Tacho’s

[baily]

Hi all can anyone point me in the right direction port tacho’s both upper and lower working ok Stb side upper and lower not working volt meter showing 13.5v worked ok last time out?
Just wanting some ideas on what to look for?
Ian

 

[Andyroonot]

Hi all can anyone point me in the right direction port tacho’s both upper and lower working ok Stb side upper and lower not working volt meter showing 13.5v worked ok last time out?

Just wanting some ideas on what to look for?
Ian

Engine make/model?

 

[DAKA]

Hi all can anyone point me in the right direction port tacho’s both upper and lower working ok Stb side upper and lower not working volt meter showing 13.5v worked ok last time out?
Just wanting some ideas on what to look for?
Ian

Could you have inadvertently pulled out a wire while tugging on the radar cable ?

My tachometer is nut/bolted on at the sender and the gauge but there are bullet connections between

 

[oldgit]

Start at engine end . Depending on engine, signal will be usually picked up from an alternator or sensor normally around gearbox or fly wheel.

 

[baily]

Sorry guys forgot to say the engines are Kamd42

 

[Poignard]

Can you temporarily swap over the connections between the sensor and the instrument to determine which is faulty?

 

[rafiki_]

Hi all can anyone point me in the right direction port tacho’s both upper and lower working ok Stb side upper and lower not working volt meter showing 13.5v worked ok last time out?
Just wanting some ideas on what to look for?
Ian

Check that the starboard engine alternator is working. On my boat the rev counter is driven by the tachometer.

 

[PaulRainbow]

The KAMD42 has a tacho sensor, it doesn't use the alternator for RPM.

 

[DAKA]

Sorry guys forgot to say the engines are Kamd42

Snapped fan belt if it’s not a dislocated wire

 

[PaulRainbow]

Snapped fan belt if it’s not a dislocated wire

How does that stop the tacho sensor from working ?

 

[DAKA]

How does that stop the tacho sensor from working ?

Hi Paul
You obviously know the engine well so perhaps you can explain , all I can do is detail the events

The boat in question is a sealine 360 Flybridge
Bailey says it has Volvo penta kamd42

My experience was on a sealine 350 Flybridge also with Volvo penta although I don’t remember the exact engine model

I was on passage from Lowestoft to the Humber , midway in the middle of the wash the rev counter went to zero
No loss of power
Lower helm also indicated zero revs

I looked in the engine bay and one of two fan belts had snapped

The remaining fan belt was still driving the water pump

We carried on at cruising speed with no further issues

Was the broken fan belt a fluke
Did the fan belt dislodge one of the rev sensor wires
does the alternator directly power the rev sensor

I know the rev sensor that you mention isn’t a mechanical cable going all the way to the Flybridge so I thought I would share with Bailey , it will take Bailey less time to check for a broken fan belt than it has taken me to reply to you

 

[PaulRainbow]

Hi Paul
You obviously know the engine well so perhaps you can explain , all I can do is detail the events

The boat in question is a sealine 360 Flybridge
Bailey says it has Volvo penta kamd42

My experience was on a sealine 350 Flybridge also with Volvo penta although I don’t remember the exact engine model

I was on passage from Lowestoft to the Humber , midway in the middle of the wash the rev counter went to zero
No loss of power
Lower helm also indicated zero revs

I looked in the engine bay and one of two fan belts had snapped

The remaining fan belt was still driving the water pump

We carried on at cruising speed with no further issues

Was the broken fan belt a fluke
Did the fan belt dislodge one of the rev sensor wires
does the alternator directly power the rev sensor

I know the rev sensor that you mention isn’t a mechanical cable going all the way to the Flybridge so I thought I would share with Bailey , it will take Bailey less time to check for a broken fan belt than it has taken me to reply to you

Pete, if the tachos are driven by the alternators a broken alternator drive belt obviously stops them working, but, in the case of an engine sensor that doesn't happen.

 

[piratos]

May I add another question about Tachos - I had new Tachos installed on the Fly, but kept the lower station unchanged (afterall hardly use it).
My problem is that after some time the needles start going up and down and after crusing when you slow down to less rpm then may well go up to 2000 rpm although engines are idling. This does not happen with Tachos lower station. I was told the problem is the heat to the sender... and have been proposed new senders at EUR1400. But as the old VDO lowerstation work I beleive its something with the new elctronic tachos. Should I simply change to another style or find some old Analog VDOs if available ???

 

[PaulRainbow]

May I add another question about Tachos - I had new Tachos installed on the Fly, but kept the lower station unchanged (afterall hardly use it).
My problem is that after some time the needles start going up and down and after crusing when you slow down to less rpm then may well go up to 2000 rpm although engines are idling. This does not happen with Tachos lower station. I was told the problem is the heat to the sender... and have been proposed new senders at EUR1400. But as the old VDO lowerstation work I beleive its something with the new elctronic tachos. Should I simply change to another style or find some old Analog VDOs if available ???

Almost certainly the new Tachos causing this. Wiring them up to the alternators, rather than the senders may fix the problem, as long as the Tachos can be configured for alternator input. What engines do you have ? What make are the Tachos ?

 

[piratos]

Almost certainly the new Tachos causing this. Wiring them up to the alternators, rather than the senders may fix the problem, as long as the Tachos can be configured for alternator input. What engines do you have ? What make are the Tachos ?

Engines are MAN and the new tachos are „ecms“. I fear the altenators have no sender for rpm ? I would not mind change the instruments as long as long as im dure to buy suitable units

 

[PaulRainbow]

Engines are MAN and the new tachos are „ecms“. I fear the altenators have no sender for rpm ? I would not mind change the instruments as long as long as im dure to buy suitable units

I have fitted KUS tachos to my own boat and one behaved similar to yours, the other was OK. Perhaps a new sender would have fixed it, but I connected them to the alternators and they work fine.

If the alternators have a W terminal you can connect to that, if not you may be able to get an auto electrician to fit a wire for you to use. Alternatively, change the Tachos, the only sure ones to fit would likely be the original (or similar) VDO ones.

 

[baily]

Hi all found the issue it was not the sensor as this is only for the supercharger it was a disconnected wire on the alternator but just looking at it looked ok all working ok now.
Many thanks for your posts.