Paul Richards.

As purchased 2012

Raise front of car off ground - as high as possible and disconnect expansion tank and raise this up in the air as high as possible. Ensure that system is full and run with top off expansion tank. As engine warms up, keep loosening radiator bleed valve to ensure no air lock in top of radiator. Air lock should find its way out and great bubbles come out of expansion tank. Be careful as there will be a lot of boiling hot water around. Keep checking bottom hose for temperature. This should become hot when thermostat opens. Gentle squeezing of hoses should also help. Good luck. Paul R. C7PPR K series that starts when hot!!

Dave Assume you are removing sump to change foam baffle. If you had not planned it, suggest you do so. Its only a few quid and not worth removing sump without changing. Confirm sump gasket is reusable. Paul R. C7PPR K series that starts when hot!!

Measuring bump steer is something I've kept meaning to do. As you say it's a bit fiddly, but will cost nothing. I seem to recall that suspension guru Alain Staniforth set up a lot of Sevens and virtually all needed some adjustment to eliminate/minimise bump steer. Need to take spring off shocker and move the wheel up and down through normal range of travel and watch for steering movement. You can make a hinged board with pins on it as described in some of the suspension set up books, but you can get a good indication by removing wheel and clamping a long piece of wood or metal to disc and watching end of said long piece - this exaggerates movement. Paul R. C7PPR K series that starts when hot!!

Chris W. I agree that the problem being cured is the pitted/corroded contacts in the MFU. The cure is the use of a relay which only needs a very small current (which even below par MFU can still provide) to activate the additional solenoid which activates the starter. I originally thought that sticking plunger on solenoid was the problem, but dismissed it after several cleanings and no improvement. What I can't understand is :- 1. Why did my problem only occur when hot? 2. Why was my problem worse when a battery cut off switch (along with associated extra wiring) was included? I've now decided not to worry. It works for me and continues to work, despite high engine and ambient temperatures experienced on recent Le Mans trip. Now 12 months with no hint of failure, when in the past I would have had problems at least weekly. Keep Starting. Paul R. C7PPR K series that starts when hot!!

Sorry to hear that the relay hasn't cured your problem. I suffered from a similar hot starting problem and know just how frustrating it can be. I almost felt like selling the car. Fortunately for me the relay was the complete cure and I'm surprised it hasn't worked for you. There have been other threads on fixing starters and it now points to one of the "other" faults. Unfortunately I have been unable to search for the thread, but I seem to recall that one was the cracking of the soldered joint which provides the main feed to the solenoid. Hopefully someone will expand on this for you. No doubt your auto electrician can carry out some tests to confirm. Paul R. C7PPR K series that starts when hot!!

Paul Try:- 1. How to make your car handle - Fred Puhn - HP Books. 2. How to build and modify Sportscar and kit car Suspensiion and brakes - Des Hammill - Veloce Publishing - Speedpro Series. Both above are from USA, but I could let you borrow if you ask nicely. Also there is a good book by Alan Staniforth - can't just recall the name off hand, but John E. has a copy. Paul R. Paul R. C7PPR K series that starts when hot!!

Mark Your symptoms are very much like mine were. Below are instructions for fitting a relay to overcome the problem. Although if wired as per previous posting, the following are slightly different and you should follow these:- You need a 4 pin 30 amp fuse - they cost about £6.00 or £7.00 and are available from most car accessory shops. You connect the terminals of the relay (these are shown on the relay, but are often very small) as follows:- 30 - This is live feed and should be connected to positive terminal of battery - best to incorporate an in line fuse. 86 - Signal i.e connect the original solenoid wire to this terminal. 85 - Negative - connect to negative battery terminal. 87 - connect to the solenoid - where the original wire (now connected to 86 on relay) was connected.. If you are having difficulty, or can't follow, please drop me an e-mail. I have even produced kits for some people with all the bits needed already connected to the relay. I'm also fitting at least one for somebody at Stoneleigh and if you're going can bring along an extra kit. Paul R. C7PPR K series that starts when hot!!

Silicon sealant WILL stand the heat (and it's cheap and easy). I know it sounds odd, but it should be ideal. I've used it on a number of occasions to seal exhaust manifolds direct to the cylinder head. Paul R. C7PPR K series that starts when hot!!

Happy to supply a kit with easy instructions that should take 5 mins to fit. I will obtain the bits (I can get at cost price) this weekend and anticipate charge for a complete kit with post and packing will be £15 and this will include a good donation to Nuke the Luke. If anybody wants one, please e-mail me separately and l will let you have my address and telephone no. Please be sure to include your e-mail address within the body of your e-mail (my computer sometimes has problems with "replying" to e-mails). Paul R. C7PPR K series that starts when hot!!

Ted Just say the word and I'll bring a relay "kit" to Stoneleigh. Chris W. Excellent advice and excellent contributions to thread . I'm sure there can't be a starter motor problem that can't be cured by the Blatchat archives 😬 Just brings to mind what a nice bunch of helpful people 7 owners are and what a useful forum Blatchat is 😬 Paul R. C7PPR K series that starts when hot!!

Allegro Glad it works. Another satisfied customer Graham That's how I discovered it works. If you have the problem it seems to get worse (more frequent) and becomes a real pain, especially when you,ve just spent 5 mins settling in the seat, fastening the 6 point and closing the side screen and have to get out again. FIT THE RELAY!!!! It takes 10 minutes (about the same time as getting out 4 times to use your fly lead!!!). A pity you're so far from Bury or I'd fit it for you (small donation for Nuke the Luke). Thinks....... ....... ....... This could be a nice little money spinner at Stoneleigh!!! Relays fitted in aid of Nuke the Luke????? Relay kits (complete with wiring and instructions) supplied for self fitting. Wonder if anyone will respond to this? Paul R. C7PPR K series that starts when hot!!

Angus and Tessa Starter motor on Caterham K series is fitted with a solenoid that 'flings' the cog into the flywheel ring gear. Regret from the symptons you describe that the relay "fix" is unlikley to help you. It seems as if there is a fault with the starter and/or solenoid which could be mechanical i.e. gummed up or worn. It could also be worth checking the teeth on the ring gear for damage i.e. the teeth on the flywheel into which the starter is 'flung'. You should be able to see these when starter is off and be able to view all the teeth by putting car in gear (2nd or 3rd) and pushing car to turn engine. If this reveals no obvious problems I'd personally take the car to the people who reconditioned the starter and let them investigate. It could be that the starter is still faulty despite alleged reconditioning. Paul R. C7PPR K series that starts when hot!!

Easy to fit. Pretty accurate - definitely better than standard speedo. Cheap - mine was £6. Highly recommended. If I was buying another I would splash out and get a more expensive one as I understand you can get one with a back light - very useful. Paul R. C7PPR K series that starts when hot!!

John Are you sure that your starter is duff. See separate thread on starter motor problems. How long have you had the rewound starter motor. I don't wish it upon you, but you could have problems in the future. Heavenly Why the new starter motor. Is it not just a problem which can be corrected by relay as per separate thread? If you really need a new starter I would buy John's and carry out the relay mod. I'm sure it will be satisfactory. Perhaps as he feels it's duff he will let you have it on approval Paul R. C7PPR K series that starts when hot!!

Stu Thanks for the offer of letting me open up your MFU. I may take you up on that as I would hate to damage my own!!!! Dave J. See instructions above - Terminal 87 of relay goes to original solenoid connection. Apologies for all the superfluous numbers in the instructions - i.e. ignore the "" - it appears instead of 'bullets' when I copied and pasted from a word document. I wish I understood computers more Paul R. C7PPR K series that starts when hot!!

Chris W. I always wondered exactly what the ECU did – thanks for the info. I’m impressed by your theory and it sounds pretty good to me. There is no doubt however that it is heat related and it is a fact that my car was worse when the wiring length was effectively extended (i.e. when the isolator switch was included). Correct me if I am wrong, but resistance does build up over a longer length of cable and is it also not affected by heat? I suspect it may be a combination of resistance build up caused by the contacts in the MFU and within the wiring. Perhaps what I ought to do is look in my MFU, as the contacts should presumably be very corroded as I have suffered such problems. Is it possible to clean the contacts if I open the MFU up? Colin I understand that a number of people have found a similar problem with cracked terminals on starters and this too is perhaps a common fault and presumably caused by vibration. When my starting problem first started I had a number of people who tried to convince me that this had to be my problem. It wasn’t, but your posting serves as a reminder that there are other problems to look out for. Stu I think the answer to your question is probably - Yes, but I'm wondering whether we ought to be opening up the MFU and cleaning these contacts to prevent problems in the future. Paul R. C7PPR K series that starts when hot!!

For those who have requested details of wiring a relay, I trust the following will help: - You will need a 30-amp relay – available from most car accessory shops for less than a £5. Also some short lengths of wire – I bought a roll of reasonably thick 27-amp wire, but you can colour code - a metre of red and a couple of metres of black will be sufficient. You will also need a couple of ring terminals to fit the bolts of the battery terminals and half a dozen female spade connectors. *******Disconnect battery before starting work******* I have fixed my relay to the aluminium lip in front of battery i.e. top corner of foot well (relays will often have a small tab with a hole in them that enables you to attach with a small self tapping screw or pop rivet). The relay will normally have 5 male spade connectors which will be marked as shown below (the markings are often very small and you may need to look very close). I have used 27-amp wire i.e. reasonably thick for the live feed and for the lead from terminal 87 to the solenoid.  Common (usually marked as '30' - at least on a 30 amp relay) - This is live feed and on my car is currently connected direct to positive terminal of battery. If you have a battery isolator switch (Big Red Key) you may wish instead to connect to the very large red wire which supplies the main feed to the starter. Doing this will mean that the relay is cut off when the isolator switch is off.  85 = This is the ‘Signal’ terminal and the original lead to the solenoid wire should be connected to this. (This is the small lead, which already has a female spade connector and is currently connected to the solenoid on the starter). You can shorten it if you wish, as it may be a little long.  86 = Negative - mine is connected to battery terminal, but I guess any good earth will do.  87 = There are normally 2 terminals on the relay (often marked 87-1 and 87-2 or 87A and 87B). One provides a closed circuit and the other an open circuit. It seems to be the 'first' terminal in the numbering sequence that is used i.e. 87A of 87A and 87B, or 87-1 out of 87-1 and 87-2 etc. This terminal is connected to the solenoid on the starter. That’s it – job done. All you need to do now is tidy up the wires – a few cable ties will do the job. Reconnect battery and try. Now when you start the car, instead of the current going direct to the solenoid it will go to the relay and the relay will act as a switch and take the current direct from the battery to the solenoid. Forgive me if these instructions are not clear or are too simple for some, but I hope they assist. If anyone needs any help or assistance, drop me a note of your e-mail address (my computer doesn’t allow me to use the reply facility) and I can let you have my phone number or I can send a digital picture of the installation. Paul R. C7PPR K series that starts when hot!!

Tony/Chris W I obtained the cure to this starting problem from a local auto electrical engineering company (recommended by my good friend John E.) who have come across similar problems on other cars - Peugeot diesels amongst others. My original problem occurred about 4 or 5 months after the car was new and I had 2 new starter motors fitted (supplied under warranty by Caterham with one fitted by their agent who also carried out some investigation, but found no problems). Each time the problem went away for a couple of months and before long car was out of warranty. The problem returned and got worse. It became even worse when I fitted a battery cut out switch. Like most intermittent problems it was difficult to investigate and the fact that it got worse actually helped me to find the solution. I discovered that when the problem occurred it was possible to start the car by connecting a temporary wire to the solenoid and touching it to the positive terminal of the battery. This never failed. The auto electrician came up with the fitting of a relay as a cure. What Mick suggests is correct. I am not an expert on electrics, but my understanding is that as the car gets warm, resistance is built up in the wiring. The K series starter motor appears to have a solenoid which is marginal (Mick - I suspect this is the reason why only K series have the problem, or it could even be the wiring of a K series is slightly different i.e. to accomodate the Rover immobiliser or similar) and needs full power to activate it. The small drop in power caused by the resistance build up is apparently enough to prevent it working. Facts which seem to make sense:- New starter motors gave a temporary cure only as they were new with no dirt in mechanicals, new connections, no corrosion etc. and therefore able to work with a small drop in current (It is so marginal). The inclusion of additional wiring for a cut out switch had an adverse effect because this increases the length of wiring and my understanding is that this increases resistance. Suggestions that the internals of the starter or solenoid are a problem can be dismissed. I had 3 new starters in all and I can’t imagine that they were all faulty. I also swapped starter motors with someone and my starter worked on his car and my problem still persisted. This definitely points to a problem outside the starter. There is no doubt that this fix works. My problem got worse and worse. I came back from Le Mans last year and travelling on motorways, the car got “hot”. At each fuel stop had to push start the car. I then found the problem manifested itself on even short journeys - every time the car got fully warmed up (as opposed to hot). Since the modification I have had not even a hint of a problem. You cannot believe how embarrassing/inconvenient it was to have to push start the car. It got to the point where I was so fed up that I considered selling. If anyone has a similar problem, I urge you to try this mod. As Stu says it will cost less than a fiver and take about 20 minutes to fit. A number of people have had success (I am not aware of any failures). What have you to lose? It’s certainly cheaper than buying a new starter!!! Paul R. C7PPR K series that starts when hot!! Edited by - Paul Richards. on 12 Mar 2003 12:51:57

All If you use the search facility, the heading of the post I put on last year for fitting a relay was "K Series Starter - The Cure??" It has worked a treat and has never failed since that time. Previously I had regular problems on any good run where car gets hot. If anybody needs help or advice, please drop me an e-mail and I am only too pleased to assist. If you're close enough to Bury, I am even prepared to fit for a small donation to Nuke the Luke. Paul R. C7PPR K series that starts when hot!!

Stu As you know I have a heater and find the following method best and normally no need to raise front of car:- Fill system to to mark on expansion tank then put top back on. Remove bleed valve from rad and fill via small hole until rad is full. Replace bleed screw. Make sure heater valve is open - normally means pulling control knob out. Place rags under hoses around heater (to catch excess water) Remove top hose on heater (goes to water rail as I recall) and place thumb over inlet to heater. Fill with water using funnel in heater hose holding in air. When hose and heater are full refit to heater asap trying not to spill too much. Make sure everything is tight. Paul R. C7PPR K series that starts when hot!!

Careful if fitting tank before engine and radiator. Top hose fits alongside apollo tank and you need to make sure there is enough room for it without fouling on bonnet catch. Personally I would leave fitting tank until after engine and rad are in place and you can trial fit with top hose on. Paul R. C7PPR K series that starts when hot!!

Large nut on rear is 41mm and is left hand thread on nearside of car. No need to remove half shafts. In fact they are a push in fit in the diff and if you remove will lose gear oil. When caliper is removed And you'll probably have to remove brake pipe to do this (assuming rigid pipe has not been replaced by flexible hose), the disc and hub will then simply pull off the splines of the drive shaft. Replacement is reversal of removal, but need to tighten 41mm nuts to 200 lbs ft torque - that's a lot. Paul R. C7PPR K series that starts when hot!!

Colin Grundy - are you out there. I have tried to reply to your e-mail, but have a problem with my computer. Please let me have your email address and I will send reply. Paul R. C7PPR K series that starts when hot!!

John Europa do a couple of 'taps' for the heater control and one is cable operated similar to Caterham part. Will bring catalogue to LADS meeting on Wednesday. Paul R. C7PPR K series that starts when hot!!