strange 'overheating' mystery

[pinstripe pete]

Just covered 1800 miles in the Seven. The car seems fine after its long journey but I have a few concerns and would like to pick your brains! (car is an 1800 VVC)

 

Firstly whilst on a long narrow road, miles and miles from civilisation (typically) the temperature gauge climbed into the red. Fan was working okay at the time. I stopped immediately and removed the nosecone and bonnet, but there were no signs of overheating (ie rubber hose between water rail and top of radiator were 'squeezable' and I could grip it without burning myself. Coolant in header tank was only tepid). I suspected the temperature sender might be up to its old tricks again. The gauge stayed in the 'red zone' with just the ignition on. I drove it a few more miles - still it was up in the red. Stopped, checked it all again, no sign on any problems. The temp gauge was flickering a little. Ignored it for the rest of the day. Car was absolutely fine.

 

Temp gauge now nearly back to normal (80) but it still seems to heat up far too quickly when starting from cold. Clearly I'm a little concerned about the head gasket if the engine has in fact overheated!

 

Okay thats the first thing. I was also aware that the fan was now no longer cutting in. I was a little apprehensive about letting in run statonary at idle to see if it would eventually do so, so I've disconnected it from the thermostat and wired in a small overide switch for when I would (inevitably) get caught in the roadworks on the M6.

 

And another thing!!!! The car seems to sit a little bit lower on the left rear. Tyres are okay. Handling okay and no strange noises above and beyond what we're all used to.

 

Any (sensible) thoughts? Thanks!

 

'A gentleman is a man who opens the door for his wife to carry the coal in'

[Manxseven]

Sticky theomsat maybe.

 

Worth checking it opening ok.

 

L7 BDA Supersprint Joy here 😬

[neil.cavanagh]

Pete,

strange!!

my temperature gauge packed up just as I started my trip north to tour scotland!

 

It behaved a bit like yours.. it was a bit suspect for a while and then would go straight to the red all the time. It half recovered a few days later, but then packed in again.

Its very easy to replace the temp sender... I'd give that a go and see if the reading are reasonable then.

 

Neil

[paul richards]

Car leaning to one side!!!

Assuming car is dedion axle, suggest you check rear shocker mount on dedion. There have been a number of problems with the mount ripping the dedion tube - 2 of the LADS have had it in last 2 months - scary!!

 

Paul Richards

Joint AO - L.A.D.S. (Lancashire and District Sevens)

Growing old is compulsory - Growing up is optional

[Rachael]

Second Paul's comments - check the De Dion. We've just found a very big crack in ours ☹️ which does explain the grounding on Paddock Hill bend at BH and the fact that one side of the car was much lower than the other.

 

Caterham do a beefed up version of the DD tube now, which is what we have put on our car.

 

Rach

[pinstripe pete]

Thank you folks! The leaning to the left is not significant but I'll get underneath the car tomorrow and have a butcher's at the tube. Just out of interest if the DD has gone,what might have caused it? The roads on Skye were quite bumpy in places and I, er, confess that I was driving enthusiastically much of the time.

 

Whilst at the Goodwood Revival this year I did give a passenger ride to an EXCEPTIONALLY large American gentleman (I mean he only just fitted in my SV and the harnesses had to be slackened all the way out before they clipped in). Came down quite heavily at one point (once I'd taken an age to get up to speed) which caused the exhaust to ground out. Might this have weakened it?

[paul jacobs]

Pete, When I had a similar problem with my 21, which had the older unstrengthened Dd tube, Jez Coates indicated that there were NO general problems and that only the racers who constantly kerb hopped, were at risk. He wouldn't replace mine, but kindly allowed me to buy one at a discounted price ☹️, With all the abuse you have admitted to, this could be your problem, especially with that enormouse Debbie you took to Goodwood and of course, Mike Rowlands is no lightweight is he? 😬

 

Your overheating probs. could be down to a faulty thermostat and/or sender unit, as has been mentioned. Neither is expensive, and worth replacing, just to be on the safe side. Get the R500 thermostat from Caterham, it opens at a much lower temperature than normal, it might also be worth drilling a very small 2 mm hole in the outer flange, so there is always a small amount of through flow as a safeguard to the system.

[Nick Woods]

Maplin sell a basic multimeter for £15 which includes a thermocouple - its a good way of doublechecking the temperature guage.

 

Nick

Red and Black 1.6K supersport

visit Carrotland.co.uk

 

[pinstripe pete]

Paul - 😬 😬 😬 😬!

 

The temp sender has failed before and been replaced; I seem to be getting through them every 6 months! The only thing is that this time I going have to replace the whole water rail (DOH....after overtightening the replacement sender through impressive ignorance!!). I'll have a look at the De Dion tomorrow. The leaning to the left is not at all severe. Would a cracked tube affect handling? There was one 'moment' in Skye when I was coming round a right hand bend in the rain and the car oversteered suddenly as I started to accelarate. It was never going to get away from me (despite being a little surprised, I held it on the slide quite well 😬 ). Road surface and camber were not conducive to causing snap oversteer (as far as I could see). Might this be significant? Or is this just the wannabee racing driver in me blaming the car before myself?

 

'A gentleman is a man who opens the door for his wife to carry the coal in'

[brookside2004]

As regards the 'overheating' mystery, I had a similar problem earlier this year with mine (K1600 R/Sport), where the guage would quite suddenly indicate a severe overheat, and then wander between normal and red, dependant on engine revs and speed. It turned out to be the temp guage sender wire laying tight against the engine block. Once re-routed everything was fine !

Paul

 

Just like a novice but less experienced !!!!

[j_thombs]

Temp sender would be my guess.......in the past I have also had to replace the water rail

 

Jon

 

Ex Beaulieu no31 now Supersport R..

 

My Caterham Pics

[paul jacobs]

The DD crack could indeed cause that sort of incident. Basically the lower shock absorber mount is peeled off the tube, although there is now more reinforcing, I think it could still conceivably happen. If I remember, I'll bring my old tube along nest Thurs. to show you.