Hello all,
While replacing the water pump, timing belt and seals I am restoring many wires on my 85 245 engine harness.
I was cleaning up the main ground screw attachment to engine block. That is the one that connects the Negative battery cable to the block. The screw location is just behind the power steering pump.

I found attached also at same screw two more ground lines. One is for the A/C compressor. The other line, well, the line was no longer there. I only found the lug. Rather heaver gauge. Possibly for an awg 10 wire size.
Does anyone know where that lost ground line was going to?

Thank you so much.

Richard

Hi,

What you have there is normal for factory.
The extra lug could have and most likely someone’s additional ground for an accessory.

While you are under there give the positive wire under the crankshaft pulley a good cleaning.
Any seal leaking goes on the sheathing.
If it rubs itself to ground, via the engine blocks underside it can be toasty.

The engine has its own ground because in essence the power train is sitting on three rubber mounts.

You should have two ground wires coming off the negative post.
One to the engine ground and another one to the left fender for a body grounding.
A ground is one-half of all circuits, plain and simple .
The current flow is out to all components and back to positive terminal through controllers.
Disconnect the negative battery terminal stops all sparks.
If you only undo a positive side of a component then the wire can still spark to ground.
Inspection of your grounds is very wise maintenance to keep what seemingly doesn’t move, working.

There will also be a flat braided fine sized wire running to the firewall to a valve cover stud.
This is for electronics to have a closer ground for the injectors, but sensors using very low signal voltages things happen.
The braiding disrupts the paths of higher frequencies, than can induce currents from what seems to be nowhere.
For instances with ignition system wiring and radio static.
This is a very passive in idea but made more robust in these years.
Borrowing from Michael Faraday’s Capacitors and Nicolas Tesla safety cage.
It’s much like what is called shielding inside signal cables today.

How effective those on the 240s were is anyone’s guess. Must be something to spend an extra coins and was a concerted effort from an area of R&D to tool it into production.

I have pondered the usefulness of putting ignition coils right on top of the spark plugs and have them subjected to enormous cycles of heat.

Have you seen prices on new car replacement coil packs from FCP Euro.
Tune up kits? I don’t know how they afford to stock them or sitting on anyone’s shelf.
Whoops, wait a minute, mark up(s) are there. Tennis is not the only game using rackets!

A Failure rate, you bet cha!
Scott Kilmer chases them all the time with his Elimination technique.

Phil

Machine man,

Thank you for the reply.
I have not added any images to Brickboard yet. Cannot figure out how to upload them. Otherwise I would.
But yes the cable from battery neg post to chassis and then continuing to the engine block is still there. I should replace soon though, very stiff after 38 years and I don't like the fatigue on copper at the joint with chassis.
In regard to the AWG 8 size positive cable under the crankshaft - Cable linking up alternator to starter post - Yes I actually had to replace that cable. You are correct. It was likely rubbing against the anti-sway bar and broke thru the insulation. I am lucky it did not cause serious trouble.

I own this 245 since 91. Fromm 85 to 91 someone could have done a mod to it like adding a ground line but I think it is a slim possibility.
I know the previous owner changed the A/C circuit and caused it to run constantly. Not sure how it would be related to that large lug I found.

Thanks again.

Richard

Hi,

There might be a small “tell” coming from that wiring harness that went over to the alternator.

The alternator housing has to be grounded as Volvo for some strange reason rubber mounted it.
They use a short and no. 10 wire to go directly to the engine just below the alternator.
They get broken easily.
The wire is more for exciter ground and idiot light purposes and of course some currents are needed in between the whole cars grounding system.
But once the alternator is up and running the load to the system is less.
It’s there to charge through the battery to the system.
A battery is a big bucket of reserve power or system shock absorber.

The positive wire runs through a starter connector and up directly to the battery.
If having a charging issue maybe someone adding a bigger and it must be better, wire to the actual grounded system there.

So, The tell is the harness was moved. It shouldn’t be near any of the suspension components.

The next thing that comes to mind is this car was used during the rage of Citizen Band radios.
They liked to use amplifier power boosters with them. They put out as much as 100 watts over a 5-7 watts that was required with a license. Mobile units were nearly impossible to track on so the FCC dropped that whole licensing bit. They saw cell phones a coming from a short ways off.
The radio telephone was essentially expensive but more private.

Time changes every thing.
My head won’t even hold snow anymore. 😬

Phil

Phil

Hi Richard,

Just a stab at this, I'm not a 240 wizard.

What voltage do you see at the battery terminals with the engine running?

See if its about 14.0 VDC and stable.

That would help confirm the Voltage regulator D- ground and alternator ground are not floating.

Good luck, Bill

Hello B.B.,
Thanks for the reply.

I will check voltage.
I am still busy putting all components back together. As I rebuild I find things to replace or improve. Takes time and it is not my main line of work.
I will give feedback later on.

Regards

Richard