Inlet Air Heater

Discussion in 'Class A / Diesel Pushers' started by Triple E, Jan 24, 2010.

  1. Triple E

    Triple E Senior Member

    I need to replace the relay on my "Inlet Air Heater" on a Cat 3126B. Do any of you fine folks have a drawing or can suggest a location on the where about's of this relay? I am assuming it is my relay because the glow light comes on for about 2 sec. then goes off and I cannot hear the clicking sound of the relay. Normally I can hear the relay when it energize's. Now I am having to plug in the block heater over night to start the engine. -Steve



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  2. Triple E

    Triple E Senior Member

    Re: Inlet Air Heater

    I found a drawing. If anyone else needs to have a copy, let me know and I will email it to you.


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  3. Guest

    Guest Guest

    Re: Inlet Air Heater

    Sorry Steve ,, i was gonna look that up for u last night but it slipped my mind ,, but good thing u found something ,, but one thing ,, is u'r cat that hard to start in the cold ??? ,, my cummins was never plugged in ,, and most of the time i forgot to wait to start ,, it would start ,, run rough ,,, i know alot of the Cummins dealers around me say not to plug in the block heaters ,, unless really needed ,, the engine gets used to being plugged in ,, kinda like the old Mack's ,, that got used to the on board ether injection system ,,
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  4. Triple E

    Triple E Senior Member

    Re: Inlet Air Heater

    I never had a problem either until the inlet heater stop working. I have started the MH at 8 below with no problem but now I have to crank her and crank her until she starts. O'boy do I get the white smoke. When I plugged her in overnight she will start right up like it use to with the inlet heater. I started to notice last summer that the relay would not stay on steady as usual. I would hear the relay click on and off, on and off. Now the light comes on for about 3 sec. and goes off. Will not come back on until I turn the key back on. I do not hear the relay at all. I am hoping that it is just the relay. While I have her in storage, I start her on the first Sunday of the month. Let it run for 2 hour at 1150 rpm's. I also start the generator for the same amount of time with a load on it. I hope that it does not get to use to being plug in, that would be the pits.
    If you think that I might have another problem, please let me know. I am always open to any suggestion. Thanks, -Steve :)
     
  5. Triple E

    Triple E Senior Member

    Re: Inlet Air Heater

    Rod, Is it safe to assume that since the glow light comes on that the system is OK. ie, no blown fuse? MY drawing is a oneline drawing. Appears that one wire from the ECM is to the relay and another wire going to the light. So I am assuming that the relay and light are parallel inside the ECM. Am I on the right track or am I out in left field? Thanks, -Steve


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  6. Triple E

    Triple E Senior Member

    Re: Inlet Air Heater

    One more question, I hope. Rod or anyone, the inlet air heater is controlled by the ECM. I would assume the heater is controlled the same on the Cummins as is on the Cat. Question; Is the heater controlled by a timing sequence or by ambient and or engine air temperature? The temp is 38 degrees and my MH started like it should. If have never seen a relay fix it self. :question: :question: :question:
     
  7. LEN

    LEN Senior Member

    Re: Inlet Air Heater

    I have the 3126 in mine as well. The time the inlet heater is on apears to be related to the outside air temp. Seems in the 10 degree or so it takes a looong time for the wait to start to go out and just a little time in 40 degree temps. Could it be possible the temp sensor is the culprit, seems like about 50degrees is where the preheat comes on.

    LEN
     
  8. Triple E

    Triple E Senior Member

    Re: Inlet Air Heater

    Len, here is some info that I found today. The Air Inlet Heater will come on for 2 seconds regardless of engine coolant temperature. Air Inlet Heater will turn on for 30 seconds when the SUM of the engine coolant AND air inlet temperature is less than 77 degrees.
    So this tells me that there are two temp sensors involved and a timer.

    Well for some reason it started working today so I guess I should stop being worried until the next time it stops working. Can't fix's something when it isn't broke. :approve:

    Also, I have a good write up on the HEUI pump. If you would like a copy, PM me with your email and will send it to you. ;)


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  9. brodavid

    brodavid Senior Member

    Re: Inlet Air Heater

    helping each other, the way to do it
     

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