Farmall M Compression Oil Pressure Testing Help

Hi All,

Have a Farmall M that was looking to do a
compression test as well as a oil pressure
test.

The compression test should be easy as I
have a tester with M18 female head (as well
as M14 adapter).

For the oil pressure test, it has been a
bugger to find a 1/8" NPT adapter.

McMasty looks to have the following:

•M18x1.5 female to 1/2" NPT male adapter
(or 3/8" NPT male)

•M14x1.5 female to 1/4" NPT male

From there a 1/4" male to 1/8" male should
be simple, but anyone have an easier way to
do this versus me buying all these fitting
adapters?
 
Why don't you just buy a separate gauge for the oil pressure, with a appropriate adapters. some would need a 1/4 X 1/8 reducing coupling, I'm not sure what size the hole in the block is. A 0 to 100 would work on about anything. I tried using a compression tester for oil pressure once, the kind with the tapered rubber tip. I didn't hold it in quite tight enough and it sprayed some oil, obvious that I had adequate oil pressure and need a new sending unit for the car!
 
first of all have you done a compression check on an engine before. ? you need two separate gauges. compression testers are for checking compression. for oil pressure you need a 100 lb. glyserin filled gauge and hooked into the oil gallery. and if you want to watch it while using the tractor attach a 1/4 " hose so you can have it beside you. it will be in 5 lb. increments so you can see whats going on. when your oil pressure drops once engine is hot you know you have excessive brg. clearance. as for the compression check you need 5 compression puff's for each cyl. the first 2 will pretty much give you your max pressure if engine is good. have the throttle off idle so the butterfly is open. and if you want to get fancy install a good readable oil pressure gauge in place of the original. and if you have the original gauge it will be pegged once engine starts and stay there. if it drops thats not a good sign. i have spent enough time on a w6 to know the oil pressure was always pegged when running with the factory gauge.
 
Hi Rustred,

Why would I need two seperate gauges, or specifically an oil filled gauge?

Sadly, the original gauge is busted and poopooed.

I haven't decided on which IH gauge I am going to pick up - the dummy gauge which is original or use a legit gauge.

Will prolly go dummy gauge, but that is why I want to test the oil pressure, so I can then compression set my dummy IH gauge.
 
Cuz I am cheap 😂

Actually, I could certainly order an oil pressure test kit but, then I would have to order online, which I am not a fan of - would be adding another tool to the chest when just a fitting should suffice - and kinda like the idea of making something multi-purpose.

But yes, you are correct, picking up an oil gauge would be the simplest route. 😀
 
I sure wouldn't want to fill my compression gauge with motor oil. Sounds like you are trying to use a compression gauge to check oil pressure? Hopefully not trying to use and oil gauge to check compression, that sounds like a trip to the ER. Compression gauges are made to measure higher pressure of an air column, and likely wouldn't tell you much as an oil pressure gauge. Oil pressure gauges are made to measure the pressure of a liquid column, and would be likely to come apart violently if used as a compression gauge.
 
If a compression test gauge was intended to check oil pressure, it would have come with adapters for fittings other than spark plugs.

You don't need to order on line to get a gauge to check oil pressure. An oil pressure gauge, 0-100 psi with an 1/8" NPT back port, 1/8" NPT coupling, and an 18" 1/8" NPT grease gun hose from your local auto parts store and you can check your oil pressure; without ruining your compression tester by contaminating it with oil. Oil filled is nice but not necessary for what you want to do, automotive gauges aren't oil filled.

You say your cheap. What good is a dummy gauge? Why not just buy a legit oil pressure gauge and install it properly, then you always can see the actual oil pressure, and not need to buy a separate test gauge set up, so you can save that cost. JMHO
 
All tractor mechanics should have an oil pressure test gauge and assorted fitting in their tool box, also a compression gauge, even if its an inexpensive one. A Farmall M should not be operated without a working oil gauge.
 
Oil will completley ruin a compression gage.Go to your local hardware store for fittings. A grease gun hose will work for hooking up a remote oil pressuse gage.Screw the greas gun hose right into the block. then hook the gage to the hose. Use a bell reducer,reducer bushing,nipple,as needed.As was said,go ahead and install a working gage in the tractor. Quit screwing around trying to 'save' money. Do it right and be done with it.In the end,that is the cheapest way to go.
 
You can buy a conventional 2" oil pressure gage for $330 and less.
Mount it on either side of engine where you can see it from the seat.
Leave the original in it's place for now.
 
on hyd. equipment the liquid filled gauge is the most accurate to use as a master gauge. as i said it will be in 5 lb increments as you said you want to check pressure. if you just want a gauge to look at stick anything in there. what is a dummy gauge... i dont understand your thinking here. and what are u talking about compression setting the dummy gauge. as i said you CANNOT use a compression gauge for oil pressure. no word in your first post about the original oil gauge not working. do not buy any chinese of other import gauge, they are not accurate. go get a used gauge from a another tractor is the best.i gave instructions for checking oil pressure but your doing something totally off the wall. i never said you needed 2 separate oil gauges.the master gauge gets removed once you know your pressure results. checking compression is a totally different operation. and thats the joys of mechanical work is you need all kinds of adapters for different applications.
 
Check with Auto Zone.

They may have one in the loan a tool program.

Basically, you buy the tool with the understanding you will use it and return it.
 
Would you believe me if my local auto parts
store do not have oil pressure check kits?

Sadly, they do not - these turds don't
stock them.

I will likely end up just buying a cheap
pittyburg kit from the interwebs - ohh
well.

As for the dummy gauge, I agree, they are
worthless, but that is what the tractor
came with originally and so figured I may
as well keep it looking stock - maybe I
won't as it is stupid to have a useless
gauge...
 
Hi Rusty,

The original gauge on the tractor was a dummy gauge.

A dummy gauge is a gauge which actually doesn't provide very useful info - think modern temp gauges in cars... hot, cold, the little line is somewhere in that zone so it must be some temp - what that exact temp is? Who knows.


To get around this, and keep the gauge looking original to the tractor (ie a gauge with no numbes, just a zone) I was going to set mark it with a compressor, high and low.
 
what the heck are you calling a dummie gauge??? never ever heard of this before. the ihc gauge registers pressure... so when tractor is running gage is to the far right when stopped gauge drops off , that is all most farmers are interested in. pressure or no pressure! i have explained so many times to you about all this stuff but you fail to comprehend it now really wondering about this dummie stuff.
 
Hi Rustred,

I am surprised you never heard the term dummy gauge before - if you have used a simple pressure/no pressure IH gauge then you have lots of dummy gauge experience.

Maybe you are unaware, but some people like to know the specific pressure the system is producing at a given time - hence why people put on gauges that tell you the actual pressure, not just a pressure/no pressure reading.

I think the challenge is you seem to think I do not understand what you are saying, but trust me, I do understand what you are saying.

Problem is, I am not trying to do what you are saying - I am trying to do something different.

If you have any input on that, I am all ears 😀.
 
Just because the gauge isn't marked with numbers does not make it a "dummie gauge."

The needle still moves in proportion to the oil pressure. The gauge still has a range of 0 to 45/60/90 PSI. It's just not marked with numbers.

Even the gauges marked with numbers are not necessarily accurate.
 
i am all ears also, so what are you trying to do? i answer what i read here. now your doing something different. checking oil pressure means just that ,... check it with a master guage from the block . you never said u wanted to replace the original gauge with a readable lb. gauge. would have saved so much confusion. so your not even going to check the oil pressure now that you were given all this info on it. lots of those original gauges had a red zone also so you know to shut the unit down. i sure never hear of any gauge used on tractors or equipment called dummy gauges, they work! to me a dummy gauge would be nonworking one used to plug a gallery or just something for looks.
Untitled URL Link
 
Hi Barnyard,

I totally hear what you are saying, sure a
numbered gauge may be inaccurate and a non-
numbered gauge still registers something,
but that non-numbered gauge could be
inaccurate too.

It is just what I call a non-numbered
gauge, a dummy gauge. 😀
 
Hi Steve,

Yeah, I checked with our local autozone, Oreilly, auto value etc.

Sadly, non of them have a loaner program which includes a oil pressure kit.

It's okay - just gonna buy one off the interwebs.
 
I do not understand why you do not just put replace the regular gauge and be done with it. There is NO reason to temp in a gauge for testing.
 
Hi Rusty,

Oh, I plan on still checking the oil pressure from the block to give me the actual pressure.

I am just not a fan of the standard pressure/no-pressure gauge that was on the tractor, nor trying to infer, should the needle not peg on the non-numbered gauge what that not fully pegged pressure is.

Could I simply trust the "zone" provided, sure - but have seen enough times where that zone was pegged on a gauge and damage still occurred - so I just tend to avoid "zoned" gauges, as a principal, whenever possible.

I guess the simplest solution would be to put on a nunbered gauge, which is probably what I will end up doing.

Regarding the nomenclature of a non-numbered gauge, I get you don't define that as a dummy gauge - no worries - not trying to change hearts and minds, just trying to get this ole gal (Farmall M) setup in a way that works for me. 😀
 
Hi David,

Agreed.

I just figured since I have multiple tractors and people also like to ask for tools for their tractors now and then, having a pressure kit would be a nice addition.

As it relates specifically to the M, yeah, just gonna do as you describe.
 

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