Help please! Electrical issue with 1995 Defender 110 County, 300 tdi

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Joshk5000 said:
This is helpful. Any recommendations on where on the chassis? I suppose I could route a cable out of the battery compartment along with the earth to the gearbox?
Click to expand...
From memory- I put an earth from the battery to one of the starter motor mounting bolts and another one from there to the inner wing mounting bolt.

I'm not keen on only earthing through the gearbox, as aluminiumium is not as conductive as steel.
 
GRATCH said:
From memory- I put an earth from the battery to one of the starter motor mounting bolts and another one from there to the inner wing mounting bolt.

I'm not keen on only earthing through the gearbox, as aluminiumium is not as conductive as steel.
Click to expand...

No. Alluminium has 60% of the efficiency as copper where steel is only 20% as efficient (at conducting electricity).

Steel has a conductivity of 10.1 x 10⁶ Siemens/m; alumimium 36.9 x 10⁶ Siemens/m; so aluminium is more than three times as conductive as steel.

Joshk5000 said:
This is helpful. Any recommendations on where on the chassis? I suppose I could route a cable out of the battery compartment along with the earth to the gearbox?
Click to expand...

Sorry I should have explained my picture better.

main-earth-300tdi.jpg


Top cable goes straight to the negative pole on the battery battery.
Fat cable with yellow tape goes to the winch (neg).
Lower cable (which comes towards the camera) is alttached to the chassis just by the camera.
The fat cable coming from the top left and going forward is from the isolator to the winch.
The winch cables are overkill (700A) the others are 400A.
The Red (+) cables exit the battery box forward into the engine bay and can't be seen in the picture.

The engine and the gearboxes are somewhat isolated as they sit on rubber mounts.
The gearbox mounts to the bellhousing (Al) which mounts to the engine using an enormous cross setion of steel and alluminium, i'm guessing this is likely rated at several thousands of Amps.

An M10 steel bolt is rated around 230A.
There are much fewer mated, painted surfaces from the engine block back to the gearbox which will provide an easier return path than from the starter motor bolt to the inner wing.
However.
The current rating of that inner wing path is still greater than 'needed' so it isn't a problem, but the gearbox and chassis is 'better'.
 
GRATCH said:
And how conductive is the anodic corrosion between the ally and steel?
Click to expand...

When tou took your flywheel housing off the block and your bellhousing off the gearbox how much galvanic corrosion did you notice ?
Probably a little on the threaded section of the bolts between the bell and flywheel housing, but of the several I have done there was none at all on the faces either between the two housings or on the bolts of faces on the block or the cast gearbox body.
I've seen quite furry insides of bell housings (where the wading plus were never fited) but the faces were always bright metal to metal. I've seen rust flywheel rings and rusted gearbox casings, but the faces are always clean.
I have seen lots of corrosion on inner wings (just replaced a pair on a 93 200tdi) and their support brackets etc, which on this particular vehicle were mostly rotted away.
The 4 Spire nuts into the A pillar (that hold on the wing) were also somewhat corroded as was the headlamp earthpoints.

Most of the galvanic corrosion I see is between the chassis and the body, the lower seatbelt brackets, the seatbox, the floor panels. The rear panels and tub as its typically used as the earth for lights and other rear facing periferrals.
None, ever, between the engine and transmission.
 
miktdish said:
When tou took your flywheel housing off the block and your bellhousing off the gearbox how much galvanic corrosion did you notice ?
Probably a little on the threaded section of the bolts between the bell and flywheel housing, but of the several I have done there was none at all on the faces either between the two housings or on the bolts of faces on the block or the cast gearbox body.
I've seen quite furry insides of bell housings (where the wading plus were never fited) but the faces were always bright metal to metal. I've seen rust flywheel rings and rusted gearbox casings, but the faces are always clean.
I have seen lots of corrosion on inner wings (just replaced a pair on a 93 200tdi) and their support brackets etc, which on this particular vehicle were mostly rotted away.
The 4 Spire nuts into the A pillar (that hold on the wing) were also somewhat corroded as was the headlamp earthpoints.

Most of the galvanic corrosion I see is between the chassis and the body, the lower seatbelt brackets, the seatbox, the floor panels. The rear panels and tub as its typically used as the earth for lights and other rear facing periferrals.
None, ever, between the engine and transmission.
Click to expand...
I noticed no galvanic corrosion.
What about the anodic corrosion??
Especially under the earth strap?
 
Is this the 10 minute or the full 1/2 hour ?

GRATCH said:
I'm not keen on only earthing through the gearbox, as aluminiumium is not as conductive as steel.
Click to expand...

I presume that you still think this is true (as it appears to be the basis of your argument) ?

GRATCH said:
What about the anodic corrosion??
Especially under the earth strap?
Click to expand...

That was a strawman response @GRATCH

I would counter with, yes, the earth strap (to chassis) can be a problem especially if your main earth is connect through the inner wing ie back through the body/chassis only. It becomes a somewhat narrow concentration point and will need regular maintenance to keep it clean.
After all it's only an M8 bolt with a small cross sectional lug.
If it were only carrying the lighter currents (see what I did there) it would take a lot longer to become negatively affected and need cleaning perhaps every 24 months rather than every 9 ?

Remember we are trying to help @Joshk5000 not engage in whataboutery or Ad hominem.
 
miktdish said:
Is this the 10 minute or the full 1/2 hour ?



I presume that you still think this is true (as it appears to be the basis of your argument) ?



That was a strawman response @GRATCH

I would counter with, yes, the earth strap (to chassis) can be a problem especially if your main earth is connect through the inner wing ie back through the body/chassis only. It becomes a somewhat narrow concentration point and will need regular maintenance to keep it clean.
After all it's only an M8 bolt with a small cross sectional lug.
If it were only carrying the lighter currents (see what I did there) it would take a lot longer to become negatively affected and need cleaning perhaps every 24 months rather than every 9 ?

Remember we are trying to help @Joshk5000 not engage in whataboutery or Ad hominem.
Click to expand...
Fine.


Tell him to not bother with the extra earths then, as they are obviously not needed.:vb-surrender:
 
Hello all!

First, thank you for all of the guidance. I'm truly grateful for your time.

Well after all that, I ran a grounding cable from the gearbox ground bolt straight to the frame/chasis... and this completely solved the problem. Don't I feel dumb!

This of course was after I replaced the starter motor and ignition switch. Oh well, expensive but fun way to get to know the truck. I did lose one of the tiny little screws that connect the ignition switch (rear section with wiring terminals) to the housing. Does anybody know the part number/order information? It works fine and sits in place ok with one of the two screws in place but looking to finish the whole thing out.

Again, thanks everybody! Let my story be the cautionary tale: do the cheapest stuff first and listen to your friends at Landy Zone before you buy a ton of replacement parts! 😂😂:oops:🤦‍♂️🤦‍♂️
 
GRATCH said:
Tell him to not bother with the extra earths then, as they are obviously not needed.:vb-surrender:
Click to expand...
Joshk5000 said:
Well after all that, I ran a grounding cable from the gearbox ground bolt straight to the frame/chasis... and this completely solved the problem. Don't I feel dumb!
Click to expand...


Not as dumb as some that's for sure ...
default_roflmao.gif


You listened, acted and learn't, that's how it works with landrovers.
Well done.
 
Hello - I seem to find myself in a similar situation as @Joshk5000 as a new defender owner of a 1996 110 300TDI suffering from some electrical/starting issues so I thought this specific forum would be the best place to seek assistance!

Hoping for some help with the issue I'm facing.

Backstory:

Last week the defender wouldn't start - when ignition was turned it would crank but wouldn't start and the lights and power were working fine, I am very new to mechanics so I resorted to utilising my AA breakdown cover - the man who attended done a number of checks re. the starter motor, battery health/charge, solenoid & others. He was getting rather stumped at what was causing the issue as all checks appeared fine, so I contacted the previous owner to double check there were no hidden immobilisers - they advised they had a similar issue that was linked to a broken/faulty relay. We then swapped the full beam relay into the starter relay and that worked - happy days!

This worked fine for a few days, then when I went to start the Landy a week later and it had the same issue - so I went and bought two new brand new relays from halfords to resolve the issue and replace the existing ones, this again worked for a couple of days. I've now just went to start landy this afternoon and I'm coming into the same issue again now with both of the new relays.

Can anyone assist in what could be causing this issue and a remedy? Its greatly appreciated!!
 
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