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Topic: Valve adjustment on Cummins C8.3 (Read 2168 times) previous topic - next topic

Valve adjustment on Cummins C8.3

Yesterday I had the valves adjusted on my Cummins  C8.3 at industrial power, McKinney Texas, which is a Spartan and freightliner approved motorcoach facility along with servicing primarily medium duty commercial trucks and is a dealer for Hino, the Toyota commercial trucks.

This has been on my mind for a while because I could find no records of a valve adjustment on my engine over the 23 years and 92,000 miles. There were no operational concerns other than the manual recommends valve adjustment every 48,000 miles, or eight oil changes.

The mechanic said it was not way out of adjustment, but that it needed to be adjusted. The only part involved was a gasket for the valve cover.

I had considered doing this myself but it requires two people and spending some time in awkward positions. I've only adjusted valves once in my life and I can't even remember what that was on, probably a karmann  Ghia.

I drove it to the repair facility and camped outside the gates so that when I pulled it in at 7:30 AM the motor was cold and ready to be serviced. We agreed that this would be done by the end of the day since I live in the motorhome full-time. They had it done by 2 PM. I used my E bike to navigate around town while it was being worked on. My wife was out of town with the pick up.

Curious about how many owners adjust the valves themselves, it's a significant cost savings if you have the skill, and helper. The other question is how many owners pay attention to the valve adjustment schedule?

Re: Valve adjustment on Cummins C8.3

Reply #1 –
Quote from: Realmccoy –

Curious about how many owners adjust the valves themselves, it's a significant cost savings if you have the skill, and helper. The other question is how many owners pay attention to the valve adjustment schedule?

Yup, on both the diesel pusher and LOTS and LOTS of VW's.  The VW engines are sure easier to turn over by hand! Air cooled VW's every 6,000 miles and #3 exhaust a little loose.

Re: Valve adjustment on Cummins C8.3

Reply #2 –
Once in 125,000 miles at 107,000. All close to normal but piece of mind is worth it

Re: Valve adjustment on Cummins C8.3

Reply #3 –
I did the valves on the Monaco with an 8.3 Cuminns at 40,000 miles and they
needed doing and I adjusted the valves on my M11 when I installed the Jake
Brake at around 134,000 miles.

Re: Valve adjustment on Cummins C8.3

Reply #4 –
Had my valves adjust last winter got a cummins mechanic to come in to my shop and do it while I was replacing my radiator and all the other cooler  and changing  all the hydraulic hose and fuel lines and other items  brakes also a lot of love and care  got him to check for any updates on the ENGINE COMPUTER there was about 34 up dates that cummins had put out there it had never been done. He was also able to tell me the the true mileage and hours on the engine 106,000 miles  since the odometer had been changed the engine hour there was 34 hr different from computer and hours on tachometer  it was a very good piece of mine

Re: Valve adjustment on Cummins C8.3

Reply #5 –
Timely post! I'm at 120,000 miles on our coach and going back through the records from the previous owner can't find anything about having the valve lash being adjusted either. Will be going to Velocity Truck ( used to be Freightliner) here in San Diego on Monday. They are so busy they don't even make appointments any more, just bring your rig in and they work on it when it's your turn, depending on what the issues are. Doesn't sound like the best option but there's not any other choices around here.
 Wouldn't even quote me a ballpark figure on what it would cost.
 I also asked about checking the ECM for any updates for the engine and he didn't know anything about that but would ask his boss.

Re: Valve adjustment on Cummins C8.3

Reply #6 –
On the M11 it shouldn't take long. It is a lot quicker if there is two people
while adjusting the valves, one to turn the engine over and one to adjust
the valves. I think I could do the valve adjust part with help in about 15
minutes and getting the tappet cover off and on in about half an hour.

Re: Valve adjustment on Cummins C8.3

Reply #7 –
Yup, this AIN'T rocket science.

A reasonably competent shade tree mechanic can to it-- any will likely take the time to adjust and then RECHECK tolerances.  Something a tech is not likely to do.

Yes, if one person, you have to go out to rotate the engine to the next cylinder/position.  So, a little exercise won't hurt.  And you WILL earn that extra adult beverage.

Re: Valve adjustment on Cummins C8.3

Reply #8 –
Have done thousands of 6 cyl. Engines including mine and acouple of freinds,pull the belt pulley off of the harmonic balancer
And you can turn the engine from there,go slow and stop at top dead center,from there you can adjust half the valves,if no.
1 cyl. Valves are loose you start there,if no. 6,start there,the sequence is every other exhaust. And the first 2 intakes then
Skip one and adjust the next,turn engine 360 degrees and repeat sequence for the rest,like Brett said,not rocket science.
PS Will be at Desert Palms Salome during Q time,will be happy to help or show anyone
How to do theirs.

Re: Valve adjustment on Cummins C8.3

Reply #9 –
That's a great offer! I would like to learn how. Should be at Q in January. Please PM me if you are doing a demonstration or helping someone.

Re: Valve adjustment on Cummins C8.3

Reply #10 –
Quote from: oldguy –
On the M11 it shouldn't take long. It is a lot quicker if there is two people
while adjusting the valves, one to turn the engine over and one to adjust
the valves. I think I could do the valve adjust part with help in about 15
minutes and getting the tappet cover off and on in about half an hour.
Did you have to have the snap on St669 tool to perform?
Scott

Re: Valve adjustment on Cummins C8.3

Reply #12 –
Is setting/checking the injectors part of a typical valve job?

Re: Valve adjustment on Cummins C8.3

Reply #14 –
That's what I kinda thought but wasn't sure.

Re: Valve adjustment on Cummins C8.3

Reply #15 –
Dave, (John 44) can do the valve adjustment in his sleep.  If you have a chance to learn from him, take it.  I've seen him in action.

Re: Valve adjustment on Cummins C8.3

Reply #16 –
Our mechanical C8.3 has a hole on the curb side to put in a tool to crank flywheel to TDC, and also know when to stop after manually rotating engine crankshaft. We have also seen a tech use his eyeballs on rocker arms because he did not have the flywheel tool.

In our several valve lash adjustments, tech said the valves were almost right on, with little adjustment needed.
 

Re: Valve adjustment on Cummins C8.3

Reply #17 –
Quote from: Barry & Cindy –
We have also seen a tech use his eyeballs on rocker arms because he did not have the flywheel tool.

Ya, if you really know what you are doing, you can use the "rocker method" to identify TDC.  That is how I set air cooled VW's for many decades-- #3 cylinder rockers rocking and #1 is TDC.  No Voodoo, just how the engine cylinder firing is done.