• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)
Tips
Tips

TR6 TR-6 Battery Drain

Share this page

davidk

davidk

Jedi Trainee
Offline
There is a battery drain on my 1974 TR-6 when everything is turned off. It is too dead to start after about a week. I checked amp draw and found about 8.5 M amps draw and traced it to the smaller brown wire on the back of the Lucas alternator. Has anyone had this happen? Is it time for a new alternator, maybe a Delco? There was also about a 2 M amp draw from the CD/radio. Does that sound normal? Thanks in advance for your help. David K.
 
Disconnect the anti-run on valve located at the charcoal cannister at the right side of your radiator. Just remove one or both of the wires. Fully charge the battery and try it out for a week or so. These things can drain a fully charged battery overnight and then act normal the next day.

If you hear a loud "clunk" up front when you attach the charger (if it is still connected), you have found a common, but seldom detected problem. The trouble is that these valves stick internally then release, so it's hit or miss unless you catch it just right. Disconnecting it will remove the valve from the circuit and you'll probably never even notice that it's off. That is unless you're idling at 1,400 rpms when warm.

It's worth a try and a lot cheaper and easier than replacing the alternator. Remember that I am guessing with you here and there is no substitute for a full load test on the battery and complete alternator output test under load and at idle.

Good luck,
 
Paul,
A solenoid that is sticking internally is not drawing power. It has to be the switch that is sticking and thus supplying power to the solenoid.
 
Under normal circumstances, I would agree with you. But this is the problem that drove me crazy for several months with a battery drain. If I remember correctly, this "solenoid" is wired through the oil pressure switch, which I replaced twice in an attempt to get it to stop sticking and draining the battery, to no avail. So whether or not it is switched internally or exactly what causes the problem, I do not know.

I just know that after all of the attempts to fix it by cleaning contacts and replacing OP switches failed, the ultimate end of the dead batteries was caused by simply disconnecting it. I did get a used one on ebay, but I've had no problems with the valve being disconnected, so until I get really ambitious in the spring, it will remain in the permanent off position.
 
[ QUOTE ]
Disconnect the anti-run on valve located at the charcoal cannister at the right side of your radiator.

[/ QUOTE ]


Two questions. What's an anti-run on valve and what's a charcoal cannister?
 
[ QUOTE ]
Paul,
A solenoid that is sticking internally is not drawing power. It has to be the switch that is sticking and thus supplying power to the solenoid.

[/ QUOTE ]

That is generally true. However if this solenoid contains a pullin coil and a holding coil. Then it is possible if it sticks the the holding circuit may be the culprit. Just a thought.--Keoke
 
[ QUOTE ]
[ QUOTE ]
Paul,
A solenoid that is sticking internally is not drawing power. It has to be the switch that is sticking and thus supplying power to the solenoid.

[/ QUOTE ]

That is generally true. However if this solenoid contains a pullin coil and a holding coil. Then it is possible if it sticks the the holding circuit may be the culprit. Just a thought.--Keoke

[/ QUOTE ]

Bingo...Current can flow through a hold in coil if the solenoid plunger sticks. The reason for the two coils is that it takes alot of magnetism to pull the solenoid plunger in, but once it's in, it takes much less current to hold it there. So they put in two coils. Starter solenoids have this feature also.
 
Brosky's anit-run on valve was causing the drain on my 76(Brown) TR6...Drove me crazy until Brosky suggested that valve. It's to the bottom right of the radiator bellow the big charcoal canister(black plastic)....but only on equipped cars(my 75 doesn't have one, PO might have removed??).
 
When my father's TR6 was draining the battery, I was first told to check the anti-run on valve. These have a long history of drain problems. So, I can back up Brosky in his statement.
 
David
I had a similar problem with a slow drain on my battery. Mine turned out to be faulty electrical panel on the back of the Lucas alternator. Replacing this and getting the alternator serviced stopped the drain. Paul also highlights a possible cause.
Regards
Craig
 
[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
Paul,
A solenoid that is sticking internally is not drawing power. It has to be the switch that is sticking and thus supplying power to the solenoid.

[/ QUOTE ]

That is generally true. However if this solenoid contains a pullin coil and a holding coil. Then it is possible if it sticks the the holding circuit may be the culprit. Just a thought.--Keoke

[/ QUOTE ]

Bingo...Current can flow through a hold in coil if the solenoid plunger sticks. The reason for the two coils is that it takes alot of magnetism to pull the solenoid plunger in, but once it's in, it takes much less current to hold it there. So they put in two coils. Starter solenoids have this feature also.

[/ QUOTE ]

Sorry fellows but this is my business, I design and manufacture industrial solenoids. No, the solenoid used for the anti run on valve is not a dual coil unit. It is a single coil two wire solenoid, it is not internally switched, and it does have an internal return spring. If you physically lock the plunger in the engaged position so that it cannot move it will not draw power once the power is removed. Actually, no solenoid would.
One thing with the way this solenoid circuit is wired is that the ground wire is switched. The brown with red trace wire at the solenoid is always hot. When the oil pressure comes up it turns the solenoid on. When the car is turned off the pressure drops the circuit is opened and the solenoid turns off which allows extra air into the intake preventing the run on. What I have heard can happen with these solenoids is that the insulation on the white with purple trace wire from the solenoid to the oil pressure switch fails, creating a ground path so that the solenoid is always on. So look for breaks in the insulation of the white with purple wire.
 
Thanks for the information guys. The anti run-on valve is long gone. The drain does go away when the small brown wire on the alternator is pulled loose. I'm leaning towards a Delco replacement. David K.
 
David:

I had the same issue with my 74 TR6. I replaced the Lucas alternator with a rebuilt Lucas alternator that I got from NAPA. Solved my battery drain problem and I have left my battery connected all year with no drain.

Matt
 
[ QUOTE ]
I'm leaning towards a Delco replacement. David K.

[/ QUOTE ]

Hey David. You won't regret the alternator upgrade. I have lots of additional electronics on my TR6 and appreciate the added umph that the 66 amp (approx.) Delco-style alternator provides. Even the lights burn brighter. A great weekend project. I got mine from AutoZone, their top of the line new alternator, basically the same one that fits in a late 60s Nova SS.
 
Hey, thanks for the technical know how! I just eliminated a problem, but did not actually fix it, so this will be a good project when it warms up again, now that I know where to go to fix it.
 
Back
Top