Valve Clearance Calibration

[ejuan]

How often do you guys recommend to adjust engine valve clearance as part of a preventive maintenance program? Manufacturers don´t seem to come together about this. Some say every 2000 hours, others say 3000, others say 4000, etc. I'd like to know what's your opinion on this subject.

Have you seen the benefits of adjusting valves as a preventive maintenance action, or seen best results in fuel consumption etc?

Thanks in advance for your help.

Juan

 

[nuley1]

yes the benefits are worth it. we check ours every 500 hrs. that's the norm.

 

[ejuan]

Thanks for your reply Nuley. Could you name the benefits, I've to convince the boss here at the jobsite but Im not sure if my arguments are good enough.

 

[John C.]

You go by the manufacturer's recommendations. Some manufacturers use a soft material that wears fast and requires valve adjustments at shorter intervals. Others use hardened rocker arm pads and valve bridges and usually only need to be checked.

Cummins engines seem to require the shorter adjustment intervals. On the older Komatsu engines I worked on, you only adjusted the valves when the valve cover gaskets started leaking. On today's high pressure fuel systems with the throw away fuel system tubes, I would be leery of anyone adjusting valves before it was absolutely necessary.

 

[excavator]

Go by the manufacture's recommendations, however, the way they shove some engines in equipment it's no wonder the valves rarely get adjusted. I had a customer call one time thinking that the pumps in his Hitachi excavator were tired. No power at all, asked him if the valves had ever been adjusted. No, it only had 8000 hours on it. Valve adjustment fixed the problem.

 

[OzDozer]

Regular valve adjustment at periods of around 1000 hrs will often surprise you with the difference in performance. Poppet valves haven't changed since IC engines were first invented - even if metals and materials have improved - and they're still the weakest part of the IC engine, and the area where engine performance is most affected.

 

[ejuan]

Thanks for your help guys...

Juan

 

[craneman435]

excess valve clearance will destroy camshaft lobes

 

[rare ss]

CAT recommend 2000hr checks, we used to do them at 1000hrs if there were any valves that were tight or loose we would take note of it and you could see trends forming if a certain machine would keep having a tight valve you know the head/valve is on the way out

later model engine is just as importaint to do as MUI or HEUI injectors can also benefit from being keep adjusted correctly, the height gauges from CAT arent too $$$ to buy.. these can make a big differance for performance if their out of range