Thornycroft Instrument Panel

[christophert]

I'm hoping someone can help me please.

My narrow boat has a Thornycroft instrument panel  with VDO gauges - being a rev counter, temperature  gauge, oil pressure  gauge and volt meter  gauge. When I switch  the ignition on the temperature  and oil pressure  gauge  swing across to the far right as though there is a shot circuit  of some kind, but are earthed Ok. None of the dials are working,  except  the voltage gauge.
The engine is a Thornycroft BMC 1800 diesel  I believe  also known as a 108


The cost for a new instrument  panel is £850.00 !  It's just far too expensive.
Is there any way I can test the gauges to see if the issue lies with them? Or does anyone know of a second hand unit for sale?

Any assistance will be much  appreciated.

 

[Tony Brooks]

I know that you claim they are "earthed OK", but as far as the oil pressure and temperature gauges are concerned, then the symptom is typical of the loss of the negative. The loss of the negative would also stop the rev counter working. The lamps go to negative on the engine, not the instrument panel negative.

 

It sounds as if there is no negative to the panel, so probably a wire off the battery/negative bus bar, the main negative to the panel fallen off at the panel *they are often "piggybacked".

 

Try running a test negative cable from engine battery negative to the negative cables on one of the instruments. The negatives on the instruments are often daisy-chained, so ensuring the cable/terminal on one should provide it for the rest. If that solves the problem, you will need to find out where the broken connection is and mend it.

 

Note for others - some very old boats may have slow moving two terminal gauges that use a voltage stabiliser and for the two gauges a duff stabiliser would give that symptom, but not the rev counter not working. I am sure VDO are three terminal bi-coil gauges, hence the above.

[alan_fincher]

Even if you can get a replacement panel at a price you are prepared to pay I would be far from confident it would solve your problems

 

To me this looks like a wiring fault, not an instrument fault.Are you saying the tachometer isn't working either?

 

 

[Tonka]

Just now, alan_fincher said:

Even if you can get a replacement panel at a price you are prepared to pay I would be far from confident it would solve your problems

 

To me this looks like a wiring fault, not an instrument fault.Are you saying the tachometer isn't working either?

 

 

Surely best off sorting the wiring and changing the instruments in the panel if needed

[Tracy D'arth]

The gauges are not faulty, its wiring.

[Tony Brooks]

8 minutes ago, alan_fincher said:

Even if you can get a replacement panel at a price you are prepared to pay I would be far from confident it would solve your problems

 

To me this looks like a wiring fault, not an instrument fault.Are you saying the tachometer isn't working either?

 

 

 

6 minutes ago, Tonka said:

Surely best off sorting the wiring and changing the instruments in the panel if needed

 

It has the classic symptoms of no negative on bi-coil gauges, whatever the OP may claim, so yes, sort the wiring out before condemning the instruments. I have explained how to do it without using a meter. I would be interested in knowing exactly, and I mean exactly, how the OP tested the negative to form his conclusion, because I am all but sure it was not a valid test. I suspect it was more likely a thought exercise based on a lack of knowledge and coming to the wrong conclusion.

[beerbeerbeerbeerbeer]

I have an identical panel and a few years ago I had a very similar issue. 
 

The earth had simply come loose. 
Very easy to fix, once identified.

 

If it’s something you’re unable to find or fix any competent yard will have it done in a jiffy 👍
 

 

Edited October 5, 2023 by beerbeerbeerbeerbeer

[christophert]

56 minutes ago, Tony Brooks said:

 

 

It has the classic symptoms of no negative on bi-coil gauges, whatever the OP may claim, so yes, sort the wiring out before condemning the instruments. I have explained how to do it without using a meter. I would be interested in knowing exactly, and I mean exactly, how the OP tested the negative to form his conclusion, because I am all but sure it was not a valid test. I suspect it was more likely a thought exercise based on a lack of knowledge and coming to the wrong conclusion.

Hi Tony,  thank you for your reply. This is way over my head so I called out an engineer. He was stumped and could not find what the issue was. He put it down to the panel being old and warn out. 

Could you recommend an electrical specialist who could take a look ? 

[Tony Brooks]

Just now, christophert said:

Hi Tony,  thank you for your reply. This is way over my head so I called out an engineer. He was stumped and could not find what the issue was. He put it down to the panel being old and warn out. 

Could you recommend an electrical specialist who could take a look ? 

 

I am afraid not, I don't suppose that you are within 40 miles or so of Reading by any chance. If so, I would be happy to come and have a look FOC.

 

If the panel is still connected, why not do as I suggested with a length of cable between the engine battery negative and one of the gauge's negative terminals, but leaving the negative wires connected. If you did I think it would all do exactly what it should.

 

I suggest that you do not call him out again for an electrical fault, especially as my diagnosis has been backed up by several others.

 

If you want a recommendation then you need to give us your rough locations so someone with local knowledge can make a recommendation.

[Tonka]

7 minutes ago, christophert said:

Hi Tony,  thank you for your reply. This is way over my head so I called out an engineer. He was stumped and could not find what the issue was. He put it down to the panel being old and warn out. 

Could you recommend an electrical specialist who could take a look ? 

Which part of the country are you

[beerbeerbeerbeerbeer]

3 minutes ago, christophert said:

Hi Tony,  thank you for your reply. This is way over my head so I called out an engineer. He was stumped and could not find what the issue was. He put it down to the panel being old and warn out. 

Could you recommend an electrical specialist who could take a look ? 

where abouts are you?

 

be very careful who you deal with, I have given the short story about my panel,

the long story would include someone trying to rip me off with them providing new instruments and new wiring. 
 

All I needed was a new terminal crimping on to an earth wire. 

 

[Tonka]

I assume you haven't got a manual for the engine with a wiring diagram in for the panel.

[christophert]

2 hours ago, Tony Brooks said:

I know that you claim they are "earthed OK", but as far as the oil pressure and temperature gauges are concerned, then the symptom is typical of the loss of the negative. The loss of the negative would also stop the rev counter working. The lamps go to negative on the engine, not the instrument panel negative.

 

It sounds as if there is no negative to the panel, so probably a wire off the battery/negative bus bar, the main negative to the panel fallen off at the panel *they are often "piggybacked".

 

Try running a test negative cable from engine battery negative to the negative cables on one of the instruments. The negatives on the instruments are often daisy-chained, so ensuring the cable/terminal on one should provide it for the rest. If that solves the problem, you will need to find out where the broken connection is and mend it.

 

Note for others - some very old boats may have slow moving two terminal gauges that use a voltage stabiliser and for the two gauges a duff stabiliser would give that symptom, but not the rev counter not working. I am sure VDO are three terminal bi-coil gauges, hence the above.

 

19 minutes ago, christophert said:

Hi Tony,  thank you for your reply. This is way over my head so I called out an engineer. He was stumped and could not find what the issue was. He put it down to the panel being old and warn out. 

Could you recommend an electrical specialist who could take a look ? 

Hi Tony, I spoke with the engineer, he said this is what he was looking for and found no problem.

16 minutes ago, Tonka said:

Which part of the country are you

I'm in Polesworth, B77 Near Tamworth

[Tracy D'arth]

3 minutes ago, christophert said:

 

Hi Tony, I spoke with the engineer, he said this is what he was looking for and found no problem.

Yes, OK, but Where Are You!  He is no electrical engineer, don't call on him again. A vehicle electrician may be the second choice.

I seem to remember that the RAC commercial fleet patrols would come out to boats on the inland waterways for a flat fee, do they still?

[christophert]

15 minutes ago, Tonka said:

I assume you haven't got a manual for the engine with a wiring diagram in for the panel.

Unfortunately not, nor can I find a diagram for this panel on the web also

[Tony Brooks]

18 minutes ago, christophert said:

 

Hi Tony, I spoke with the engineer, he said this is what he was looking for and found no problem.

I'm in Polesworth, B77 Near Tamworth

 

I regret that is too far away for me.

11 minutes ago, christophert said:

Unfortunately not, nor can I find a diagram for this panel on the web also

 

You will find generic diagrams for the temp. & pres. gauges in the electrical notes on my website (address in my signature). The fact that the voltmeter works suggests to me that there is a working negative up to the control panel, so the fault is likely to be a loose/dirty/fallen off/bad crimp on a terminal between the voltmeter negative and the other instruments.

 

Often this wiring is done with two cable crimped into one terminal or what is known as piggy back terminals. I suspect piggybacks with one dirty, loose or fallen off. If so, it will be the blade that pushes onto another crimp rather than the one on an instrument.

[beerbeerbeerbeerbeer]

Polesworth: drop in at Alvecote. 
 

I wouldn’t worry too much ( providing you’ve no issues with the engine). It can keep til you find the right person to help out. 
you’re on the Cov, lots of boat yards up and down 

[Tracy D'arth]

What test instruments did this engineer use to look for the fault that he could not find?

[Tony Brooks]

3 minutes ago, beerbeerbeerbeerbeer said:

Polesworth: drop in at Alvecote. 
 

I wouldn’t worry too much ( providing you’ve no issues with the engine). It can keep til you find the right person to help out. 
you’re on the Cov, lots of boat yards up and down 

 

Would that make what was valley cruisers a good bet. I think there is/was a marine electrical set up there.

[Tonka]

5 minutes ago, Tony Brooks said:

 

Would that make what was valley cruisers a good bet. I think there is/was a marine electrical set up there.

Did ABC boats keep that bit when they took over

[christophert]

12 minutes ago, Tracy D'arth said:

What test instruments did this engineer use to look for the fault that he could not find?

I'm not sure, but he's 30 years experience and sure he knows his stuff, just the thought of parting with £850 for a panel isn't something that's appealing. That's not his quote, that's what Thornycroft has quoted. A lot of money for a few dials.

[Tracy D'arth]

There are mobile auto electricians in Tamworth, Coventry, Nuneaton and Atherstone according to Yell.

Just now, christophert said:

I'm not sure, but he's 30 years experience and sure he knows his stuff, just the thought of parting with £850 for a panel isn't something that's appealing. That's not his quote, that's what Thornycroft has quoted. A lot of money for a few dials.

BUT if you buy a new panel it will do exactly the same! Its not the clocks, its wiring!!!!

[Tonka]

2 minutes ago, christophert said:

I'm not sure, but he's 30 years experience and sure he knows his stuff, just the thought of parting with £850 for a panel isn't something that's appealing. That's not his quote, that's what Thornycroft has quoted. A lot of money for a few dials.

and does that fee include new senders which may be needed to match the new guages

[Tony Brooks]

6 minutes ago, christophert said:

I'm not sure, but he's 30 years experience and sure he knows his stuff, just the thought of parting with £850 for a panel isn't something that's appealing. That's not his quote, that's what Thornycroft has quoted. A lot of money for a few dials.

 

You have no idea how often those of us with proper knowledge and experience have heard that said.

 

In any case, you do not need a new panel. I am sure VDO supply both US and European standard gauges, and a decent electrician can find out which one is needed by measuring the sender resistance. Even if his diagnosis was correct, all you will need is new instruments. I advise that you do not even contemplate that course of action.

Edited October 5, 2023 by Tony Brooks

[christophert]

1 hour ago, Tonka said:

and does that fee include new senders which may be needed to match the new guages

I'm wondering if changing the sender's is first port of call. Chances of both going together is slim but worth a pop.The rev counter failed after the gauges behaved as though they were shorting, so possibly a separate issue

1 hour ago, Tracy D'arth said:

There are mobile auto electricians in Tamworth, Coventry, Nuneaton and Atherstone according to Yell.

BUT if you buy a new panel it will do exactly the same! Its not the clocks, its wiring!!!!

I'm wondering if it's worth paying to have a new wiring harness fitted, as the electrics do look a mess

1 hour ago, Tony Brooks said:

 

You have no idea how often those of us with proper knowledge and experience have heard that said.

 

In any case, you do not need a new panel. I am sure VDO supply both US and European standard gauges, and a decent electrician can find out which one is needed by measuring the sender resistance. Even if his diagnosis was correct, all you will need is new instruments. I advise that you do not even contemplate that course of action.

Going to see if someone local can test panel to rule it out, then maybe pay to have new wiring harness fitted as wiring very untidy and messy