Unsolved mysteries… ID this part

[Bronco_007]

Good evening, my people. I got under the hood today and one thing led to another. You know the drill.

1974 stock 302, 3 on the tree.

Mystery #1:

I went to start the engine and nothing happened. Lights wouldn’t work either. Time for a new battery.

So I got one, and installed it. Tried to start it; an attempt was made without success. I hear a loud click from the area of the starter, and nothing else. The lights work, so the battery is good.

I checked under the hood again and found this just hanging out:

The connector looks pretty gnarly. Might need to be replaced; certainly cleaned.

I have no idea where it is supposed to go. It originates at the bottom of the alternator:

Could it have anything to do with why she won’t turn over?


Mystery #2:

While looking around under there I notice this (also have no idea what it is), that looks like it might oughtta have a hose or two attached to it, maybe?

Passenger side, top of engine, above the valve cover, at the front corner. School me, please.

Mystery #3:

Awhile ago I noticed what looks to be some type of ground connection in the engine bay, one the drivers’ side, just medial to the fresh air vent box. It appears to be made of fiber, not wire. It wasn’t attached to anything at first, just laying there. But I found a hole just above it in the hood, so I used a small bolt and washer to attached it. Figured if it was some type of ground, it should probably be grounded…

What is this? Is it just a connector to ensure any aberrant static in the hood grounds out in the body?

Appreciate all the schooling I can get, as always. Happy New Year!

 

[DirtDonk]

Yes, you guessed correctly. But it’s probably not factory.
At least I’ve never seen one from the factory so likely one of your previous owners added it perhaps to reduce radio noise interference.
it’s a braided stainless steel or a galvanized. Not actually a fiber, but a metal that is a material that was often used as ground straps from the factory on other vehicles. Broncos were not so blessed for the most part, however. And I don’t think Ford would’ve ever put a hole in the cowl because it would’ve guaranteed a leak into an area that was already prone to rusting through.

I’ve seen that connector before, too, but never noticed one on a bronco alternator.
Is the wire color white with a black stripe by any chance? Looks faded to yellow, but maybe you could push back some of the fiber jacketing to see an unmolested section.
If it’s white with black, then it was the stator wire from the alternator to the carburetor choke. Perhaps that’s the choke end of the wire?
The buggered up end it looks more like old dielectric grease than anything else. Doesn’t look too bad from here.

The vacuum thingy circled in red is a factory TVS or thermal vacuum switch.
Yes two vacuum lines are supposed to be there. One is vacuum from the intake manifold or carburetor, and the other one is only active when the engine temperature reaches a certain point, and the valve opens up inside and lets the vacuum be pulled through from whatever device is at the other end.
Probably the distributor advance?
Do you have hoses on the distributor vacuum advance canister?

 

[MarsChariot]

I seem to recall that on some models, 73 and beyond, there was a wire directly from the alternator to an electric choke. Since you appear to have a non-stock carburetor, then perhaps that wire was left orphaned. Various emissions systems used that thermovalve to activate vacuum for various purposes. The braid ground strap to the hood(?) is indeed weird.

 

[DirtDonk]

Later, full-size Ford trucks had that ground strap to the hood. Probably a PO saw that and decided it was a good idea.
I personally think it is, but I might’ve tried a different location for it.

 

[B RON CO]

Hi, none of the things in the picture should prevent your starter from spinning. I would double check and clean all the connections, including the grounds. It seems the starter solenoid is working since you can hear the starter clicking, so my guess is either the battery is not fully charged or the starter is bad. Good luck

 

[Bronco_007]

Thanks for all the advice everyone. I truly appreciate that I can come here for help! I’ll get back under it and report!!

 

[Slowleak]

Thanks for all the advice everyone. I truly appreciate that I can come here for help! I’ll get back under it and report!!

Yep…. Sounds like a grounding problem. Check the battery cable where it grounds to the engine block. That’s a common problem point.

 

[DirtDonk]

In addition to the big cable to the engine block, there should be a smaller wire from the battery to the body.
When adding them afterwards, we often use one of the starter relay, mounting bolts as its attaching point. The relay itself needs to be grounded to the body to function. If yours doesn’t have one, then perhaps the connection is intermittent.
Although in your first instance where the lights didn’t work, that would not have caused that. Or maybe it would have if it was bad enough.
Perhaps the battery was low, or perhaps you have other issues.
There are some simple tests you can perform.

Can you provide some additional pictures? One of the starter relay/solenoid area with the battery connections, and one of the starter itself.
Thanks.

 

[Steve83]

Changing the battery for a no-start doesn't make sense. Would you change the gas tank if it ran dry? For any electrical problem, always start by CLEANING THE BATTERY TERMINALS. Read this page:

(click this text)


Always ID factory wires by color. Look them up on this & the NEXT several pages:

(click this text)


The '74 wiring diagram doesn't show a Wh/Bk coming off the alternator.

(click this text)


But '75 does.

(click this text)


The component on the heater hose nipple is a thermal vacuum valve (TVV), often used by Ford to manage (OE) carburetor functions. The ground strap to the hood is not original, but it is a good idea - Ford did that on later vehicles to shield the radio from ignition noise (RFI).

(click this text)

 

[Bronco_007]

Changing the battery for a no-start doesn't make sense. Would you change the gas tank if it ran dry? For any electrical problem, always start by CLEANING THE BATTERY TERMINALS. Read this page:

(click this text)


Always ID factory wires by color. Look them up on this & the NEXT several pages:

(click this text)


The '74 wiring diagram doesn't show a Wh/Bk coming off the alternator.

(click this text)


But '75 does.

(click this text)


The component on the heater hose nipple is a thermal vacuum valve (TVV), often used by Ford to manage (OE) carburetor functions. The ground strap to the hood is not original, but it is a good idea - Ford did that on later vehicles to shield the radio from ignition noise (RFI).

(click this text)

I changed the battery because it was dead. Lights, horn didn’t work… Wouldn’t start AFTER the battery change.

 

[DirtDonk]

It’s still a good idea to check some things. Because of one of the more and more common failure points on older vehicles is the battery cables themselves.
How old are yours?
Now I’m sure you can tell that you had a dead battery with a voltmeter, but you can’t automatically tell by headlights. In fact, when a positive or negative battery cable fails often things work initially, but as soon as you turn the key to start everything dies because the load is too heavy.
Sometimes it will come back after messing with things sometimes not. In your case it does sound like there was an issue with the battery, but it’s not an automatic assumption anymore.

 

[sprdv1]

Later, full-size Ford trucks had that ground strap to the hood. Probably a PO saw that and decided it was a good idea.
I personally think it is, but I might’ve tried a different location for it.

what I was thinking too

 

[Steve83]

I changed the battery because it was dead. Lights, horn didn’t work… Wouldn’t start AFTER the battery change.

Yeah, that's what I understood when I read it before.

 

[Bronco_007]

Yeah, that's what I understood when I read it before.

Gotcha. I’m sorry for my misunderstanding. Appreciate you!

 

[Bronco_007]

It’s still a good idea to check some things. Because of one of the more and more common failure points on older vehicles is the battery cables themselves.
How old are yours?
Now I’m sure you can tell that you had a dead battery with a voltmeter, but you can’t automatically tell by headlights. In fact, when a positive or negative battery cable fails often things work initially, but as soon as you turn the key to start everything dies because the load is too heavy.
Sometimes it will come back after messing with things sometimes not. In your case it does sound like there was an issue with the battery, but it’s not an automatic assumption anymore.

Got it. Love everything I learn from you people!

No idea how old my battery cables are, but I’ll be replacing them now!

 

[Bronco_007]

It’s still a good idea to check some things. Because of one of the more and more common failure points on older vehicles is the battery cables themselves.
How old are yours?
Now I’m sure you can tell that you had a dead battery with a voltmeter, but you can’t automatically tell by headlights. In fact, when a positive or negative battery cable fails often things work initially, but as soon as you turn the key to start everything dies because the load is too heavy.
Sometimes it will come back after messing with things sometimes not. In your case it does sound like there was an issue with the battery, but it’s not an automatic assumption anymore.

Changing the battery for a no-start doesn't make sense. Would you change the gas tank if it ran dry? For any electrical problem, always start by CLEANING THE BATTERY TERMINALS. Read this page:

(click this text)


Always ID factory wires by color. Look them up on this & the NEXT several pages:

(click this text)


The '74 wiring diagram doesn't show a Wh/Bk coming off the alternator.

(click this text)


But '75 does.

(click this text)


The component on the heater hose nipple is a thermal vacuum valve (TVV), often used by Ford to manage (OE) carburetor functions. The ground strap to the hood is not original, but it is a good idea - Ford did that on later vehicles to shield the radio from ignition noise (RFI).

(click this text)

Thank you so much for putting all this together. That is a great link and I understand the battery system much better now. Definitely need to replace my battery cables.

 

[Bronco_007]

In addition to the big cable to the engine block, there should be a smaller wire from the battery to the body.
When adding them afterwards, we often use one of the starter relay, mounting bolts as its attaching point. The relay itself needs to be grounded to the body to function. If yours doesn’t have one, then perhaps the connection is intermittent.
Although in your first instance where the lights didn’t work, that would not have caused that. Or maybe it would have if it was bad enough.
Perhaps the battery was low, or perhaps you have other issues.
There are some simple tests you can perform.

Can you provide some additional pictures? One of the starter relay/solenoid area with the battery connections, and one of the starter itself.
Thanks.

I’ll get pics for you. But I recall the grounding wire is worn and looks to have been tampered with; but it does connect to the fender and then the engine. But it needs to be replaced.

 

[Bronco_007]

Changing the battery for a no-start doesn't make sense. Would you change the gas tank if it ran dry? For any electrical problem, always start by CLEANING THE BATTERY TERMINALS. Read this page:

(click this text)


Always ID factory wires by color. Look them up on this & the NEXT several pages:

(click this text)


The '74 wiring diagram doesn't show a Wh/Bk coming off the alternator.

(click this text)


But '75 does.

(click this text)


The component on the heater hose nipple is a thermal vacuum valve (TVV), often used by Ford to manage (OE) carburetor functions. The ground strap to the hood is not original, but it is a good idea - Ford did that on later vehicles to shield the radio from ignition noise (RFI).

(click this text)

I’m wondering if there’s anything I can even do with the TVV since the PO installed a Holley carb. Any reason to not just let it be?

I’ll be back on here again with more pics. Got a few errant hoses under there with no home. But I don’t think they go to the EVV.

 

[gnpenning]

With the quality of new parts please don't replace any parts without testing first. You can introduce new problems. There is a difference in being able to test items and replacing known bad items verse not knowing if you have really fixed the problem or kicked it down the road. Guessing if you have fixed a actually problem is never very comforting.

A DVOM and test light should be requirements for all vehicle owners. Doesn't need to be expensive and plenty of videos on how to use them, plenty of people here can help as well.


If it's been driving fine without the TVV hooked up you can keep doing so. As mentioned more pictures would help in getting it right.

 

[Bronco_007]

With the quality of new parts please don't replace any parts without testing first. You can introduce new problems. There is a difference in being able to test items and replacing known bad items verse not knowing if you have really fixed the problem or kicked it down the road. Guessing if you have fixed a actually problem is never very comforting.

A DVOM and test light should be requirements for all vehicle owners. Doesn't need to be expensive and plenty of videos on how to use them, plenty of people here can help as well.


If it's been driving fine without the TVV hooked up you can keep doing so. As mentioned more pictures would help in getting it right.

I understand. More pics coming this afternoon.