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Pinto alternator with CBS 12 module box


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Engine back in after fixed core plug and subsequent sheared clutch housing bolt. 

Engine runs nicely (needs fine tuning/timing, but sustains at idle) BUT horrible screeching sound eminating from Engine.

After alot of ruling things out (initially thought it was solenoid failing to retract, so stripped and lubed) finally tracked noise down to alternator. It seems that when the alternator is plugged in instead of producing current it is drawing (PD across battery is 12.5 when inactive, drops to 11-11.5), which seems to make a vibration. when alt unplugged engine runs quietly and smoothly, and alternator reads ~16V.

All is plugged in to CBS 12 module unit which otherwise works fine - no loss of charge overnight, all circuits working.

Any ideas?

PS, alternator warning light only half extinguishes when engine running. The alt, starter and battery all new, and apparently otherwise healthy. Am a bit stumped, any ideas - are some alternators pos earthed or summat??🤪

Edited by zhap135
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0k hard to be 100% sure without hearing it but the screeching is prob the alt belt not tight enough and when the alt is under load it’s slipping.   That’s why when plugged it it’s drawing current not supplying 

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4 hours ago, blue said:

0k hard to be 100% sure without hearing it but the screeching is prob the alt belt not tight enough and when the alt is under load it’s slipping.   That’s why when plugged it it’s drawing current not supplying 

Thanks Blue. That did occur to me, however the noise is less squeal and more screech. It's pretty grindy. It also is in unaffected by tightening and loosening fan belt

Also voltage across battery drops by one, rather than rising

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Posted (edited)
9 hours ago, Peter Bell said:

Assume you have a filament type bulb as a charge light?

Hi Peter, no led,

Edited by zhap135
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Realy does sound like pos earth alternator. not that I know of any, in the 1960s some cars were positive earth for early germanium transistor radios but I think that they were all dynamo.

When you read alternator volts what polarity do you get?

do you get the same volts on ACvolts as DCvolts?

It is a new alternator so most probably duff.

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7 hours ago, IanS said:

Realy does sound like pos earth alternator. not that I know of any, in the 1960s some cars were positive earth for early germanium transistor radios but I think that they were all dynamo.

When you read alternator volts what polarity do you get?

do you get the same volts on ACvolts as DCvolts?

It is a new alternator so most probably duff.

I'll have a look at that, thanks. Didn't think to actually check the polarity cos it was me

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Just a thought. Initially you suspected that the starter was not disengaging. You might want to check that it is not re-engaging after the engine has started. Theoretically this is simply to disconnect the feed to the starter solenoid after the engine has started. In practise of course this difficult to do safely, one would probably need to add an extension to the wire that goes to the solenoid so that it can be disconnected easily without hands/spanners etc close to the running engine.

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Posted (edited)
4 hours ago, Sparepart said:

Just a thought. Initially you suspected that the starter was not disengaging. You might want to check that it is not re-engaging after the engine has started. Theoretically this is simply to disconnect the feed to the starter solenoid after the engine has started. In practise of course this difficult to do safely, one would probably need to add an extension to the wire that goes to the solenoid so that it can be disconnected easily without hands/spanners etc close to the running engine.

Thanks Spare. I think I've literally just tracked down the issue.

Was going back to basics last night and tracked all wires back the switch. Now the switch is original Sierra, but I bought the kit as a part complete. The previous owner hadn't got very far with it, so i assumed that the original harness all correct and untampered with. Last night I noticed whilst looking at the Haynes manual and the switch that the wire colours into the switch terminal were wrong (I've been keeping wire colours true to their  original ford purpose as much as poss, even when using the CBS FB)- up until now it hadn't even occurred to me to verify the wires going into the switch. 

So all this time the ign and start had been swapped over. I had probably "made things work" with a bit of swapping and splicing - I didn't keep a full diary of what I'd done, but it might explain a couple of minor oddities that I've had to work around since

Now have reconnected the switch terminals, redirected the ign switch wires to the proper CBS modules. Engine starts, alternator provides about 13.5V with no noise and I'm a happy bunny.

Will have to go through all other functions now to test (superficially everything seems to work well), but whereas I didn't keep a diary, I know most of the workarounds that I did.

I'm really glad it wasn't the starter or alt as they were both new units

So, as ever, thanks all for your inputs

Edited by zhap135
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On 6/5/2021 at 10:14 PM, Peter Bell said:

Assume you have a filament type bulb as a charge light?

Now have tracked the issue and largely sorted, the battery light light seems to be much improved, althoug there is a slight illumination when running normally - very faint. Not sure that it matters much?

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Have you put a diode in the circuit ?  If not the light could come on slightly if the alternator voltage is more than the voltage feeding the other side of the bulb.  Normally they should be the same but depending on where the feed from the light comes from there could be a slight difference.

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Were these the 3 main wires going to the connector for the ignition switch, red, black, black/yellow? If so I had a similar problem when the connector failed, I cut it off connected them up  as seemed obvious but discovered it should have been Red to red, black to black/yellow and black/yellow to black/blue! 

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18 hours ago, Peter Bell said:

Were these the 3 main wires going to the connector for the ignition switch, red, black, black/yellow? If so I had a similar problem when the connector failed, I cut it off connected them up  as seemed obvious but discovered it should have been Red to red, black to black/yellow and black/yellow to black/blue! 

Similar thing yes, exactly that. Now that I've corrected that all the mechanicals work no probs.

I now have issues with the lights regarding the CBS module. So this is getting a bit frustrating - it's like playing Waccamole. I believe due to the wiring of the ford paddles (being consistent with ford relays) there are certain conflicts with the CBS relays. Some is clearly functional - the lights switch feed is off one fuse, and is always live. My belief is that the heads should not be able to be left on when teh key is removed, whereas the sides can. Does it matter? Maybe only to me.

I've already had to isolate the wiper circuit and reincorporate the ford relay there. Now I fear that I might need to do the same with the sides, heads and beam, and the hazards. In particular the inds/hazards are just not drawing enough to get an audible click from the blinker switch (on one weird misconnection the other day the heads started flashing with the hazards - hey presto a satisfying click from eh blinker!)

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On 6/7/2021 at 4:44 PM, alanrichey said:

Have you put a diode in the circuit ?  If not the light could come on slightly if the alternator voltage is more than the voltage feeding the other side of the bulb.  Normally they should be the same but depending on where the feed from the light comes from there could be a slight difference.

Yes, the light itself is an LED. I've since properly wired it, and it seems to have improved. I guess that my temporary connection/test wiring wasn't good enough, and now I've done it properly the [problem has evaporated

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