Lotus Elan

Elan Sprint Misfire

PostPost by: andrewdmoore » Wed Jul 07, 2004 9:37 am

Sometimes my starter motor will hardly turn the next minute it's fine. Also the car develops an intermittent misfire once its fully warmed up. All the relevant electrics have been renewed apart from the alternator and its been rolling roaded tuned & the carbs cleaned.

Driving home with the lights on last night they kept going dim then back to full power, this coincided with the misfire. Could I have a problem with the earth 'straps' I hear people talk about and if so where are they/is it?

Would a duff earth strap cause misfire, starter motor problems & lights dimming.

Thanks, Novice Mechanic
andrewdmoore
Second Gear
Second Gear
 
Posts: 64
Joined: 23 Sep 2003

PostPost by: types26/36 » Wed Jul 07, 2004 10:46 am

Andrew,
Sounds like you could have problems with the earth straps and this IS where to start, normally there is one on the left side engine mounting bolt to chassis and one on the rear gearbox mounting bolt to chassis. Quite often people fit extra ones which could be anywhere, the basic idea is to connect the engine/gearbox to the chassis.
Rgds Brian.
Brian
64 S2 Roadster
72 Sprint FHC
User avatar
types26/36
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 3882
Joined: 11 Sep 2003
Location: U.K.

PostPost by: worzel » Wed Jul 07, 2004 10:52 am

Could be the earth- there is one fitted on the exhaust manifold side connected to the engine mounting.

When mine snapped I rigged up one from the front left side chassis bolt (inside the engine bay into the front turret) and from the tapped threads at the front of the block (exhaust manifold side) just under the head. Faulty engine earths can play all sorts of tricks particularly if intermittent in nature. Why the lights should dim I'm not sure. I'd also check the one in the boot and the front earth tags by the top of the radiator.

John
worzel
Fourth Gear
Fourth Gear
 
Posts: 626
Joined: 13 Jan 2004

PostPost by: andrewdmoore » Wed Jul 07, 2004 2:53 pm

John & Brian,

Thanks for the feedback, now really down to basics - what do they look like?

Are they like heavy duty versions of the braids/pick ups that Scalextric Cars use?
- thousands of individual criss crossed wires?

Thanks again, Andrew

ps I warned you I was a novice!
andrewdmoore
Second Gear
Second Gear
 
Posts: 64
Joined: 23 Sep 2003

PostPost by: types26/36 » Wed Jul 07, 2004 3:35 pm

Andrew,
Dont know about this scalextric thing but they could be as you describe a cris cross
of fine wires or they could be a thick strand of wires covered in a plastic coating (should be black) BLACK=EARTH RED=LIVE as per battery wires, usually about +- 8" long attached at both ends with bolts and washers.
Dont forget to check the battery terminals (should be clean and tight) also where the battery earth wire bolts to the chassis.
It may be as easy to get an other earth strap and attach it some convient place on the engine and chassis (as John described) just make sure you clean the attachment points with some rubbing paper or steel wool etc.
Good luck.
Brian
Brian
64 S2 Roadster
72 Sprint FHC
User avatar
types26/36
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 3882
Joined: 11 Sep 2003
Location: U.K.

PostPost by: elansprint71 » Thu Jul 08, 2004 6:54 am

After cleaning the earth contacts don't forget to put a smear of vaseline on them before bolting them up.

I have been trying to eliminate an earthing fault on my Sprint for nearly five years and despite a chassis change, it is still there, although nothing like as bad as it was. I have run a "ring main" of earth wires back to the battery from all the earthing points.

Cheers,

Pete
User avatar
elansprint71
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 4438
Joined: 16 Sep 2003
Location: Cheshire, UK.

PostPost by: john-c-elan+2 » Thu Jul 08, 2004 9:48 am

I added an xtra one to my +2, I ran it from the oil pump to the o/s bolt to chassis
turret on inner wing. I had earthing problems and however tight I did the one up on the nearside engine mounting, it kept happening periodically. This so far has cured it - fingers crossed. John
john-c-elan+2
Second Gear
Second Gear
 
Posts: 122
Joined: 22 Sep 2003

PostPost by: dougweall » Thu Jul 08, 2004 10:10 pm

Guys,

Just to add my bit regarding earths. I am in the process of a rebuild on my S4. I know the Elan has the problem earth's, so talked to an electrician I work with about them. (He has rebuilt 3 "older than any Elan" cars). His suggestion was to run the earth cable from the battery right through to a starter motor bolt. This he says will give a direct route for the power on start up. Then for the other earth's around the car link them all with a kind of ring main back to the boot earth point.

So I have run the main earth to the starter motor, (still used the original boot earth point to battery lead as well, bolt on lug type) then from the offside engine bay chassis bolt, run a 2.5mm cable to the nearside chassis bolt, then to the lower dash earth point, and on to the boot earth point. At each point I have made a small copper plate to fit the chassis bolt at one end and the new "small" earth wires at the other. These plates are approx. 1/2" wide by 1" long.

At the moment all this is untried, but looking at it, it looks good to me. You may not agree, so be it.
If you are interested in how it looks send me an e-mail and I will send some photo's.

Regards,

Doug.
User avatar
dougweall
Third Gear
Third Gear
 
Posts: 273
Joined: 12 Sep 2003
Location: Darfield, S.Yorkshire

Total Online:

Users browsing this forum: No registered users and 12 guests