Chassis Earth Points

[catretriever]

Hi All,

my S1.5 has been a temperamental starter for a while now with the starter motor seemingly not getting enough juice to turn over. I replaced the battery a couple of weeks ago but that hasn't helped. So this weekend I set about checking/cleaning the earthing points during which I discovered that only one of the earth points on the chassis diagonals has anything attached to it. The nearside point has no wire connected nor is there any loose wires in the vicinity. I'm afraid I'm not much of an auto electrician so if I were to try and reinstate this earth can anyone advise on what should be connected to what?

Failing that, what should be the next thing I should check? I'm assuming that if the car starts fine when jumping it from another vehicle then my starter motor should be fine? Is that right?


thanks in advance for any and all assistance

[tvrgit]

I am sure that mine only has earth wires connected under the nearside wheel arch, and that, although there is a similar bolt on the offside tube, there has never been anything connected to it.

[phillpot]

Mine has an earth strap underneath, near the gearbox crossmember. this creates a circuit between engine and chassis,might be worth checking ?


However, if starts ok with "jump leads" would suggest battery or dodgey connections to it ? Where does the cable from battery negative terminal connect to ?

[TVR-Stu]

tvrgit said:

I am sure that mine only has earth wires connected under the nearside wheel arch, and that, although there is a similar bolt on the offside tube, there has never been anything connected to it.

Mine is exactly the same as Andrews, all earth wires to the nearside diagonal tube and none at all to the offside.

[catretriever]

phillpot said:

Where does the cable from battery negative terminal connect to ?

Thanks all for clarification on the earth points. I will check for the strap near the gearbox.

Philpot- the neg connection runs from the battery to a point on the front of the chassis near the base of the swirl pot. I have taken this off and given the connection point a good clean with a wire brush. Is it worth getting a new strap for there?

[ketvrin]

my S3 has an earth strap to the offside diagonal as well as the nearside as well and from the gearbox and below the swirl tank (from the battery neg)

K

ETA the gearbox strap

Edited by ketvrin on Tuesday 2nd March 19:30

[mep12345]

ketvrin said:

my S3 has an earth strap to the offside diagonal as well as the nearside as well and from the gearbox and below the swirl tank (from the battery neg)

K

ETA the gearbox strap

Edited by ketvrin on Tuesday 2nd March 19:30

IIRC mine has an earth on offside diagonal as well (S3), I believe it comes through the bulkhead from the ignition area inside the car. I haven't been and looked though so I may be wrong on the routing, although I know there is an earth strap

[phillpot]

catretriever said:

phillpot said:

Where does the cable from battery negative terminal connect to ?

Thanks all for clarification on the earth points. I will check for the strap near the gearbox.

Philpot- the neg connection runs from the battery to a point on the front of the chassis near the base of the swirl pot. I have taken this off and given the connection point a good clean with a wire brush. Is it worth getting a new strap for there?

Thats where mine goes too, does it look like lots of the strands are broken ? if not it should be ok but any doubts and probably worth replacing (should be able to get something suitable from any decent car spares shop)

Regardless of what other earths there are (and being a fibre glass car there are many) only ones that should effect starter are the one by the g/box mount and the one you mentioned from chassis to battery, this completes the circuit plus, of course, the feed cable from battery +ve direct to starter soleniod.

Edited by phillpot on Tuesday 2nd March 21:12

[graham kay]

Don't rule out the starter motor being knackered, when you use jump leads from another battery you're doubling the cranking amps and this can make a dodgy starter turn faster especially if your using another vehicle that is still running to jump it off with. Sometimes when starter motors are on their way out they won't turn fast enough when cold but speed up when their warm.
Quiet often though all they require is a good clean up and possibly some new brushes, this isn't to hard a job to do if your mechanically minded.

[hvdweerden]

some pics from the 3 earth points on my S3

Br, Han

[orange_dodo]

I had recurring starting issues which I thought was the starter itself. Disassembled it and cleaned/greased it 3 times to try and fix the issues but they kept coming back.

In the end I took the solenoid wire off and replaced the whole thing. Took the main battery to starter cable off and soldered the ends back on (they fell off in my hand!), and cleaned up all the wires and contacts. The starter has 2 or 3 washers on each connection lug which aren't exactly obvious but all were badly corroded and needed cleaning.

Also the starter earths through the engine which had a good layer of muck on it. I cleaned and wet 'n dried a few inches of the engine casing, the gasket and the starter but a separate earth strap probably would have been easier although it would have to be pretty long.

I tested the contacts with a multimeter and took them all from ~0.6Ohms down to ~0.1 or less. No wonder the thing was struggling!

Anyway car starts first time every time now



ETA I only have wires attached to the earth in Hans' second picture

Edited by orange_dodo on Tuesday 2nd March 22:13

[catretriever]

Thanks guys for all the tips. It looks like that's my Saturday sorted. The missus will be sooooo pleased

[catretriever]

orange_dodo said:

I had recurring starting issues which I thought was the starter itself. Disassembled it and cleaned/greased it 3 times to try and fix the issues but they kept coming back.

In the end I took the solenoid wire off and replaced the whole thing. Took the main battery to starter cable off and soldered the ends back on (they fell off in my hand!), and cleaned up all the wires and contacts. The starter has 2 or 3 washers on each connection lug which aren't exactly obvious but all were badly corroded and needed cleaning.

Also the starter earths through the engine which had a good layer of muck on it. I cleaned and wet 'n dried a few inches of the engine casing, the gasket and the starter but a separate earth strap probably would have been easier although it would have to be pretty long.

Edited by orange_dodo on Tuesday 2nd March 22:13

Well I spent a good few hours on sunday hunting around the chassis and cleaning connections, including the connections on the starter solenoid. When I reconnected everything and tried to fire the engine....nothing ...nada ....zilch. Bugger!

I checked the feed to the solenoid which seemed fine. The solenoid wire looked a bit tired so I poked it around a bit, reconnected, and managed to get the engine to fire, but not every time. So I would seem to be back at square one in terms of the starting (although admittedly with nice shiny earth points), but may have isolated the problem to the solenoid wire. How difficult is it to replace that orange_dodo ? At the moment I'm contemplating the removal of the starter with some trepidation..... any tips for a (very) amateur mechanic ?

cheers,

Matt

[orange_dodo]

It was a while since I did it but my solenoid wire came to a bullet connector about 10" from the solenoid connection. The connection and wire were really corroded all the way along its length. Chucked it and cut back the loom wire until I hit fresh copper and put a new (thicker) wire from there to the solenoid.

You may be able to track the problem down by testing the resistance between the solenoid wire and the battery positive, starter positive and battery positive, and the starter body and battery negative. At least then you could figure out if any of those 3 connections are more likely to be the problem. Just be careful about what is connected to what before you test anything!

My problem was the solenoid wouldn't fire properly so all you would get is a click but no cranking. By the sounds of it your solenoid is getting enough power as the engine is turning (sometimes) so I would imagine that your problem is on one of the starter connections unless you are also getting a click but no cranking when you turn the key.

Have you considered a separate earth from a bolt on the starter to the chassis? That was going to be my next change. Also the main earth from the swirl pot to the battery may need a clean up at both ends to get a decent connection.

Mine always refused to start at the most inconvenient times, usually when there were lots of people watching!

Good luck!

Tom



Edited 'cos I can't spell!

Edited by orange_dodo on Tuesday 9th March 12:27

[Barkychoc]

Don't forget to check the yellow connector in the steering column if it hasn't been done

[catretriever]

orange_dodo said:

My problem was the solenoid wouldn't fire properly so all you would get is a click but no cranking.

Yep that sounds familiar Tom. Sometimes I get just a single click; sometimes it will crank after one or two attempts with just a click; sometimes if I rock the car in gear it will then start; sometimes I get it going with a gentle bump start just from rolling; if all that fails it usually starts first time with a jump from another (running) vehicle.

orange_dodo said:

Have you considered a separate earth from a bolt on the starter to the chassis?

Good idea. I'll add that to my list of things to try.

Barkychoc said:

Don't forget to check the yellow connector in the steering column if it hasn't been done

I've never checked that Chris so I'll take a look...am I right in thinking it has a tendency to burn out?

[orange_dodo]

May be worth giving the solenoid a bit of a clean and grease.

2 bolts to get the motor off and 3 screws to get the solenoid apart. Could probably do it in 5 minutes in my sleep now I've had so much practice!

[Gerald-TVR]

Hi Matt - Yellow connector connects ignition switch to the rest of the electrics. Remove and replace, i didnt bother witha new connector just soldered wires