Glow plugs and injectors, when to throw old ones out

[outback]

I gave a value of 50k – 80k km for glow plugs in the Di motor based on readings both here and elsewhere. This was for the ceramic tip ones.

Note in the Di motor the glow plug initially stays on for a longer time vs the common rail motor. Suggested times for start up on a standard, no mods, Di is 5 minutes or until the motor reaches operation temp.
Hence the concept of a glow plug timer for the Di motor.

Purchasing the most expensive brand name does not solve the matter of a warm motor spraying fuel on an over extended hot glow plug. They all suffer crazing and tip loss.

As for the concept of life time injectors.. Don’t believe a word out of Nissan on this.
True they are a replace non fixable item and at about $1000 plus not cheep to replace, but a fully functioning injector is better than a so called "operational" one.

Cleaners do the job, but don’t fix wear in the jet, nor its spray pattern as the injector gets old.

At present my opinion is:

1. Install a glow plug timer set at about 30 seconds operational time. This overrides the on board computer time set.
   Details re these are on this site and the other Patrol site.
2. 80,000Km glow plugs removed and physically checked. Any crazing all replaced. No 4 cyl being possibly the worst culprit for issues.
3. 100,000km injectors physically checked. Any variance from standard , replace all.

With respect to glow plugs, much is based also on what I saw when my ceramic Nissan plugs came out at about 150K and only one was operational. The rest lost tips o r were non operational. At 168k the metal ones I had showed huge burn wear. Most of this was due to the long time the tips were kept hot by the system.
The injectors were covered in carbon crud, fuel cleaner or not. How much the actual jet was effected I cant say but I suspect it was, based on fuel consumption a bit wider than specs.