C2 ground from chassis to engine

[William F.]

Is there a major ground strap/cable to connect chassis grounds such as ground points on radiator support to engine(not talking about ground straps to decrease radio interference)? If so, where is it on a '67. I don't have the AIM.
Thanks

[William S.]

Re: C2 ground from chassis to engine

The ground from the engine to the frame is at the left engine mount. The ground for the accy's is from the starter to the heater blower and then daisy chained to the other accy's.


Bill

[John H.]

Re: C2 ground from chassis to engine

Bill -

Oddly enough, the design of the base car (no radio) doesn't provide any direct ground path from the engine to the frame; the clutch cross shaft and the shift linkage are the only ground paths from the engine to the frame.

The black ground wire under the outboard starter-to-block bolt only provides a ground for the heater blower motor and the wiper motor.

[William F.]

Re: C2 ground from chassis to engine

When you say "front left engine mount" do you mean driver's side? Is this ground in the form of a cable or strap?
Problem is , I'm having low systrem voltages with accessories including factory AC and lights on. There's also an electrical smell and there was a puff of smoke from under driver's side of dash. Starter doesn't drag, horn blows,ammeter works, and battery doesn't run down, though. Does this mean that grounds are definitely OK and something else is problem or do I need to add a big ground wire from frame or motor mount to engine and see what happens?
HELP!

[William F.]

Re: C2 ground from chassis to engine

John,
In reseaching the archives for my problem, in one of your previous posts, you said" ground from voltage regulator goes to bolt on alternator bracket." Mine goes to a bolt(with no nut) on driver's side radiator support next to horn relay. Could this be a problem. Also I have aftermarket battery wires with neg. grounded to rear of driver's side of block rather than to starter bolt. As mentioned, no starting problems, but low voltages in system and something getting hot enough under dash to smoke.Am I supposed to have an engine chassis ground strap other than for radio suppression?
Help appreciated-no " antique" auto electric shop near.

[Jack H.]

Re: C2 ground from chassis to engine

Bill, we already discussed this. Plus, John Hinckley has confirmed there are TWO native ground paths between the engine and chassis (shift linkage and clutch cross shaft). I think you're whipping a dead horse...

Want to prove the path exists? Take your ohm meter and measure the relative resistance between a clean metal engine surface (e.g. the ignition coil bracket) and a good/clean measuring point on the frame...

[Jack H.]

Re: C2 ground from chassis to engine

Some more reflection(s)... It's the 'smoke' and 'smell' comments that are rather recent additions to your symptom description that trigger me.

Suppose there's absolutely NOTHING wrong with your car's charging system. Further, assume the v-reg and alternator are doing exactly what they were designed to do. Now play with the notion that your car's wiring system has an electrical short circuit.

Depending on the ohmic contact profile of that wiring fault, the amount of current flowing through it will vary based on system B+ levels and electrical loading. In this case, the v-reg and alternator may be 'trying' to charge the battery and running at/near maximum. But, they simply can't supply enough current to compensate for the drain imposed by the wiring short circuit fault...

How to test this hypothesis? Install a good sized ammeter in series between the battery and the car (either positive or negative battery post works). With the engine and ignition off, see what current flow you have from the battery. If there's more than a fraction of an amp, you've got a short (full or partial) in one or more of the car's un-switched electrical branches (cig lighter, glove box light, clock, Etc.).

If that tests OK, now move on to profile the switched circuit loads. Momentarily disconnect the primary side of your ignition coil to keep it from drawing current through ignition points that just happen to be at rest/closed. Re-run the current draw test with the ignition switch moved to the RUN (NOT the START) position. The total current draw on the battery should be pretty similar to what you observed in the un-switched test provided your doors are closed and interior lights aren't ON.

[John H.]

Re: C2 ground from chassis to engine

John,
In reseaching the archives for my problem, in one of your previous posts, you said" ground from voltage regulator goes to bolt on alternator bracket." Mine goes to a bolt(with no nut) on driver's side radiator support next to horn relay. Could this be a problem. Also I have aftermarket battery wires with neg. grounded to rear of driver's side of block rather than to starter bolt. As mentioned, no starting problems, but low voltages in system and something getting hot enough under dash to smoke.Am I supposed to have an engine chassis ground strap other than for radio suppression?

Bill -

I think you'll find that I said that the other end of the ground wire in the harness from the voltage regulator base goes to the ground stud on the back of the alternator. See UPC 12, sheet A7 in the A.I.M. Do you have a black wire from the harness on that ground stud on the alternator? Unless the alternator and voltage regulator are grounded together, the regulator won't work properly.

Your battery ground cable location is correct for your car; with factory A/C and the battery on the driver's side, the battery ground cable goes under a bellhousing bolt on the driver's side. See Section C60, sheet E3.

There should be a braided copper ground strap on the driver's side, from the top front motormount-to-block bolt to a hole on the front side of the motormount bracket on the frame; that's the only direct engine-to-frame ground (although it's only specified on a car with a radio). See Section U69, sheet A3, lower left illustration.

[William F.]

Re: C2 ground from chassis to engine

Thanks again,
John, Yes there'a a black wire ion the grnd. stud of alternator.
Jack,I'll check for shorts and good Ground. When you say connect between battery and "car" to check for shorts, I assume you mean a clean spot on frame(or do you mean engine or does it matter)?On checking grounds, I assume no ohms would indicate good grounds between engine and frame?I know these questions are elementary to you, but clarification will be appreciated. I think you can appreciate the sphincter tightening excitement of seeing smoke coming from under dash.This may be just when factory AC is on-does this narrow search?
Thanks again

[Timothy B.]

Re: C2 ground from chassis to engine

Bill,

I can't think of what's under the dash that would be specific to factory air and smoke when the A/C is turned on. Take a hard look at the cigarette lighter and wire..

[Joe R.]

Re: C2 ground from chassis to engine

Thanks again,
I'll check for shorts and good Ground. When you say connect between battery and "car" to check for shorts, I assume you mean a clean spot on frame(or do you mean engine or does it matter)?On checking grounds, I assume no ohms would indicate good grounds between engine and frame?

Bill,

Checking for shorts means looking for undesirable shorts (such as what may be causing the smoke). So that would be shorts (low resistance or Ohms) between say +12 V and ground.

Checking a ground would be putting one lead of the Ohmmeter on a known ground, put the other lead on the node you want to check. If the meter reads low resistance (less than an Ohm or so), it's a ground.

It may have been mentioned already, but disconnect the battery before doing these tests. I would recommend fixing the problem before re-connecting the battery. That smoke is a warning sign, it could become fire. Or at the very least it will melt some wiring insulation.

Joe