Smithy77

Sorry to resurrect an old thread. I will soon be getting back my 230bhp R400 K engine after a fresh rebuild. Before the rebuild it suffered quite badly from the unexplainable K-series overcooling issue - any cruising above 40-50mph and with ambient temps below 15C, the temp gauge settled at a constant 60-65C. This was on a standard coolant circuit, without heater, and fully functioning 82C drilled stat. It would seem nobody can explain how this phenomenon occurs; if the coolant is 60C as measured as it exits the top of the head, it can be no warmer when it reaches the standard stat housing, so in theory the stat should close, and therefore coolant temps should rise, but they don't. The symptoms are exactly what you would expect from a stat stuck open. Blanking the radiator helped a lot to reduce the problem, which must mean that while the coolant is measured at 60C, that the stat must be staying open (after initial warm up) if blanking the radiator helps to control the temps. Anyway, the reason for resurrecting this particular thread is because I plan on adopting Mankee's idea (and indeed using his parts) to make a DIY version of the remote stat. However, I plan on deviating slightly from his original idea which, as I understand, was based more closely on the QED circuit whereby the original "heater bypass" remains in situ, but the bypass out of the remote stat is plumbed into the the expansion bottle bypass circuit. I'm not sure I like the idea of having 2 bypasses bypassing the radiator as you are making it easier (by reducing the resistance) for the coolant to flow through the 2 bypasses rather then through the radiator. So my idea involves deleting the heater bypass circuit completely and introducing a new bypass from the remote stat directly to the original stat housing. Link to coolant diagram It should be noted that the bypass inlet/outlet from the stat housings are 20mm and I plan to reduce the bypass hose to 16mm for the majority of it's length to help maintain some of its resistance. The QED kit has an 8mm bypass outlet I believe which Tee's into the 16mm hose between expansion bottle and submarine pipe, but I think you are also supposed to retain the original heater bypass circuit too. I'm hoping this might go some way to resolving the overcooling and general temp stabilisation. Will this solution be any better or worse than a) the standard circuit, or b) the QED kit? Thoughts/problems/ideas welcome before I go experimenting on my new engine!

While I've got the engine out I'm looking to sort out the oil weeps from my diff and gearbox. It looks like one (or probably both) of my drive shaft seals are leaking from the diff. I plan on replacing both seals with the diff in situ. The gear box is collecting drips of oil on the tail; looks like it is most likely the speedo drive sender, but it could also be the prop seal. Since, from reading the archives, it sound easier to sort the speedo sender with the gearbox removed, and since the engine is out, I will take the box out and so will replace the prop seal to be on the safe side. I'll drain the box before removing and refill with fresh oil once refitted with the engine. Some questions before tackling the work... 1) What oil do I need for the box and what quantity? 6 speed box from a 2002 Superlight. Does the 6 speed have a more reliable method of checking level vs the 5 speed, which I hear can have different filler hole locations? 2) What should I look at replacing for the speedo sender? I'm pretty sure it is the electrical type 3) Anyone know part numbers for the prop shaft and drive shaft seals? 4) What oil should I use for topping up the diff (LSD)? Any other tips and points please let me know. Thanks!

Could you not get a couple of mates round to help you "manhandle" the car out of the way??

From when I had a K with IACV, I remember the stepper motor chattering/hunting for a second or two after switching off, which is normal as I believe it is finding the starting position for next start up. I don't ever recall hearing anything before starting though.... I would look for a spare IACV and do a swap and see if it does the same. They are handy to keep as a spare

Aero will mainly be for track so I need the quick interchange ability

I do have the knee trim panels so they would be the ideal solution. I might take your advice and try it without the brackets too!! Need another helmet to make it a bit more passenger friendly...

I have just got an aero screen and I'm after the brackets which make it interchangeable between aero and windscreen. Anyone have any lying about?

Superlight buddy! I have #189

I also tried the "overfill" method too, as I noticed the catch tank was dry. I topped up twice with about 0.25L at a time and after the 2nd little top up, I started getting oil in the catch tank, so thought I was covered with that method too. I wouldn't rely solely on that method....

Regards the rebalance, so that's the crank, along with the rods and pistons presumably? Are you able to confirm the extent of balancing work whilst in your hands Dave? Did you balance the flywheel, clutch and pulleys?

Standard oil capacity is 4.5L from memory isn't it? To be giving false (good) readings with a 2.5L discrepancy is very worrying. Once I get to know the engine with correct oil levels, all will be good I'd like to think....

Thanks for the info Dave. Do you suggest getting the whole lot fully balance again too? What is involved? The cause was a lack of oil. Only 2L was drained, this is despite me regularly checking the level using the standard Caterham dry sump method (while running AND straight after switch off) and all the time looking like the oil was plentiful. I even had fellow club members check the oil with me and we all agreed it looked fine. Doing some reading on the subject it would appear the Caterham method is far from accurate or reliable.... seems I learnt the hard way

So not long ago I bought my "dream" Caterham - a mint 2002 Superlight with a 230bhp K-series lump, complete with 6 speed/3.92 LSD, full cage, Quantums etc etc. I bought it knowing it needed a remap, so after a month of farting around adding serial connectors to the MBE and not really driving it, I eventually got it remapped at Track and Road. A healthy 230bhp@8000rpm was the result. I got a mere 24hours of mind blowing enjoyment out of it before the bottom end let go. Oil starvation was the cause (long story). To cut to the chase, the engine is currently in bits in the hands of Tom New. Pistons, rods and crank damaged beyond repair. Thankfully, the head has escaped unscathed. I'm posting to canvass opinion on what spec I should rebuild the engine to. The engine when I bought it was a Caterham supplied Minster R400 spec K-series with Caterham dry sump belltank system, but it underwent a rebuild and upgrade by DVA in Feb 2015 which included the following: Full engine balance; 32.5 inlet valves with full big valve porting to head; 1444 cams; VDSK springs; steel caps; original pistons retained with modification for valve clearance; head fettled for cam and follower clearance; piper verniers; TBs port match to head; Turbo 11.5mm oil scavenge pump. So other then being balanced the bottom end is standard R400 spec. Can anyone confirm what this is exactly over and above a standard 1.8 K-series? Just out of curiosity. So, what spec should I rebuild the engine to? I'm not wanting anymore power, so any upgrades would purely be for longevity as this car will be a keeper for many years. I'll be meeting Tom tonight to discuss, but he immediately suggested steel rods and new valve springs (the latter I am a little unsure of the necessity as since the DVA work it hasn't been on track and only covered a 1000 or so miles). Let me know your thoughts! Cheers

Further reduced

Yes please! How old are they, and do you have any idea on courier cost?

You already know my thoughts, but for the purpose of readers and contributors... I would never run an exhaust on a single rear mount. I know many people do but I think the majority prefer to use a front mount too. The thought of the weight of the entire exhaust system being spread reasonably equally (for sake of argument) between just a single rear mount and primary attachment to the head worries me. The additional stress at both ends must be significantly reduced (by roughly 33% for sake of argument) by the addition of a front mount. This can only be a good thing. During my reading on this subject, I found that the only argument/case for not having the front mount is that it somehow added more stress at the primaries by making the system too rigid. I think a couple of people experienced a cracked primary and put it down to the front mount. However, as long as the system is fitted properly, with all the fixing points tightened progressively and evenly, and as long as both of the exhaust bobbins are of suitably flexible rubber, I can't see there is any truth to this argument. I wouldn't use anything other than normal rubber bobbins. As alluded to above, the rubber mounts need to absorb the movement to relieve the stress. You could add a fail safe device onto the single rear mount but I'm not sure it be of much use. You will need to fit said device so it doesn't restrict the flexibility of the bobbin, so a loose strap type thing is what your thinking, I think. Even without the strap, a bobbin failure wouldn't see the exhaust falling to the floor as there is enough rigidity in the system to suspend it more or less where it is. The problem is the whole system will now be bouncing about suspended only by the primary bolts to the head. The safety strap will not be doing much to prevent the primaries cracking. A far better "fail safe" is to have a 2nd exhaust mount in my opinion. A decent exhaust fabricator will be able make you up a bracket, whether is needs to be fixed to the cat or the pipe, it shouldn't be a problem. If you're worried about the thickness of the cat casing being insufficient, they could probably fit a strengthening plate to the cat or something.

Radiator blanking was what I resorted to as well and did the job of maintain temps around 80C. If there is enough demand for them, maybe someone can run a production of clip-on aluminum blanking panels which would be quite a neat solution, then easily removed for hot / track days. It remains a mystery how certain specs of K series engine don't suffer from over cooling on cold days. Revilla for example, with his fleet of VVC 160 engines, reports a steady 80-85c in all conditions and all air temps on all his engines. But then we have a 1.4K classic and a 230bhp K both over cooling!! There has to be an explanation....

Yes, that was my last car which cam with the triple core jobbie. A single core rad didn't completely cure it, just made it much less extreme and managable to a degree; it still over cooled with ambient temps below 10C. Strangely enough, I have experienced exactly the same symptoms with my new 230bhp K series, but this has a standard 40mm single core ali radiator

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There will be others Jonathan, I'm sure

Hi Neal! Car sold today, finally! Needed some more power so got a Superlight with 230bhp K series :-)

Reduced!

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Jonathan, the injectors now match because they were all cleaned!?? Or am I missing something...? PS. It was a team effort ;-)