harbor freight compression tester

[Shadetreemechanic]

As many on here have already posted, the Harbor Freight diesel compression tester has a glowplug attachment for our engines that will not screw in the glowplug hole.
The problem is that it is too fat at the end to fit far enough into the head for the threads to catch.
You can fix this by unscrewing the schrader valve from the end of the adapter and cutting about 3/16 of an inch of length off of the adapter. Be sure to leave enough internal threads to reinsert the schrader valve and the thing works like a charm.

 

[Thatguy]

This is good to know as I have one of these I bought a few years ago and have never taken it out of the box.

 

[Shadetreemechanic]

here are a couple of pics of my modified glow plug adapter. The piece I cut off is laying on the bench as well.

 

[itsacrazyasian]

I have this one from Harbor Freight. No modifications necessary.
Just used it today on a 7.3 actually.
http://www.harborfreight.com/14-piece-diesel-compression-tester-set-46800.html

edit: as i look at your pictures a little more closely, all my adapters are black tool steel not silver. Is yours the 14 piece set?

 

[Shadetreemechanic]

It Looks like they have changed vendors for the 14 piece kit. Their 12 piece is US General and still has the too fat adapter.
My kit is a couple of years old and always worked great on mercedes. Last weekend was my first attempt on an International.

 

[Shadetreemechanic]

I am bumping this thread for thefarmboy21.

 

[Sycostang67]

This is good to know, I wonder if there is enough room to rethread the inside if you cut too much off.

 

[ToughOldFord]

Just get the more expensive one, it works fine.

 

[Thefarmboy21]

Awesome! I have to got tomorrow regardless, so now I'll just add this to my list

 

[4x4manonbroke]

.. I will be purchacing one too, so after im done with the HG's .. i will do this before filling it up with coolant .. Check to see that its all sealed up ..