Lotus Elan

Another Amusing Failure

PostPost by: JGeezer » Sun Mar 11, 2018 12:30 am

Love these cars. SO it's running a bit rough, and I see a bit of smoke coming from under the hood. Take a look - and the choke cable is smoking. What? Huh? I was so dumbfounded that I touched it (mistake, nice finger burn).

OK, so turns out it rubbed through the insulation on a switched +12 wire under the dash, and made a nice path to ground from there via the carb! And the very hot cable then did a nice job of melting the insulation on some other wires under there, and melted though my headlight switch vacuum lines.

Gotta love it.
J Geezer
2004 Cadillac CTS-V
2003 Corvette Coupe
1969 Elan+2 Federal
(Past MGA, MGB, TR6, AH 3000 BJ8, XR4ti, BMW E39 540i/6, Lola T644 ... )
User avatar
JGeezer
Second Gear
Second Gear
 
Posts: 201
Joined: 09 Nov 2012
Location: Winchester, Virginia USA GMT-5

PostPost by: RichC » Sun Mar 11, 2018 4:20 pm

lucky not to have torched your motor :shock:
User avatar
RichC
Fourth Gear
Fourth Gear
 
Posts: 857
Joined: 28 Apr 2009
Location: Tendring Essex

PostPost by: RichardHawkins » Sun Mar 11, 2018 9:47 pm

I know this will offend the purists, but I rewired my Elan to a more recent standard in the hope of avoiding such a situation. When I dismantled the car I thought the wiring was worrying, melted and charged insulation, and a radio coaxial cable that had somehow carried a high current and looked quite frightening.

Richard Hawkins
RichardHawkins
Fourth Gear
Fourth Gear
 
Posts: 565
Joined: 05 Jul 2008
Location: Lincolnshire U.K.

PostPost by: JGeezer » Sun Mar 11, 2018 10:01 pm

Yes, I installed an entire new harness, completely rewired. Didn’t consider the very abrasive choke cable outer when routing things!
J Geezer
2004 Cadillac CTS-V
2003 Corvette Coupe
1969 Elan+2 Federal
(Past MGA, MGB, TR6, AH 3000 BJ8, XR4ti, BMW E39 540i/6, Lola T644 ... )
User avatar
JGeezer
Second Gear
Second Gear
 
Posts: 201
Joined: 09 Nov 2012
Location: Winchester, Virginia USA GMT-5

PostPost by: Craven » Sun Mar 11, 2018 10:57 pm

I think checking of all the major chassis earth bonding be included in a regular servicing regime.
Poor chassis connection between it and the starter motor can result in the starter trying to pull 150 amps through the minor wiring, a smoking choke cable and burnt harness returns are old favourites.
Craven
Fourth Gear
Fourth Gear
 
Posts: 762
Joined: 14 Sep 2013
Location: south coast uk

PostPost by: Elan45 » Mon Mar 12, 2018 2:04 am

Also look at where the battery cable rubs against the rocker panel steel rebar girder, especially where it crosses over to the back side of the firewall.

Roger
'67 Elan S3 SS DHC
'67 Elan FHC pre-airflow
'67 Elan S3 SE upgrade to 26R by Original owner
'58 Eleven S2 (ex-works)
'62 20/22 FJ (ex-Yamura)
'70 Elan +2S RHD
'61 20 FJ project
'76 Modus M1 F3
Elan45
Fourth Gear
Fourth Gear
 
Posts: 767
Joined: 23 Nov 2008
Location: Ohio, USA

PostPost by: tonyr27 » Mon Mar 12, 2018 8:51 am

I'm aware of two instance were the interior light circuit shorted onto metal work, one being the choke cable.

TonyR
1968 Plus 2 Cirrus White
1966 S3 FHC Medici Blue
tonyr27
Second Gear
Second Gear
 
Posts: 155
Joined: 02 Sep 2013
Location: South Yorkshire

PostPost by: Donels » Mon Mar 12, 2018 11:24 am

I once had the battery lead on a mini short through the exhaust pipe. The exhaust is of course rubber mounted so the only earth is where it connects to the engine. This is also where the throttle return spring connects. So the battery earths through the spring which gets hot, stretches and no longer closes the throttle. An interesting drive home ensued......
Elan +2
Elise mk 1
Donels
Second Gear
Second Gear
 
Posts: 137
Joined: 10 Sep 2016
Location: Tamworth

PostPost by: denicholls2 » Mon Mar 12, 2018 3:45 pm

My Fiat 124 Sport had a hand throttle in addition to the choke (very useful for keeping the RPM high enough in winter to charge the battery with the lights on.). One day while performing some unrelated restoratory task, I watched as the plastic shielding started to smoke, then the solid wire inside glowed red, then orange, then melted through.

Would have been a sadder story on a glassfiber body, I fear. :shock: Root cause, Fiat bodies of the era were made of compressed iron oxide, like glassfiber unsuitable as a grounding medium. Separate strap from the alternator and starter to the battery fixed the problem.
denicholls2
Fourth Gear
Fourth Gear
 
Posts: 543
Joined: 23 Jan 2006

PostPost by: billwill » Mon Mar 12, 2018 3:50 pm

denicholls2 wrote:
Fiat bodies of the era were made of compressed iron oxide, like glassfiber unsuitable as a grounding medium. .


Well I suppose that's one way of avoiding the rust problem. Make it out of rust in the first instance.

:mrgreen:
Bill Williams

36/6725 S3 Coupe OGU108E Yellow over Black.
billwill
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 4500
Joined: 19 Apr 2008
Location: London UK

PostPost by: Mick6186 » Mon Mar 12, 2018 8:22 pm

Electricity is a slippery customer!
I once rallied a Hillman Imp which needed some welding on a front wishbone. The job could be done with the wishbone in situ, so on went the stick welder earth clamp to a suitable point on the bodywork. Under I went , welding merrily when in the gloom of the wheelarch I spied a dull red glowing 'worm'! Puzzled I reached out to touch it and received a very hot hand. The only earth path from the rubber bushed wishbone was the aeroquip brake pipe!!
A lesson learned.
Mick
Mick6186
Second Gear
Second Gear
 
Posts: 193
Joined: 11 Mar 2014
Location: Gravesend

PostPost by: Bigbaldybloke » Sat Mar 17, 2018 10:05 am

I used to have a Morris Minor, it was common on them for the choke cable to get very hot, as if the main engine earth strap was corroded or broken, it was the next best earth back to the metal dashboard. Mind you, many years ago I had a mate with one that kept blowing 35A fuses, so he used his back door key instead of the fuse. Served two purposes, made the car difficult to steal and also ensured he never went out without his house key!
Change is inevitable, except from a vending machine!
Bigbaldybloke
Fourth Gear
Fourth Gear
 
Posts: 559
Joined: 16 May 2017
Location: Lincolnshire

Total Online:

Users browsing this forum: Type28 and 2 guests