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Post by paddymk2 on May 9, 2020 23:51:21 GMT
Hi Guys
Hope you're all keeping well and getting some projects done.
I recently had the engine out to repair the gearbox.
When restarting the battery charge light came on.
I checked the voltage across the battery - getting 12.65V engine off.
But when I turned on the engine (it took a bit to start it) but getting 12.36V
I checked the contacts and alternator belt - everything looks good.
Is there some way to isolate the alternator and check it?
Its a 1969 Mark II
and I'm in Adelaide.
Cheers
Paddy
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Post by 1800heap on May 10, 2020 7:23:31 GMT
Hi Paddy
Assuming the alternator was working before you pulled the engine out I would suspect that you have a problem with a connection. Do you get an ignition light before you start the car? The oz cars don't have a self contained alternator like the UK cars do but have a control box on the fire wall I think. Its is called an email alternator according to my Oz manual. There is a complicated test proceedure in the book that I wouldnt bother with. Best bet check all the connections on the control box and alternator are good and clean. Also check you haven't forgot to put the engine earth strap back and that the earths on the inner wings are all good.
Nick
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Post by 1800heap on May 10, 2020 7:32:52 GMT
Actually it seems there are two types an email unit and a 11AC both of which have a control box on the fire wall. The 4TR box is an 11AC unit. Same deal needs good connections to function properly!
Nick
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Post by dave1800 on May 10, 2020 8:46:56 GMT
As Nick says, check all the connections and then check the wires for continuity. I'm not familiar with the Oz alternators but have experience with an old Toyota that had a separate control box.
If you disconnect the wires from the alternator and check the output with a voltmeter between ground and the power terminal on the alternator you will see an unregulated voltage that will quickly rise above 20V or more as the engine is revved up. Make sure you have the voltmeter on a high range! That will tell you if the alternator is at fault. (Depending on how it's configured you may have to blip the throttle to raise the engine briefly to around 3000 rpm to get the alternator to produce an output with the warning light disconnected (it feeds a small current that "kick starts" the output).
David
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Post by paddymk2 on May 10, 2020 12:04:06 GMT
Thanks Nick Yes, it was working before. The main output contacts looks good. But the wires going to the connector could be checked. Those contacts could do with good clean - thanks for the encouragement. The voltage regulator could be the issue also. It could also do with a clean.  |
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Post by 1800heap on May 10, 2020 22:06:09 GMT
Thanks Nick Yes, it was working before. The main output contacts looks good. But the wires going to the connector could be checked. Those contacts could do with good clean - thanks for the encouragement. The voltage regulator could be the issue also. It could also do with a clean. No problem Paddy. Electrical issues can be very frustrating! As David said check the continuity of the wires. What happens is the copper corrodes but the plastic holds on so the wire/connector can look intact but actually be bad. Happend on my UK car before it got shipped resulting in the lights not working!
The main output terminal on the alternator goes accross to the starter solenoid that you pictured. The one that is bolted on with the battery pos cable. The big spade connector on the solenoid (2 browns) goes to the bulkhead connectors. If you have a multimeter test from the alternator main output to the battery positive with the battery disonnected. This should give you continuity or zero ohms. Some multimeters dont show zero but slightly above for continuity. Hold the two leads of the meter together and see what the reading is. This is your target figure for continuity. Depending on the quality of the meter you may or may not get zero. Much more than the target figure when testing fairly thick cables like the alternator output cable is a worry.
My Oz car is the email type. The engine is out at the moment so I had a quick test. The two other wires, the field and aux wires from the alternator, both go to the control box. If I test at the alternator connector with the connector and the battery disconnected, between the two wires I get almost continuity. Less than half an ohm. Mine was working b4 and I think this is a normal resistance so you should get the same. Good luck. Nick |
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Post by paddymk2 on May 12, 2020 13:24:31 GMT
Hi Nick,
This is an email type with separate control box.
i cleaned up some of the contacts.
i had low resistance from the bpost contact to the battery connector.
and about 7 ohms from the fld and aux to the control box connector.
The fld and aux connectors are both connected to gnd with around 15ohms. Does that seem right? i need to work through the wiring diagrams in the manual.
cheers
paddy
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Post by 1800heap on May 12, 2020 23:56:35 GMT
Hi Nick, This is an email type with separate control box. i cleaned up some of the contacts. i had low resistance from the bpost contact to the battery connector. and about 7 ohms from the fld and aux to the control box connector. The fld and aux connectors are both connected to gnd with around 15ohms. Does that seem right? i need to work through the wiring diagrams in the manual. cheers paddy No that sound high Paddy. My unit was less than 1 ohm. I will have another check this morning and get back to you with some pictures. Nick |
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Post by 1800heap on May 13, 2020 1:09:52 GMT
Had another look just to confirm what I had paddy. As I said when I pulled the engine out the alternator was working ok so hopefully we can assume my readings here are what you should have so here goes! First thing to do is check your meter is good. Good practice to check it every time you use the meter. Its caught me lots of times! So red and back touching together on ohms range gives me zero ohms.  I think first compare the control box to mine, so disconnect the spade on the left side of the box and the screwed terminal on the right and test across the two. I got 0.2 ohms so call that continuity.  Then go to ground and the Screw terminal (right side of box) and I got 15.5 ohms. It shouldn't matter which way round you have the meter leads and you will get a similar reading on the spade terminal(Left side of box) to ground.  Now these next tests are where I think you might find the issue! The plug on the alternator which I have next to the control box so you can see it, has two spades in a T pattern. I have the meter pushed into the leg of the T as it were, rather than the cross at the top of the T. Clear as mud!  Hopefully you can see what I mean from the picture! I have the other end on the control box screw terminal (Right) but for you as you have disconnected the wire from the screw terminal go to the wire only. This should be 0.1 ohms (continuity) or at least very low because you are only measuring the wire.  Next do the other wire so the top of the T connector to the spade left side wire on the control box. Here I got 0.2 ohms so still continuity.  Let us know what you get. I bet one of your wires has a bad connector and that is where you will find your 7 ohms. Nick |
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Post by 1800heap on May 13, 2020 1:31:50 GMT
Just to confirm Paddy you should do all the tests with the battery disconeccted as any voltage on the wires will upset the readings from your multimeter!
Nick
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Post by paddymk2 on May 13, 2020 13:40:56 GMT
Thanks for doing all that. And thanks for the reminder about the multimeter.
I was getting only 2.2 ohms on the meter test, but if i wasn’t careful the ohms went up to 10 or so.
So across the control box was 2.2 ohms so we can call that zero.
The RH screwed on contact had a bit of rust that i cleaned off.
It was harder to see the condition of the LH spade connector and i really only got to brighten up the tab at that side.
i measured continuity (2.2 ohms)for both parts of the T connector to their respective connectors for the control box.
i tried starting the car again, but pretty much the same as before, voltage drop from 12.65v to 12.3v when starting and the red charge warning light stays on.
On the positive side, the interior cabin light started working, mmm, maybe there’s some other leakage?
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Post by dave1800 on May 14, 2020 0:41:27 GMT
Just a thought. On the RB340 voltage regulators used with the crab dynamos there was a weakness in the grounding wire arrangements. Not sure if that was carried forward to the Oz alternator looms? I always used to improve this to avoid damage to the RB340 (the local Lucas agent recommended this as they believed it was the most common reason for the RB340 failures on crabs).
If you've not already done so, carefully check the ground wire for the control unit. The best after a visual inspection is to measure the voltage between the control unit ground terminal and the battery negative with the engine running. It should read 0V (or no more than 0.1v at worst). Checking resistance to ground can be misleading as a poor connection can still read 0 ohms if there is a single fine strand connected but it cannot handle the current.
As you know measuring very low value resistance is fraught with problems and inaccuracies because of resistance in the meter leads etc which is why a voltage drop measurement is always preferable if possible as it proves continuity and current handling capability.
David
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Post by 1800heap on May 14, 2020 1:15:59 GMT
Thanks for doing all that. And thanks for the reminder about the multimeter. I was getting only 2.2 ohms on the meter test, but if i wasn’t careful the ohms went up to 10 or so. So across the control box was 2.2 ohms so we can call that zero. The RH screwed on contact had a bit of rust that i cleaned off. It was harder to see the condition of the LH spade connector and i really only got to brighten up the tab at that side. i measured continuity (2.2 ohms)for both parts of the T connector to their respective connectors for the control box. i tried starting the car again, but pretty much the same as before, voltage drop from 12.65v to 12.3v when starting and the red charge warning light stays on. On the positive side, the interior cabin light started working, mmm, maybe there’s some other leakage? No worries Paddy. I was thinking because you had the engine out it was likely a wiring problem hence the continuity testing, but with your results it is looking more like a control box or alternator problem! One more continuity check you can do just to be sure is check your alternator is grounded properly. So go from the body of the alternator to the battery negative looking for continuity. Just to be clear to all who read this the following tests involve some risk to the vehicle and you if not done with care so please be careful! Sorry Paddy I have to give a couple of warnings for everybody at this point as we don't know who might use the info or their skill level! I am going to get you to energise the field coils of the alternator for a short time, which should result in it charging the battery, if it is working properly! There are risks in doing this that you must except! Lets go through them just so everyone who reads this is aware what they could be and can do it safely. 1- If the alternator is faulty and has shorted diodes it could be charging your battery with AC with this procedure, which the battery will not like if you do it for too long! 2- Working on the alternator while the engine is running can be very risky. If you make a mistake you risk loosing fingers but there is potential for it to be life threatening if you get anything caught in the pulley or belts! 3- Alternators and wiring can get very hot with high loads and cause fires as can inadvertent short circuits you make with a test cable or meter! 4- If you cause a spark where there is petrol or fumes you are going to have a big fire very quickly! Note this test is only to be used on this type of Email alternator set up! Now we have gone through the safety bit and accepted the risks we can do the test! Make up a piece of wire with an insulated spade terminal on one end and the other end needs a 21 watt bulb attached in series. Leave the other connection to the bulb with a small bit of the insulation removed. You will need a wire that is long enough to go from the alternator to the battery positive. Its should look something like this.  Disconnect the battery and then disconnect the T connector on the alternator and place it where it won't short or get caught in anything. Then connect one end of your test wire as shown.  Make sure the test wire is away from pulleys etc and is run over to the battery. Do not connect the bare end at this stage. Reconnect the battery. Connect your test meter, with it set to voltage, to the positive and negative of the battery so that you can monitor the voltage. Have an assistant start the engine when you are ready. You should be holding the insulation of the test wire near the bulb. Note the voltage on the test meter when the engine is running. Momentarily touch the bare end of your test bulb on the positive of the battery. There may be a small spark so this is where you don't want any petrol leaks! The voltage on the test meter should go up considerably while the test wire is connected to positive, indicating the alternator is charging and passed the test. Only hold the wire on positive for only a few seconds while you check the voltage as there will be no voltage regulation! If it charges at this point you will need to do another test to check the exciter diodes of the alternator which should tell us if it is an alternator or control box fault. Nick Post edited to include test lamp as suggested by David 16/05/20 |
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Post by dave1800 on May 14, 2020 1:33:52 GMT
Nick, a great idea and thanks for the warnings. We never know who is reading the guidance and as you suggest there could be novices who may not be aware of the potential dangers.
I have just one suggestion. If Paddy has a spare brake bulb (21W)he could wire this in series with the wire jumper. This would limit the current to the field coil to somewhere around what it would normally expect and reduce the risk of damage. Again it should only be held in place for a few seconds. Sometimes you can hear the difference when an alternator is working especially if loaded by switching on the headlamps - and maybe a slight reduction in idle speed.
David
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Post by 1800heap on May 14, 2020 1:46:39 GMT
Nick, a great idea and thanks for the warnings. We never know who is reading the guidance and as you suggest there could be novices who may not be aware of the potential dangers. I have just one suggestion. If Paddy has a spare brake bulb (21W)he could wire this in series with the wire jumper. This would limit the current to the field coil to somewhere around what it would normally expect and reduce the risk of damage. Again it should only be held in place for a few seconds. Sometimes you can hear the difference when an alternator is working especially if loaded by switching on the headlamps - and maybe a slight reduction in idle speed. David I have tried this on my email alternator and it worked fine and is the same method as suggested in my Australian manual. I agree though that a bulb in the circuit as an initial test is a great idea so would suggest this Paddy. It would lessen the risks of testing an alternator that might be faulty as well ! Thanks David Nick |
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Hopefully you can see what I mean from the picture! I have the other end on the control box screw terminal (Right) but for you as you have disconnected the wire from the screw terminal go to the wire only. This should be 0.1 ohms (continuity) or at least very low because you are only measuring the wire.