[MacKenzie]

:lol: Help please !!
I was happly spending an afternoon changing out the fuel filter on my 7.3 PS. So I had the hood up and was making sure there was no fuel leaks. NO LEAK, Sooo as I was closing the hood, I noticed smoke riseing from one of the two identical relays that are located one next to the other on top of engine and to the left.I'am calling it a relay, Not sure ??
I removed the wiring and i burned my fingers. I knew this was a dead short.
Now, I was told by a neighbor who works on catipillor deisels that this more than likly was the "Manifold air heater circuit". It is supposed to warm up the air intake to the motor.
Can anybody help?? Where is the heater element and can I safely drive the truck with this system out of the loop for now? I would like to be able to replace this element myself if possable. Any help will be greatly appreciated.
Regards: MacKenzie

 

[morrisbeer]

I have had my air intake heater out and plugged for about 4 years now. Right behind the fuel filter, slightly left of it there is a plug in the "Y" pipe, rather large (3/4" or so I guess) that has a couple large wires that go to it. I just capped off the wires and went to the hardware store and bought a plug that fit.

 

[wittmeba]

Is this it - just right of the 'Cold Side Only' hose clamp and below the boost tube for my gauge?

 

[TTBadDog]

http://www.thedieselstop.com/forums/f25/air-intake-heater-plug-214676/

 

[catch&release]

:lol:
I was happly spending an afternoon changing out the fuel filter on my 7.3 PS.

Let's see........"happily" and "an afternoon"........just to change the fuel filter? I'm guessing beer was involved? Seems like lots of guys use this method when working on their trucks.:lol:

 

[jwspencer]

Mac:
You might want to check that relay, there shouldn't have been any current going to the intake heater unless the outside temp was pretty cold. Your intake heater relay might be stuck closed " carrying current all the time". just my $.02

 

[Camshaft]

You have a bad relay - likely GP circuit.

The contacts are burnt and making more resistance.

 

[klhansen]

Just to add my 2c, do you remember which relay was smoking? If it was the front one, that's the IAH relay, which RARELY operates (only low ambient temp, extended idle immediately after start - go pedal NOT pressed, and AFTER the GPR is deactivated). The IAH isn't a starting aid, it's just there to reduce smoke on extended cold idle. Like the others have said, you can remove and plug it without ill effect.

More likely it was the GPR (rear relay), as it gets exercised often and the contacts can pit and go high resistance and get HOT.

The Hard/No Start link in my sig has more info on GPR system.

 

[chuck767]

If it was the front one, that's the IAH relay, which RARELY operates (only low ambient temp,.

At what temperature does the heater come on and for how long?

 

[SmokeyWren]

At what temperature does the heater come on and for how long?

With intake air temp below freezing, after you start the engine and the glow plugs turn off, the oil temp must be less than 131° F, and the engine must be idling. As soon as the engine oil warms up to 131°, or as soon as you start driving, the intake air heater (MIAH) goes off.

Manifold Intake Air Heater (MIAH)

To reduce white smoke during long idle periods at low ambient temperatures, the PCM will activate the intake air heater. Specific conditions must be present before the heater is activated:

• ambient temperature must be below 0°C (32°F)
• engine oil temperature (EOT) must be below 55°C (131°F)
• vehicle power (IVPWR) must be between 11.8 and 15.0 volts
• parking brake must be applied on manual transmission vehicles
• the transmission must be in PARK or NEUTRAL on automatic transmission vehicles
• glow plugs must be off