mudguard

Thanks for all the suggestions on this thread, and indeed during my four years of ownership. Not many get to have the privilege of owning such a machine as their first car. I've sold the Seven - with, of course, full disclosure of its difficulties. I'm sure it'll be sorted out and be back on the road making its next owner very happy. For me - not quite sure yet what's next. Maybe another Seven, or maybe I'll try something else. Nothing will ever live up to it, I'm sure. Many fond memories of chip runs, weekend blats with the Kent and Sussex groups, Dunsfold, the evening meets at Toys Hill and Penshurst, all with great camaraderie from you. And outside of the club, most corners of England and Wales, and a bit of France, 28,000 miles. Thanks - it's been a blast!

Could be, but my feeling is this is less likely. The reason why I think this is that the original cat was already destroyed before the HG work, by (presumably) the same problem which has now, 8 months later, apparently destroyed the second cat. This problem appears to be overfuelling, root cause unknown, so it seems reasonable to think it's been the same problem all along, and not detected and corrected during the HG work.

No verniers, stock pulleys, stock cams, stock everything really.

Yes, but the major "misfire" lasted one day 6 weeks ago and vanished immediately on cleaning the HT springs. The symptoms were two things it has never done before or since: On idle, run very rough, hunt and never settle. On acceleration, stutter and then recover. The other "misfire", the more long-running one, whose onset was immediately after the HG work, seems strictly idle-related, and this was improved significantly by cleaning the IACV. The symptom of this is occasional stumbling and sometimes stalling when slowing down, and then (if not stalling) recovery to a fast idle, and then settling down. Absolutely no stutter under acceleration, and no idle hunting. The reason why I think these are not the root cause of the cat failure is that they both began long after the original cat was in significant distress.

Like this:

That's my feeling too Andrew. And as for easily passing the emissions test; I found the 2017 report - lambda 1.016, CO 0.07%, HC 29ppm. I don't recall ever seeing the 2018 numbers, and I don't have the 2019 numbers to hand (2019 was about 4 months pre HG work), but I remember thinking at the time that it had just scraped through on the lower boundary of the lambda, but not understanding the significance of that. So if I'm remembering correctly, something started to go wrong in 2018 or early 2019, which would make it completely unrelated to the HG work. Perhaps, even, the cat destruction that was addressed during that work was nothing to do with the overheating, but this other, earlier problem, which has remained unresolved ever since, and will keep eating cats. It's like a detective puzzle!

Lambda sensor has been changed, and spark plugs. Old lambda was badly sooted, believed to be caused by a spark plug related misfire. The outgoing plugs were 2-year-old NGKs, replacing the - believed - original Rover plugs, which in 2018 were still in good condition after 16 years. Runs better, but emissions are worse, and apparently this means the soot has gone into the cat and destroyed it, so needs to be replaced. The car got through an MOT with the old near-destroyed cat last year. No mention of checking ECU temperature sensor, ODB2 diags, injector cleanliness, injector leakage, air filter health, cam timings, exhaust leakage. To their credit they're willing to back up their convictions and try to borrow another cat as a test. If they're right I'll happily cough up for a new one.

Standard MEMS3.

It's a 2002 kit build, first registered Jan 2003. As far as I can tell, it's always been subject to emissions testing. Certainly all MOTs in my ownership (4 years) have. And it's always passed emissions, until now.

No TBs, just standard VVC (silver) ally inlet with single throttle for all 4. Would anybody be able to recommend a specialist to do the sort of work being suggested?

Thanks for that Opplock. From my reading of that thread, the "correct" wider lambda limit (0.95-1.09) was applied and the car failed even that by a whisker (0.94). However, the big problem appears to be CO rather than lamdba; the car is measuring at > 6x the permitted CO maximum. Which would seem not to be a case of a slightly wrong limit applied?

It was just a skim. I don't have the car as I didn't want to drive it the long distance home following the failed test. It's now sitting in CC's workshop (they presented it for MOT) and whilst they're trying very hard indeed to be helpful they don't seem to be completely sure what to do next - K series emissions seem not to be a core part of workshop knowledge these days, which is understandable to an extent. They want to change the lambda, and they have a new one available - which seems a good idea to me especially as the old one is partly melted. They also want to change the cat, which is going to be a long delay as none in stock, which I'm resistant to especially as it seems not to be a cat problem. I think I'll ask them to clean the injectors as well as change the lambda, and then see where we are on emissions. I'll also ask them if they know how to check the cam timing on a K. I don't mind spending a bit on trying to get it through, because if it can't pass, I really don't know what's going to happen to the car. It's quite sad really.

Thanks Andrew, that's very helpful. Lambda is on no.4 primary in the engine bay, it's 4 primaries out to side of car then a collector there into 1 ahead of the cat. The ECU could be thinking the engine is too cold. The thermostat was changed to the summer type due to the winter type not opening due to surge of coolant into the expansion tank due to historic removal of the ball valve in the inlet manifold - as previously discussed on a thread here. The thermostat now opens 100% reliably, but the temperature sticks at around 65, which is quite a bit lower than its previous normal running temperature of 80. But I believe plenty of Ks are on summer thermostats with no issues. The cat gets very hot as it should, but the old damaged one stayed cool. Air filter was cleaned this year - seems to be in good condition. The car felt considerably better after the HG work - it became able to pull in 4th gear from low speeds - and the overheating is 100% cured. However I think the improvement is mostly due to the old cat being in such a poor state that a lot of energy was being wasted in forcing the exhaust through it. Surprisingly, it did get through the 2019 MOT, a couple of months prior to the HG work, in this state. The idle became quite a bit rougher post-HG, it is not so easy to start, is more prone to stalling, and occasionally stumbles and stalls on throttle release. I have cleaned the IACV, which was full of soot, and this is now improved, if not completely eliminated. I have kind of ignored these idle issues as TATDS after major head work, as the results were so good otherwise. But maybe it's a clue as to what's gone wrong. About 6 weeks ago I had an occurence of misfiring. I checked the HT leads and found mild blemishes on the spring to no.1. That completely resolved the misfiring problem. I'm not aware of the injectors ever having been cleaned - so that sounds like a good thing to do.

Any advice on what to check/change? K-Series 1.8 VVC EU3, since last MOT new HG and head skimming, replacement cat. Car (and cat) were warm, straight from a 20 mile run. But the results were very similar on a previous attempt where it wasn't exercised much before the test. So perhaps less likely to be "cold cat syndrome". Fast idle test Engine Speed 2450-3050 rpm CO Max 0.3% Reading 2.00% FAIL HC Max 200 ppm Reading 155ppm PASS Lambda 0.95-1.09 Reading 0.94 FAIL Second fast idle test CO 2.38% HC 100ppm Lambda 0.93 Natural idle test CO Max 0.5% Reading 1.17% FAIL Further information: Lambda sensor has welded itself to the primary so cannot be immediately checked visually. But perhaps enough heat to weld it is enough to cook it?

... not forgetting the thick power lead which leads to the starter motor and then to the battery. So disconnect the battery first! Pretty much the same thing happened to me. I chose to simply replace the whole alternator with a reconditioned one. As it turned out I was glad I did as, aside from its (presumed) failed diode pack, the old alternator was just about ready for reconditioning itself! The replacement wasn't expensive and came in the post from Schmitz Rotary Engineering. It has worked perfectly ever since.

Guilty!

Nail on head Andrew - the "unwanted bypass" is exactly what's happening in my engine. For some unknown reason, there is considerably more flow through this bypass route now after all the work, but there was always some. That, by the way, explains why things got considerably better for a while with a hole in the stat I drilled - the hole allows some high-temperature flow through to counteract the effect of the bypass. The chaps who did the recent work aren't in favour of holes in thermostats, so as a workaround they've used an 82 deg stat, which as it's always open to some extent, consistently beats the effect of the bypass. In terms of opening when it should, it seems a perfect workaround. The downside is of course the engine runs a bit cooler than is ideal, but not overly so, and there's less heat in the interior. At some point we might revisit this - they suggested constricting the flow in the bleed hose or finding a replacement manifold - but for the moment I intend to enjoy an overheating-free car, and slightly too cool is a huge improvement over always too hot. BTW, I can't take personal credit for any of these findings or any of the work. I'm just reporting the findings of the chaps I paid to sort it, who clearly deserve their rep as K-series engine builders.

Yes JK - particularly as I had the sump off not much more than a year ago and there was no evidence of break-up. In retrospect there were a few distinctive symptoms of the obstructed exhaust caused by the failed Cat which I dismissed at the time but which I would now take much more seriously. On cold starting, the button press would rotate the engine about half a revolution before stopping. The second press would spin it strongly and it would then start. I know what you're thinking. The battery was new, fully charged, and the voltage was high. On switching off the ignition, without the rad fan running, the engine would stop immediately. Not slowing down rapidly as you would expect, just an immediate stop. Finally, one of the emissions measurements on the MOT was only just inside the boundary.

It was HGF, pressurising the coolant and filling the top hoses with air. Not at idle, but with heat and torque, and towards the end, not that much. And a missing bleed ball valve - randomly affecting thermostat opening. And a failed Cat, making much more heat to (struggle to) deal with. And disintegrating sump foam, not exactly helping either. No wonder it was so tricky to control the temperature, with that little lot. But overall it's very good news. The head is still hard, the HGF surface damage was minor, the liners have not sunk, the oil pickup was not blocked, and there were no metal fragments in the oil. But it does explain how, towards the end of its former life, the only way it could control its temperature was with a cut-out thermostat. That removed the stat opening problem and ran the head just cool enough to seal the gasket. It's early days in its new incarnation, but there's no overheating now.

White aero + helmet, at speed and making a fine noise, heading towards Croydon on B269 Limpsfield road, Saturday midday. We were walking by the side of the road in the opposite direction.

... so I just did that. I blocked off 70% of the radiator and took it out. I expected to be on the high side of the temps with this, but that was the point of the test. After warm-up the needle settled at 85 and hardly budged no matter what I did, until eventually when I hit a sustained NSL stretch it climbed gradually to 90+. I interpreted this as meaning I'd made the nosecone aperture too small so pulled over to make the hole bigger. The temp eventually dropped, with the fan running. I checked the hoses - they were all properly warm and not overpressurised, no air to bleed from the heater junction. So no recurrence of "the symptoms" in a scenario which, with the old stat in, would very likely have produced them. Not conclusive, but hopeful, I think. Now, as it turns out, it has a minor leak, due to my hamfistery, which will need yet another drain and refill to correct. I've decided that at the same time I might as well fit a new stat (with 2mm hole added) and see what happens.

I thought I had followed all of SM25T's advice: hole drilled, heater fill point in place, final fill from there. The point is that all of this seems to have helped but only temporarily. So it runs for a while as if it is airlock free, then the symptoms gradually return and get worse. At this point re-bleeding keeps them at bay for a few hours, and the re-bleeding process never ends. Surely at some point all of the air has to have been bled out! Reminder: the bled air does not smell of exhaust. There is no mayo in the coolant. The coolant tested negative for combustion products. The slight difficulty I have with the "mask any symptoms" theory is that I have seen it "go wrong" - as in climb rapidly from a particular temperature - with stat, from about 78. Now, statless, it can get above 80 if slow/stationary. Nevertheless, the theory is easily tested. I just need to block off part of the radiator, make the engine run hotter, and see if the problem returns.

Had hoped there would be no further posts on this thread, but alas not. With the drilled stat the car behaved very well over June/July/August, I wouldn't say perfect temperature control but good enough. We took it to Wales and drove the chip run in each direction but including a Snowdonia extension northbound and a Hampshire extension southbound! Then, a few weeks ago, the misbehaviour came back more severely. On every drive I had to stop, switch off the engine, let out a lot of pressurised air from the heater bypass junction, and then it would be OK-ish for the rest of the drive. This was even with gentle driving. Today I'd had enough of it and I finally followed that piece of advice I had a while back - I cut out the guts of the thermostat which means the rad is now permanently in circuit. So the suggestion goes: if the overheating/overpressurisation remains, it has to be a gasket problem, otherwise it's something less worrying/expensive. Well, on a little test drive just now, try as I might, I struggled to even get it above 80deg; being stationary is the only way. On fast stretches, even with the beans, it was at 70, which I suppose is regarded as overcooling. Is this bad for the engine? I can't imagine it's worse than creeping up towards 100, as it was previously. I know about the cardboard-blocking-off-part-of-the-rad trick; so if it still has no stat by winter I'll have to try that. Unless someone wiser and more experienced knows better, the plan now is to run it like this for at least a few weeks, and if the problem has vanished then get a new stat and see it comes back. I don't really know what I'm talking about, but it feels to me that the symptoms might be explainable by an intermittently failing thermostat, that when it fails to open causes quickly rising temperatures and then the boiling of some coolant, overpressurising the circuit.

I use 15" T1R/TR1 for road only, and there are others who use this tyre. T1R has, I believe, very recently been discontinued. TR1 is the replacement, it is very similar except for a different tread pattern allegedly offering increased resistance to aquaplaning. I think they're great on my Seven - only a bit heavier than the CR500, grip nearly as good in the dry, much better in the wet, ride is great, very confidence-inspiring and progressive, and very nicely priced. The rubber is soft but after around 10,000 miles on my car there's still plenty of tread left.

Thanks Ian -I do already have the additional plastic bleed tee close to the heater bypass junction, so that should be easy :) Worth mentioning that my thermostat sits at 45 degrees clockwise rotation relative to the above picture, with the ally raised bar running skyward to groundward (I checked carefully, and it would sit at no other position!) Hence, in my installation, the hole is drilled above where this bar joins the flange, so that the hole is in the same position as above.