The Triumph Dolomite Club - Discussion Forum

The Number One Club for owners of Triumph's range of small saloons from the 1960s and 1970s.
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PostPosted: Fri Aug 16, 2019 7:58 am 
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Looking at the current that the ignition switch has to pass. I believe that the highest current which will only flow for a very short time is the pull-in current approx. 46 amps plus the hold -in current of approx 15 amps which it should and as we all know it does carry for hundreds of operations before giving a problem.

I still recommend just checking that you are getting the battery voltage applied to the motor terminal as it is so easy to do before you start on any other changes.

This test is will do the same as suggested by Carledo but without big sparks.


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PostPosted: Fri Aug 16, 2019 11:33 am 
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Tried the voltage measurement this morning as Richard suggested. The battery voltage unloaded was 12.8v. Cranking the engine this dropped to 11.4v. I then connected the meter lead to the starter motor terminal and cranked and that also showed 11.4v. So I don't see any problem there, but worth checking.

I really think (and hope) that the 42 year old key switch is struggling to pass the initial current needed to bang in the solenoid, hence the click but no action. A relay will reduce the load on the switch to milliamps and hopefully it will then last another 42 years! Once I have fitted the relay, kindly supplied by Tony Mig Wielder, I shall report back.

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(MGB GTV8, BMW Z3 2.2, and Dolomite 1850HL)


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PostPosted: Fri Aug 16, 2019 12:09 pm 
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Definitely sure that the engine earth is in good order? Easy trick to test this is putting a jump lead from the negative battery terminal to a solid metal part on the engine.

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Current Fleet: 1974 Dolomite Sprint, 1974 MGB GT, 2000 Porsche Boxster, 2002 Laguna II and a boring 2010 Audi A4 that keeps the wife happy


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PostPosted: Fri Aug 16, 2019 1:13 pm 
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Definitely sure that the engine earth is in good order? Easy trick to test this is putting a jump lead from the negative battery terminal to a solid metal part on the engine.
Absolutely sure. I have a heavy duty braided lead directly from a bell housing bolt to the body. I installed myself just last year.

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(MGB GTV8, BMW Z3 2.2, and Dolomite 1850HL)


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PostPosted: Fri Aug 16, 2019 3:42 pm 
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Hi Mike,

Sorry to be picky but when describing faults like this it's important to get all the details.

When turning the ignition key to the crank position have the meter on the solenoid +ve connector rather than the starter connection. Apologies if that's what you did.
This will tell you much voltage you have going to the solenoid - but what is important is how much current is going through, this will be affected by any bad connections from the solenoid +ve terminal onwards, regardless of what the volt meter says. Are you sure all the connectors are nice and tight on the solenoid/starter?

And...is the battery good? Do you have another you can borrow? A car battery can show ok volts but not give enough current under high load conditions.


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PostPosted: Fri Aug 16, 2019 4:03 pm 
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The battery is brand new and fully charged because it has been connected to one of those smart chargers that you leave on permanently. The starter and solenoid are a reconditioned unit sent to me by Alun Nicholas and the terminals are brand new and tight. I measured the voltage at the large terminal connecting the solenoid to the motor.

This is not a permanent problem, it just happens at random times and with persistance it will suddenly work. For example, on my way back from Silverstone Classic I stopped at services on the M74, phoned my wife to say I would be home in an hour and a half, got back in the car and just got click - click - click every time I tried the starter. After sitting for a minute deliberating what to do, I turned the key again and it started. The same thing happened later when I stopped for petrol. Obviously I can't go on like this, because there will come a day when it simply won't work at all.

As I said before, I thought the 42 year old solenoid had had enough and ordered the recon starter/solenoid combo from Alun, but fitting that has not cured the problem. All the units sent out by the club are properly reconditioned and bench tested. It looks like new.

I am 99.9% convinced it is the old key switch not being able to pass the heavy load needed (possibly as much as 60 amps) to fire the solenoid properly. Tony's relay should prove that one way or the other. In his opinion all slant engined Triumphs need a starter relay to preserve the key switch. My MGB has one.

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(MGB GTV8, BMW Z3 2.2, and Dolomite 1850HL)


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PostPosted: Fri Aug 16, 2019 5:13 pm 
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It is a pity that the engine turned over this morning when you checked the voltage. Considering the solenoid circuit this obviously includes the ignition switch but then there is the connector from the steering column loom and the shorting link which could be making a poor connection and dropping volts. Fitting a relay will help but it would be nice to know what the real problem was.


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PostPosted: Fri Aug 16, 2019 6:02 pm 
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I hate to say it Mike and i hope i am wrong, but i wished i had a pound for every bench tested starter motor i have had faulty over the years. Including factory new units. I am sure Steve (Carledo) will back me up on this.
Please.... no disrespect to the club or the reconditioners is meant by this, but sh*t happens :(

Tony.

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PostPosted: Fri Aug 16, 2019 7:28 pm 
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I have a spare key switch loom I can send to you if you want to test that?


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PostPosted: Fri Aug 16, 2019 7:29 pm 
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Is the heat shield fitted to the solenoid?


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PostPosted: Sat Aug 17, 2019 10:22 am 
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Is the heat shield fitted to the solenoid?
Yes.

The 70 amp relay arrived this morning from Tony so I shall get that fitted and see how we go. The problem is that the fault is very random and might not occur for days anyway. Hopefully with the relay it won't occur at all. Fingers crossed.

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(MGB GTV8, BMW Z3 2.2, and Dolomite 1850HL)


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PostPosted: Mon Aug 19, 2019 6:19 pm 
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When I attempted to start one of my 1500hl Dolomites this morning the engine did not turn over. A bit of background before I go on. Like the Bumpa's this has happened from time to time but in the end it has always finally turned the engine over and started the car. Back in June I had to hit the starter motor with a hammer before it would turn over so I decided I had better do something about it. I replaced it with another that I had been given but when I fitted that one I found that it did not turn the engine over as fast as my other dolomite starters. The starter motor had come from a dolomite that was sent for scrap and had been in use up until that point. I had considered taking the motor apart to check it over but when I attempted to do this I could not get the bolts out so I decided to just use it as given to me. I have since cut the bolts off and stripped the motor. The only thing that I could find wrong was that two of the brushes were below the recommended length but even after my hard work the motor still runs slow compared to other motors. I have given up on that starter for the time being as it is not the first starter motor that I have come across that runs slower than I would expect. In the end I fitted another starter motor that I had checked out and had replaced the solenoid with a new one because I thought that might have been the problem with that starter. It has worked fine for almost two months but gave up today.
Back to today’s problem. I could not hear the solenoid attempting to pull-in so my initial action was to give both the connect to the solenoid a wiggle and to take the linking plug/socket apart a number of times as I suspected it could be a bad contact at either of these points. When these actions failed I got out my voltmeter and was able to confirm that I did get the battery voltage being supplied to the solenoid when I turned the ignition key to the start position but it did not get as far as the starter motor terminal, hence I suspected the solenoid had given up. My next check was to make certain that both the solenoid and the motor were adequately earthed by connecting one of my jump leads between the motor and the battery negative. Still no joy, so I found a length of wire, fitted a female terminal on one end, so that I could remove the normal feed to the solenoid coil and then connect this wire to it. Next when I touched the other end of the wire onto the positive battery terminal it should have operated the solenoid. This test would have ensured that there was no voltage drops in the normal circuit that were causing the problem.
This still made me think the solenoid had developed a fault so I set about replacing just the solenoid with an old one that I had stripped and cleaned. I was surprised that it was relatively easy to change it over. The most difficult part was clipping the plunger onto the reaction arm of the drive pinion. Once all the connections were made the engine turned over and fired up but there was one final check that I decided to do and this was to check that the battery voltage was also available at the ignition coil during the start period. It was NOT and based on my own experience this does make starting a bit more difficult especially in cold weather so I will have to sort this out.
I have built myself a starter test facility using the engine and the battery that came out of my dolomite that was declared a write off. See attached photo. To make the starter motor turn over all that is needed is a lead with a suitable switch from the positive battery connection on the solenoid to the solenoid operating coil connection. I actually used an old dolomite main lighting switch which can be seen by the battery. I obviously wanted to confirm that the solenoid had failed so I set about fitting it into my test facility. This did not take long and I was surprised to find that the solenoid worked perfectly so I have been asking myself what could have caused the problem?
One possible explanation might be that the drive pinion may have jammed and prevented the solenoid plunger moving.

Image


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