General Information > Troubleshooting

Is this the punishment for not lapping injectors?

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Gnarlodious:
AAZ in a Vanagon. A friend put in new nozzle inserts, ever since then trouble started. Symptoms are long cranking when hot or (especially) warm while white diesel vapor blows out the back. When it finally does fire it blows a thick cloud of white unburned fuel. So I took to letting it idle extensively, however when punching it the cloud of white smoke blows out, like unatomized fuel was collecting in the combustion chamber.
If cold enough for the glow plugs come on it starts up immediately.
Another symptom, when cold is severe bucking, as if no burn in one or more cylinders. Compression is 340, 370, 300, 300.
Runs great when hot at freeway speeds.
WHAT I SUSPECT:
My friend didn't do the ‘lapping’ as instructed here, he just took them apart and popped the nozzles in:
https://vincewaldon.com/2008/10/29/how-to-rebuild-diesel-idi-injectors/
What I think is happening is the inserts didn't seal because of not lapping, so fuel is leaking down into the combustion chamber all the time, but mostly when idling and off. If I crank it 30 seconds after shutting it off it starts pretty quick, but the longer it sits the longer cranking I can expect. This sounds like fuel draining out of the injector. I don't know exactly what happens inside the injector so I am hoping for some advice. Am I on the right track?

ORCoaster:
Have you checked your timing lately?  White smoke is also a poor time condition.  But if you put in new nozzles without smoothing those surfaces there very well could be a bad seal there allowing fuel into the cylinders. 

fatmobile:
Having a compression of 300psi on 2 cylinders will cause white smoke.
 Kind of surprised it starts at all when cold.

 Other cause could be retarded timing, like ORCoaster said.

The lapping keeps fuel from leaking out the side of the injector,
 between the 2 halves.
 not into the combustion chamber.

Gnarlodious:
Well it does start up and run really good, it will go 70 if I want to. And that is the high elevation of the American West. It didn't smoke or have the hard hot starting before the new nozzles were put in. I don't know how new nozzles could change the timing, it has the Giles pump which is set to his timing recommendation. Do you think new nozzles could change the popping pressure? If fuel is leaking out the injector side wouldn't it vent down the side of the injector?

ORCoaster:
You put in new nozzles and didn't pop test them aferwards to see that they were letting go at the proper bar pressure?

Say it isn't so!!!  You GOTTA DO THAT!!!   

In fact you should make sure they are balanced, all popping at nearly the same pressure.  If you didn't follow up on that then you may be getting more fuel sprayed in at a lower pressure than you should. 

Go back two giant steps and redo that install.  Then report back to us how the engine runs.

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