4A-GZE Earth Strap

[ulysess1966]

Hi all. I'm in the process of upgrading the tinny 35Ah battery in my SC to a 55Ah one and discovered that the earth strap to the engine isn't connected. I've owned the car 11 years and I never took it off, so this was a bit of a shock and explains a few problems I've been plagued with.

Anyway, where does the earth strap connect to? I can't work out where it should go because it was loose and tucked out of the way where I couldn't see it.

Is there a better place to connect an earth to than the original? I'm good at electrics so making up a cable isn't a problem if it makes the electrics more reliable.

This car never ceases to make me look stupid

[Tony jinxy froude]

On a 4AGE its connected to the small bolt which holds the thermostat body to the gearbox, I imagine its the same on an SC, good luck, Jinxy

[MartG]

Which earth strap - there are several. The main heavy one goes between the thermostat housing and connects to the chassis below the fusebox. There are other small earths primarily meant to act as local signal earths for ECU sensors scattered around e.g. one from the inlet manifold.

[ulysess1966]

Thanks guys, the thermostat bolt was the one.

[ulysess1966]

I sheared off the bolt that holds the thermostat on when I went to re-connect the earth strap. Ruined my Sunday afternoon. I'd put a lot of easing oil round it overnight, but looking at what's left, 25 years of water running down there had rusted it in very tight. Made me realise why the earth strap was never re-connected before now!

Any advice on fixing this? I was going to tap it out, but maybe there's a better way to go?

[jon_st205]

I'd be very careful drilling it out! Might be better just to make up a new earth lead and attach it to another point.

[elbon50]

I'd be very careful drilling it out! Might be better just to make up a new earth lead and attach it to another point.

Yes, if it's similar to the N/A you could perhaps attach the existing earth strap to one of the bolts that hold the selector end cap

I suppose the bolt sheared level with the transmission casting ?

[kaiowas]

If it was me I'd leave the thermostat housing attached by just the one bolt with the earth also attached there. Trying to drill out a steel bolt in an aluminium casting has much potential for doing more damage.

[MartG]

You could try some broken-stud extractors - they don't need as big a hole drilling to work.



They work by having a left hand thread - as you tighten them into the hole you drill in the broken bolt they grip harder until either the bolt comes out or they snap

[elbon50]

You would need to centre pop the broken stud dead in the middle

Then use a top quality drill bit

Cobalt bits are superb

[LimeyMk1]

You could try some broken-stud extractors - they don't need as big a hole drilling to work.

Image Replaced With URL For Quote http://images.esellerpro.com/2176/I/318/3/da70.jpg

They work by having a left hand thread - as you tighten them into the hole you drill in the broken bolt they grip harder until either the bolt comes out or they snap

They also snap if you don't keep the force rotational. Any movement sideways snaps them too.

Hate the damn things with a passion.

If you remove the thermostat housing will there be an of the bolt left to grab hold of?

[ulysess1966]

I'm not a huge fan of the extractors myself having broken a couple over the years.

Elbon - yes it's almost level so there's nothing to get a hold of.

I'm a bit confused now because my thermostat is hanging loose after the bolt sheared off and I can't see where the other bolt should be. I'd be happy enough to leave the thermostat in place on one bolt and put the earth there as well.

To make matters worse I've just found a broken bit of casting down there, could this be for the other bolt I wonder.

[elbon50]

Pictures would be a help

I agree, screw in extractors are not an easy option, particularly when the bolt is seized in sufficiently to snap off

An extractor that gets hold of the outer edge of the bolt shank is much better but not an option if the bolt snapped level with the casting as is

On my N /A the other thermostat bolt is at the other side of the stat housing, nearer the bellhousing

Presumably the S / C is similar in that respect

Again piccies would help (including one of the broken bit of casting)

[ulysess1966]

I went out to the garage to take some photos, but didn't really need to. When I got some light in to see what was what it was obvious where the broken piece of casting had come from, the other side of the thermostat. It looks like it broke off a long time ago and there is no bolt in the hole in the engine.

Basically I have a thermostat with one hole and a mounting point, but on opposite sides of the thermostat. I think I might try making a bracket up to go under the thermostat and at least mount it on one bolt along with the earth strap. I don't like things rattling around loose.

PITA this!

[ulysess1966]

UPDATE -

Against all good advice (!), I bored a 5mm hole with a very high-quality bit into the dead centre of the broken off 8mm bolt and then carefully tapped this for 6mm. Then used a good spec M6 bolt to hold the thermostat on. Sorted.