Too many engine earth wires??

[jimrat]

Hi

Quick Q about engine earth leads (waterboxer 2.1 DJ) I have the usual braided earth wire off the back of the gearbox, and a second braided strap in the engine bay which connects the crankcase to the body. Is it normal to have this second strap? I haven't seen it mentioned in Haynes manual

I was going to add an earth wire between the starter motor and the body (as Aiden recommends), but then I would have 3 engine earth wires - seems a bit OTT.

Also, there are 4 or 5 brown earth wires that bolt onto the nearside cylinder head. Why are these not earthed directly to the body?

Cheers
Jim

[T3luestar]

I have the same amount of earthing on my 2.1DJ, so don't worry. I have also added an extra earth strap to the starter as you mentioned and it did solve the intermittent starting problem.

[California Dreamin]

These two earths are factory fit.

BTW there isn't such thing as 'Too many' earths lol...more the better!

Think of it this way, with a Diesel starter motor drawing anything up to 180 amps on a cold winters morning through a 'HUGE' feed cable on the starter solenoid, that feed needs to be 'matched' or exceeded in amps by a similar earth lead to complete the starter circuit with as little resistance as possible. Any resistance will cause slow cranking and or possible non start.

The small brown 'collective' earths are for the various switches and sender units around the engine, you definately don't want the starter trying to earth through these as they would just pop like fuse wire .

The the main issue here, is where Volkswagen decided to locate the main earth lead (on the gearbox nose cone)... where the presence of two metals (aluminium/steel), salt water and electrical activity leads to galvanic corrosion. This is an electrochemical process in which one metal corrodes preferentially to another when both metals are in electrical contact, in the presence of an electrolyte (salt water).
What this means for us as owners is that the nose cone can become heavily corroded causing a high resistance/slow cranking and worse still, damage to our precious gearbox casing that incidently is no longer available from Volkswagen.
Adding an extra 'main' earthing point reduces this effect, whilst making the starter circuit more reliable. Fitting a heavy braided wire from one of the bell housing starter bolts to the chassis leg, provides the starter with a earth return path with 'least resistance'.
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Martin

[clift_d]

You can also end up with galvanic corrosion to the bell housing where it meets the engine block. As above, there's no problem with adding a few extra earths.

[jimrat]

OK thanks for all the replies. I'll leave the factory earths as they are and all an extra to the starter

Cheers
Jim