What to expect after 250hr Valve and fuel rack adjustment

[Arl798]

Was wondering if anyone can shed some light on what if anything I can expect to see or feel on my 1999 400 Sedan Bridge, after my 250hr valve and fuel system adjustment. Ie: Less smoke, smoother idle, temperatures, fuel economy etc etc.

Just had this service preformed yesterday after finally finding a mechanic I could trust to do it. Looking forward to seeing how she runs now.

As well on a side note he replaced my thermostats. Turns out I had a 180 in my starboard and a 190 in my port engine. Which would explain why my one engine ALWAYS ran hotter than the other and I babied that engine for 2 years to be on the safe side.

I decided to go with the 180's.

 

[trit21]

Valve adjustment won't give any better fuel economy or any changes except maybe a little quieter, not so much valve rattle. I am not sure what they adjusted on the fuel rack and maybe someone else could shed light on that.

 

[Arl798]

ok well that is a start in the right direction. Quieter is always better. He said had something to do with injector timing or something along those lines.

 

[Skybolt]

Not to point out the obvious, but if everything was running fine a, i.e. no smoke when warm smoothly running etc. Then you won't see any difference. But Injector timing you could see smother idle and running, depending on how far out it was. Even less smoke a idle and while spinning up under a load, but again it all depends on how far out it was.

I doubt you will hear any difference with the valves on a diesel. If you can, something was horribly wrong. The most I would expect is that they still run as good as they did and hopefully you will see longer life as a result.

 

[fwebster]

Caterpillar requires resetting the overheads at 200-250 hours, I forget which. The 3116/3126 uses Cat's unit injector system meaning that the injector is mechanically fired by a second lifter/pushrod, etc. driven off the camshaft, unlike some other diesels that fire the injector with pressure pulses from the injection pump. Cat's injectors, therefore are mechanically controlled; Cummins, for example, are controlled by the fuel pump. Cat's system is mechanically more complicated from an engine build standpoint, but significantly simpler to operate and maintain, more smoke-free and more efficient. In discussing the valve and injector setting with a Cat mechanic, the usual terminology is "to reset the engine overheads" meaning everything on top of the heads, the intake and exhaust valve lash and the injector timing and opening, is checked and reset. If you had the required 250 hour service by Caterpillar, then this is what you had done.

Cat's next required service is at 2000 hours, but here is where it gets tricky. There are other parts of the engine that may require service/maintenance before 2000 hours and some of those items may involve more than just the needed repair only because it makes sense to do it at the same time. If you have an injector seat fail, you will need to have that engine's injectors removed and the injector seats reamed and the injectors reinstalled. Since you are already in the engine and are paying for the mechanic to set up the indicator gauges when he reinstalls the injectors on the fresh seats, it only makes sense to have the valves reset at the same time while he is finding top dead center on each cylinder....because you are already paying for 90% of the job by reseating the injectors. In my case, I will probably do the 2000 hour service between 1500-1600 hours, if things continue as they are. I am just beginning to pick up some transom soot so in a few hundred hours I will need to have the aftercoolers removed and cleaned. I will be at the end of the useful life on my coolant at about that time and you lose the engine coolant on 3116's when you remove the aftercoolers. Since the mechanic (the best guy here is scheduled months ahead ) is hard to get, I will have him remove and pop test the injectors and reset the overheads at the same time. It will be an expensive service trip, but I have no complaints......1200 hours, 17 years and all I've done is the 250 hour service and regular maintenance. You just have to love Cat's simple fuel system, its efficiency and they fact that this design doesn't "maintenance" you to death.

Hope that helps...........

 

[ttmott]

To add to Mr. Webster's above - At between 1500 and 2000 hours the five little check valves and fuel pump should be replaced in the injector pump; These are key to stable fuel pressure and are simple and inexpensive to perform while the technician is there. Also, typically, the turbocharger should be pulled and inspected and heat exchanger pulled and boiled.