Sherman M4A2 Detroit Injectors

[Malcolm Towrie]

For those that don’t have a tester, I’ve seen a neat way of doing a quick check on an injector. With the injector in your hand, fill the inlet fitting with WD40 using the red straw. Stroke the follower up and down by hand. When it goes solid on you, give the follower a rap with a rubber mallet. You should see a misting spray from all the spray nozzles.
Of the 6 spare tips I have, I found 3 had at least one one nozzle plugged. The N65 tips have 8 nozzles. These nozzles are only about 0.006” diameter so I don’t have anything to poke them clear with. Detroit had a tool that I guess had a 0.005” wire attached to a handle but it must have been very fragile. And anything driven into the nozzle under 2000 psi pressure ain’t going to move very easily.
Malcolm