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Alternator repair - gone wrong?


RichardB

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I took on a task of rebuilding the alternator in the TR6 as we were fairly sure it had packed up. The ammeter had been stuck on -D for a while, moving a little but not much in operation, and the car wasn't charging the battery.

After sourcing a rebuild kit on ebay, I changed the brushes, terminals, regulator and diodes. The slip ring seemed alright so I just gave that a very light clean with acetone. As far as I can see, everything was exactly as before, it's a simple set of changes and I was careful not to overheat the diodes. I've done thousands of solder joints in my time so would be surprised if I have.

Anyway upon putting it back in this morning and connecting the terminals in the same way they came off, the moment the negative lead went clamp touched the battery it sparked like mad and stuck like it had shorted. It didn't appear to have blown any fuses (I forgot to measure them) but now there's no ignition at all, the car's electrics are completely dead.

I didn't have time to dig out the wiring diagram for the car, but before I do and start investigating - has anyone had this happen before? I'm just baffled as to what could have shorted out, I'm guessing the alternator is the culprit but couldn't say where.

Before:

20230625_153008.thumb.jpg.a48eae4f885f8efb109f694d5ca4f446.jpg

After:

20230625_163037.thumb.jpg.e7fc8c6da1c51a30795f222907989c5a.jpg

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The new diode stack looks to be a later type than the original as it has the two large and one small spade tabs - how are you making the connections to it? 

It may just be the camera angle but the stack looks to be a tad further to the left than the original as the mounting pillar is different- are you sure that no part of it is shorting on the case?   

If you have lost all power even with the alternator disconnected then something has certainly blown. As standard there are no fuses to protect that bit of the circuit.  I assume the battery still has voltage? Are all the circuits dead as well as the ignition - e.g. horn and lights? 

If it is just the ignition and lights affected  but the horns work, I would suspect something has happened at the ammeter. Possibly one of the connecting leads has burned out or perhaps even the current loop inside which is is usually soft-soldered to the terminals at each end, might have detached.

 

Edited by DeTRacted
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Thanks Rob you were right on the money. Had another look this evening and took the gauges out to see what had happened.

Horn sounds but no lights. The ammeter is toast, there's bits of it rattling in the bottom when you shake it. The wires measure ok with no resistance but short of a megger I'm not sure how one would check the insulation.

I also worked out the cause. The diode pack is different, both large terminals are positive and electrically connected, where as on the old one there was one negative and one positive. I should have spotted this when connecting it up as the black lead from its connector goes to the block ignition coil mounting.

Feel pretty stupid but that's what happens when you multi task. Just consider myself lucky I didn't get covered in battery acid.

This might be an opportunity to ditch the ammeter for a voltmeter, and wire a new cable that bypasses it.

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Richard,

 

you have a major short to blow the ammeter. I would work backwiords from there, which is a very small part of the whole system. Th elikely culprit is the alternator and if you disconnect it and measure from the ammeter input terminal it should be openb circuit (Battery also disconnected). The one other factor is that you say your horns work, they shouldn't I don't think, all power should go through teh ammeter first apart from teh starter.

You cant use a megger without disconnecting all earth points or you will get a zero reading.

 

Alec

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Alec, it seems the short was due to Richard having connected the new diode stack the same way as the old one. The power tabs on the new one have different function from the old and a direct short from the battery to earth (via the ammeter) was the result.  The alternator itself was not at fault. 

On the TR6 the power take-off for the horns does not go via the ammeter which is why I suggested that test. 

 

Richard -  if you are feeling brave you could try fixing the ammeter.  They are pretty simple inside. You can see the heavy current loop in the photo and it is likely this which has detached. If nothing else is damaged it might be possible to just solder it back on. 

ampinner.jpg.e15c72a6ff32973a87b56ccc99ad2e0f.jpg

Edited by DeTRacted
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Thanks both. I definitely won't throw it out Rob as a few years ago I painstakingly repainted the fascia.

You can just about see some bits behind the fascia now, rattling around and I think looking at your photograph, the current loop has actually exploded into several bits! Maybe repairing it is a wet weather job for the future I guess.

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So we've decided to replace the ammeter with a voltmeter for now, and get the car back on the road so my Dad doesnt miss the summer. I think in future I will probably get a 60A ammeter and try swap the fascia, ive seen it done on the TRR forum.

I'll use it as an opportunity to do a bit of a rewire and some jobs we've been talking about for years:

- fit a modern fuse box

- electric fan

- relays for headlights and bosch pump

- refit the courtesy light behind the seats that was missing when he got the car

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P.s. any recommendations on an indicator relay that clicks loudly like a modern car? Even with a brighter light it's still easy to leave it on. Always been an annoyance when following the TR over the years.

Not keen on a buzzer, just something with a louder click :biggrin:

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1 hour ago, RichardB said:

P.s. any recommendations on an indicator relay that clicks loudly like a modern car? Even with a brighter light it's still easy to leave it on. Always been an annoyance when following the TR over the years.

Not keen on a buzzer, just something with a louder click :biggrin:

I have one of the electronic units, think it came from Vehicle Wiring Products or Car Builder Solutions. Fit a standard modern 3 pin relay block or you can make up a mounting bracket and use the existing connections (I used a strip of ally with a hole stuck to the realy body with double sided flexible mount).

Louder but depends on the exhaust system on whether or not you'll hear it still. But they do at least keep a steady flash rate, unlike the old Lucas bimetal ones.

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  • 3 weeks later...

I've been using some late nights to rewire the TR6 and have made good progress. The voltmeter has finally arrived and looks good, it will just need a bezel swap before fitting.

IMG-20230727-WA0002.thumb.jpg.5bc42d950307139c561f78bc1b28f99d.jpg

Using the uninsulated style Lucar connectors, proper loom tape and the correct style wire is very satisfying. It's so much neater than the work I used to do with cheap insulated crimps and whatever wire I could source locally on my own car, and is giving me good inspiration for a rewire on the Spitfire when the body work is done.

I'm using a Durite 3x6 way terminal block to add as a nice neat way of adding more fused battery or ignition feeds later on. It may require a bigger fuse box still one day if we do any more modifications, as the 8 way is filling up fast. I've already identified a use for all 8 fuses given that we are using this as an opportunity to finally fit relays for the headlights, pump and an electric fan. The heated seat and electronic tach fuses are no longer in line behind the dash so much neater too. Good for now anyway.

Before:

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Progress so far:

IMG-20230730-WA0001.thumb.jpg.54ecd05fccd155503f132a615c5cbc65.jpg

Now the fuse box set up is in place and wiring thought through, its now a question of running all the wires to and from it and creating the auxiliary loom.

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Super effective. I liked them so much I used to sell the kits about 10 years ago!

The first generation had a wire type electric element, and then after that you could obtain them with carbon elements. Which were just as effective but thinner, can be cut, and didn't leave a faint impression of the wire in the seat fabric. I imagine all the ones sold now are the carbon type. They can fit in Triumph seats and be undetectable, depending on the covering used and how you choose to cut it.

They come with relays, all that's needed is to wire up ground, ignition and battery feeds. I will need to check current ratings today actually for this car but here's an example -  https://m.aliexpress.com/item/1005005750183368.html?spm=a2g0n.productlist.0.0.5c4c28edN9kLoS&browser_id=c4d4b942291648f0be3b4fb6b04e685b&aff_platform=msite&m_page_id=cdbfbebfbbeb189a69722611ac13080cbaa4513c21&gclid=&pdp_npi=3%40dis!GBP!20.88!11.69!!!25.95!!%402100b0d116907170798828372d0743!12000034217542302!sea!UK!133704243&algo_pvid=673080e4-65f3-437a-8a83-51a4a465bab9

I recall it being somewhere around 4A per seat, which probably contributed to the old 16ACR alternator dying as it finally gave up completely when my Dad took it out on a cold afternoon / evening. 8A isn't a lot but on top of the rest (lights, heater) maybe it pushed it over the edge.

People used to make jokes about it at club meets back in 2012 when I first fitted them to the Spitfire, but I think it's such common sense. In a convertible your heater becomes inefficient because a lot of the blown hot air leaves the car upwards, where as a heated seat has full contact with your legs and back, there's no real loss of energy. I could take the car out in late Autumn on a night with the top down and not get cold, it's a strange mix of crisp air and warm car that is very enjoyable.

You can get different switch types, the nicest ones I used to source had a round flick switch that was almost a direct fit in the centre console either side of the radio. Just needed the hole enlarging a few mm on the Spitfire.

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On 7/30/2023 at 12:48 PM, RichardB said:

It's a strange mix of crisp air and warm car that is very enjoyable.

It's a very enjoyable experience

Thanks Richard. I had wondered about these for a while as they seem such a great addition to the car.

I have recovered the standard seats in the past but the current seats for my Spitfire are Corbeau Alpines so maybe have to look into what's involved a bit more.

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  • 4 weeks later...

Small update. After taking 4 days off work to finish this and hopefully get back onto the Spitfire, disaster struck. On the last job, fitting the electric fan, I had to take off the fan boss from the front of the crankshaft.

The rope trick to lock the engine worked great and I had the nut off quickly with a breaker bar. Unfortunately the rope was old and had a very small knot in it that I didn't think would pose an issue as it slid in easily, but sadly did and got stuck coming out. Trying to carefully pull it out didn't work, the rope frayed and split leaving it inside the cylinder! Gahhhhhh

So the cylinder head has had to come off to retrieve it. Its taking ages to clean up the old gasket from the block and head faces, but at least it's revealed the engine looks to be very fresh having had new pistons and a rebore fairly recently before my Dad bought it.

IMG-20230825-WA0000.thumb.jpg.bb06a88926026b166f03d78de75c7514.jpg

I would have left a small ring of carbon around the edges of the pistons, but there wasn't anything stuck on to leave. A slight wipe with kitchen roll left the piston tops looking spotless there, just a bit in the centres to scrape off. The valves are a bit more coked up though so it might be worth cleaning them before it goes back.

IMG-20230817-WA0020.thumb.jpg.8bf01faa9cb631ad25faafaaa852000a.jpg

 

Edited by RichardB
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  • 3 weeks later...

Finally got it all back together and tuned up on Sunday. Following a drive there's only a few minor issues to address, but it definitely seems to rev a bit more freely without the mechanical fan and cast iron boss for it.

I changed the oil again when refitting the head just to get rid of all the coolant that's inevitably spilt and any crap that might have got inside from decoding. I'm a bit concerned that the oil pressure is now lower than before though by about 5-10psi either when warming up (70 ish psi at idle, was about 80 before) or when hot (10psi at idle at worst, was never under 20psi before and now doesn't seem to increase quite as much when revving to 2000rpm).

This time we used Comma Classic 20w50 which I think I've used before, I don't remember it being that bad for oil pressure? I used to use Halfords brand before we switched to Comma Sonic20w50, and I believe Halfords is meant to be the same product.

So I'm going to check the oil pressure gauge for kinks in case I've damaged it rewiring the car and also check the PRV, though the latter is unlikely to be the culprit as its not been touched. We've never had the oil pump out and I will probably inspect and blueprint it over winter if its okay, but it's a bit unnerving when pressure suddenly drops as it makes me worry the head removal job has affected something.

Edited by RichardB
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Thanks both, no sadly idle adjusted to 850-900rpm as before when following the manual.

We actually took it out at night in the wet after things have cooled, and it was no different today apparently when my Dad took it out again.

You could argue the old mechanical fan was always cooling the sump and we've taken that away. Also now that I think about it, I swapped the spark plugs for new BP5ES's instead of the 6s we had before when putting the head back which would also make the combustion chamber run a bit hotter. You wouldn't expect either to have such a dramatic effect but maybe all these things have added up.

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I remembered that there were 2 bolts at the back of the block which we loosened to get the head back on, they hold the rear lifting eye. I hadn't retightened them so have nipped them up tight. Could they cause low oil pressure? They don't appear to be connected to an oil gallery looking from outside, but I've never had a 6 cylinder block apart.

After tightening them I had the engine running at idle with the rocker cover to see if there was anything odd there. I'm surprised at how little oil is flowing out of the rockers and 4 of the 12 appeared to be flowing nothing at all. So next job is to take them off for a thorough strip down and inspection.

Another couple of issues, the fuel and temp gauges aren't working reliably and seem to stick (voltage stabiliser fried by the short perhaps?) and the inertia switch has finally packed up. Looks like the new alternator putting out more voltage again has allowed the Bosch pump to fry it, I stripped it down and the contact ring has melted into the plunger. We were thinking of bypassing it anyway for a hidden modern one when fitting the fuel pump relay but had temporarily disconnected the relay as it caused the pump to whine badly when receiving full voltage.

IMG-20230918-WA0000.jpg

Edited by RichardB
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Use a modern inertia switch - some comes with an extra wire so you will get a warning light too (in case you are in doubt what you have hit :-) ) 

Some modern alternators are prone to create high over voltage peaks, so make sure it is solid grounded and the wires to the battery are good.

A friend of mine had a fried MJ-module and I used a LT4356 overvolt protection from Linear (got a free demo board from them a few years ago).

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Fortunately weve already bought a second hand one from a Jaguar to fit with the relay. They all look identical so it wouldn't surprise me if one firm makes them in the supply chain for all marques.

Thanks for the tip on the alternator, that wouldn't surprise me as there's always a hidden cost (i.e. lower quality) from buying cheaper parts from the far east. Its relying on the alternator mount for ground but we could try augment that with a strap to the block. Now that I think of it I vaguely recall having to do something (probably fitted flyback diodes) to protect the ECU when I fitted a new alternator to the EFI spitfire

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Took the rocker assembly apart, it appears to be a replacement shaft but has already started to wear noticeably. #1 rocker has made the shaft somewhat shiny and crinkly, unsurprising that the worst wear is at the end of the shaft where oil has to go the furthest. It's not the worst I've seen but I think bad enough to justify a new shaft. I would rather just get a new shaft and spend the time cleaning any manufacturing swarf out of that one.

That then begs the question is it best to obtain a cheap normal shaft to fit whilst chasing down the low oil pressure, or would it be better to go straight to a set of new bushed rockers and shaft. The rocker tips are all indented but aren't too bad, I've never seen a used set that aren't.

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IMG-20230918-WA0005.jpg

Edited by RichardB
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Tips can be refaced.  They are chill cast, and the hardness goes 2mm or more deep.

If you don't reface, be careful if using a flat blade feeler gauge as the feeler will bridge the wear and the gap will be the feeler gauge + the wear depth......

I use Chris Witor's shafts which seem to be nicely made and finished (I think tuftrided?)

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