Vetus Starting problem

[haemophilus]

We have a Vetus 4.14 diesel engine. If we switch on the heater plugs for 10 seconds and then turn the ignition key to start the starter motor fails to engage. If we turn the switch on and off a couple of times it will engage and the engine then starts. The starter solenoid has been replaced, the starter motor overhauled and on the bench it spins up every time. The glow plugs have been checked and all show a resistance of less than 0.001 ohms. Disconnecting the heater plug feed means the starter engages every time and the engine will fire from cold after two to three seconds. The engine battery fitted went we purchased the boat had a capcaity 0f 60 AH and has been replaced with one that is new and is of 90 AH capacity. The ignition switch has been replaced and the problem remains. If we put a voltmeter across the starter battery before starting the start up process the reading is 12.9V. On switching on the heater plugs the voltage drops to less than 11.0V after about 10 seconds and we have the problem of the starter not spinning up. What am I missing as I am not an engineer or and electrician!!!

 

[VicS]

We have a Vetus 4.14 diesel engine. If we switch on the heater plugs for 10 seconds and then turn the ignition key to start the starter motor fails to engage. If we turn the switch on and off a couple of times it will engage and the engine then starts. The starter solenoid has been replaced, the starter motor overhauled and on the bench it spins up every time. The glow plugs have been checked and all show a resistance of less than 0.001 ohms. Disconnecting the heater plug feed means the starter engages every time and the engine will fire from cold after two to three seconds. The engine battery fitted went we purchased the boat had a capcaity 0f 60 AH and has been replaced with one that is new and is of 90 AH capacity. The ignition switch has been replaced and the problem remains. If we put a voltmeter across the starter battery before starting the start up process the reading is 12.9V. On switching on the heater plugs the voltage drops to less than 11.0V after about 10 seconds and we have the problem of the starter not spinning up. What am I missing as I am not an engineer or and electrician!!!

A poor connection somewhere between the key switch and the stater solenoid maybe. Just poor enough for it to not work when the volts are down but good enough for it to work when the volts are up.

Is there a relay in the circuit that could be causing the trouble. Called "Auxiliary start relay" perhaps on the wiring diagram If so check its operation. and the supplies to it incl the negative

 

[boatmike]

Very likely the problem. I had one of these engines in my last boat. excellent engine but the plug and socket connecting the loom to the engine was rubbish and gave me countless problems due to corrosion. I cured it by removing the plug and hardwiring through. Also the fuseholder connections tended to suffer the same so I replaced it with a new waterproof one. The problem here though is more likely as Vic says. Not the relay itself possibly but the connections and wiring to it.

 

[haemophilus]

Many thanks I will check this out. There is no auxiliary start relay in the wiring diagram and nothing I can find in the circuit either.

A poor connection somewhere between the key switch and the stater solenoid maybe. Just poor enough for it to not work when the volts are down but good enough for it to work when the volts are up.

Is there a relay in the circuit that could be causing the trouble. Called "Auxiliary start relay" perhaps on the wiring diagram If so check its operation. and the supplies to it incl the negative

 

[haemophilus]

Many thanks for your suggestion. I will be trying this solution and checking the fuseholder connections as well.

 

[sandymunro]

We have a Vetus 4.14 diesel engine. If we switch on the heater plugs for 10 seconds and then turn the ignition key to start the starter motor fails to engage. If we turn the switch on and off a couple of times it will engage and the engine then starts. The starter solenoid has been replaced, the starter motor overhauled and on the bench it spins up every time. The glow plugs have been checked and all show a resistance of less than 0.001 ohms. Disconnecting the heater plug feed means the starter engages every time and the engine will fire from cold after two to three seconds. The engine battery fitted went we purchased the boat had a capcaity 0f 60 AH and has been replaced with one that is new and is of 90 AH capacity. The ignition switch has been replaced and the problem remains. If we put a voltmeter across the starter battery before starting the start up process the reading is 12.9V. On switching on the heater plugs the voltage drops to less than 11.0V after about 10 seconds and we have the problem of the starter not spinning up. What am I missing as I am not an engineer or and electrician!!!

I have finally cracked the Vetus starting problem on my twin 3.10's....(after years of suffering and occasional embarrassment). The problem is poor volts at the Start Solenoid.
If you look at the helm voltmeter it is always 1 volt + below the voltage measured at the battery....presumably due to the way the panel has a diode wired in....and if the battery is not fully charged, the further reduced voltage at the Starter Solenoid is just not sufficient to operate it....(Looking at the helm voltmeter tells the tale).

The solution came from a Kubota Tractor forum where people were complaining of the same problem and were recommended to add a relay. The relay when activated takes full battery volts from the point where the battery positive is connected to the starter, and connects it to the Starter Solenoid.....which as it is now getting full voltage starts the engine cleanly and immediately.
Activating the Relay is the existing lead from the Start Switch which used to go to the Start Solenoid.....with the other relay terminal being connected to Ground.

Why does this work..?? When you hit the Starter Switch now, the reduced voltage which was unable to operate the Starter Solenoid satisfactorily is still more than adequate to activate a small relay.....which then gives full battery volts to the Start Solenoid.

I found a 14vdc 40amp relay at Maplins. At the moment it is held in place taped to the wiring loom as there was not an immediately obvious convenient bolt to fix it to.....and I am advancing the proposition that actually, being taped to the loom is probably a better place for a small relay rather than being bolted to the engine and vibrated to death...!!!

You will be told many times that your problem is simply "Poor Connections"....."Poor Earth".....etc., but, with two engines on a Cat and having spent hundreds of hours checking and cross-checking volts and resistance in the systems.....I have to say...."Listen to that man on the Farm"....then SMILE as you hit the Start Switch....

 

[pathfinder]

The heater plug resistance seems very low could this be causing a voltage drop and preventing the starter solenoid from engaging?