Thread: 302 Stroker??

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Are you thinking of a flyback diode - Flyback diode - Wikipedia, the free encyclopedia From what I see the diode is there to protect the contacts in the relay from arcing, not from pushing power into the system vs being driven. I'm a gearhead vs a spark chaser, and that generator thing just doesn't make sense to me. Then again, on big power generators (electric utility size) one of the most important pieces in the generation controls is the backfeed prevention to keep from motoring the generator with grid power if the turbine trips..... I think you've got some other gremlin to chase, and good luck with it!! Keep us in the loop as you try/find things. Interesting, interesting......

Disconnect components until it goes away.

Just run for short periods with the components isolated.

I'd start with the alternator.

A capacitor to ground might be the ticket for your fans, maybe an in-line diode as well.

Originally Posted by rspears

Are you thinking of a flyback diode - Flyback diode - Wikipedia, the free encyclopedia From what I see the diode is there to protect the contacts in the relay from arcing, not from pushing power into the system vs being driven. I'm a gearhead vs a spark chaser, and that generator thing just doesn't make sense to me. Then again, on big power generators (electric utility size) one of the most important pieces in the generation controls is the backfeed prevention to keep from motoring the generator with grid power if the turbine trips..... I think you've got some other gremlin to chase, and good luck with it!! Keep us in the loop as you try/find things. Interesting, interesting......

Yes, the diode acts as a one way valve to stop the backfeed. I also realized that I had changed the wires when I re-installed everything. Before the dual fans were wired in series. I became concerned that a single failure would take out both fans so I changed the connections so each fan is independent but share a common power supply. (As an aside, when running dual emergency generator sets, a synchronizor on the motor govenors must be used as one generator will become dominant and force the other generator to become a motor and drive the prime mover.. so you end up with a electric motor driving the engine! The synchro keeps the generator output matched and in phase.)

Originally Posted by firebird77clone

Disconnect components until it goes away.
Just run for short periods with the components isolated.
I'd start with the alternator.
A capacitor to ground might be the ticket for your fans, maybe an in-line diode as well.

I think a diode would be the way to go if I can prove the fans can become a generator. I know it is potentially possible depending on the motor. I just don't know these fan motors. Since it only happens above 70, I don't see me "testing" many things on the highway. But thanks for the thought~~

Had similar issues once upon a time with an electric speedometer.....is yours electric or mechanical???

The one I had trouble with was a Dakota Digital....took the dash unit and speedo to them, they did some of their wizardry, no more problem.

And that would be pretty much be the extent of my knowledge on feedback problems!!!!!!!!!

Originally Posted by Dave Severson

Had similar issues once upon a time with an electric speedometer.....is yours electric or mechanical???
The one I had trouble with was a Dakota Digital....took the dash unit and speedo to them, they did some of their wizardry, no more problem.
And that would be pretty much be the extent of my knowledge on feedback problems!!!!!!!!!

Yeah, it's electric.. The other change that was made over the winter was the lower pan behind the grille was added. To help force all the air through the radiator..
Is this the culprit?? I don't know.. I guess I'll just drive it the speed limit and it'll be fixed!

HAH! NOT!!!

I think I have another fan from a wrecked vehicle. I'm wondering how my buddy will feel about holding it out the window while we run down the highway with it hung out there with a volt meter attached?!?!?! rofl..

Originally Posted by 34_40

...I think I have another fan from a wrecked vehicle. I'm wondering how my buddy will feel about holding it out the window while we run down the highway with it hung out there with a volt meter attached?!?!?! rofl..

Let's see, you're sayin' I can buy a Prius or Volt, mount a bunch of electric fans anywhere they will catch air going down the road and I'll have a perpetual motion machine that runs off the batteries, but re-charges the batteries from the air velocity through the fans?? Too many things wrong with that picture, Mike.

Originally Posted by rspears

Let's see, you're sayin' I can buy a Prius or Volt, mount a bunch of electric fans anywhere they will catch air going down the road and I'll have a perpetual motion machine that runs off the batteries, but re-charges the batteries from the air velocity through the fans?? Too many things wrong with that picture, Mike.

You're funny! No, that's not what I'm saying! But what I am investigating is a fan motor(s) becoming a generator that's out of phase with the rest of my electric system. Something is causing the speedo and tach to go crazy! Didin't check the other gauges so I can't speak about them.. And don't you know sarcasm when you read it??? And here I thought I was transparent!

If your speedo and tack are digital it could be a frequency feedback from the fans that is causing the problem, a ferrite bead could possibly be the solution.

Only above 70, I missed that part.


Sounds like an AC component in your power.

Fans sound like a good suspect.

Originally Posted by 36 sedan

If your speedo and tack are digital it could be a frequency feedback from the fans that is causing the problem, a ferrite bead could possibly be the solution.

No, they aren't digital but they are electronic.. Tell me more about this ferrite bead?

Originally Posted by firebird77clone

Only above 70, I missed that part.
Sounds like an AC component in your power.

Fans sound like a good suspect.

That's what I was thinking! I may be way off base but I have heard of it before!

Sounds to me like the flux capacitor is whacko again, hate it when that happens!!!!!!!

Originally Posted by Dave Severson

Sounds to me like the flux capacitor is whacko again, hate it when that happens!!!!!!!

Nah.. the flux capacitor only reacts at 88 mph! ROFL!....

Ferrite beads are what we call "Gremlin Catchers", they're used on most electronics now days, you'll often see one on the power cord and other cables on your computer (the bulge in the cord). Basically they trap and store unwanted frequencies (A/C).

Most likely at the higher speeds the fans are forced to turn faster than their motor will allow (sometimes referred to as the generator effect), this can cause the brushes to arc on the commutator producing A/C frequencies that can interfere with sensitive equipment.

The ferrite bead, either applied to the sensitive equipment (speedo) or the the source equipment (fans) will absorb the phantom frequencies and store them until the equipment is turn off. Ferrite beads are usually applied to one (sometimes both) wire of the equipment, usually the wire goes through a hole in the bead (bead slips over the wire’s insulation), the bead does not physically contact the wire electrically (leave the insulation on the wire), rather it works by inductance.

Ferrite beads come in all sizes, you’ll find them online. Check with your speedo manufacture for a size (frequency range) they recommend. Slip the bead over the wire tape it in place and it’s done.

Originally Posted by rspears

What I don't understand is how this "frequency feedback" travels without a complete loop. At 75mph your fan is not needed, and the thermostat/controller would be open, eliminating the path for 12v power to the fan motor. The fan is freewheeling, but the path back to the electrical system is blocked by an open switch, either a physical contact or an electronic switch in a controller. How does this feedback get to the other components if the fan is OFF?

I only control the ground side with the relay! The positive side goes right back to the main power connection, aka battery.

Originally Posted by 36 sedan

Ferrite beads are what we call "Gremlin Catchers", they're used on most electronics now days, you'll often see one on the power cord and other cables on your computer (the bulge in the cord). Basically they trap and store unwanted frequencies (A/C).

Most likely at the higher speeds the fans are forced to turn faster than their motor will allow (sometimes referred to as the generator effect), this can cause the brushes to arc on the commutator producing A/C frequencies that can interfere with sensitive equipment.

The ferrite bead, either applied to the sensitive equipment (speedo) or the the source equipment (fans) will absorb the phantom frequencies and store them until the equipment is turn off. Ferrite beads are usually applied to one (sometimes both) wire of the equipment, usually the wire goes through a hole in the bead (bead slips over the wire’s insulation), the bead does not physically contact the wire electrically (leave the insulation on the wire), rather it works by inductance.

Ferrite beads come in all sizes, you’ll find them online. Check with your speedo manufacture for a size (frequency range) they recommend. Slip the bead over the wire tape it in place and it’s done.

One of my "tasks" over this coming winter is to replace existing gauges with a new set from Classic.. Thanks for the info on the beads!

overpost sorry