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Cummins ISC 350hp Valve Adjustment Schedule

supercub
Explorer
Explorer
I have a cummins ISC 8.3 350 hp engine. I know on Cats, they recommend a valve adjustment at 30,000 miles. What is the schedule for the ISC. I'm just shy of 30,000 miles. Thanks
Brian
10 REPLIES 10

WILDEBILL308
Explorer II
Explorer II
Donna and Rob wrote:
I think Mr.Mark's about right 250,000 and 15,000 on oil change but I change mine about every 3-4000.

You only need to do it at 15000 miles or annually. I run oil analysis on my engine and at 12,000 miles the oil showed good for another 10,000 miles but I change annually per Cummins guide. I do run 5-40 Mobil 1 Turbo Diesel. But it's your money and you can spend it any way you want. I would rather by fuel.
Bill
2008 Newmar Mountain Aire
450 HP CUMMINS ISM
ALLISON 4000 MH TRANSMISSION
TOWING 2014 HONDA CRV With Blue Ox tow bar
A man who carries a cat by the tail learns something he can learn in no other way.
-Mark Twain

ScottG
Nomad
Nomad
supercub wrote:
I have just under 30K miles.........but it's 10 years old........how important is the 4 year interval? Why would you need to adjust the valves if the engine sat for 4 years........what could change. I can understand mileage or amount of hours the engine has run, but year? Should I have the adjusted with just 30k miles? and 10 years old?
Thanks
Brian


You have no need to adjust them until the miles build up. Time alone does nothing.

FWIW, I adjusted mine at 50K anyway and they were all well within. I adjusted them so they were all exactly the same but it didn't make any difference in performance, sound or fuel efficiency.

JamesBr
Explorer
Explorer
When I had my ISC, this was the schedule I ran close to.

Maintenance Schedule (CAPS or HPCR Fuel System)
Oil & Filter
15,000 Miles, 500 Hours, or 6 Months (I did once a year.)

Fuel Filter
15,000 Miles, 500 Hours, or 6 Months (I did once a year.)

Valve Adjustment
150,000 Miles, 5000 Hours, or 4 Years (Coach was a 2001, I had them checked once after 2 years, found only one needed adjustment.)
2006 Ford F350 6.0
2014 Primetime Sanibel 3600
Enough other vehicles to not bother listing.

Previous RV: 2001 Monaco Knight

wolfe10
Explorer
Explorer
Valve clearances do not change based on time. The change based on miles/wear of mechanical components.

And, yes 150,000 miles is the official answer from Cummins with the additional statement that these engines tolerate a WIDE range of clearances with no adverse affect on performance.
Brett Wolfe
Ex: 2003 Alpine 38'FDDS
Ex: 1997 Safari 35'
Ex: 1993 Foretravel U240

Diesel RV Club:http://www.dieselrvclub.org/

BigSkyBob
Explorer
Explorer
supercub wrote:
I have just under 30K miles.........but it's 10 years old........how important is the 4 year interval? Why would you need to adjust the valves if the engine sat for 4 years........what could change. I can understand mileage or amount of hours the engine has run, but year? Should I have the adjusted with just 30k miles? and 10 years old?
Thanks
Brian

I'm with you on the age of the motor Brian. I have 34K on the clock and have no plan to have the valve lash adjusted.
2008 Monaco Camelot 40PDQ, 4 slides, 2016 Dodge Ram 1500 Hemi Quadcab 4x4. Blue Ox, Garmin 760 LRM GPS, Doran Pressure pro on all 10, M&G Brake, 50 amp SurgeGuard, FMCA, Coachnet.

supercub
Explorer
Explorer
I have just under 30K miles.........but it's 10 years old........how important is the 4 year interval? Why would you need to adjust the valves if the engine sat for 4 years........what could change. I can understand mileage or amount of hours the engine has run, but year? Should I have the adjusted with just 30k miles? and 10 years old?
Thanks
Brian

ScottG
Nomad
Nomad
Yes, 150K but it's a very easy job and won't hurt anything if you check them early.

RedRollingRoadb
Explorer
Explorer
Valve Adjustment 150,000 Miles, 5000 Hours, or 4 Years

http://www.diesel-service-parts.com/cummins-isc.html

Donna_and_Rob
Explorer
Explorer
I think Mr.Mark's about right 250,000 and 15,000 on oil change but I change mine about every 3-4000.
2003 38ft Travel Supreme
350hp Cummins

Mr_Mark1
Explorer
Explorer
The Cummins guy told me 250,000 miles (425 hp ISL).

(2008 Dynasty with just shy of 70,000 miles).
MM.
Mr.Mark
2021.5 Pleasure Way Plateau FL Class-B on the Sprinter Chassis
2018 Mini Cooper Hardtop Coupe, 2 dr., 6-speed manual
(SOLD) 2015 Prevost Liberty Coach, 45 ft, 500 hp Volvo
(SOLD) 2008 Monaco Dynasty, 42 ft, 425 hp Cummins