my 90 set on fire twice in 3 days!!

its the truth, it set on fire and burnt through the throttle and handbrake cable. The result of a bad earth/ no earth i think.

The first time it was because i removed and bent the exhaust back into shape because it was welded to the chassis for some reason so i bent it back into shape and attatched it with rubbers and when i went to start it, it set on fire and burnt through the throttle and handbrake cable.

so i added another earth to from the battery to the seating box(maby a bad idea) but it sorted it out.

and today i was bolting the passengers chair back on and poof it did it again and decided to roll down the hill into another car (luckely no damage) i think i might of caught the battery or something with the spanner:doh

can anyone tell me where the existing earth leads should be and where a good place is to put some extra ones just for good luck. its had a 300tdi fitted into it and im starting to question how well its been done.

there should be an earth from the engine block to the chassis. There's a lug to bolt it to on the front of the engine just above the sump.

what he said. The earth would have been through the exhaust before. Now it needs to go somewhere, so it picks the throttle and handbrake cable.

On all of my eninges, the earth runs from the back of the starter to the chassis, and is a nice thick wire.

The handbrake cable shouldn't have gone up while you were putting the seat back in, something else has moved here i think - if you caugth the spanner on the +ve battery terminal the main thing that would happen would be the spanner getting hot, unless the spanner was touching the gearbox at the other end.

You still woudn't have been able to hold on to the spanner though.

Check EVERYTHING very carefully, as it could go up large style with a new earth, if its chafing somewhere or summat.

If the spanner went from V+ to the seatbox say, it's path may have been via the handbrake cable, if the best route was seatbox, cable, gearbox, gearbox earth to battery and it could very well have melted first before the spanner (solid lump of steel) would even get warm.

The 300tdi SHOULD have an earth from the engine to the chassis - the best one would be the stud on/near the starter to the chassis, the make sure you have a good solid cable going from the negative on the battery to the chassis. My 2.5 NA had one from the gearbox to the chassis and there to the battery, the engine started fine, no hot wires etc... My 300tdi was fitted with no proper earth, I soon welded a bolt to the chassis and ran an earth from there to the engine. Starter went like a jet engine!

As said above check there is no dead short. Then look at your earths, see where the heavy one from the battery goes - take it off, clean it up with a file and bolt it on and add another one to the engine if not already fitted, and make sure it's onto a good clean surface.

if it was touching the seatbox i would be absolutley amazed if the handbrake cable was a better earth than the bolts and rivets that hold it in place!!

oh yeah an battery clamps are 13mm bolts, a 13mm spanner aint that big...

Wouldda made a hell of a spark an all

Hbrake cable is puny in diameter mabe 3 or 4 mm and its current capacity compared to a thick old spanner is nowt. Not that its designed for it anyhow. It used to happen alot in Discos when the earths rusted off on a cold morning while starting. Result was lots of broken hand brakes.

James Mac,

Firstly I would fit 2 good earths with decent winch wire or circa 100A wire. Make sure everything bolts to clean metal surfaces and once done cover in grease to stop corrosion.

My own 90 I have 250A @24V marine grade cut out. This isolates the twin 12v batterys positive sides to everything. It will not however cut my engine as yet as I have not fitted the ballast resistor but that will come some time. I had a 100A @12v one from the MSA but that was short lived and the winching we did killed the switch internals (they really are poor quality) I have also fitted an earth point on the chassis near the starter motor. A thick cable aprox 150A wire possibly more @ 12mm cross section goes from the twin batterys to this point. Then my winch -ve also goes to this point and another earth cable to my engine bay. I have also fitted another earth from the battery to the rear chassis next to the gearbox. and from that point to the gearbox. My starter spins over so quick now its unbelievable. Jai

boydy1989 said:

oh yeah an battery clamps are 13mm bolts, a 13mm spanner aint that big...

Wouldda made a hell of a spark an all

Click to expand...

Thicker than the hand brake cable. A bad earth via the seatbox could have meant there wasn't a big spark, shorted it out for long enough to get the hanbrake cable glowing red hot though.

ya want to run earth core from engine to body to chassis.Not just engine to chassis

Oh yes sorry Its a disco, my 90 has various body earths too

even more reason to run a circuit earth....

discos like static for a start...

pray explain that BoB? With actual sound phyics behind it?

if you create a good earth circuit the excess leccy will go without useing the easiest way like thin cables.

thanks for the advice guys, iv been to the landy show today and picked a few peoples brains aswel. im going to check it all out tomorrow, clean up and re-attatch the existing earths and add a few more, just in case.
cheers

James_mac said:

thanks for the advice guys, iv been to the landy show today and picked a few peoples brains aswel. im going to check it all out tomorrow, clean up and re-attatch the existing earths and add a few more, just in case.
cheers

Click to expand...

Thats the way....
You may find a nice utility van at side of road doing powerline work that may part for cash with some nice copper core.

thats a good point actually, there replacing all the street lights in my area so i might just stumble into some nice thick wire

James_mac said:

thats a good point actually, there replacing all the street lights in my area so i might just stumble into some nice thick wire

Click to expand...

Don't use "nice thick wire" of any kind, and best not use the aluminium wire usually used by the utility people for safety-earthing power cables.

Thick wires will fatigue fail soon enough.

Ends crimped on to aluminium earthing cables are poor conductors at our measly 12 volts.

ALWAYS use tin-plated multi-stranded BRAIDED flat cables with SOLDERED ON ends.

Anything else is going to be trouble sooner or later.
That's why earthing straps look like what they look like.

CharlesY

CharlesY said:

Don't use "nice thick wire" of any kind, and best not use the aluminium wire usually used by the utility people for safety-earthing power cables.

Thick wires will fatigue fail soon enough.

Ends crimped on to aluminium earthing cables are poor conductors at our measly 12 volts.

ALWAYS use tin-plated multi-stranded BRAIDED flat cables with SOLDERED ON ends.

Anything else is going to be trouble sooner or later.
That's why earthing straps look like what they look like.

CharlesY

Click to expand...

bollix they last 3 months down ere in the salt.I use copper powerline and i get 18 months or so.

CharlesY said:

Don't use "nice thick wire" of any kind, and best not use the aluminium wire usually used by the utility people for safety-earthing power cables.

Thick wires will fatigue fail soon enough.

Ends crimped on to aluminium earthing cables are poor conductors at our measly 12 volts.

ALWAYS use tin-plated multi-stranded BRAIDED flat cables with SOLDERED ON ends.

Anything else is going to be trouble sooner or later.
That's why earthing straps look like what they look like.

CharlesY

Click to expand...

Spot on CharlesY,

By the way the Rave manual has a section called Electrical Library which then has a sub section called "Earth Points & Header Joints" which shows you where the primary earthing points are. Duplicate earth paths should be avoided as you can end up with current circulating between them and different potentials giving varying electrical performance of the components around the vehicle.

Hope you sort it, but earth strapping is what you need.

BoB,
Love that "Chain saw" photo, bloody classic