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  #1  
Old 10-19-2004, 04:26 PM
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How does the older GP relay work

Switched to the fast GPís last Saturday. Much better starts, but I also put in new (rebuilt injectors) so that may be some of it. I didnít install the new relay that came with the kit after reading all the posts here, and not really having a clue about how to wire it in. The price of the kit was less than a relay so I canít think itís very good anyway. I didnít throw any old parts away. So how does the old original relay work? Does it sense the temp of the plugs, or is it a timer? Plugs now glow quicker but itís still about 15 seconds, and I wait until the lights off to start the car. Must be a temp sensor as theyíve always glowed for just a spilt second after the cars run.
By not putting in the new relay, am I throwing a strain on the electrics in any way?

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  #2  
Old 10-19-2004, 04:51 PM
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I recommend that you install the new relay, otherwise you're just wasting your money on the kit. The relay in this kit is the same as the one you can buy by itself and the main feature of it is the afterglow (glow plugs keep glowing briefly after starting the engine). There is a temperature sensor that's bolted into the engine, but regardless of the sensor the relay will cut out after a brief time (about 30 seconds). You can hear this as a click.
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Old 10-19-2004, 05:40 PM
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Every diesel I've had before I got my benz, the GP would "cycle" on/off a couple times when engine first started. My benz GP light comes on when the key is first turned, I wait for light to go out then immediately start. After it starts, the glow plugs don't cycle at all .


Is this normal?

Cheers,

Bill
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  #4  
Old 10-19-2004, 05:53 PM
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Yes that's normal. But the plugs don't stop glowing as soon as the light goes out, though they do stop if you start the engine unless you have one of these new relays. The light just indicates the recommended wait time before starting. With older relays, this recommended time is often too short so just let it glow longer before starting the engine.
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Last edited by DieselAddict; 10-19-2004 at 05:59 PM.
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  #5  
Old 10-19-2004, 06:40 PM
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crash9,

I'm surprised you even need glowplugs where you live!
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Old 10-20-2004, 10:11 AM
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Quote:
Originally Posted by DieselAddict
Yes that's normal. But the plugs don't stop glowing as soon as the light goes out, though they do stop if you start the engine unless you have one of these new relays. The light just indicates the recommended wait time before starting. With older relays, this recommended time is often too short so just let it glow longer before starting the engine.
I thought my GP's needed replacing because I have to start twice at times. Before i replace them I will surely try letting them glow longer.

Once again, THANKS!!

Cheers,

Bill
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  #7  
Old 10-20-2004, 12:17 PM
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Quote:
Originally Posted by jbaj007
crash9,

I'm surprised you even need glowplugs where you live!
Iím up higher at about 5,000í Ė 95 deg summers and snow and mid teens in the winter, but yeh. I should try with the new injectors just to see, but the cars at around 390lbs. comp., and they put the plugs in for good reason.
Now Iím getting confused about the relay. The glow light does not stay on as long as it did with the old GPís, so Iím assuming it is not a timer, but a heat sensor. Then again maybe Iím imagining things. I understand the afterglow thing, but also have read mixed ideas about whether thatís such a good thing.
My concern is removing the ground strap on the new plugs Ė were the resistors on the old plugs insulated from the block? Iíve been around to many English cars to want to mess with the electrics too much. I guess the fuse strip would have blown if this werenít proper Ė Iím also just a little paranoid by nature. I drive in the middle of no place most of the time.
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72 Westy
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85 Jeep CJ7
86 Chevy 6.2l diesel PU

"The object of life is not to be on the side of the majority, but to escape finding oneself in the ranks of the insane."
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  #8  
Old 10-20-2004, 03:15 PM
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Quote:
Originally Posted by crash9
I Iíve been around to many English cars to want to mess with the electrics too much. I guess the fuse strip would have blown if this werenít proper Ė Iím also just a little paranoid by nature. I drive in the middle of no place most of the time.
So you know the saying about MG's--don't go out after dark

Never understood how positive can be ground....

Cheers,

Bill
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  #9  
Old 10-20-2004, 03:17 PM
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Quote:
Originally Posted by bill murrow
So you know the saying about MG's--don't go out after dark

Never understood how positive can be ground....

Cheers,

Bill

They don't call Lucas "The Prince of Darkness" for no reason at all...................

Ever hear the comment about British electrical systems being inferior to and at best equal to an elaborate system of Tallow candles?
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Last edited by boneheaddoctor; 10-20-2004 at 03:29 PM.
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  #10  
Old 10-20-2004, 03:24 PM
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Quote:
Originally Posted by boneheaddoctor
They don't call Lucas "The Prince of Darkness" for no reason at all...................
I've had several Triumph/BSA motorcycles converted to "normal" wiring just so I would have lights to see the deer in the road. Flashlights don't work well, even in a pinch

Not much wiring on a bike compared to cars so I guess bikes are fairly easy to convert because my buddys friend didn't charge much to do the conversion


Cheers,

Bill

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