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Old 17-06-2016, 16:30   #1
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Ignition Switch Voltage Drop

I am not so good at using a voltmeter, so if an electrical issue comes up on my 33 year old Catalina 38, I am more likely to just replace the component with the best guess method. With new batteries just installed, I get the starter to engage but not really turn over the Universal diesel. Until I switch it on and off a few times. Then it cranks fine. I cleaned the terminals on the ignition switch, but no help. I am the original owner and sort of remember the same thing about 15 years ago. But my memory ain't what it used to be either. Bad ignition switch, right?

Thanks for your help!
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Old 17-06-2016, 16:49   #2
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Re: Ignition Switch Voltage Drop

There is set of high current contacts inside the solenoid (that round thingy on top of the starter). You can tear the solenoid apart and turn the contact disk over -last ditch repair to be performed on an isolated island somewhere- or just get a new solenoid or starter.
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Old 17-06-2016, 17:12   #3
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Re: Ignition Switch Voltage Drop

Second Solenoid over ign switch. Also check engine ground and battery to solenoid cables for corrosion and tightness before solenoid replacement. Any of the above can cause symptoms described.
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Old 17-06-2016, 17:15   #4
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Re: Ignition Switch Voltage Drop

To answer your question, place a voltmeter across the 2 terminals of your switch. If there is a voltage drop, there will be a voltage on the meter. It could be .6v for example.
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Old 17-06-2016, 22:50   #5
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Re: Ignition Switch Voltage Drop

rewire from ignition switch to starter solenoid.
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Old 18-06-2016, 09:36   #6
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Re: Ignition Switch Voltage Drop

Another vote for the solenoid. About 99% sure.
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Old 18-06-2016, 10:00   #7
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Re: Ignition Switch Voltage Drop

Quote:
Originally Posted by elittke View Post
I am not so good at using a voltmeter, so if an electrical issue comes up on my 33 year old Catalina 38, I am more likely to just replace the component with the best guess method. With new batteries just installed, I get the starter to engage but not really turn over the Universal diesel. Until I switch it on and off a few times. Then it cranks fine. I cleaned the terminals on the ignition switch, but no help. I am the original owner and sort of remember the same thing about 15 years ago. But my memory ain't what it used to be either. Bad ignition switch, right?

Thanks for your help!
To eliminate a few potential problems take your main earth lead off the current earth (usually a stud on the engine block) and bolt it to a clean bolt somewhere else (like on the bell housing or starter motor bolt) if it fixes the slow turnover of the engine then the stud into the block has some rust or dirt that is diminishing the earth. (Been there via a much longer route of testing all connections...)
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Old 18-06-2016, 10:33   #8
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Re: Ignition Switch Voltage Drop

Quote:
Originally Posted by elittke View Post
I am not so good at using a voltmeter, so if an electrical issue comes up on my 33 year old Catalina 38, I am more likely to just replace the component with the best guess method. With new batteries just installed, I get the starter to engage but not really turn over the Universal diesel. Until I switch it on and off a few times. Then it cranks fine. I cleaned the terminals on the ignition switch, but no help. I am the original owner and sort of remember the same thing about 15 years ago. But my memory ain't what it used to be either. Bad ignition switch, right?

Thanks for your help!
I would still use the voltage drop test. Connect the voltmeter to the large terminal at the solenoid (the one that the battery cable is on) and try cranking... this voltage should read anything above 9.5 volts. Then repeat these steps on the other large terminal at the solenoid (the one that enters the starter) and the reading should be the same. If there is more than .2 colt difference... the solenoid needs replacement or repair.
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Old 18-06-2016, 11:29   #9
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Re: Ignition Switch Voltage Drop

If you have a Universal engine and the trailer connectors are still inline between the instrument panel and the engine, you need to remove them.

I chased an intermittent no start problem for a long time, it turned out to be a bad connection in one of the trailer connectors.

There is a wire that goes to the panel, that powers the panel, glow plugs, and the starter solenoid. Then another wire goes back to the solenoid.

I had two trailer connectors, and about 6 ft of extra cable coiled up inside the loom. From battery to panel and back to solenoid, it goes through this lot twice!

I ran whole new power and solenoid wires, and the rest I crimped together in place of the trailer connectors. No more problems.

To add insult to injury, some panels are wired so that the glow plugs have to be on to energise the start button. So the 20 or 30A that the glow plugs require is dropping your solenoid voltage through all the bad connections and unnecessary wiring.
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Old 18-06-2016, 21:01   #10
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Re: Ignition Switch Voltage Drop

this is all easier when you can get your hands (and VOM probes) on the various lugs. :-)
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Old 19-06-2016, 10:29   #11
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Re: Ignition Switch Voltage Drop

If your marine engine has a gear reduction starter, it is possible the the starter is bad because there are two windings in the solenoid a pull in winding and a hold in winding. The ground for the pull in winding is not the same terminal as the hold in winding. The pull in winding makes the initial contact using a starter case ground then the winding is passed to the starter ground return when the contacts close so if the starter does not draw current the solenoid will drop out unless you cycle the start switch.
For example if the starter brushes are going bad it is difficult to determine if it is the starter or solenoid causing the issue. I have found US made GM and Nissan starters (DENSO DESIGN and copies) are this way, older designed starter did not use this technique and were easier to trouble shoot starting issues.
This design technique allows a smaller cheaper solenoid to be used.
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Old 19-06-2016, 12:18   #12
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Re: Ignition Switch Voltage Drop

I vote for solenoid contacts, but...
Another consideration is the wire age. I have found corrosion in the marine environment sometimes will creep into wiring. This can be battery cables and ordinary electrical wire.
Many yachts have a single wire from the battery/solenoid going to the ignition switch that powers anything engine related. So power goes to the switch and back to the start solenoid. The wire may have been large enough when new but not now.
Some newer engines now have a relay on or near the engine, in addition to the solenoid, to engage the start circuit without making the trip to and from the switch. Only the very low requirements of the additional relay make the trip.
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Old 19-06-2016, 12:31   #13
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Re: Ignition Switch Voltage Drop

Quote:
Originally Posted by elittke View Post
I am not so good at using a voltmeter, so if an electrical issue comes up on my 33 year old Catalina 38, I am more likely to just replace the component with the best guess method. With new batteries just installed, I get the starter to engage but not really turn over the Universal diesel. Until I switch it on and off a few times. Then it cranks fine. I cleaned the terminals on the ignition switch, but no help. I am the original owner and sort of remember the same thing about 15 years ago. But my memory ain't what it used to be either. Bad ignition switch, right?

Thanks for your help!
If you are old enough that your memory isn't what it us to be. Try to remember that was a common problem with autos, circa 47 through the 50s models. Solenoid contacts would go bad and you would rock the key until they made enough of a connection to get you going. A low battery and bad battery connections can cause it, but with new batteries just check the heavy leads. Bad switch about the least probable thing.
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Old 19-06-2016, 17:45   #14
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Re: Ignition Switch Voltage Drop

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Originally Posted by MarkSF View Post
If you have a Universal engine and the trailer connectors are still inline between the instrument panel and the engine, you need to remove them.

I chased an intermittent no start problem for a long time, it turned out to be a bad connection in one of the trailer connectors.

There is a wire that goes to the panel, that powers the panel, glow plugs, and the starter solenoid. Then another wire goes back to the solenoid.

I had two trailer connectors, and about 6 ft of extra cable coiled up inside the loom. From battery to panel and back to solenoid, it goes through this lot twice!

I ran whole new power and solenoid wires, and the rest I crimped together in place of the trailer connectors. No more problems.

To add insult to injury, some panels are wired so that the glow plugs have to be on to energise the start button. So the 20 or 30A that the glow plugs require is dropping your solenoid voltage through all the bad connections and unnecessary wiring.
STOP right here. Mark is RIGHT.

There is also a dumb FUSE an fuseholder cleverly hidden right beneath the alternator. Either replace it or remove it since it's at the wrong end of the f-ing wiring anyway.

These might help:

Diesel Engine - c34.org

Critical Upgrades CRITICAL UPGRADES - DO THESE OR ELSE!!!
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Old 19-06-2016, 18:23   #15
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Re: Ignition Switch Voltage Drop

I highly suggest if possible that you run a direct line from the positive side of your new batteries directly to the positive side of the starter. I had this same issue once and thought it was the solenoid. it wasn't and ended up being the hot line to the starter. All the solenoid does is jump the terminals of the starter and doesn't require a whole lot of current. The starter motor is a different story. You say it engages. Bad voltage to the starter will cause the problem you are.describing and besides, running a temporary line direct will tell you without a doubt where your problem lies. You can also take a big screwdriver and ground out the two starter motor posts and take the solenoid out of the equation too for that matter.
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