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    Oil Pressure Switch, Timing Marks, Heater Valve (Sorry-Visually impaired)


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    Join date : 2014-05-26

    Oil Pressure Switch, Timing Marks, Heater Valve (Sorry-Visually impaired)

    Post  z1 on Mon May 26, 2014 8:05 pm

    '79 Impala 305 4 door

    I'm visually impaired so sorry if some of these questions seem basic.

    1) I'm installing mechanical gauges and have been searching for the oil pressure switch. I read it's under the distributor, I can feel the wires (I think) but the space is so tight I don't see (no pun intended)  how to get it out.

    2) I think I found the timing mark on the balancer but I don't see any kind of pointer on the motor.

    3) Does anyone have a diagram of the heater/ac connections. My heater control valve has a pinched nylon hose going no where.

    Thanks, Bernie

    Last edited by z1 on Tue May 27, 2014 12:06 pm; edited 1 time in total
    Sweet Seventy9
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    Re: Oil Pressure Switch, Timing Marks, Heater Valve (Sorry-Visually impaired)

    Post  Sweet Seventy9 on Tue May 27, 2014 12:08 am

    Hi Bernie, welcome to the forum.

    Oil pressure sending units are tough to remove.
    Reach in from the drivers side in the area under the distributor, at the very back of the engine block.  The sending unit is there.

    Here is what it looks like -


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    Re: Oil Pressure Switch, Timing Marks, Heater Valve (Sorry-Visually impaired)

    Post  GM B-Body Forum on Wed May 28, 2014 12:05 pm

    Hey Bernie welcome aboard! Im assuming the nylon hose your talking about is the little vacuum hose that turns the heater control valve off and on. Now that i wouldnt worry about, its defualt position is open so youll always get heat. Thats only there to turn it "off" to stop the coolant flow when you move the selector inside to "cool". Ive had alot of issues with replacement heater control valves leaking, so i have altogether got rid of it. When you move the selector to cool it closes a door inside the heater box so youll get cool air regardless if the heater core has hot or cool fluid in it.

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    Re: Oil Pressure Switch, Timing Marks, Heater Valve (Sorry-Visually impaired)

    Post  solo79 on Thu May 29, 2014 7:17 pm

    Welcome to the forum!! Ok, looks like #1 and #3 have been answered, I'll take #2.

    Look behind your water pump and on the timing chain cover there should be a timing tab attached to it. If it's the factory engine/timing cover, it should still be there as they are welded on and rarely fall off. Some aftermarket covers have bolt on timing tabs, so yours may be missing if it's aftermarket (usually chrome).

    Here's a picture for you of a stock cover. Red arrow points to timing tab:

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    Thank you,

    Post  z1 on Sat May 31, 2014 10:37 am

    You guys are great, thanks so much for your help. I'll poke around tonight, much easier for me to see with just a drop light.


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    Re: Oil Pressure Switch, Timing Marks, Heater Valve (Sorry-Visually impaired)

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