Up in smoke (starter)

[RobsRR]

So after filling up at the gas station I heard a noise, hard to describe like a swishing noise at idle. I did notice my battery voltage seemed a little bit low but it came up with more rpm. So I got home to my house a couple miles away and still heard the noise. I start looking around don't see anything and it gets worse. I then smell electrical burn then starter starts smoking. This happened quickly. Then more smoke and the engine stop turning over. Much more smoke.
I turned the key off and thought do I grab my fire extinguisher or a wrench to pull the battery cable off. Since there were no flames I pulled the cable off. A few minutes later when the smoke cleared I touched the cable to the battery and it slowly tried turning over. The ignition was turned off at this point.
I assume the solenoid on the starter is stuck on. This is a Denso starter that I bought new a few years ago. I had a problem with starting when hot last summer but after making up new battery cables the problem went away. At that time I made a heat shield.
So the question.
Has anyone seen this with the Denso starter?

Am I right to assume that the solenoid stuck and is it from heat (headers).

I always thought to put on a kill switch. Now I Will. Are the ones on the top of the battery terminal as good as a switch?

Sorry for the long post.

 

[pnora]

Could be the starter also could be the relay. Take the wires off the relay and see if it still cranks. If it does its the starter. If not its could be the relay or wiring.

 

[1967coronet]

Also take a look at your heat shield you built. Make sure it has not made contact with the terminals.

 

[RobsRR]

Also take a look at your heat shield you built. Make sure it has not made contact with the terminals.

Yes I was planning.

 

[slepr1]

It was your lucky day...you were at home when it happened!

 

[RobsRR]

It was your lucky day...you were at home when it happened!

Sooo glad I was home thats why a kill switch will be going in.

 

[Nate S]

Had a solenoid stick on when starting my Roadrunner years ago. Revved the engine and spun the darn thing up to jet engine speed! When I took it apart the centrifugal force had pulled all the windings out and they were dragging to the point of press-fit in the housing.

 

[4406bbl]

Common for a Denso starter, the contacts weld together and it stays engaged key on or off until the battery goes dead. Always carry a wrench so you can unhook the battery to save the ring gear.

 

[4406bbl]

What actually happens is one contact wears down faster than the other side so when everything is perfect the contact washer edge jams tight against the worn contact edge and can't release then welds solid from heat. If your Denso ever does a click, no start, then click start you better change at least the worn contact or your stuck starter days are coming. I am going to try a modded diesel contact on the worn side to try to equalize the wear, or weld one up to see it the weld wears slower than the plain brass. When you change your contacts rough them and the contact washer with a little 60 grit paper, otherwise it could intermittent start at first. I stay out of the Denso starter threads because everyone thinks they are so great, they are but this is their issue. Aftermarket contacts may be an issue, but some new cars have had the issue too.

 

[Fran Blacker]

Had a solenoid stick on when starting my Roadrunner years ago. Revved the engine and spun the darn thing up to jet engine speed! When I took it apart the centrifugal force had pulled all the windings out and they were dragging to the point of press-fit in the housing.

Had my ignition switch stick in start position, heard bang. OOPS!
$60 bucks 2 years ago.

 

[RobsRR]

Common for a Denso starter, the contacts weld together and it stays engaged key on or off until the battery goes dead. Always carry a wrench so you can unhook the battery to save the ring gear.

Thanks for your info about the starter contacts. What I am thinking is the starter had to be engaged because of a stuck starter relay. When I took a look at it this morning I touched the positive cable to the battery and it still tried to turn over. Is there any way this could happen with the key off if the relay contacts we're not stuck together?

 

[RobsRR]

Also take a look at your heat shield you built. Make sure it has not made contact with the terminals.

Heat shield looks good

 

[RJRENTON]

What actually happens is one contact wears down faster than the other side so when everything is perfect the contact washer edge jams tight against the worn contact edge and can't release then welds solid from heat. If your Denso ever does a click, no start, then click start you better change at least the worn contact or your stuck starter days are coming. I am going to try a modded diesel contact on the worn side to try to equalize the wear, or weld one up to see it the weld wears slower than the plain brass. When you change your contacts rough them and the contact washer with a little 60 grit paper, otherwise it could intermittent start at first. I stay out of the Denso starter threads because everyone thinks they are so great, they are but this is their issue. Aftermarket contacts may be an issue, but some new cars have had the issue too.

IMO.... The stationary contacts, usually a copper alloy for electrical conductivity, (there are 2, one is the battery connection and the other is connected to the armature/brush holders)....the Denso and other mini starters use permanent magnet fields...no field windings. The moving contact, usually a copper alloy for conductivity, is operated by the solenoid, engaging the starter drive while connecting the battery connection to the brush holder, causing the drive to engage and connecting to the battery. The starter relay's sole function is to power the starter solenoid on command of the key switch and neutral start switch or the clutch start switch.
If the spring that backs up the starter solenoid's moving contact gets tired, then possibly contact welding can occur, resulting in the starter being engaged.....to the point of self destruction....limited to the drive's one way clutch (aka "Bendix"). The starter relay DOES NOT handle actual starter armature current, only the solenoid coil current. Ideally, IF the contact alloy configuration was known, it may be able to be improved upon. These contacts control 300 to 400 amps (possibly more if the engine has high compression or thick oil) of starter current and deterriorate fairly quickly. The fix???....inspect annually...replace parts as required???? Just thinking out loud....
BOB RENTON

 

[4406bbl]

Thanks for your info about the starter contacts. What I am thinking is the starter had to be engaged because of a stuck starter relay. When I took a look at it this morning I touched the positive cable to the battery and it still tried to turn over. Is there any way this could happen with the key off if the relay contacts we're not stuck together?

That sounds like the starter is the problem to me.

 

[dadsbee]

Bendix is stuck forward, which makes the main contact connection to the battery cable. The starter relay doesn't carry that current. Take the wire off the starter solenoid that goes to the starter bendix solenoid and then hook up the battery... I bet it still turns.

 

[RobsRR]

Bendix is stuck forward, which makes the main contact connection to the battery cable. The starter relay doesn't carry that current. Take the wire off the starter solenoid that goes to the starter bendix solenoid and then hook up the battery... I bet it still turns.

Ok that clears it up sorry I am a little slow. I was thinking the starter relay carried the main current to the starter. I will be taking out the starter.

 

[RobsRR]

Ok that clears it up sorry I am a little slow. I was thinking the starter relay carried the main current to the starter. I will be taking out the starter.

Thank you everyone for your help with this.

 

[RobsRR]

Bendix is stuck forward, which makes the main contact connection to the battery cable. The starter relay doesn't carry that current. Take the wire off the starter solenoid that goes to the starter bendix solenoid and then hook up the battery... I bet it still turns.

 

[RobsRR]

One more question. If I put a kill switch on the negative side by the battery would it of stopped the starter from being energized in this case. I pulled the positive cable off when it was smoking up.

 

[dadsbee]

One more question. If I put a kill switch on the negative side by the battery would it of stopped the starter from being energized in this case. I pulled the positive cable off when it was smoking up.

Either one, but another reason I have never tightened the negative cable on with a wrench. I put them on by hand and give the cable end a twist to snug. I pull them off every time I park the car in the garage.