PDA

View Full Version : What is this?



Cuda
08-25-2007, 01:29 PM
And what does it do? It's some sort of solenoid. It's mounted at the rear of the engine. When I hit the starter, I get a click from it. I measured across the poles. I only have continuity between the two small poles. Is this a Merc specific piece?

1982 454/330

gcarter
08-25-2007, 01:38 PM
Slave solenoid for starter?

zelatore
08-25-2007, 02:01 PM
Sure looks like a starter solinoid...

What's it wired to is the question.

Of course, continuity on the small terminals is a little wierd.

justleft
08-25-2007, 02:20 PM
Looks just like the starter solenoid I just replaced in my Bronco.

When you apply 12v across the small terminals it should
connect the large terminals together. (the click)

Normally it is used to send voltage to the starter without frying your
ignition switch.

But it could be used to send voltage to all the boat when the ignition
switch is turned on.

zelatore
08-25-2007, 04:44 PM
On re-reading your post, I'm guessing you measured continuity on the smller terminals with everything disconnected?

That would make more sense as basically it's just a coil between those two terminals. Put 12v accross them and you should have continuity accross the larger terminals.

And yeah, it looks just like an old Ford starter solinoid.

So again, the magic question is what are the large terminals connected to?

Mr X
08-25-2007, 04:58 PM
Slave solenoid for starter?
Exactly.
It is is series with the one on the starter.
They usually go bad long before the one on the starter, unless the starter has been wet.

Cuda
08-25-2007, 07:25 PM
And yeah, it looks just like an old Ford starter solinoid.

That's exactly what I thought. It's been many years since I messed with the old 289 Ford engines, but it looks just like what I remember. We used to us a pair of plier handles to jump the two smaller wires to make the starter turn.

Cuda
08-26-2007, 10:33 AM
I bought a solenoid from AutoZone. The bolt holes don't line up, but I'm sure one will hold it tight enough

zelatore
08-26-2007, 12:02 PM
I bought a solenoid from AutoZone. The bolt holes don't line up, but I'm sure one will hold it tight enough

Did you have to wack the kid behind the counter in the head when he insisted he couldn't just get you a ford starter solinoid unless you told him exactly what year and model Ford it came from so he could look it up on his computer? I needed a solinoid for a generator recently and eventually I gave up trying to tell the kid what I wanted and just made something up. 'er, ok kid, how about you try '85 F150 2x4 w/302?'

Autozone and the like are convienient, but most of the staff seem like they could work at the mall or quicky-mart just as easily as an autoparts store.:rolleyes:

Cuda
08-26-2007, 12:25 PM
It was a young guy who brought out the first part, it was close, then an older guy told him to try the F492, and it was closer.

Cuda
09-06-2007, 06:36 AM
I'm confused now. I finally got around to trying to put the new solenoid on. The old one only had a mark on the back at one of the large poles indicating positive. The new solenoid only has markings on the back at the small poles, with the letters "s" and "I", which I assume means starter, and ignition. On the boat, one of the smaller wires runs into a wiring harness, and the other straight to ground. Any ideas if this is going to work, and if so, how should I wire it?

zelatore
09-06-2007, 11:41 AM
Well, generically speaking a starter solinoid should have one large wire from the battery 12v+ on one big terminal and one large wire running to the starter on the other big terminal. Then you would have one small wire that shows 12v+ when the key is in 'start'. ....

Aw Crap...I can't remember what the 2nd small wire is for... :( Not much help after all!

zelatore
09-06-2007, 11:50 AM
Look at it this way- you can't really go far wrong and you've got a 50-50 chance of getting it right.

The two big wires you know - they go on the two big terminals of the solinoid. Doesn't really matter which is which - all they do is connect to each other when you turn the solinoid on.

The small wires - the one going to the wiring harness should be the switched 12v starter signal from the key switch. I'd stick it on the 's' pole on the solinoid and ground the other small terminal. Since a solinoid is just a big relay, I'm going to say it's not case-grounded so that's what the second wire is for, to allow the coil to energize and make the contact for the large poles.

Worst case, you switch the two small wires... like I said, 50-50 chance you get it the first time.

The only thing I'd consider is - is this a 'always on' solinoid? i.e. when you hit the key does it stay engaged the whole time or does it only engage when in the start position? I don't belive a Ford solinoid is rated for 100% duty cycle and will work for a while then will burn up. You can get 'always on' rated solinoids, but they cost more - probably still less than what Merc would charge though!

TXDONZI
09-06-2007, 12:44 PM
There are several types of them some are grounded internally and some are not. Some have a connection inside that will send a 12vdc signal momentarily to the ignition coil. In the old days you would send 12vdc during starting and run on something less than 12vdc and that is why there was a resistor in the circuit. Looks like to original solenoid you have is externally grounded without the "I" ignition connection. The one you bought is internally grounded with the ignition connection. Try hooking the wire in the harness to the "s" and leaving the ground loose or attaching it to the mounting bolt. before you install it, Ohm between the "s" and back plate you should see continuity on the new one. When de-energized (not pulled in) you will see 0vdc on the "I" and 12vdc on the "I" when energized (not pulled in). On the old one you should read nothing to the back plate on any of the terminals. Nothing between the large terminals but some sort of ohm reading between the two small terminals unless the coil is completely burnt open. I hope this helps.

Tt

TXDONZI
09-06-2007, 01:29 PM
I would take that one back.... After looking at the pictures that is not going to your starter the large wires are NOT big enough to start the motor. It should be the proper design. The one you have will work if need be. Try looking at Tractor Supply if you have one close they may have one in the proper configuration with a SS back plate. If it clicks when you turn the key to "on" you need continuous duty, if it clicks when you turn the key to "start" you need intermitting duty. Using the intermitting duty one in a continuous service will shorten the life of the coil considerably.

Tt

DickB
09-06-2007, 09:17 PM
Is it OK to use an automotive solenoid in this application? I'm always concerened about big booms in the engine compartment.

Forrest
09-07-2007, 08:46 AM
That is a slave solenoid. It is only energized when the key in in the start position. In this case, it acts as a relay to shunt current across it's large lugs to the GM-type starter-mounted solenoid's "S" terminal when energized by the key switch is in the start position. Usually, a slave solenoid is grounded through its mounting tabs.

The "I" terminal is connected to the primary side of the the ignition system to a provide higher than running voltage to the ignition system during starting. The "I" terminal is only energized during cranking when the key is in the start position. The "I" terminal is only applicable when a ballast resistance is used to reduce the running voltage (typically 8Vdc) to the primary side of the ignition system in the case of standard, or non-CDI, ignition.

Also Joe, though others may work, get the correct marine slave solenoid. You can get them pretty cheap from places like eBasicpower.com (http://www.ebasicpower.com)

Cuda
09-07-2007, 10:08 AM
So, if one of them goes straight to ground (and it does), I guess the I post would be the one with the wire that goes somewhere, and it really wouldn't matter about the two big posts?

Cuda
09-07-2007, 10:12 AM
I would take that one back.... After looking at the pictures that is not going to your starter the large wires are NOT big enough to start the motor. It should be the proper design. The one you have will work if need be. Try looking at Tractor Supply if you have one close they may have one in the proper configuration with a SS back plate. If it clicks when you turn the key to "on" you need continuous duty, if it clicks when you turn the key to "start" you need intermitting duty. Using the intermitting duty one in a continuous service will shorten the life of the coil considerably.
Tt
All four of the posts are exactly the same size as the posts on the original.

RickSE
09-07-2007, 11:14 AM
This is probably your neutral safety solenoid, in-line with but separate from the starter solenoid. Your starter solenoid will not energize unless this solenoid is energized, when the shifter is in neutral. If this is what it is then one set of wires will go to the neutral safety switch and the other set to the starter solenoid trigger loop; both 12V low current.

This is why my boat would not crank at Dora. I had a loose wire on the neutral safety solenoid so I couldn't energize the main starter solenoid.

Pismo
09-07-2007, 12:08 PM
I had a problem with this solenoid in an old boat. I got a new one that looked exactly the same but it was ground thru post rather than ground thru bracket. I got a correct thru bracket one and that made all the difference. Maybe a problem.