Over the past month I've had two NAPA solenoid relays fail in my 1986 F250 5.0 EFI. Both worked for about a week before they failed -- in both instances the starter engaged but then did not disengage . These were both 4 pole solenoids (as opposed to the three pole units from Motorcraft).

I'm wondering if others have experienced this problem with NAPA solenoids and if not, is there something else that may be causing these hummers to fail. Maybe the solution's as simple as staying with the Motorcraft part but I thought I should ask.

Thanks for your help

Jeff

 

Some say you should pick up a used Motorcraft from the salvage. Others say that bad connections can cause the solenoids to fail. I'm not sure what the truth is. But, in your case I'd do both - look for a Motorcraft, whether new or used, and also check your cables and connections.

 

Also might remove the starter motor and take it to a parts store for testing, see if it's perhaps drawing too much current.

 

Good point.

 

^^^^ This. The RELAY is on the fender. The SOLENOID is on the starter (even if it's built-in and there's only one wire, there's still a solenoid there). And it's the solenoid on the starter that's more likely to stick and keep the starter engaged.

 

To clarify, what is commonly referred to as the "solenoid" is officially called the "starter relay" by Ford, as shown on Page 29 here: Start & Ignition - ???Gary's Garagemahal. But I call it the "solenoid" as that's what it has been called by us shadetree mechanics for eons.

And while there is technically a solenoid on the starter, or "starter motor" as Ford calls it, that solenoid is used to move the starter gear into engagement with the flywheel's ring gear to turn the engine. Granted it can hang up, but that is rare due to the design of the Bendix which kicks the starter's gear backwards when the starter quits driving the engine. So if the solenoid cuts off the flow of juice the Bendix will pull the starter's gear out of engagement.

What usually happens is the "starter relay", aka "solenoid", welds the contacts together and the battery continues to drive the starter. And there are two causes for that - cheap solenoids with poor contacts and/or more current than the contacts are designed to handle. The latter is frequently caused by a "dragging" starter, meaning that the bearings have worn to the point that the armature is dragging on the field. That causes excessive current to flow and will ruin even good solenoids. That is why Chris suggested having the starter tested.

 

Get a Motorcraft solenoid, you can get a brand new one from O'reillys. I went throught this same thing with my 86 with a 460 but I went through about 8 solenoids that did exactly what yours is doing. I tested everything and all was fine. I even cut a solenoid open that had stuck and it had no burnt markings what so ever. Do a search under my user name and read the thread I had on this exact problem and you will see pic and there is a lot of good info in there too. I believe the Title of the thread is Burning Up Solenoids

 

We have a rash of posts like this once in awhile. Finding a better brand usually fixes it. Most of this stuff is made in china now and a lot of it is no good. That's why new is not always better anymore. And if you use the shot gun approach and replace a bunch of parts to try to fix a problem, most of the time you end up with more problems than you started with, because of inferior faulty new parts.

 

On the standard ford starter they technically do not have a solenoid on the starter. They have a movable pole shoe. The system works as such when power is put to the starter a actuating winding creates a magnetic field that pulls the pole shoe down in to the starter body and engages the starter drive. When the pole shoe is depressed it open a set of contacts that de-energizes the actuation winding and the magnetic field generated by the armature then holds the pole shoe down. This allows for full battery current to be used to turn over the starter and not have any wasted holding the pole shoe closed. This is the draw back with GM and Chryco starters as a larger portion of the battery's current is needed to keep the drive engaged compared to the Ford.

When power is removed from the starter motor the armature is de-energized and the movable pole returns to it's up right (open) position by a spring, thus disengaging the starter drive.

The old style starters with a bendix drive kicked the drive back to disengage it. On the later starters (as found in the bull noses) the movable pole shoe engages and disengages the starter drive. The Starter drive has an over running clutch in it so the engine does not turn the starter over when it starts.

 

Solenoid is just a type of electrical device. It uses a magnetic field to move a plunger. Fuel Injectors have a solenoid in them when powered up the metallic center in the windings tries to center and thus moves and opens or closes what is being activated. In the case of the solenoid or starter relay as some call it, you apply low voltage like in a relay and it closes like a relay but the difference is its a solenoid design, it has metal windings with a metal rod in the center of the windings with a flat contact plate. When energized the the rod tries to center bringing the contact plate into contact with the two battery cable lugs completing the circuit.

So yes this is a relay in the sense of using small current to control high current, but the function of the relay makes it also a solenoid by design as well.

Same thing for the solenoid on starters that Chevrolet use. Difference is not only are they completing the high current circuit like a relay it is also used to move the Bendix into and out of the flywheel/flex plate. Ford does not use this but use a sliding pole shoe design up to a certain point. Ford trucks now are using Chevrolet style integrated solenoids on the starters themselves.



Now onto the topic of why the solenoid could be sticking. Ive seen in old Chevrolets low battery voltage will actually hold starter solenoids engaged and keep cranking till the battery goes dead. I have not seen a ford do this but anything is possible in this field.

 

That is a good point Rusty the OP should check his battery and make sure it is up to snuff. If the battery is not charging to full voltage it may be drawing just enough extra amperage to weld the solenoid shut (closed)


As long as the starter relay is made in the US you will be good to go . As all the US built ones come from the same place (incuding Motorcraft) The Echlin ones from Napa are OEM. The cheaper ones from Napa,( Mileage Plus line) are off shore Chinese made

 

Motorcraft all day long. I've used them for years without fail. Even in tractor applications that weren't Ford, without fail. 3 lug and 4 lug.

 

Word. I had this problem so bad one time the bolts were melting the housing . And the runaway starter. Get new battery cables run the neg to the frame and from that connection to the frame run to a starter bolt. Wire wheel the place on the frame.

 

Did you ever get this fixed ??

 

Thanks to everyone for your comments and suggestions. Clearly I'm not along in experiencing this problem.

As suggested, I replaced the defective NAPA part with one from Motorcraft and then took steps to ensure the unit was adequately grounded by running a wire from the neg bat post to one of the screws that affixes it to the body. The later was a suggestion from a mechanic friend who, over the years, found that poorly grounded units caused many of these unit to run-on. Easy to do so why not.

Anyway, although it's only been a few days: so far so good. If it fails again, I'll turn my attention to the starter (and after so many run-on failures it may need some attention anyway).

Thanks again for your help with this.

Jeff