Cat valve adjustment

[Jerry Leonard]

I am overdue for a valve adjustment on my 400 hp C 9 and I have an appointment to do it. It got me thinking. What happens if you never do the adjustment?  Also I think Cummings doesn't require it. Why is that?  An rv cat engine is really light duty for a C9 so maybe you can go longer before the adjustment.  Say 70,000 miles???  I think the recommendation is before 40,000 miles.

[Jim Nichols]

You may possibly see a very small mileage increase.

[Jerry Carr]

We have the C-13 and did the adjustment per the PM this keeps us under full warranty. the Cat program gives a 10 year warranty. I am not sure about the Cummins program but if you are still under a warranty the valve adjustment may be a good idea.

[Bill Brown]

We had our adjustment completed last July by our local CAT dealer.  The adjustment included a complete oil change w/filters, as well as lub.  This winter we noticed about a .3 mile per gallon increase on fuel mileage going and coming between Idaho and AZ.  We do have a current extended warranty, so felt we needed to have the work completed to avoid at least one hassle with the warranty company should we have a claim.  Total cost was a bit more then just a regular service, but was probably worth the added expense.

Bill Brown
06 Monterey Laguna IV
CAT C-9, 400HP  

[Gerald Farris]

Jerry,
Most likely nothing will happen if you do not adjust the valves. However, there is a possibility that the valves can tighten up from seat to valve face wear enough to cause a burned valve if they are not adjusted, but this is a remote chance. Proper valve adjustment can also cause a slight increase in fuel efficiency if the valves are too much out of adjustment, but this is also not very likely. The summation is that it is reasonably priced insurance against a preventable, though unlikely failure.

Gerald