Injector pop testing - what does it tell you?

[tlj87]

Can diesel fuel injectors "pop test" OK but still have issues? I took three injectors to the local diesel injection shop. They pop-tested them and cleaned the exterior of each unit and said they were fine. This took about 10-15 minutes while I waited. There was no charge for this other than $3 for new washers. I'm experiencing what I would call nailing type sound that seems to be most audible around 2000 RPM (NH 1630/Shibaura N843) I've cracked the lines on each and can't discern any difference and there is no smoke from the exhaust other than white smoke right upon startup.

 

[thepumpguysc]

Sure, its possible..
If in doubt, get them to install new nozzles.
The tests are performed using a downward stoking motion by hand..
Nowhere near the speed of 2000 rpm.

 

[Agvg]

Timing issues?

 

[tlj87]

Someone mentioned cold retarded timing in another related thread. I’ve never dealt with adjusting timing before. For reference, here is what I’m hearing: NH 1630 engine sound - YouTube

 

[mini14]

timing should advance when engine is warm, retarded when cold a govorner inside the pump is changing the timing. A pop test is used to determined the predetermined pressure at which each injector fires. there are shims used to balance them out so they all fire within factory set parameters. ive listened to the video again, sounds pretty normal to me, I have 3 diesel trucks a diesel skid steer and a diesel tlb I take care of myself. this isn't a truck engine surrounded by sheet metal and sound deadening material. Most of that engine on those tractors is exposed so you will hear more of the diesel experience.

 

[Jerry/MT]

"....ive listened to the video again, sounds pretty normal to me, ..." I agree. Early in the video I hear a clicking that sounds like excessive valve lash but I don't hear it at the end of the video.

 

[CatD6]

It tells u what pressure the injector is popping off at ,also the spray pattern, CatD6 here