buy your low temp stat versus another one? Does your's work differently? It's not obvious if it does. The reason for asking is that I have recently bought a low temp stat. Of course I wanted a good price but for the non-tech enthusiast like me my approach was to look for some recommendations, scour the web, find the right product then choose a reliable supplier/retailer. In this case it happened to be ebay, my search just didn't take me down a path your way for whatever reason.

Well we have not tested any other thermostats but when we first tested the engines and worked out what we wanted we had them made to our specification and as far as I know they are exclusive to us. The speed at which they open and the range from just open to fully open can vary and the coolant pump design has to be taken into account. Centrifugal pumps can displace a lot of coolant through a relatively small gap or only slightly open thermostat - so to obtain the response we wanted (which anyone who has one will have noticed is extremely stable) has more to do with the design than just buying one with a particular temperature setting to open. We had to pay a lot to get the design we wanted in quantity to keep the price reasonable as well. However I do think most available will probably do the job just as well. The only reason I mentioned it is because it puzzled me why so many contributors feel the need to tell others where they got one from when they usually pay more and for sure no similar testing has been carried out by those suppliers - that's all. We do not make enough out of selling them to make any kind of competition for sales to be worth bothering with but we do continue to invest a considerable amount of time and money into developing various different solutions that are a great benefit to consumers and I find it odd that some do not consider returning some appreciation by way of product supplier loyalty and prefer to spend more to buy one elsewhere and then cannot seem to wait to tell everyone else about it. It is an easy thing to copy once development costs have been spent but there will have to be a limit to our own future development expenditure if we have to factor in reducing returns as a result. Baz

Thanks. To be fair at the same or similar price point I would have happily and probably preferably bought one of your own ones had I come across it. I get that parts and product sales is not what your business is about but the text you write makes a compelling sales ad which is nowhere to be seen on your website.

Would this low temp thermostat fit/benefit GT3's as well?

Thanks Baz. Which company first came up with ltt?

JarmoL said: Would this low temp thermostat fit/benefit GT3's as well? Given that it is specced for the 'issues' surrounding the 986/7 and 996/7 non GT engines, then I doubt it. Edited by Trev450 on Wednesday 1st January 09:42

It is a strange subject - engine cooling seems one of the simplest technical issues to master yet is actually extremely complicated and can be confusing. A lot depends upon the position of the thermostat, the capacity of the radiators and the volume delivery potential of the coolant pump. As long as the car as a whole has the capacity to cool under any normal circumstances - then the following applies. If the thermostat is on the engine outlet then you are controlling the maximum temperature that the engine can run at but variations in driving styles and conditions, air temperatures and wind speed etc all influence the engine entry temperature. If you add more cooling capacity the entry temperature will go down because the thermostat will slow the flow through the engine and increase the temperature gradient as the coolant passes through the engine. It is not a good thing therefore to have too much cooling capacity as this simply increases temperature gradients inside the engine. If the thermostat is on the entry to the engine - you are controlling the entry temperature and so differences as described above will raise or lower the temperature gradient in the engine and alter the outlet temperature. In this case too much cooling capacity will slow the coolant flow and actually increase the engine outlet temperature. So getting the right amount of air flow through the radiators, the right radiator capacity (core numbers, depths and spaces), a pump that can vary flow rates as the thermostat opens etc are all part of quite a complex design. The issue with M96 and M97 engines is that the coolant flow is different in bank 1 and bank 2 and this results in the temperature in bank 2 near where the pistons and cylinders score being hotter than in bank 1. Then there is the fact that bank 2 is where the problem is and not bank 1. It is difficult to conceive a way to alter the internal coolant flow but the LTT does help lower the temperature in the critical area of bank 2 but in fitting it bank 1 is running even cooler than before when it didn't give a problem. Of course if the basic cooling capacity of the system is the problem it may need extra radiator area, air flow, coolant speed etc - but most manufacturers can get all this right. It is unfortunate that our tests prove that during a pause after a fast run - when idling - the bank 2 outlet temperature raises significantly (because both coolant flow and air flow are reduced while heat is still soaking into the engine). This is not directly shown up by the dashboard temperature gauge because not only is it damped to give false readings but it also measures the mix of coolant from both sides of the engine and the head (with about 85%) and the cylinder block (with about 155) of the flow mixed back together sgain. It shows a general increase but not the individual affect on bank 2 cylinder thrust face. It is only tests like we have set up with individual sensors fitted to crucial areas that can identify these issues and work out what the problems are. A coolant pump that is not controlled by the engine speed could help reduce this if sensors were placed in the right place and controlling the right pump speed so it could speed up coolant flow when the engine is idling but the engine soak is high - to avoid driving off again with hot cylinders with low oil viscosity between the pistons and cylinder bore - especially when this is aggravated by the fact that bank 2 oil film will naturally run away from the thrust face downwards under gravity while bank one does the opposite and fills the thrust face area. The problem for small businesses trying to help owners when the manufacturers have not avoided a problem or solved it - is high because they neither have the financial resources to do as much as they would want to - nor the eventual control over spares supply that would result - to ensure a return on their development costs. I don't imagine it is important who did what first - just that some people have properly investigated and tested things out while others have just sold something similar because there is a demand they can make a return from. We continue to test different issues as much as we can and you will find that we have new improved solutions under test that could make engines last much longer even than the LTT. We are also going to fit extensive test capture systems to our 996 race car for 2014 - to further learn and test out what is going on - doing as much as we can and we can afford - but we cannot continue to do this if we never get a financial return for all the investment and that needs some customer loyalty to those businesses that do try and help - to sustain their efforts and to improve things for owners. That is my message for 2014 - whoever they are and wherever they are based - it would improve things for everyone if owners could show some appreciation of those businesses that are investing in solutions despite their relatively small size compared to the manufacturers who seem unwilling or unable to support the ownrs of products they failed to make as reliable as they should have been. Baz

Once again Baz a very informative post. If the worst should happen to my M97 engine, I would have no hesitation in bringing it to you to be rectified.

Trev450 said: Once again Baz a very informative post. If the worst should happen to my M97 engine, I would have no hesitation in bringing it to you to be rectified. +1

Baz, thanks again for the spoils of your testing. I know its rare but have you ever seen significant bore scoring on a 987 2.7 engine? Many thanks.

No The smaller capacity engines use the same basic cooling system and flow yet generate less heat in the piston area - especially at low revs where the significant difference is less torque. Most piston scuffing is thought to occur at low revs and high torque which the bigger engines create more of. Drivers therefore tend to rev the smaller engine'd cars more before changing gear or opening the throttle more to get better acceleration and this seems the best way you should drive the bigger engine'd cars as well. This may be why it seems more 3.8 tiptronics suffer than manuals as we have found drivers tend to run a manual at higher revs in each gear before changing gear whereas the torque converter allows the revs to rise with throttle opening and tend to be driven at relatively high throttle openings from slow speeds but not enough to kick down. Effectively the smaller engine creates less loads and heat to dissipate and therefore - cool better, maintains better oil film strength between the piston and the bore and lasts longer. I guess they may be a problem one day in years to come as basic wear on piston coatings eventually takes it toll but the smaller the capacity the longer it should last. Baz

Good post Baz, and hence why in my 3.6 Tip i drive in manual and pull away in 1st. Takes some getting used to but the usual negative aspects of a Tip are gone, still prefer a PDK though.

hartech said: Finally I am not sure why there seems to be some form of competition to demonstrate where readers obtained their own lower temperature thermostats from and at what price - ours is just £35 + Vat and these test results only apply to our thermostat and do not necessarily apply to any others. Baz great post. However some advice: Your forum articles are renowned in the community for being well informed, researched and authoritative. Your work has an excellent reputation. Your website does not really reflect this. Your articles and research findings should be written into articles published on your own website! For example your website states your thermostat is £42+vat not the £35+vat you say above. If you had a page with your article above and an up to date price and online ordering on the website, you would get more sales.

Thanks Was 8V we are well behind on bringing our web site up to date but it is in hand - a whole revamp with a modern subject selection system - but it is a big job and meanwhile I try to respond to owners greatest needs for advice and fears of which the bore scoring seems particularly prominent. The racing with 4 cars last season really took a toll on our time but the results were well worth the effort - now we need to get back to other stuff. Recently we have built a customer area at the factory with Internet Access imminent and a race car simulator (to keep customers occupied when waiting), there are a lot of technical developments going on still and more technical stuff to get the race cars even more competitive and hopefully reliable - so we are not sitting around doing nothing and meanwhile engine rebuilds and repairs grow on an ever rising scale. No chance to get bored in 2014 either. I hope we can keep up the reputation and even improve it if possible - but many thanks for your appreciative comments - it makes it feel worthwhile. Regards, Baz

hartech said: Recently we have built a customer area at the factory with Internet Access imminent and a race car simulator (to keep customers occupied when waiting) Hmm.. its a long old way from central London but you may just have persuaded me to make a road trip in the next few weeks and drop in to savour the delights of my engine being rebuilt by Grant

Awesome stuff !!!

Time to update on the third radiator issue. Before we start - we have just stripped an engine with all three bank 2 pistons and cylinders scored but bank 1 has one piston in which absolutely all the piston coating has disappeared (and two partly gone) yet has no scoring or seizure marks. This reinforces the point we keep making that it must be the higher piston to cylinder wall temperatures on the thrust side of bank 2 that at some point in driving the car - fail to provide a suitable oil film barrier between the piston and the cylinder - and that this really is all about cylinder/piston face (and hence oil film) temperatures that get too hot on the thrust side where we know they are higher than in bank 1. Following disagreements about the value of the third radiator - we have now conducted the tests with the third radiator fitted and then blanked off - on the same day, same test route and speeds etc. Weather 7 degrees and dry. They confirm what the theory would predict - that the part of the engine we are concerned about (thrust face bank 2) runs hotter with the third radiator fitted when the system is working within its normal capacity (I cannot test it on a very hot day at this time of year). Before you avoid thinking why or believing this because you think it must be illogical and impossible please think about the following attempt to explain. If you need to I suggest you do a drawing with a square box marked "engine" - a line to another square box marked "radiator" - a line back towards the "engine" box and draw a circle marked "thermostat" and a line back to the "engine". Now imagine the coolant circulating round the loop. Once the thermostat has stabilised the temperature - the same amount of heat going in at the engine is being removed by the radiator - so the coolant goes into the engine and gets hotter and then on to the radiator and gets cooler - by the same temperature rise and fall (otherwise the engine temperature would not be stable and would continue to increase or decrease). The thermostat controls the coolant flow until its pre-set temperature is reached. If the radiator fails to fully cool the coolant - the temperature reaching the thermostat goes up and it opens some more to increase the flow and this lowers the temperature back again (and visa versa). Now increase the size of the radiator box and imagine what would happen if the radiator cooled the coolant more and lowered the temperature more on its way back to the engine. The thermostat would react to the cooler temperature and close a bit to slow the coolant flow until the coolant reaching the thermostat is back to the control temperature. This in turn means the coolant passing through the engine is going slower and therefore it gets hotter on its way through and reaches the radiator at a higher temperature - but that is OK because we have a bigger radiator now to cool it back again. So - the rule is - if the radiator area is too big and the thermostat is returning to the engine - the temperature rise in the engine will be increased to match the increased cooling when the coolant passes through the "radiator". Now the temperature of the coolant going into the engine is controlled by the thermostat (so it always enters the engine at the same pre-set temperature) - so if it goes in at the same temperature and the temperature rise as it passes through the engine is higher (with the larger radiator and slower coolant speed) - it MUST be leaving the engine at a higher temperature - and it is the thrust face of bank 2 (just where the coolant leaves the engine) that we want to keep lower not higher. Because so many people seem unable to grasp this simple concept (and in fairness to others what was just a theory) - we have as promised tested the results with and without a third radiator. Remember we have fitted temperature sensors inside the engine to read the temperatures of the coolant going into the cylinders and heads and leaving the cylinders and heads. The sensor reading the temperature leaving the heads is exactly adjacent to where the thrust face is and the scoring occurs. Remember also that all the coolant in the cylinders then mixes with the coolant in the heads on its way back to the radiators (about 85% goes through the heads and 15% through the cylinders) - and that the dashboard temperature sensor is reading that mixed output (sometimes from bank 1 or 2 depending on the model) - but is actually irrelevant in these tests as the dash board gauge read exactly the same 80 degree temperature while we conducted all of our recent tests of both thermostats and with or without a third radiator - when the actual combined outlet temperatures ranged between 86 and 103. The original change to the LTT on average lowered the coolant temperature by about 8 degrees. The introduction of the third radiator made the following differences comparing the figures with and without the third radiator. When the car was running normal and fast - the temperature difference of the inlet and outlet was relatively small (only raising the temperature at the thrust face of bank 2 between 1.5 and 2 degrees higher than it was before). When the car was stopped with the engine ticking over for 2 minutes - the difference on bank 2 thrust face was increased by 5 degrees (13 degrees higher than with the std thermostat and 2 radiators). When the engine was switched off for2 and then 5 minutes (after a run) the difference was 4 degrees. The oil temperature was also 1 degree higher when running with the third radiator. If the thermostat had been fitted at the exit of the engine - the exit temperature would probably not have been higher with the third radiator but the entry temperature would have been lower and this increase in radiator area would have been a good thing for a car with temperature problems where the coolant enters the engine. Unfortunately our problem is where it leaves bank 2 - so this increase in exit temperature is not what we are seeking. It is also true that if the ambient conditions were very hot then not only would the radiator area be more critical but also it is likely that the air con would be on high and this increases the air temperature reaching the 2 std radiators (reducing their effectiveness) - whereas the third radiator is open to air intake flow and would contribute more to the average cooling than the mathematical increase in area would suggest and could be beneficial if that is the circumstance that causes scoring. These tests prove what the theory would predict - that as long as the overall cooling capacity can match the needs of the engine, 2 radiators will keep bank 2 thrust face cooler than with three radiators - especially after a period of resting the car (engine on or off) before setting off again. However - if the ambient conditions plus the amount of material blocking the std radiators and the amount of air-con in use cannot keep the engine cool enough - then a third radiator would be better at keeping bank 2 cool than not having it (but I cannot test this at this time of year and doubt it is an issue or cars sold to hotter Countries would need increased radiator area). The question really is which is more important since experts advise that cylinder scoring is more prevalent at low revs and high torque while the engine would get hotter at rest or relatively slow road speeds. At high road speeds (even with high throttle openings) the increased air and coolant flow seems to reduce the problem temperatures all round. Tiptronics do seem statistically worse but although they have a third radiator - this is used to cool the gearbox oil. Although this matches the manual temperatures in normal driving it does cause an even higher rise in bank 2 and the oil when static or temporarily switched off (as the oil is hotter than the coolant feeding heat back into the system quicker than it can cool it). When pulling away in second as a tiptronic - @ <10mph on full throttle the torque converter can let the engine revs rise to 3000 (76% of max) immediately after the heat soak has reduced the cylinder wall oil film viscosity - while the car is slow off the mark but delivering very high torque almost instantly (more than you would get comparably in first in a manual or it would be uncomfortable and probably dangerous in normal driving conditions). It seems to me that the engine would have been better if the internal coolant flow had delivered the entry coolant to the top of bank 2 first and the thermostat was on the exit from the engine. However the castings are designed to bye-pass the normal route from cold to speed warming up and so whatever changes are made there is still a need to fit a standard design double acting type thermostat first to the entry of the engine - whatever else is contemplated (hopefully a LTT). Fortunately the theory behind our next version should fix all the known problems and result in an almost perfect cooling system in which the third radiator will provide a double insurance (for very hot days) without adding to the temperature rise inside the engine in normal use. I hope the new theory turns out to be as well proven in practice as this third radiator test has shown and will keep you all informed soon. Busy working on the improved solution right now so might not be able to find time to argue or explain just now - but will try later if necessary. Baz

Thanks Baz. The appliance of science, and evidence based advice? A welcome change on PH :-)

Yet another very informative read. Thanks Baz, I'm glad someone is fighting our corner.

Trev450 said: Yet another very informative read. Thanks Baz, I'm glad someone is fighting our corner. +1 Just a real shame I can't buy a 997 and be assured that it hasn't got really bad scoring already. My ideal scenario would be to buy a second hand 997 without impending engine failure, give it to Baz to put in a 3rd rad and LTT and enjoy with piece of mind!

if I need to buy a Hartech low temp thermostat do I need you guys to fit it or can I buy one and use someone local to me? Anyone recommend somebody in the surrey/hampshire area.

You can just buy the thermostat but be sure whoever fits it knows how to bleed the system and preferably has vacuum bleeding equipment. Baz

steve singh said: +1 Just a real shame I can't buy a 997 and be assured that it hasn't got really bad scoring already. My ideal scenario would be to buy a second hand 997 without impending engine failure, give it to Baz to put in a 3rd rad and LTT and enjoy with piece of mind! why not get get hartech to inspect the car including the bores and negotiate on price if they are scored? if he gives the car the thumbs up have the LTT fitted and place on their maintenance plan. I read somewhere else that the 3rd radiator is not required.

All good info, I will be getting LTT fitted soon on my 996.

I haven't got much to add here (other than that my C2S started to show early signs of bore scoring) before I got rid. Slightly tongue in cheek: the moral of this tale suggests one should seek to buy a Boxster/Cayman or 996/997 Carrera that has lived a life on track and not from a little old lady who lives in the middle of London (i.e. the very sort of previous ownership we diligent Porsche fans seek to avoid!).

AlexH997 said: steve singh said: +1 Just a real shame I can't buy a 997 and be assured that it hasn't got really bad scoring already. My ideal scenario would be to buy a second hand 997 without impending engine failure, give it to Baz to put in a 3rd rad and LTT and enjoy with piece of mind! why not get get hartech to inspect the car including the bores and negotiate on price if they are scored? if he gives the car the thumbs up have the LTT fitted and place on their maintenance plan. I read somewhere else that the 3rd radiator is not required. Problem is finding a car on private sale that is in/near Bolton that the seller doesn't mind such an investigation

steve singh said: Problem is finding a car on private sale that is in/near Bolton that the seller doesn't mind such an investigation Good point

GreatPretender said: I haven't got much to add here (other than that my C2S started to show early signs of bore scoring) before I got rid. How did you sell it? private? Did the purchased have it inspected?