Ammeter/fusible-links ......late model 40-series (1 Viewer)

[lostmarbles]

Some people (perhaps only those who frequent the diesel section) will already be aware that my ammeter has recently started showing "big readings" after 30 years of "barely moving".

Here are some pictures of the readings..

Headlights on with engine off:



Engine just started (so the battery is charging):



Now I was previously wondering whether my battery could somehow be to blame. But I've just replaced that:



The new battery in the above photo is the one on the right. I replaced the old one because my cruiser failed to start after 3 weeks of lying idle (and it was left idle because I've been refurbishing my doors). And at the first hint of battery problems ... my policy is REPLACE IT as a first step (provided it is at least 3 years old .... and this battery had just reached that age).

Note: Diesels have very high compression compared to petrol engines so they especially need a good battery. And they also need heat for combustion to occur (because they have no spark plugs). So 3 weeks of lying idle affects compression (and the associated "heat of compression") .. particularly in a worn engine ...and tends to make them "crank colder" and therefore more reluctant to start (even though the glow plugs may be performing OK).

Anyway...I've placed this thread on the general 40-series board because I think the charging system, fusible links, and ammeter (with its associated "typically seldom moves" description) is applicable to both petrol and diesel versions. and this is what the thread is really about.

And those pictures of the ammeter are not the full story. Immediately before ripping into this, my ammeter was showing "full-scale negative deflection" simply for "glowing my plugs".

 

[lostmarbles]

Anyway ... renewing my battery had zero effect on reducing the swing of my ammeter needle. If anything it made it worse!

So this brought me back to my main suspicion .. which was that my fusible link(s) has/have "deteriorated and developed high resistance".

Here a diagram I put together some time ago to explain the charging system on my cruiser:




You can see from the above schematic that the ammeter works off the "voltage drop" through one of those fusible links. (The white one to be exact.)

And here are my fusible links:



And a closer look:



At this stage they certainly looked OK.

 

[lostmarbles]

Anyway, so a few minutes ago I removed my fusible link assembly (which Toyota located between 2 connectors to enable easy removal):



I can see corrosion on the blue fusible link strands and that whole wire is actually "stiff" (which is evidence of internal overheating/corrosion). But unfortunately that's NOT the fusible link my ammeter is monitoring. (It is monitoring the white one and that one ...at this point in time .... doesn't appear to have a problem!)



And an ohmeter-check doesn't yield any clues. (I get a "0.2 ohm reading" on each fusible link which is virtually the same reading I get by touching the probes to each other.)

 

[lostmarbles]

So my next step was to start taking the fusible link assembly apart .... with the aim of at least replacing the BLUE fusible link wire ... because I know that one is corroded and stiff. (On the other hand, the White fusible link wire feels flexible and in good condition ...at this stage.)

Hmm. I'll have to use the old connectors because my kit has a match only for one of them (and that's the one that supplies the ammeter current):



And here is the tool I use:




I got one side (spade) of the blue fusible link out easily enough and here is how I did it with the tool:



Can't post any more at this stage ..... because I'm having trouble removing other "spades".

 

[85fr16]

Where do you get the right new fusable link wire from? I need to get some for my 83.

 

[lostmarbles]

Where do you get the right new fusable link wire from? I need to get some for my 83.

Seems to be plenty of suppliers in the States but I couldn't find any suppliers in this part of the world. (So I had to get mine through a MUD friend in the States - ..........Thanks Drew)

It is lucky that I always like to "be prepared" and I've been suspicious of my fusible links for quite some time ... so I asked his help at least 6 months ago.

Anyway - I've got the spades out now and I believe I've gotten to the root of my ammeter problem. It's this little sucker here (the white fusible link):



It broke away from one termminal with ease as I was attempting to remove a spade terminal from a connector. (It appeared to be holding by just a strand or two.)

And here's the blue link that I've now got to copy. (My copy may well end up being a different colour.)



And here is the white one. (I must remember to put the fabric sleeve back on the replacement.)

 

[lostmarbles]

Two things I've neglected to explain (that I intended to):

1. Normally ... (based on my experience and on the experience of others I've talked to) .... ammeters on 1978-onwards 40-series cruisers seldom show any needle movement. (Hence my recent big needle movements concerned me rather than pleased me) .....and
2. The reason I had some trouble extracting my spade-terminals from my connectors was because I trying to pull the spade out (by its wiring) at the same time I was depressing the locking spring-tab with my tool. But the trick is actually to have the spade pushed FORWARD before you depress the tab and THEN pull backwards on the connecting wiring!

So now that's covered ... I'll move on.

The spades are 8mm wide:



And I didn't have any new ones so I decided to reuse the old ones (rather than delay things by trying to track some down).

 

[lostmarbles]

As far as determining what size link-wire to use .... I did it by eye.

14AWG for the blue one and 16AWG for the white one:



These photos should confirm that the cross-sectional areas of the copper in these link-wires match fairely well:





Edit ... I don't know why that black tag says 18 and not 16. Perhaps the black fusible is really 18AWG? (The writing on the wire itself is too small and poorly-printed to read clearly .. because the small diameter of the wire made it difficult for the manufacturer to print onto it.) Although thinking about it more, I believe it's more likely that 16 is an American figure for the "gauge" whereas 18 is the European figure.

 

[lostmarbles]

Pity about the colours ..... because my old blue one is now Gray (which incidentally is spelt "Grey" in this part of the world) and my old white one is now Black!

And on the subject of spelling ..... you write out a CHEQUE (not a CHECK) and those things that stop you are called BRAKES (not BREAKS)

Here is the new replacement for the blue one:



And here is the finished product with both replacement links:



(I know I said before that the fusible links sit between TWO connectors. They do really ..... but as you can see there are THREE connectors involved with the smaller (third) one supplying current to the ammeter (and this current is produced by the voltage drop across my BLACK fusible link ...that was formerly WHITE)...

this is getting confusing.........

 

[lostmarbles]

Well I've now run out of "day" so I'll have to fit that "fusible link assembly" tomorrow and see what fireworks I get then..

Actually I can't wait to try it because that stiff/corroded BLUE fusible link may have been dropping the voltage to my glowplugs and thereby slowing their heat-build-up (and thereby making cold-starts more difficult).

And the WHITE fusible link (that was in worse condition through hanging on by just one or two strands) could have been

• making my headlights go dim when my engine revs drop to "idle" (and encouraging other problems at this time too such as - slower heater fan, weak horn, slower wipers etc)
• Inhibiting "battery charging"

and that is all in addition to making my ammeter swing wildly of course! (Maybe this explains why I couldn't start the cruiser a few days ago and ended up buying that replacement battery! )

Tomorrow I'll also be careful to check for any signs of overheating in these new fusible links (in case I have accidentally undersized them).

So ......(with the engine off of course) I'll feel the GREY one after glowing for say 30 seconds. And then I'll turn all the lights on with the wipers and hazards on too and feel the BLACK one.

(Of course if the engine were running the load on the BLACK fusible link would fall because the alternator would be supplying the juice to the lights etc instead of the battery ... and that alternator current wouldn't be flowing through the BLACK link.)

Anyway ... I'll continue this tomorrow and let you all know how it works out.

PS. I guess some people won't like my use of solder on my fusible link connections ... but I did crimp them as well (although nowhere near as well as the originals would have been crimped). But overall .... I think I've done a job that should be at least as reliable as what the factory did. (Provided I haven't undersized the wire that is )

 

[herbs]

I didn't have any fusible link wire handy, so I just scrounged some thin wire from work, only 0.5 or 0.75mm squared and now I have a functioning edic system. I'll find some fusible link wire when I get the chance). On my HJ 45, I've never bothered reinstalling the ammeter as I think they have their limitations. A PO removed all the ammeter wiring. One day I'll install a voltmeter instead.

 

[BreckenridgeCruiser]

Tom,

Awesome write up! Where did you get that electircal plug kit!? I need one for when I do my resto as I have some of the plastic that is in bad shape.

BTW... Breaks is not a colloquialism here in the states... It is purely the wrong word. Same as some use Loose as opposed to Lose. You lose your keys, but only when the ring is loose. Sorry, pet peeves!

 

[lostmarbles]

I didn't have any fusible link wire handy, so I just scrounged some thin wire from work, only 0.5 or 0.75mm squared and now I have a functioning edic system. I'll find some fusible link wire when I get the chance). On my HJ 45, I've never bothered reinstalling the ammeter as I think they have their limitations. A PO removed all the ammeter wiring. One day I'll install a voltmeter instead.

Hi Herbs

(A new day has dawned .... but I haven't ventured out to my cruiser yet. My routine always involves breakfast and ih8mud first )

I'm always suspicious. And personally I wouldn't be surprised if the whole idea of "fusible links being different from ordinary wire" is just a marketing/profit-boost thing.

The copper strands in a fusible link wire certainly look the same as those in ordinary wire to me.

But if it is "just marketing".....then I got sucked in. (But at least I have the benefit of fancy little printing on the insulation that says I've fitted "true fusible links"...)

Here's something on sizing them (courtesy of the MAD Enterprises in California):

Tom,

Awesome write up! Where did you get that electircal plug kit!? I need one for when I do my resto as I have some of the plastic that is in bad shape.

Thanks for the praise Kraig

I got the kit from Vintage Connections. They're great people to deal with too. (See www.vintageconnections.com)

But unfortunately I've found my kit doesn't contain many of the connectors used in our cruisers. (I bought Kit CK-4)

...BTW... Breaks is not a colloquialism here in the states... It is purely the wrong word. Same as some use Loose as opposed to Lose. You lose your keys, but only when the ring is loose. Sorry, pet peeves!

Thanks for the clarification. "BREAKS" enjoys such widespread use over there that I thought it must be the correct spelling!

.... But I don't want to give the idea that I'm truly fussy/moaning about spelling. In fact I never use spell-check (well at least not for my Internet ramblings) and I think the main idea of a post is simply to get across clearly what you're trying to say. So when I see I've mispelt something ..I usually just leave it be unless I think it would harm comprehension.

 

[lostmarbles]

Fitted the refurbished fusible link assembly this morning and found no sign of any heat build-up (as current passes through either of the links).

And my ammeter has returned to its long-held/former habit of "recording zero movement" no matter what I do (except for twitching almost imperceptably when I have the hazards on).

So I'm happy.

My intentions had be to travel at least 1500kms this weekend (to pick up a spare engine I was silly enough to buy on trademe) but luckily the seller was unavailable so the trip is postponed. (... I don't think I would have made it with my fusible links the way they were and with my habit of doing a lot of night-time driving.)

So I'll just finish off this thread (as I finish off a beer too).

This image shows how the connect that supplies the ammeter (via the two 5A ammeter fuses nearby) is connected either side of one fusible link:



And I use a lanolin spray inside all electrical connectors to exclude moisture and prevent corrosion:



And here is the "fusible link assembly" initially installed:

 

[lostmarbles]

But I decided that the main reason for the failure of the old white fusible link was vibration/movement in the wiring .... causing fatigue in the copper strands.

So I beefed up that area using a piece of 5/8" heater hose cut in half:







End of thread .... (well ..... except to reply to comments etc if any arise)

I'm now off to go and see a mate and give him my old battery. (He has a few old wrecks around his property that he uses my reject batteries to jump-start.) This'll give the cruiser a bit of a test-run too.

 

[lostmarbles]

End of thread .... well ..... first I'll just add a few pics of my mate's place where my old battery will be put to use .....

perhaps to start this ..........



Or one of these........



But with the view like this from your deck.... who cares whether anything starts?:

 

[Pin_Head]

Lanolin in New Zealand?

That reminds me of an old sheep joke. It goes: A Pommy and a Kiwi are walking in a paddock and the Kiwi spies a sheep with its head stuck in the fence.....

 

[BreckenridgeCruiser]

Tom,

I mistype some of the time, misspell every one in a while and misspeak all the time!

K

 

[bsmith123]

Nice Job

Nice Job on the write up LM,

A bit of trivia on the fus links---the actual fusible link type wire has insulation that will not burn vs regular wire which has insualtion that will melt/burn away

 

[lostmarbles]

--the actual fusible link type wire has insulation that will not burn vs regular wire which has insualtion that will melt/burn away

Ahhh. Thanks.

That makes sense. (I should have thought of that )







(And sheep jokes aren't welcome in my threads Charlie .. )