# how do you add a oil pressure light to a 25hp kohler



## Topdj (Jun 9, 2004)

where do you plumb it?


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## jodyand (Sep 16, 2003)

It should be around the oil filter. If you dont already have a sending unit there should be a plug.


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## Argee (Sep 17, 2003)

On the opposite side of where you drain the oil is a plug, you should be able to pick it up there.


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## bigl22 (Sep 16, 2003)

I was just on the GW forum reading about oil pressure[ { all I can do is read since I am apparently permanently banned from posting by the knothead spike] -- -------------------------- they had a question about accurate readings and MGM said be sure to let oil line bleed out air after hookup and let a litle oil out to blow any trapped air in oil line out to ensure acuracy--------------------------- I was stunned to read Kevin beitz declare that it didn't mater whether air or oil in line , all the same-- wrong! ---------------------------- air in a tube will compress much more than even motor oil[ which is famous for compression qualities]-- to ensure accuracy, bleed all air out to allow the ful pressure to be read-- air can cause a loss of lubrication in any given point and will show a lower reading in any guage-- bigl22


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## tjw in kans (Oct 10, 2003)

the port for a new style 25hp kohler is an 1/8 inch port on the front of the motor behind the carb. the older motors had a port by the oil filter, mine didnt. i opted to add an adapter plate at the filter location instead of fumbling around with the carb linkage and springs while it was still under warranty. plus any leaks would be readily visible. ck pg 4 in the craftsman section for my old post on oil pressure gauge. the electronic sender works the gauge and it had an extra post for a warning light hookup. i may add a temp gauge to the second port of the adapter. an automotive type sender would be the cheap way to go in the front port of the engine. topdj i would like to see your tach installation when you get it. i would like to change the bezel on my oil pressure to match what i think will come with your tach. good luck with project.


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## balmoralboy (May 22, 2004)

*GONG*



> _Originally posted by bigl22 _
> *I was just on the GW forum reading about oil pressure[ { all I can do is read since I am apparently permanently banned from posting by the knothead spike] -- -------------------------- they had a question about accurate readings and MGM said be sure to let oil line bleed out air after hookup and let a litle oil out to blow any trapped air in oil line out to ensure acuracy--------------------------- I was stunned to read Kevin beitz declare that it didn't mater whether air or oil in line , all the same-- wrong! ---------------------------- air in a tube will compress much more than even motor oil[ which is famous for compression qualities]-- to ensure accuracy, bleed all air out to allow the ful pressure to be read-- air can cause a loss of lubrication in any given point and will show a lower reading in any guage-- bigl22 *


Technically, big guy, Kevin is right on the money! Air may compress more than oil but that doesn't change the pressure, it merely allows the pressure to be transmitted faster to the gauge.That's the principle behind liquid filled gauges which have a liquid section under a membrane between the active pressure zone being measured and the measuring sensor. The liquid damps out fluctuations in pressure and protects the gauge mechanism.

Now, for the reality check. Oil exposed to air in the tube may oxidise and crud up, clogging the tube and making the readings low. Not too likely, but it's good practise to bleed it out.


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## jodyand (Sep 16, 2003)

*Re: GONG*



> _Originally posted by balmoralboy _
> *Technically, big guy, Kevin is right on the money! Air may compress more than oil but that doesn't change the pressure, it merely allows the pressure to be transmitted faster to the gauge.That's the principle behind liquid filled gauges which have a liquid section under a membrane between the active pressure zone being measured and the measuring sensor. The liquid damps out fluctuations in pressure and protects the gauge mechanism.
> 
> Now, for the reality check. Oil exposed to air in the tube may oxidise and crud up, clogging the tube and making the readings low. Not too likely, but it's good practise to bleed it out. *


OK i just learn something THANKS i was always told to make sure there was no air in the lines or you would get a false reading.


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## balmoralboy (May 22, 2004)

*Re: Re: GONG*



> _Originally posted by jodyand _
> *OK i just learn something THANKS i was always told to make sure there was no air in the lines or you would get a false reading. *


Jody, be careful here. Air is not an issue for pressure sensing. But, Air is really a big issue if you are sensing temperature, because it's such a good insulator. You get a temperature gradient along the line if it's filled with air, and heat losses from the line so that it will never read correctly. Big, big difference!!!


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