[Chris65LeMans]

Okay, I took the car out yesterday for the first local cruise of the year. Took the battery off the tender and fired ‘er up. Tested the heater blower motor immediately, and it worked fine.

After the show, we cruised around town for an hour or so. When I got back home, I tested the heater again - popping out the tailpipes again.

I May replace the under hood harness to match my new under dash harness. Or maybe the battery is weak? I’ll need to dig into it this week.

[torqhead]

Originally Posted by Chris65LeMans

Okay, I took the car out yesterday for the first local cruise of the year. Took the battery off the tender and fired ‘er up. Tested the heater blower motor immediately, and it worked fine.

After the show, we cruised around town for an hour or so. When I got back home, I tested the heater again - popping out the tailpipes again.

I May replace the under hood harness to match my new under dash harness. Or maybe the battery is weak? I’ll need to dig into it this week.

Gave you the answer in post #37, not sure why you would waste your time doing something with a harness. Your alternator has taken a crap and this additional post you added further validates it.

[Chris65LeMans]

Originally Posted by torqhead

Gave you the answer in post #37, not sure why you would waste your time doing something with a harness. Your alternator has taken a crap and this additional post you added further validates it.

The alternator is brand new, so that’s surprising. (It’s a CVF, not some parts store model.). That’s the first thing I’ll check tomorrow.

[64speed]

I don’t know if it’s your alternator for sure or not but I would be really surprised it’s your wiring harness.

[TedRamAirII]

What is voltage at the big wire on the Alternator while running? is it different than measuring at the battery? Connect a voltmeter between your alternator big wire and the battery positive and read the voltage. Connect the meter between the alternator case and battery negative, read the voltage. Anything more than .3 volts, that's a problem.https://video.search.yahoo.com/searc...b&action=click

[Chris65LeMans]

Okay, I did some measuring.

I discovered that the reason the heater works fine immediately after start up is that my electric fans have not turned on yet.

No fans -
13.5 at battery with no accessories on
12.43 with brights and heater blower on high
14.6 at back of alternator.

Fans on:
12.6 at battery

At alternator: (and cooling fans on)
14.6 with no accessories
14.5 with headlights on
14.4 with heater blower and headlights on
14.35 with all of the above on.

Voltage drop measures the difference between the battery and alternator readings, in all cases.

The line out the back of the alternator runs to the starter, then the battery cable goes back to the battery. My battery was moved to the passenger side, so I have an extra long battery cable.

I read these results as indicating a wiring, rather than an alternator, problem. Thoughts?

[Old Goat 67]

These are all measured to ground?

Definitely a problem.
Now the question is "Where does it change?"

[Chris65LeMans]

All measured to negative battery terminal.

I forgot to mention- it’s zero between the alternator case and negative battery.

[ponjohn]

What size wire is the wire you lengthened?

[Old Goat 67]

Forgot, all measurements made with engine running?

If so, where does the 14.4 volts from alternator output drop down to 13 Volts?
Starter lug or before it back up to alternator?

[Chris65LeMans]

Originally Posted by Old Goat 67

Forgot, all measurements made with engine running?

If so, where does the 14.4 volts from alternator output drop down to 13 Volts?
Starter lug or before it back up to alternator?

Yes - all with the engine running. Winding it up doesn’t change any measurements.

Where does it drop is certainly the $64,000 question. I have a mini starter, but still need to drop it to get at the connections. (They look good.). Anybody have any suggestions how to get an engine running measurement from under there, or is there an easier way?

[Old Goat 67]

Yes, put a wire on the connection and extend it to where you can access it easily, beside the tire if necessary or next to the console while driving the car.

Just call it an extension of your test lead! Done it many times.

[Cardo]

I wouldn't think you would have to have it running to check. Measure the resistance of each leg or the circuit seperately you should be able to narrow it down that way. The wire should have .5 ohm or resistance or less. You can also perform a voltage drop test across the wire with the circuit intact, (checking for voltage from a point to a point of the circuit) looking for as close to 0 as possible. If you see voltage starting to show up in that test, that component is you suspect.

[johnta1]

I May replace the under hood harness to match my new under dash harness.

Since you are running a modified electrical system, why worry about a stock type wiring harness?

Are your fans on a relay?

I would probably have ran a starter relay on the driver fender.
The starter cable run from there to starter.
The new battery cable (bigger wire probably) over to the starter relay.
The alternator main wire to the starter relay.
A big wire to a relay for the fans with the switch now to other end of fan relay.

Fans and blower motor use a lot of voltage/power to run.
Running any of those wires with small wires will be a big drag on system.
(best to have relays for them)

[STEELCITYFIREBIRD]

You can’t measure resistance with power on in ohms...voltage drop, yes...
Power off when checking resistance in ohms, may not show the “restriction”.
Follow the large wire from alternator back, you will likely find a splice before you get to the starter.. begin your voltage drop test there.

Where do your cooling fans get power from?
Ground?

Is your body ground strap there and in excellent condition?

[Chris65LeMans]

Where is the body ground strap?

The cooling fans are on a relay - I had them installed by a professional auto electrical guy soon after I bought the car. I'm not sure where the power comes from (I could follow wires and find out), I forget where it's grounded, but do remember checking their ground in the past and finding it OK.

It looks like the weakness is between the alternator and the battery, and that's what I need to track down. The next chance I get, I'll drop the starter and do some ohms measurements. If that doesn't find anything, I'll install some temporary wire leads so I can test voltage going in / coming out of the starter.

As for a new underhood harness: if I did it, I'd have M&H make one for me for a one wire alternator, HEI, electric fans, etc.

[Old Goat 67]

Originally Posted by Cardo

I wouldn't think you would have to have it running to check. Measure the resistance of each leg or the circuit seperately you should be able to narrow it down that way. The wire should have .5 ohm or resistance or less. You can also perform a voltage drop test across the wire with the circuit intact, (checking for voltage from a point to a point of the circuit) looking for as close to 0 as possible. If you see voltage starting to show up in that test, that component is you suspect.

Simple. The main thing I'm trying to help him do is to find the reason that he is not getting 14.5 v at the battery from the alternator.

If the alternator is not supplying an EMF (Electro Motive Force) of 14.5 V, the the main power source is the battery voltage of 12.7v at best.
Changes the whole testing process and current flow.

By reading voltage values down the wire at different points, that will tell you where the drop has occurred, greatly simplifying the hunt and peck process.

[JC455]

Chris,
You've been given a lot of good info to follow- i.e. the voltage drop tests. Even if you don't understand them, do the tests as described- they'll help to pinpoint the location of the issue.
Your ground connections should be as follows:
Battery Neg to engine block(Neg battery cable)
Engine block to frame
Engine block to firewall
Frame to body/firewall

Personally, I'm not a fan of the 1 wire alt, they always seem to have issues.
Good luck!

[george kujanski]

As mentioned, there is a problem in the wiring between the alt output and battery. Not only that, depending on where the ignition is connected, the battery may not be filtering out noise and voltage transients that are affecting the ignition.

The battery is a BIG filter for electrical noise and alternator ripple voltage, but to do it's work, it needs to have a low impedance connection to the system wiring. Wherever the problem area is, it presents a higher impedance to the battery.

Has the integrity of the fusible link been checked?

George

[Chris65LeMans]

Originally Posted by george kujanski

Has the integrity of the fusible link been checked?

Where can I find that?

Also - can anyone tell me where to look for the body to frame ground?