earth strap

Big lumps of metals and spanners. Including servicing and fluids.

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matthew13
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earth strap

Post by matthew13 »

I have a 2ltr Aircooled T25 1983. I have real trouble starting the engine when it has been running for a long time and is hot. Would it help if i added a new earth strap and where would the best pleace to fit it be?

cheers

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a1winchester
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Re: earth strap

Post by a1winchester »

Doesn't fire? Doesn't turn over? Can you be more specific please?
1990 Autosleeper Trident. Water cooled 1.9L DG + 4 speed manual box

matthew13
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Re: earth strap

Post by matthew13 »

I can turn the key in the ignition and nothing happens, if i pump the accelerator loads it starts up but very sluggishly. When its cold it starts first time, just struggles when hot.

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sarran1955
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Re: earth strap

Post by sarran1955 »

Hello,

Oilite bearing for starter motor.. :?:

Cordialement,

:ok
Image

matthew13
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Re: earth strap

Post by matthew13 »

the Oilite bearing was only replaced last year so wouldn't have thought it would be that. Would adding another earth strap not help with the hot starting?

California Dreamin
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Re: earth strap

Post by California Dreamin »

It certainly wouldn't hurt....chassis to starter bolt (flexible braided) order with M10 one end M8 the other.

http://www.ebay.co.uk/itm/24-Car-Earth- ... Swv-NWaFQw" onclick="window.open(this.href);return false;

Martin
1989 California 2.1MV

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Mr Bean
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Re: earth strap

Post by Mr Bean »

I had a similar problem after a clutch replacement and finally sussed it out by clipping a multi-meter between the chassis and the threaded stud end - not the nut or cable/ring terminal - on the starter. In my case I measured full battery voltage here when attempting to spin the starter. While all components appeared clean and corrosion free it wouldn't start until I abraded the contacting faces of the starter stud, nut and ring connector. I couldn't believe that a visually clean set of surfaces could be open circuit when torqued together with a spanner.
Typically electrical resistance increases with temperature and this together with thermal expansion in materials affecting contact forces can result in intermittent faults. In general it is a good idea to measure for voltage under load between components such as clamps and battery posts to check for voltage drop although this may require an assistant to turn the key. Her Ladyship declines from this activity after being dragged out of the comfort of the house too often over the years. :roll: You may find a volt drop of a volt or so between your battery positive post and the vehicle chassis when you operate the starter. On a really cold winter morning the voltage at the starter can drop to nine or ten volts due to a combination of resistance in the leads etc, and internal resistance in your battery so there isn't much headway for success unless everything is up to scratch.

CS
Well-timed silence hath more eloquence than speech.
"A quiet shy boy who took little part in games or sport"
88 High top 2.1 WBX

California Dreamin
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Re: earth strap

Post by California Dreamin »

The issue here is the high amperage flowing under cold cranking..somewhere in the region of 120 - 150 amps for you CU. Looking OK is simply not good enough. Compare those figures to the 10 amp draw of a headlamp circuit, 15 amp heater blows and you can see how they pale into insignificance when compared to monster that is the starter circuit.
Now you can understand the need for such heavy weight cables and the need for connections to be just so.

Its also worth noting that alternators also suffer from poor earthing and will benefit from the edition of a strap between the body of the alternator and engine. In fact this is something that is often done on other models.

Martin
1989 California 2.1MV

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