Phillip Meyer Posted July 28, 2021 Share Posted July 28, 2021 I was caught in a tropical style downpour today whilst stuck in traffic. The Caterham really didn't like it and was not running smoothly after a short while, seemed to be misfiring and a bad smell. I managed to bunny hop to a fuel station and hide under their roof. It seemed tO be okay after drying out but then I had the same problem again after the rain stopped but with very wet roads.I'm currently waiting for it to dry out a second time, fingers crossed it will be okay now the sun is out.However, should i by worried that it's done some damage?Any thoughts on the cause so I can avoid this happening again if caught in the rain? Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted July 28, 2021 Member Share Posted July 28, 2021 IIRC the most commonly reported cause is water in the recess above the spark plug. But I can't remember which engines were affected.https://www.lotus7.club/forum/techtalk/plugs-and-duratech-warning https://www.google.co.uk/search?&q=rain+sigma+plug+site:lotus7.clubJonathan Link to comment Share on other sites More sharing options...
Area Representative Piers300 Posted July 28, 2021 Area Representative Share Posted July 28, 2021 Chances are that the plug wells will be full of water.Remove everything needed to get in there and dry it out. Piers Link to comment Share on other sites More sharing options...
SM25T Posted July 28, 2021 Share Posted July 28, 2021 Once water gets in to plug wells, it can't escape as rubber caps prevent it evaporating. Have to remove each cap and use paper towel. That's my experience with a flood and a k-series engine. Link to comment Share on other sites More sharing options...
aerobod - near CYYC Posted July 28, 2021 Share Posted July 28, 2021 From the symptoms (especially the bad smell comment), it may be a case that water has got into the lambda sensor connector or wiring, too. Link to comment Share on other sites More sharing options...
Phillip Meyer Posted July 28, 2021 Author Share Posted July 28, 2021 It was insanely wet, like a tropical storm, good job I only had the aeroscreen on!It worked better after a while but then I had the problem intermittently all the way home until it stalled about 10 mins from home. Then after a restart worked absolutely flawlessly which is Also odd. Link to comment Share on other sites More sharing options...
Area Representative Piers300 Posted July 28, 2021 Area Representative Share Posted July 28, 2021 As Ian says (#4). You need to get in there and dry it out. Obviously, don't take out the spark plugs till completely dry.Piers Link to comment Share on other sites More sharing options...
Phillip Meyer Posted July 28, 2021 Author Share Posted July 28, 2021 I have to figure out how to get at them first, I had a look earlier and it didn't seem obvious. Needless to say, I haven't built a Caterham! Link to comment Share on other sites More sharing options...
David aka Blue7 Posted July 28, 2021 Share Posted July 28, 2021 I don't understand how rainwater is getting into the plug wells unless a coil cover has not been fitted? I thought all 620S had a coil cover? Link to comment Share on other sites More sharing options...
Benton Posted July 28, 2021 Share Posted July 28, 2021 #8 Just checked mine as I was caught in a biblical storm this morning coming back from CC Gatwick, and fortunately they were dry as a bone. Given the lip/rubber seal tightness on my coils to get water down to the plugs you'd really have to be unlucky.To check.....Remove coil cover, 2 torx screws, watch out for the fibre washers that are either side of the cover for the screw Remove individual coils, undo 8mm bolt and pull.Look down hole Good luck! Link to comment Share on other sites More sharing options...
John Vine Posted July 28, 2021 Share Posted July 28, 2021 I'm inclined to agree with James (#5), especially re the smell.JV Link to comment Share on other sites More sharing options...
Phillip Meyer Posted July 30, 2021 Author Share Posted July 30, 2021 It turned out to be the lambda sensor that needed to be replaced (which is slightly worrying because it was only replaced 3/4 weeks ago, although I have driven ab0ut 1,000 miles!). They said that it was really coked up so I don't know if that was caused by rain or just use. They also said that they updated the mapping as this should help stop the problem going forward. Maybe I will start carrying a spare lambda sensor with me in the boot. Link to comment Share on other sites More sharing options...
John Vine Posted July 30, 2021 Share Posted July 30, 2021 Well, lambda sensors should last a lot longer than that! The coking-up suggests that you're running much too rich. Could that be due to the perennial over-cooling problem afflicting 620s? If so, the ECU will be assuming the engine is in warm-up mode and be specifying a richer mixture. Was the map update intended to weaken this mixture setting, I wonder?JV Link to comment Share on other sites More sharing options...
Phillip Meyer Posted July 30, 2021 Author Share Posted July 30, 2021 I suspect that running cold abs therefore rich is the cause. Hopefully the new map will help. Caterham might get fed up with getting the car back every 4 weeks for a replacement lambda sensor, especially as they told me that it doesn't affect the engine's longevity.To be fair to Caterham cars, they have been absolutely fantastic and jumped on every problem immediately and fixed it while I wait. I can't fault them on that, excellent after sales service. Link to comment Share on other sites More sharing options...
Mrp Posted July 30, 2021 Share Posted July 30, 2021 Given the history of over cooling, I think I might be blanking part of the radiator as a temporary fix to see if it helps Link to comment Share on other sites More sharing options...
HendrixsWhiteStratReturns Posted July 30, 2021 Share Posted July 30, 2021 Given the issues with such a new car aren't you tempted just to offload it and get into something (another Cat) that you can just jump in and drive ?(Edited to say : Not trying to be facetious with this post - just seems a shame that you've had a pretty rotten time with the car !) Link to comment Share on other sites More sharing options...
ScottR400D Posted July 30, 2021 Share Posted July 30, 2021 What about the rattling issue, any update? Link to comment Share on other sites More sharing options...
Phillip Meyer Posted July 30, 2021 Author Share Posted July 30, 2021 I am away at the moment so had to cancel my track day due to the rattling noise, I suspect it's something in the gearbox otherwise it would happen in other gears. It is back to Caterham on Monday.I could return the car and ask for a different one but I could have another set of problems with that.I love the 620, once the Caterham warranty expires I may go to PGM and have their upgrade. In the mean time I will try covering a part of the radiator, any recommendations on which bit to change and how, silver foil? Link to comment Share on other sites More sharing options...
Area Representative Golf Juliet Tango Posted July 30, 2021 Area Representative Share Posted July 30, 2021 blanking part of the radiator as a temporary fixTemporary? this works for me every winter on the Crossflow when I want the engine to get warm, so that I can get a bit of heat into the cockpit. Nothing wrong with this, I got the idea from taxis in London. Cost: £0. Link to comment Share on other sites More sharing options...
Phillip Meyer Posted July 30, 2021 Author Share Posted July 30, 2021 How do you do it?I am guessing silver foil over front and back, maybe the top third as heat rises?I did read the old Low Flying article about the PGM approach but I don't think it explained how he covered the radiator at first. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted July 30, 2021 Member Share Posted July 30, 2021 I wouldn't use silver foil. It's electrically conductive, and it might end up somewhere where you wouldn't want that.I've seen mention of corrugated plastic sheet and of aluminium sheet.I don't think that the position on the radiator matters. It only needs to be one side, and I'd put it in front.https://duckduckgo.com/?q=site:lotus7.club+radiator+blankingJonathan Link to comment Share on other sites More sharing options...
David_Long Posted July 30, 2021 Share Posted July 30, 2021 Lambda sensors are sensitive to damage from water. They are meant to be mounted vertically in the exhaust (the top of it) so than any condensate drips off the shield and does not enter into the sensor in liquid form. It is electrically heated during start up to avoid contamination. But Caterham seems to have missed that bit in the design, and I suspect that is why we see so many failures. It is possible water was forced through the exhaust joint if there was standing water. Link to comment Share on other sites More sharing options...
Benton Posted July 30, 2021 Share Posted July 30, 2021 To shield the radiator I use plastic correx sheet cabled tied to the inside of the nose grill. About 1/3 area covered I found works for my 620R ...... however .... that's when the outside ambient temperature is less than 10 degrees i.e. winter, you shouldn't need it atm. Link to comment Share on other sites More sharing options...
John Vine Posted July 30, 2021 Share Posted July 30, 2021 Re #22:But the OP reports "coking-up". If that's down to running too cool and using warm-up fuelling, could water ingress have caused his problem?JV Link to comment Share on other sites More sharing options...
Phillip Meyer Posted July 30, 2021 Author Share Posted July 30, 2021 My 620s runs at 90 if it's hot weather and I'm driving around normally BUT if I head onto the motorway it drops right down to between 50 abs 60, especially as I pull off the motorway (then it drops right down). Also in the morning when it's not as hot it is very hard to warm up, it generally sits just below 60.I think long term I will go down the PGM solution but this will obviously invalidate my warranty so I will wait until that has expired.I would be really interested though if the coke could be caused by the water or just running rich, the Caterham cars engineer told me it was coked up. Link to comment Share on other sites More sharing options...
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