1/8 NPT zerks

[kc5gxc]

I have a Ford New Holland 1715. 1996. The grease zerks are not metric, not SAE, but a European thread. I had to go to the New Holland place to buy one after trying the other kind I bought at the auto parts place. The correct threaded one fit right in. They will do anything to get one into the tractor parts places....ha ha ha!!!!!!!!!!
Pete

 

[Ford850]

Are you sure the holes are not metric and the plug you used is not also metric ?

Some of the zerks are listed in the parts diagram as 6mm. The two I am replacing are listed as 1/8 NPT on the diagram. The pipe plug I have is indeed 1/8 NPT, but I realized when reading this today that I did not test it as I originally said. I compared it to the zerks and it 'looked' perfect, but layed it on the bench where I found it this morning. So I tested the pipe plug in the holes and it does NOT fit any better than the 1/8 zerks. I need to get a tap to see if it spins in partially with my fingers, telling me the thread size is correct but that it needs to be cut deeper. I already bought metric zerks to test and they do not fit at all.

 

[Soundguy]

You need to invest in a couple sets of ID thread gauges.. they are little feeler looking things.. just fold them out and test... sure beats the guesing game you are playing.

I have a sae and metric ID and OD set, as well as a bolt, spark plug, rod gauge as wella s machine screw.. etc. That and a good mic.. and you really take the guessing out on most projects.. unless you run into British thread or something like that..

soundguy

 

[Farmerford]

Soundguy:

I just saw your May 21 question to me. The pipe tap for shallow holes is called a "short projection" tap by McMaster Carr. I have not counted the chamfered threads, but I think there are more than on a bottom tap, but fewer than a plug tap.

McMaster Carr also has British Pipe Thread grease zerks which are common on Asian machinery, and DIN grease zerks that appear on German and some other European machinery.

If I recall the US 1/8 NPT is 27 tpi and the 1/8 BSPT is 28 tpi, and the thread major diameters are very close, so the two types will screw together, but they will leak both oil and coolant, even with lots of Teflon tape (don't ask how I know).

With the right attachments, one can probably have at least four different size grease zerks, of which one-eighth will leak, one-eighth will not take grease, one-eighth will be accessible only by taking off another part or turning the rig upside down, and one-fourth will get stuck on the gun tip so hard that you pull them out.