Volvo MD11D with freshwater cooling won’t start

F

fulmarnyc

New Member
Joined
10 May 2020
Messages
14
Visit site
Situation started when bolts on freshwater pump came loose, spraying quite a bit of coolant all over my engine bay. Immediately killed engine, fixed pump issue, let engine, cool and then restarted without a problem. Later that day, and since then, engine won’t restart. Temp and oil pressure gauges normally tick up when key is turned on, now they don’t move. When I turn the key to start, there is no noise or movement from the solenoid or starter. Cabin lights don’t dim when I turn key to start. Nothing happens when I bridge solenoid main to ignition wire or bridge two solenoid mains. Voltmeter connected to the two solenoid main leads shows 12.8V when key is off, 1.6 V when switch is on and drops to millivolts when key switch is turned to start. Next steps? Any ideas on what is going on here?
 
fulmarnyc said:
Situation started when bolts on freshwater pump came loose, spraying quite a bit of coolant all over my engine bay. Immediately killed engine, fixed pump issue, let engine, cool and then restarted without a problem. Later that day, and since then, engine won’t restart. Temp and oil pressure gauges normally tick up when key is turned on, now they don’t move. When I turn the key to start, there is no noise or movement from the solenoid or starter. Cabin lights don’t dim when I turn key to start. Nothing happens when I bridge solenoid main to ignition wire or bridge two solenoid mains. Voltmeter connected to the two solenoid main leads shows 12.8V when key is off, 1.6 V when switch is on and drops to millivolts when key switch is turned to start. Next steps? Any ideas on what is going on here?
Click to expand...
Clean and remake all main battery connections from battery to starter motor, including the isolator switch and battery negative to engine block . Check isolator switch itself.

Be aware that a digital volt meter takes so little current that it will give a normal reading through bad connections and will make a fool of you sooner or later. A test lamp is often better for these types of trouble shooting. ( I have an old type car headlamp bulb on a couple of long leads)
 
VicS said:
Clean and remake all main battery connections from battery to starter motor, including the isolator switch and battery negative to engine block . Check isolator switch itself.

Be aware that a digital volt meter takes so little current that it will give a normal reading through bad connections and will make a fool of you sooner or later. A test lamp is often better for these types of trouble shooting. ( I have an old type car headlamp bulb on a couple of long leads)
Click to expand...
If everything worked, do you know what the Appx voltages should be at the solenoid at different key positions? Specifically wondering about the drop from 12v to 1.6v when key goes from off to on
 
fulmarnyc said:
If everything worked, do you know what the Appx voltages should be at the solenoid at different key positions? Specifically wondering about the drop from 12v to 1.6v when key goes from off to on
Click to expand...
Measuring from " ground", eg the engine block I'd expect battery volts on the large solenoid terminal with the battery lead connected as soon as the isolator is closed. Zero volts on the other large terminal and zero on the small terminal

When the key is tuned to the normal running position nothing should change significantly.

When turned to "start" the engine should crank. Battery volts and the voltage on all the solenoid terminal will probably be somewhere around 9 to 11 volts but the exact value will depend on the battery size, its state of charge and general health.

The fact that the cabin lights do not dim when the key is turned to "start" suggests that the battery + connection and the isolator switch are OK or that they are supplied from a different battery.
 
Its probably a bad contact in the relay feeding the starter solenoid it will show the voltage but will drop off when under load. Anything else would show up as an alarm. Cant really see it being anything else apart from possibly a bad connection from your Instrument panel. I know my loom is in a bad shape with oxidation.
 
Metalicmike said:
Its probably a bad contact in the relay feeding the starter solenoid it will show the voltage but will drop off when under load. Anything else would show up as an alarm. Cant really see it being anything else apart from possibly a bad connection from your Instrument panel. I know my loom is in a bad shape with oxidation.
Click to expand...
I don't think the reis a relay. Have you looked at the wiring schematic for an MD11D.
 
The reason your voltage drops off when you turn the key on is because current flow is being restricted by a bad connection somewhere in the circuit. The starter coil pulls a fair amount of current to energize the starter relay so if there is a bad connection anywhere in that circuit it can fail to energise. Even if the the starter solenoid energises, there has to be enough current supplied to the starter. If your cables are degraded, bad connections or low voltage the necessary current cannot be supplied. Your starter circuit is quite simple, forget about voltage measurements and concentrate on finding connections with high resistance. (y)
 
It looks like it was as basic as a bad main ground. I bench tested the starter (OK), checked for ground leak as per Calder (none found), replaced a bunch of instrument panel wires, when I happened to feel the ground return from the block to the battery and the crimp-on connection felt loose. Replaced that cable (and the main hot for good measure) and it started right up.
 
You must log in or register to reply here.

Other threads that may be of interest

N
Volvo Penta Alarm Module/Alternator Issues
Replies
1
Views
170
superheat6k
superheat6k

Share this page

Top