'89 Ford F250 with 5.8 Liter motor.

Sometimes when I try to start it, it makes a loud knocking noise. Sounds like it's coming from the thing bolted to the right front fender. The hot wire from the battery bolts to this thing.

When I turn the key, it sounds like this thing makes a rapid knocking noise.

The battery seems to have plenty of power, but sometimes it won't start.

Any ideas?

Thanks.

 

On fords the poo...
uhm... Brain fart..

Celinoid?

The thing on the fender engages the starter.
On GM and Dotch it's on the starter itself. On fords, its on the fender.

Cheep to replace, make sure you get everything in the right spot.

 

Thanks for the fast answer. Is the loud knocking an indicator of a bad solenoid? Or is it possible that it only does that when the battery power is low or something?

 

Well, if its bad, it wont engage the starter.

I"m not really sure, havn't replaced one. I hear they go bad often.

Pehaps try cleaning all the connections before replaceing.

 

Something you may want to check is the wires connecting to the starter itself...Although the solenoid is a 10 dollar fix, just dbl check the starter..It doesn't sound like the solenoid is bad if your hearing the tapping. I went through the same thing, then I found the hot wire going to the starter was corroded real bad...The starter was original (180,000 miles) so I just replaced it. Never had a problem since. But i replaced the solenoid as well, it's only 10 bucks or so...Good luck, let us know how it turned out..

 

On a weak or poorly charged battery, your solenoid will chatter sometimes.
Also if you have dirty or corroded battery cable connections and a poor ground connection from the negative terminal to the body of the truck.

It is caused by the solenoid engaging therefore connecting to the starter. The starter draws a lot of current, so a weak battery or poor cable connection causes a drop in the voltage from the ignition switch to the solenoid, so the solenoid drops out.
Of course when it drops out, it disconnects from the starter and the voltage from the ignition switch rises again. So it engages again, then the starter loads the system again. This just cycles again and again causing the chatter.

This is usually NOT the fault of the solenoid.

A starter that draws too much current can also cause this, but probably 98% of the time it is a weak battery or poor/loose/corroded connections around the battery area, or on the solenoid itself.

 

Yes. all that information is correct. awesome guys!

 

Thanks for all the help. I'm going to thoroughly clean all the connections first to see if that fixes the problem. There is a little corrosion at the battery posts, so I think some cleaning of *ALL* connections will probably go a long way.

Does anybody know of a a way to check the alternator with a simple multimeter?

Thanks!!

 

http://www.autozone.com/az/cds/en_us...rInfoPages.htm

 

If all your connections are good you can ballpark measure at your battery terminals to determine if your alternator is functioning.

A fully charged battery with the engine off and all accessories ect off, should read about 12.75 volts, depending on the condition of the battery.

With the engine running the voltage accross the battery terminals should read 13.5 volts or better.