TR6 72 TR6 alternator questions

[roofman]

Pretty sure my alternator has quit. Being an amatuer Tinster I have a few questions.
1. How do you test alternator output and what should it be?
2. My old alt. is a lucas. On the black plastic cover it shows a large 1 with small 5 6 7 next to it. The 5 6 7 is stacked w/ 5 on top and 6 7 below it next to a large 1.
This seems to indicate it is a 15, 16, or 17. What does it REALLY mean?
3. Simple amp upgrade suggestions?

 

[RomanH]

A quick and easy way to determine if your alternator is charging is to connect a volt meter to the battery. While the engine is running get the RPMs up a bit, the voltage should be between 13 and 14.6 volts IIRC. If your voltmeter is showing 12 volts or less you are not charging.
As for the rest, I don't know.

 

[TR3driver]

3. Simple amp upgrade suggestions?

Order the Bosch alternator for a 78 Ford Fiesta with air conditioning. 55 amps, more output at idle, more robust; and it's a drop-in replacement.
https://www.britishcarforum.com/bcforum/ubbthreads.php/ubb/showflat/Number/310459

 

[Got_All_4]

I agree with Tr3driver. If your current Lucas alternator has a internal voltage regulator then it should be a drop in conversion. Some have said that the terminal is the same and others said they had to eject the terminals out of the terminal block and plug them in individually. I did one in my 250 and what a difference. I did have to do some wire jumping because mine has an external voltage regulator. Also had to grind off some of the adjuster bracket. I now can run a radio, H4 headlight conversions and my dash lights are still bright. Good luck. Larry

 

[TR674]

roofman
good chance it is the voltage regulator. Is the ignition light on when the motor is running?
Regards
Craig

 

[roofman]

No ignition lightwhen motor running. I did not drive the car for about 2 weeks and when I went to start it and battery went weak. Put the battery charger on it and all was well for the day, but amp guage hovered at center line showing no charge. Went to start it 3-4 days later and same thing. I have a newer Optima Gel battery, so I am pretty sure that is not the issue.
How do you tell if mine has an internal or external voltage regulator?
Does the Fiesta alternator have the 3/8" pully?

 

[TR3driver]

No ignition lightwhen motor running. I did not drive the car for about 2 weeks and when I went to start it and battery went weak. Put the battery charger on it and all was well for the day, but amp guage hovered at center line showing no charge. Went to start it 3-4 days later and same thing.

That description sure fits a bad battery. Does the ammeter stay centered when you turn the headlights on ?

At the very least, I would want to check the charging voltage before putting a lot of work into replacing an alternator that may be fine.

How do you tell if mine has an internal or external voltage regulator?

Only the TR5/250 had the external regulator; all TR6 were internal. Look for the black plastic cover on the back of the alternator; externally regulated models have no cover.

Does the Fiesta alternator have the 3/8" pully?

Some do, some don't. Best plan on moving the pulley from your old alternator.

 

[roofman]

Stopped at auto zone today, and can order the Fiesta model for $108 w/no pully ( not available with pulley so I guess I have to hope the shaft size is the same also. I will check the recommended alternator and battery checks after work tonite. The battery is only 6-8 months old but i guess could be bad based on the other posts of crap parts.

 

[TR3driver]

The battery is only 6-8 months old but i guess could be bad based on the other posts of crap parts.

Not hard to kill a car battery in just a few weeks; all it takes is leaving it run down. Or overcharging it (which I believe the Optimas are particularly sensitive to).

 

[roofman]

Just came home for lunch. I charged the battery for 3-4 hours this morning.
With car not running turned on headlights and amp guage goes 3/4 up towards discharge.
Started car amp guage goes up 2/3 for a minute or 2 and settles in just barely into charge range. Turn on headlights and goes barely into discharge. both these last 2 readings only 1/8 inch above and below the bottom center line. Turned on the lights and revved up engine and no change in readings.
Put the volt meter on the battery with car not running and got 12.25. With car running partial choke at 1200 rpms I get a reading off battery terminals of 13.66 and with more revs about 13.8. Thoughts?

 

[TR3driver]

Did the ammeter stay on discharge when you revved the engine with the headlights on ? Or did it swing back to zero or slightly positive ?

The former would likely indicate an alternator problem (probably one bad diode so it still puts out something); while the latter sounds more like a bad battery.

Check the voltage (and the ammeter reading) with the engine at fast idle (like ~2000 rpm). Between 13.9 and 14.4 with little or no charge on the ammeter is correct; but it can be lower if the ammeter shows charging. Check first on the battery posts, and then as close to the alternator as you can get.

Bad connections are common, and can act like a bad alternator (or bad battery). The voltage at the alternator is allowed to be a few 0.1 volts higher, but anything over 0.5 says you have a bad connection somewhere.

I had a Chevy once where the ground lead to the motor was loose. It would make contact enough to start the engine, then let go again going down the road. That was a fun one to find !

 

[roofman]

Tried again, 12.37 sitting and not running.
Start car and idle to 2000 rpm I get 13.67 amp guage staight down. When I turn on the lights at 2000 rpm it drops to 13.4 and guage still staight down and showing no positive or negative gains.

 

[TR3driver]

Still sounds more like a bad battery to me.

I would be looking for a way to do a load test on the battery. Walmart and Sears I think used to do it for free.

I mis-typed before, 13.6 is the lowest acceptable votlage (according to Lucas) rather than 13.9. And Optima says their battery should charge at 13.3; so your 13.67 should be charging the battery.

The 13.4 sounds a bit low, but that might just be voltage drop in the wiring.

 

[roofman]

Battery tested ok at autozone, will attempt the alternator drop test above tonite. Is 13.66 at the battery with car running at 2000rpm enough to keep battery charged or should that number be higher?

 

[TR3driver]

Is 13.66 at the battery with car running at 2000rpm enough to keep battery charged or should that number be higher?

13.66 should be fine. As I mentioned before, Optima says minimum is 13.3 and up to 15.0 is acceptable.
https://www.optimabatteries.com/publish/o...ical_specs.html

If your AutoZone has one of those automagic battery testers, I wouldn't place too much faith in it. Few years back I had what I knew was a failing battery, but the gizmo at Pep Boys said it was fine. Within two weeks, it wouldn't start the car at all. Their machine just said "needs charged". When I told them it had just been charged, they claimed my charger was defective. So, I challenged the manager to charge the battery any way he wanted to and then start my car with it ... he finally backed down and admitted the battery was bad. Screwed me on the replacement too, but the problem went away. Although I didn't cut the battery apart to find out, I'm pretty sure it had a broken or partially broken conductor inside the case.

 

[roofman]

Thanks for all you help TR3driver. I brought the battery home cleaned the terminals, cleaned the alternator connections up and now I get a 14.2 reading. I guess I will just have to wait and see what a few days brings.

 

[martx-5]

Sounds like you solved the problem. Dirty conections can easily account for a 1/2 volt drop. /bcforum/images/%%GRAEMLIN_URL%%/driving.gif