VCCA Home Forums TECHNICAL - GENERAL Electrical - 12 volt Back to the basics...

Going to show my ignorance here:

"What does the solenoid do and why?"

Gator I am guessing you are refereing to a starter solonoid?



If so it could be compared to a remote switch to activate a high current device. otherwords to make a starter button operate the starter motor on a car. A relay, it usually uses a low current voltage to pull a electromagnetic switch on a high current circuit. They also are used to run a winch or a convertible top motor, shift a overdrive, lock a gate, and many other high current devices, Enough?

Huh..."...uses a low current voltage to pull a electromagnetic switch on a high current circuit...". Simple English (non-tech.) is my first language so could you explain it again using my English, you know like you were talking to a F*rd person.

Starter is what I need to know about. Sometimes I turn the key and nothing happens and I mean nothing, no sound or anything. Then later turn the key and it starts right up.

It's like using a small switch to control a large switch because only the large switch can conduct the larger current going into the starter. There could be a worn or dirty contact in the solonoid or it could be worn brushes or an open armature in the starter.

gator,

a solenoid is nothing more than a wire wound around a piece of iron (core) to make an electromagnet...a magnet stays magnetic all the time...an electromagnet is magnetized only when electricity is applied...(look at those nice pictures mrmack posted...most of them show just two wires emerging...)

the earth is a big magnet with a north & south pole, because it has an (molten) iron core...many planetary bodies & sattelites are not, because they lack an iron core...

anyway, when one applies a current to the wire, it creates a magentic field...if one designs this device correctly, the iron core is either attracted or repelled, dependent upon the orientation of the poles...reverse to "polarity" of the wiring, that is, switch which wire is connected to positive & negative terminals of the baterry, and the magnetic orientation reverses, too...

so, the solenoid type electric door locks use this principal...push the conrol switch one way and the solenoid pulls the door lock linkage to "lock," push the switch the other way and it provides a reversed wiring connection so the solenoid "unlocks"...

solenoids are cool because they can operate things from a remote location, like your auto's door or trunk locks, or your home's doorbell chime...

in a vehicle with an electric key start, the key switch applies current to the engine's starter solenoid...this way, one doesn't have to step on the starter switch, like those of us with the foot starters...

with a relatively small amount of electrical energy (small wire), two things occur: 1) the solenoid pulls a linkage to engage the pinion gear of the starter motor to the ring gear on the flywheel and 2) connects the starter motor contacts to the battery (big cable) to start the cranking of the engine...

since nothing happens when you turn your key switch, your switch may not be supply any or enough power to the solenoid...to see if the solenoid/starter/battery cable part of the system is working, you can jump the solenoid terminal with the starter terminal (battery) to see if the solenoid engages and starter motor turns...if so, then you know to look for trouble back towards the keyswitch circuit...


hope this helps,


kepi

Well Gator, what year and model car are you talking about, Is the solonoid mounted on the starter (49 - 54) cars or is it a mechanical floor button (1928 - ?) cars, 192x to 1957 six cylinder trucks, or a modern one with the solonoid mounted on the firewall or fender well?


...now how it works,like Chevrolet says, There is a electromagnet (know what that is?) that pulls a piston onto a set of contacts, battery cable size, and this passes the full battery power to the starter motor, (still following me?) This electromagnet is powered by the starter button switch which uses power from the battery and hooks up to the solonoid with regular electrical wire like 14 gauge that charges a coil wound around the plunger ,an iron core, the plunger slams a piston into contact with the (in) and (out) battery cables. So....when you short across the two battery cables, one from battery,and the other to the starter motor, with pliers or a jumper cable you are by-passing the switch and the electromagnet piston and making direct contact. If I had a pencil and paper I could draw you a simple picture, there is a good picture of one in the 49 to 54 shop manual

If you don't understand shake your head from side to side, if you do understand then shake your head up and down! (just kiddin')

It's a '85 Chevy 350 motor, in a PU. Key start.

"...since nothing happens when you turn your key switch, your switch may not be supply any or enough power to the solenoid...to see if the solenoid/starter/battery cable part of the system is working, you can jump the solenoid terminal with the starter terminal (battery) to see if the solenoid engages and starter motor turns...if so, then you know to look for trouble back towards the keyswitch circuit..."

and

"So....when you short across the two battery cables, one from battery,and the other to the starter motor, with pliers or a jumper cable you are by-passing the switch and the electromagnet piston and making direct contact."

I would like to try and start the truck with "jumping" the solenoid, but I'm still not quite sure as to how to do it. I have been "bit" by electric stuff before

As difficult as it would be to get under a pickup to "jump" the solenoid, just go ahead and remove and replace the starter/solenoid as a unit. It is 99.9% sure that will solve your problem. The proximity of the starter to the exhaust manifold makes this a weak point on this type unit. When you replace the starter unit insure the shield is reinstalled. If it wasn't there to start (pun) with go to the wrecking yard and secure one.

You could have the parts house check the starter for you, however after it has been jarred around in the replacement procedure it will probably test good.

Gator, I had the same trouble on a 76 small block I reached under the truck and hit the starter with a large ball pein hammer ( oilfield roughneck tool set) it started and I drove it up on ramps and removed the starter & solinoid, Took it to a parts house and traded it and some money for one that worked. If you hit it with a hammer sometimes it will jar it enough to start, just don't let a young person see you because they will beat the starter off their truck when the battery is dead, I know. I had a son-in- law that did that, Thank goodness that he is now an ex-son-in-law

I'd like to point out something in MrMack's reply. A weak battery will cause symptoms that mimic a solenoid problem. There is enough power to make the lights or horn work but not enough to run the starter. I'm sure many of us have replaced a good solenoid. [been there]

A quick way to check if the battery is too low is to open the door so the dome light comes on, attempt to start the engine. If the dome light goes out or gets very dim, you have either a battery problem or corroded connection in the system. If the dome light doesn't change brightness, it is probably a starter/solenoid problem.

Thanks for the input, I will remove and replace it.

I remember years ago someone would say there was a 'bad spot' and we would move the car back and forth (in gear) to move it out of the 'bad spot', is this like the hammer? :confused:

No. that is a whole different situation!

Thanks for the dome light tip...beats getting out the mirror and watching a headlight!!

Gator you say that sometimes the starter works and sometimes it doesn't.To get a correct diagnosis of an intermittent electrical problem, you have to catch the problem while it is happening. Jumping solenoids and switches are ok for those of us who have some background in electricity, but if you don't you can get into trouble. If you jump the starter and it starts, who's to say it wouldn't have started with the key at that time. Before you go changing parts, try the following.

1: Make sure you have good connections at the battery and a good clean ground strap connection to the frame/engine.
2: check to see if your wires at the starter are all tight and have a clean connection. A loose/dirty cable or solenoid wire will give you the problem you are describing.
3: Connect a test light to a good ground , and touch the tip of the test light to the wire on the solenoid that comes from the ignition switch.While doing this, have someone try to start the car.If the light is on and the car doesn't start then I'd replace the solenoid on the starter. If you have a remote solenoid on the fender or firewall, then make sure you test for power going in and out of the solenoid and down to the starter.If there is power getting to the starter terminal then the starter would be your problem.
4: Tapping the starter with a hammer to get it to start is a sign of weak or worn brushes in the starter. (remember to catch it while it is in a NO-START mode to get a correct diagnosis and not guess and change parts for no reason)

Good Luck

gator,

just to add to all the good replies here, to clarify, the "bad spot" relates to a worn starter ring gear on the flywheel...usually a burr won't allow the starter's pinion gear to fully engage on demand, so the electrical contacts to the starter motor are not connected (remember the solenoid does both in the same motion?)...

because of piston compression, the engine, when shut down, tends to come to rest at certain positions...upon start up, these parts of the ring gear get disproportionate wear...rocking the vehicle aligns the gears better or moves the gear around to another tooth...


epi

Just for the sake of argument I would like to elaborate on Chevrolet’s comments.

In the scenario you described there would not be a problem with the electrical system but would be mechanical in nature. The starter would engage and turn each and every time, however the engine would not turn over and start as you indicated because of the broken teeth. This one is easily diagnosed because of the extremely loud clashing of gears.

The more common explanation of the “dead spot” is the situation where the brushes have worn excessively or one of the turns in the starter armature is defective. Under these conditions the starter does not respond to the turning of the key. By some means of movement (taping with a hammer - jarring the starter by removal - ect) the armature is turned to a new spot or the brushes seat more firmly and then the starter will respond. PLACING THE CAR IN GEAR AND ROCKING IT WILL NOT HELP IN THIS SITUATION.

Another starter problem so far not mention on the Chevrolet V-8 engines is the overheated starter. This one shows up when you pull into a service station for fuel. When the refueling is completed the starter fails to respond to the key because of the over heated (cooked) condition. After the vehicle sits for a spell or cold water is splashed on the starter it will function as if nothing had happened. This is an indication the starter is failing and should be replaced at the earliest opportunity and INSURE THE HEAT SHIELD IS REINSTALLED OR IF MISSING REPLACED.

Experienced mechanics can usually make a correct diagnosis of starter problems without elaborate testing based upon the described problem by the operator. Testing may in fact add more expense to the total job and if the problem doesn't manifest itself at the time of the testing is a waste anyhow.

One more thing, I think this engine's starter bolts on from the bottom , seems that there were some shims on my 400 csb 1976 surb 4x4 that set the engagement distance, however it has been a lot of years (1980) since I rebuilt that starter, and I may have it confused with the 400 Pontiac engine in my 72 wagon.
The 350 and 400 sbc engines did indeed have a heating problem from the engine and exhaust manifolds the 400 sbc would get hot enough under the hood when pulling a heavy trailer in the mountains that it would melt wireing harness connectors on the engine! There was an aftermarket kit that moved the solonoid from the starter up onto the firewall ala Fourd.

You guys are great, learned a lot (I hope), I will try what you said Steve before I replace the solenoid, thanks.

I should have said this has happened in the mornings and the truck had not been driven for several days. :confused:

I'm afraid to drive it anywhere until this is figured out. :( :(

I don't have any electricial diagnostic tools, what basic tools should I buy so I can start doing some problem solving? :confused:

An elf with a lot of experiance on auto electrical problems! and get him a cheap analog multimeter (VOM) and a big hammer!

Gator MrMack said it all. A volt/ohm meter or a 12 volt test light. They sell them at automotive stores and at Sears hardware. Look at the tool purchase as an investment. They are reusable. If it is the solenoid that's bad , you may want to compare the price of that to another new/rebuilt starter.The solenoid will be new but the starter will still be old.(new hart in an old man) Anyways...Good Luck...glad to have been a help to you.

Measure twice / cut once

Gator one more thing that we haven't touched upon. There is a device under the dash above the clutch pedal(standard tranny) or on the base of the steering column next to the ignition switch(automatic tranny)that's called a neutral safty/back up light switch.This is what the PURPLE wire that goes to your starter solenoid comes from.It gets its power from the ignition switch.If you get any deeper than that; you might want to get a shop manual for your truck or someone who had been there before. :)

Thanks guys, I will try and not cause any other damage when I try to "fix" the problem. :rolleyes:

As you can tell I don't have a lot of confidence in my ability, but I hope to learn something in the process, anyway. :eek:

gator,

you got a lot of good input here from all the guys...just remember that the starter cable can do a lot of welding, if improper contact is made...

if you are going to try to jump in down under, you might consider going to your local parts house first...explain what you're up to...the guys around here would pull a unit and show you what you'd need to do...that way, you'd be more confident of what you're looking to do under there...

work carefully & good luck,


epi

Yeh like Chevrolet said!

While you are at the parts house you might pick up a remote starter switch and use it instead of that clumsy ***** drivwer.

Ok, DandyD, now you will havta tell him how to use that Remote Starter Switch! Won't he Gator?

Attach one gator(short for alligator)clip to the battery post on the solenoid and the other gator clip to the ignition post and firmely mash the button.
dandyd

Now, things could be perfect if I could get one of you guys to come over to my garage and watch me "fix" the problem :rolleyes: or burn myself, or get a shock, or weld myself to the truck or ???? Free beer

Don't let anyone watch. Have them show you. :love:

FREE BEER !!!!

If it's Coors, I'd be willing to bet that Junkyard Dog is packing the car to get to your place, even as we speak !! -Bob

Already on the road!!!!

Cool deal, I'm waiting with a keg in a ice tub chilled ready to drink with frosted Chevy mugs sitting in the freezer ready to use.

We are some 3 weeks down the line on this thread and unless I overlooked it, what was the ultimate conclusion? Or, was this a rhetorical question?

Raymond, please fill me in on this. But didn't it have something to do with something electrical?

maybe a clue sould be the forum heading ELECTRIAL 12V.

Oh! I know it was about a starter solenoid! Seems that

Chevrolet said it well in his post on 11/24/03:

"a solenoid is nothing more than a wire wound around a piece of iron (core) to make an electromagnet...a magnet stays magnetic all the time...an electromagnet is magnetized only when electricity is applied...(look at those nice pictures mrmack posted...most of them show just two wires emerging...)

the earth is a big magnet with a north & south pole, because it has an (molten) iron core...many planetary bodies & sattelites are not, because they lack an iron core...

anyway, when one applies a current to the wire, it creates a magentic field...if one designs this device correctly, the iron core is either attracted or repelled, dependent upon the orientation of the poles...reverse to "polarity" of the wiring, that is, switch which wire is connected to positive & negative terminals of the baterry, and the magnetic orientation reverses, too...

so, the solenoid type electric door locks use this principal...push the conrol switch one way and the solenoid pulls the door lock linkage to "lock," push the switch the other way and it provides a reversed wiring connection so the solenoid "unlocks"...

solenoids are cool because they can operate things from a remote location, like your auto's door or trunk locks, or your home's doorbell chime...

in a vehicle with an electric key start, the key switch applies current to the engine's starter solenoid...this way, one doesn't have to step on the starter switch, like those of us with the foot starters...

with a relatively small amount of electrical energy (small wire), two things occur: 1) the solenoid pulls a linkage to engage the pinion gear of the starter motor to the ring gear on the flywheel and 2) connects the starter motor contacts to the battery (big cable) to start the cranking of the engine...

since nothing happens when you turn your key switch, your switch may not be supply any or enough power to the solenoid...to see if the solenoid/starter/battery cable part of the system is working, you can jump the solenoid terminal with the starter terminal (battery) to see if the solenoid engages and starter motor turns...if so, then you know to look for trouble back towards the keyswitch circuit...


hope this helps,


kepi"

This is a quote from an earlier post by Gator:
Unless I have missed it, the question still remains:

Has the problem been diagnosed and repaired?

Some answers could be way back on page 1 of this thread.

So I read that as a, NO the problem still exists.

Ray, I don't know what else could be said about a solenoid, Do You? Except if the one for the 350 is questionable go to the Chevrolet house or Battery and electrical repair shop and pluck down some money for a newly rebuilt starter Asmbly / with solenoid, and heck while you are there behind the tow truck hold on tightly and enjoy the ride!

Boy am I glad I came back to this thread and read all the posts, here I thought it was all about Beer!

No, No, glyn, first the guys give you their expert opinions and answers and then and only then do we turn to beer

Ahhh! now the grasshopper understands!