Oil sender test

34fordy

34fordy

Well-known member
1936 Oil pressure gauge registers 5 lbs. I installed a mechanical gauge to check and it registers 35-40 lbs. Does this most likely indicate a faulty sender?
Is there a test to confirm this?

Does anyone have a picture of the inside after taking it apart from another gauge like mine in the picture on post #4, either 50# or 80#? Also, does anyone know the correct orientation vertically as after taking the cover off I do not know which way is supposed to be up. I did get the small hairlike wire reattached.
 
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Can check using air pressure. Look on the square brass area of the sender to make sure it is not marked 80 which an original 36 engine will not use. If not marked it should be the 50# style, which is good. I have found some used senders to have a build up of old oil blocking the oil passage on the bottom. A drill bit inserted by hand can remove any blockage, in the passage, just be careful not to damage the brass diaphragm inside, bottom the passage. Spray brake cleaner in the passage to remove all residue of old oil. You may be able to get the sender to read properly.
 
Terry said:
Can check using air pressure. Look on the square brass area of the sender to make sure it is not marked 80 which an original 36 engine will not use. If not marked it should be the 50# style, which is good. I have found some used senders to have a build up of old oil blocking the oil passage on the bottom. A drill bit inserted by hand can remove any blockage, in the passage, just be careful not to damage the brass diaphragm inside, bottom the passage. Spray brake cleaner in the passage to remove all residue of old oil. You may be able to get the sender to read properly.
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I will go out to my shop and see if a bit of cleaning will help. Thank you!
 
I ended up taking the sender apart. Pretty sophisticated device to me. A small wire was broken as seen in the picture where the little red arrow points. The sender installs horizontally and has a side requiring to be up. I have not figured out how the sender operates as it needs a certain amount of pressure to close the points. I will study it more tomorrow sending different air pressures.
 

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They all (fuel, oil, and temperature) operate on the "King-Seeley" principle that uses bi-metallic arms in both units.

They do not operate by resistance.
 
34fordy said:
I ended up taking the sender apart. Pretty sophisticated device to me. A small wire was broken as seen in the picture where the little red arrow points. The sender installs horizontally and has a side requiring to be up. I have not figured out how the sender operates as it needs a certain amount of pressure to close the points. I will study it more tomorrow sending different air pressures.
Click to expand...
509033
 
Looks like it can be adjusted on the back side.
A small screw driver thru the hole on the back can be used to rotate that 1/2
gear varying the pressure.
 
convert 40 said:
Looks like it can be adjusted on the back side.
A small screw driver thru the hole on the back can be used to rotate that 1/2
gear varying the pressure.
Click to expand...

I believe that was used in the beginning to adjust it for either a 50# or 80# gauge. The only way to get to that stage is to ruin the gauge, as I have done.
 
If you try to repair it, see if you can attach another small pc of wire somehow. Then try it. Just fiddling with that small gear to change the reading can become a big PITA. terry
 
tubman said:
If you do try to adjust the wheel, do it in small increments.
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I am hoping that fixing the wire will be sufficient. I am assuming that this particular instrument was set before the final assembly and be correct. I suppose i could not put the case on until after testing and try to set it to agree with the mechanical gauge. I have the mechanical gauge installed in the top port above the sender port. I do need to find the correct orientation for up as evidently this is required. After taking the cover off I have lost orientation.
 
On my 36, I don't think orientation is required. You just screw it into the block until it"s tight. Did this change for newer vehicles? terry
 
terry said:
On my 36, I don't think orientation is required. You just screw it into the block until it"s tight. Did this change for newer vehicles? terry
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The sender I have has an arrow on the front and says UP. The letters KS-7 which I presume are King-Seeley are also on the front. The engine is a late 1938. Being a 50# sender it is possibly original to the engine. There surely is a reason that King-Seeley designated an orientation for proper operation. I am amazed how well the solid brass or copper diaphram "grows" with pressure. It was surely built to last. It appears that the tiny thin wire on the inside is the weak point. It appeared to me that it got too hot and separated. If I could find a picture of the inside of a KS sender, I think it would possibly have been taken in the "up" position.
 
You guys amaze me honestly. In todays world 99% percent of the car guys would trash a part and source a new one. I commend the thirst for knowledge of repairing and understanding how a part functions, with that I'l admit I have never had a oil pressure sending unit apart.
 
35fordtn said:
You guys amaze me honestly. In todays world 99% percent of the car guys would trash a part and source a new one. I commend the thirst for knowledge of repairing and understanding how a part functions, with that I'l admit I have never had a oil pressure sending unit apart.
Click to expand...

I'll tell ya Michael, when ya get this age, even if you don't have much money, ya do have lotsa time to dig into the workings of stuff you always wondered about. You have so much knowledge that I wish I had also. When trying to grow and make a business tick and most importantly love, support, and spend time with your beautiful family, piddling with an old man's quest is not of much importance!
With respect, Don
 
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