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post #1 of (permalink) Old 12-21-2002, 01:43 AM Thread Starter
 
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Manifold Heater Question

My Jeep runs like crap when it's cold and I have finally decided to do something about.

When I rebuilt the Scrambler I rewired everything and dumped all the emissions crap. So, I don't have the relay that the manifold heater used. Is there any way to check to see if it works? Can I just hook it to a 12V source and listen?

Also, is there any way to check if the heat riser valve/tube is working?
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post #2 of (permalink) Old 12-21-2002, 12:25 PM
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Re: Manifold Heater Question

1. ith the engine cold...
2. Hook up the heater to 12volts (fused).
3 Start the engine after 35 seconds letting the heater heat.
4. See if the engine runs better.
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post #3 of (permalink) Old 12-21-2002, 02:35 PM
 
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Re: Manifold Heater Question

Mine does the exact same thing. I tried to let it warm up a while before I cranked it today, but I don't think it helped much. It ran better but it's relatively warm today. Shouldn't the manifold get warm to the touch with the key on? I don't think mine was...

I traced the wires back to a small box attached to the firewall.
Is this the relay? (see attachment) Could it be bad?
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post #4 of (permalink) Old 12-21-2002, 02:48 PM
 
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Re: Manifold Heater Question

I just wired mine back in this morning. There is a heavy red wire, about 10 gauge that goes to battery (actually it runs to the connector on the wirewall, drivers side and gets battery power, ie always live). There is a thin red /white stripe wire that goes to key on power. That powers the relay. There is a green wire that goes to the sensor on the intake manifold, and provides ground, thus closing the relay, until the motor heats up, and an orange wire that goes to the heater element. The heater element is self grounded thru the intake manifold and bolts.

If all works as planned, turning on the key with a cold engine will close the relay via low current running from the thin red wire, thru the relay coil, out to ground by the green wire thru the temperature activated switch. This circuit controls and closes the relay when the engine is cold. The closed relay then provides high current (say 20 amps) through the closed relay contacts to the orange wire that powers the heater element. If you want to test the element, see that it will draw current when hooked to the battery by a 10 gauge wire. If you find the element good, and that it improves cold running, you will need to wire up a relay to handle the current draw and turn it off once the engine coolant gets up to temperature. It's a black topped sensor with a single round lug on top located on the top surface of the intake manifold that controls it, as mentioned earlier, by providing a path to ground when it is cold.

I tested the element on the bench, and in 20 seconds it gets very hot, in 60 seconds the whole assembly is too hot to touch.

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post #5 of (permalink) Old 12-21-2002, 09:18 PM Thread Starter
 
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Re: Manifold Heater Question

Thanks for the replies. I will check to see if mine works tomorrow. In the meantime, do you have part # for the relay. If not, how many amps is it? I don't know if I want to put the relay back in (I have a Painless Harness) or do the switch thing. Also, what's the chances that my sensor is still working if I decide to go the relay route?

As an aside, does anyone know where you can get harness plugs for relays. When I upgraded my HEI with a rely I had to make each individual wire using heat shrink and all the works. It wasn't hard it just took awhile and and doesn't look too well.
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post #6 of (permalink) Old 12-21-2002, 09:58 PM
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Re: Manifold Heater Question

1. An aftermarket generic Headlight relay will work just fine, and it's cheap.
2. I usually go to a local Pull-It yard and remove varied OEM relay sockets that will fit the Headlight relay.
3. If wired correctly the sensor may work... the caviet is wiring it correctly.
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