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Old 11-26-2018, 04:10 PM
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Default GPR - Stancor, White Rodgers, Emerson...any better than the OEM one

Is the Stancor, White Rodgers, Emerson relay really better than the OEM one?

I had to swap out my third relay today. The original Stancor relay last 90k miles. The Stancor relay was replaced with a White Rodgers relay and that one lasted 60K miles. Now the relay is called an Emerson one. All the relays carry the same part #586-105111 except for the original Stancor which was known as the 586-902. I'll be referring the aforementioned relay as a "586" relay.

Before I get into the 586 relay, the operation of the OEM relay is as follows. Inside the OEM relay is a disc. Everytime the OEM relay energized, the disc would rotate. The theory behind this was everytime the GPs energized, there would be a new contact surface. The OEM relay was an intermittent use one. Unless it's 90* out or the motor as some internal heat in, these motors need the GPs to start.

Now the issue I had was with my truck was temperature related. When the outside ambient temperature was around 60* +/- 10*, the GPs would not energize. I thought to myself since I have a HD 200A continuous duty relay, that shouldn't be a problem. When the temps raised out of that range, GPs energized and the truck started.

I have the Ford AIC in my truck. When I turn the key on to energize the GPs, I hit the "Charge Protect" button and it tells me the battery voltage. I got a reading of 10.9 volts when the GPs energized. I began to look at the battery cables on the truck. I decided to make custom ones out of 3/0 and 4/0 welding cable and utilize the military style battery connectors. I have the crimpers from being an electrical contractor.

Positive cables
- Passenger battery to starter - 4/0
- Passenger battery to driver side - 3/0
- Passenger battery to fender relay - #1 or #2 (I think)

Both negative cables were made out of 3/0

After making the cables, the motor cranked faster. Now when the GPs energized, the voltage is 11.4 volts. I guess I needed batter cables.

Fast forward to these two past weeks, the GPs would not energize. I had to jump the big terminals with a hammer to start the motor. So I bring my truck into my shop and began diagnosing the issue. I put a bulb across the control circuit of the relay. The bulb lit everytime I turned the key on. I let the PCM time out and the bulb turned off. I have a bypass switch in the cab for the GPs and activated the GPR manually after it timed out. I heard the coil activate with every press of the bypass switch but no GP activation. With the coil activated, I had power only on one side of the big terminal studs.....bad relay.

So I install another so called HD 200A continuous duty relay. And the GPs once again start energizing. So I took apart the White Rodgers relay and this what a 200A continuous duty looks like after 60k miles:

So is the 586 relay any better than the OEM one? Others have tried the GPR-109 (NAPA), the Western Plow one, generic auto parts store ones, etc, etc but to what success or failure?

This might be my next relay to try. Rated at 500A


Thoughts, discussion, comments

Billy T.
'97 Black F250HD SC, 3.55s, Punisher Trans, PI Converter, Dana 60 RSK w/ V & C SD springs, PIS 175/80s, T500, Cale's tunes, 910s, Smith Bros, ARPs, Fluidampr, IC, E-Fuel, 3" Plenums, CJC Traction blocks, HFHV IDM, T4/BASB, Horton, 268K
- 2016 F350 DRW Ultimate (stock for now )
- 1987 Buick Grand National (Staged)
- 2004 Mercury Marauder
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Last edited by gnxtc2; 11-26-2018 at 04:14 PM.
Old 11-26-2018, 05:08 PM
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79jasper 79jasper is offline
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I had to warranty a autozone one several times.
Cant say how old the motorcraft one was. I also somehow only had one working glowplug.

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Old 11-26-2018, 05:54 PM
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I vote for the 500 amp solution, but that is just my humble opinion. I have a tendency to take things to extremes far too often though, and it doesn't determine the root cause of your problem.

This might be a case of inferior relays manufactured poorly, or another underlying issue burning every relay out that you install. Did you happen to do an amp draw with a DC ammeter to make sure both glowplug circuits are drawing close to the same amperage? Just another troubleshooting step I would take.

Also, judging by the datasheet for your 500 amp choice, you should get 100k life cycles out of it if you so choose. Even if you started your truck multiple times a day every single day, that relay should be good for years to come, at a much higher amperage than what it will actually be switching.

Last edited by jjsalz; 11-26-2018 at 06:17 PM.
Old 12-06-2018, 06:58 AM
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My vote is for the Western plow relay. Same specs as the Stancor for half the cost.

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Old 12-07-2018, 03:13 AM
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I went thru many Napa GPR109s. Garbage. They lasted me a year and would be toast. The price even went up as they use to be like 20$. I installed a stancor maybe two years back and it is starting to fail.
97-250 7.3 Eaton TVS Supercharged, S369sxe, R&D IDI performance T4 mount, my B350/200s, Honey Badger SR with My tunes, BMW M3 seats, Sky 5" RSK skyjacker drop pivot brackets, Sky shackles and hangers, Toyo M/T

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Old 12-07-2018, 12:24 PM
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Originally Posted by hucorey View Post
My vote is for the Western plow relay. Same specs as the Stancor for half the cost.

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Right there with you. Most GPR's are rated at 12VDC. Even though it says 12 VDC on the batteries and everywhere else. We need stuff rated for 15VDC. The Western plaw relay is rated for 15VDC.
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Old 12-14-2018, 05:29 PM
m_j m_j is offline
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try the trombetta
Old 12-18-2018, 08:34 AM
Copperhead Copperhead is offline
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Originally Posted by hucorey View Post
My vote is for the Western plow relay. Same specs as the Stancor for half the cost.
What's the part # for the Western Plow Relay ?
Old 12-18-2018, 12:09 PM
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I believe I'm having GPR issues on my truck. Where can you get a Wstern plow relay?
Old 12-18-2018, 08:39 PM
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Hucorey has ya covered...

2000 F250 CCSB GT4294R, 250/100s, Dahl/Fuelab, BTS, PHP tuning, stock 17* pump
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