I picked up one of these cheapo $45 cylinder leak-down testers from Harbor Freight last year. I'm now in need of trying to use it to diagnose my leakage problem. However, despite having a 14mm x 1.25 threaded adapter within the kit, I am completely unable to get the damn thing to thread into the spark plug hole from the top. I've confirmed that it IS the proper threading, since I can thread it on an old head from the cylinder side. My guess is that it is either too short on threading and/or too fat above the threading.

Does anybody have a lead on a M14x1.25 spark plug adapter that they know to work on these '98 4.6L v8(s)?

-Steve
Titusville, FL




thread adapter next to spark plug




threads from the cylinder side, but not the top




cheapo HF leak-down tester

 

seems I already had an old thread going on this https://www.f150online.com/forums/v8...endations.html

 

just to circle back on this, if anyone else has the same issue, I bought a "Star Products (STA70328) M14 HOSE ASSEMBLY - LONG THREAD XXX" and it worked perfectly ... just make sure you take the shrader valve out first