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Author Topic: C-12 Valve adjustment  (Read 5174 times)

Marty and Suzie Schenck

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C-12 Valve adjustment
« on: February 23, 2009, 11:47:41 PM »
I have a 2002 Patriot Thunder 455 (16,000 miles) and the valves have never had the after break-in adjustment. There is a piece of 2x2 angle iron right above the center head with about 1.5 inches of clearance. Does anyone know if this is enough clearance to get that valve cover off or am I going to have to modify that piece of angle iron. There are no bolts at the ends to remove it but I want to be sure that the cover can come off so the valves can be adjusted.   Thanks, Marty
1998 Monterey 2003-2007
2002 Patriot Thunder 2007-2017
2004 Patriot Thunder 2018-?

Gerald Farris

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Re: C-12 Valve adjustment
« Reply #1 on: February 24, 2009, 05:31:13 AM »
There is a modification bulletin showing how to cut the floor above the center valve cover to gain clearance for removal of the valve cover. The bulletin also shows how to reinforce and reinstall the floor. This modification is needed on many but not all C-12 and C-13 equiped coaches. If you are thinking of doing the work yourself, I can e-mail you a copy.

Gerald
2002 Solitaire (2017 -  )
2000 Marquis, C12 (2004 - 2017)
1993 Patriot  (2000-2004)
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Jay and Raylene Todd

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Re: C-12 Valve adjustment
« Reply #2 on: March 10, 2009, 07:18:27 PM »
Gerald,

I don't know if Marty asked you for a copy of the modification bulletin you spoke of but I would sure like a copy. If Marty wants it I can walk it across the street to him.

Thanks.

Paul Champagne

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Re: C-12 Valve adjustment
« Reply #3 on: March 13, 2009, 06:59:26 PM »
Marty

Not sure what engine you have  but if it is a CAT they recommend a valve adjustment  at 50000 miles not before as it needs to break in first.

I had mine done 2 years ago BIG difference in performance not sure if you need to remove the part but it is tight in their,it is a full day job

Good luck

Paul
2006 Patriot Thunder
C13 525 hp

Fred Cook

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Re: C-12 Valve adjustment
« Reply #4 on: January 08, 2020, 02:35:53 PM »
 I have the same motor you have and had mine done a couple years ago at around 60,000 miles. I believe the recommendation is to have it done at around 50,000 miles.  I took mine to Fabick  CAT  in Fenton Missouri. The mechanic took out the angle iron and had to cut a wooden cross beam above the valve cover.   My valves were not out of tolerance but they adjusted them to the exact specs.  He pieced it all back together nicely and you cannot tell that it was ever exposed. After all was done I could not tell any noticeable difference in performance. IMHO....  you would most likely be wasting your time doing this at 16,000 miles because they are more than likely not out of spec.
Fred & Cindy
2002 Beaver Patriot Thunder 455, C12 CAT
Towing 2019 Chevy Equinox, AWD Diesel
South Central Missouri, US Army Retired

Marty and Suzie Schenck

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Re: C-12 Valve adjustment
« Reply #5 on: January 08, 2020, 03:18:29 PM »
I don't know how or why this thread came up again but I had my valves adjusted way back in 2009 when I found the floor mod. I have sent a copy of it to Steve so maybe he could post it on the forum. I had no luck doing so. Marty
1998 Monterey 2003-2007
2002 Patriot Thunder 2007-2017
2004 Patriot Thunder 2018-?

Steve Huber Co-Admin

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Re: C-12 Valve adjustment
« Reply #6 on: January 08, 2020, 04:42:44 PM »
05 Marquis/Pat Thunder C13 Engine Access Retrofit info is loaded on Coach Assist under Service Bulletins.
Steve
Steve
2015-          07 Contessa Bayshore C9,  400 hp
2013-2015: 00 Marquis Tourmaline, C12, 425 hp
2005-2013: 01 Contessa Naples, 3126B, 330 hp

John Hennessey

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Re: C-12 Valve adjustment
« Reply #7 on: January 10, 2020, 02:56:52 AM »
I talked to Tom at Massey in Phoenix and he advised me that he suggests that  valvecadjustment be done at 100,000 miles.
John & Linda Hennessey
2003 Marquis

Dave Atherton

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Re: C-12 Valve adjustment
« Reply #8 on: January 10, 2020, 12:52:17 PM »
Gentleman, this subject valve adjustment is located in the Ask Dave technical section on the
forum under Ask Dave. There are many different ideas as to when to adjust the overhead on
you C-12 engine.  Let me post this information again ( Between 15,000 and 60,000 miles )

Compression Brake - Inspect/adjust  Note: The slave piston lash adjustment must be preformed
after engine valve lash is preformed.

Electronic Unit Injector - Inspect/Adjust. Adjust the electronic unit injector at same interval as
the valve lash adjustment. Note: in proper adjustment of electronic unit injector can reduce that
power and result in excessive fuel usage and/or shorted engine component life.

Engine valve lash - Inspect/Adjust
Only qualified service personnel should preform these operations

Next PM Level 3 Inspection ( 300,000 miles )
Compression Brake - Inspect/Adjust/Replace
Electronic Unit Injector Inspect/Adjust
Engine Valve Lash - Inspect/Adjust
Same time the following:
Turbocharger Inspect
Crankshaft Vibration Damper- Inspect
Air Compressor - Inspect

Dave Atherton Retired Cat Mechanic

Jerry Emert

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Re: C-12 Valve adjustment
« Reply #9 on: January 10, 2020, 01:32:05 PM »
Gentleman, this subject valve adjustment is located in the Ask Dave technical section on the
forum under Ask Dave. There are many different ideas as to when to adjust the overhead on
you C-12 engine.  Let me post this information again ( Between 15,000 and 60,000 miles )

Compression Brake - Inspect/adjust  Note: The slave piston lash adjustment must be preformed
after engine valve lash is preformed.

Electronic Unit Injector - Inspect/Adjust. Adjust the electronic unit injector at same interval as
the valve lash adjustment. Note: in proper adjustment of electronic unit injector can reduce that
power and result in excessive fuel usage and/or shorted engine component life.

Engine valve lash - Inspect/Adjust
Only qualified service personnel should preform these operations

Next PM Level 3 Inspection ( 300,000 miles )
Compression Brake - Inspect/Adjust/Replace
Electronic Unit Injector Inspect/Adjust
Engine Valve Lash - Inspect/Adjust
Same time the following:
Turbocharger Inspect
Crankshaft Vibration Damper- Inspect
Air Compressor - Inspect

Dave Atherton Retired Cat Mechanic
Dave, have I misunderstood some of your older posts?  I read one where you said that unless there was a problem that it wasn't really worth tearing the engine apart at 30K or whenever to get valves adjusted.  Now are you saying it should be done between 15k and 60K?  Just trying to understand.  Thanks.
Jerry, Chief USN Retired
2003 Patriot Thunder Lexington 40' 3 Slides
C-12 Ser#  2KS89983
4000MH

Mike Shumack

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Re: C-12 Valve adjustment
« Reply #10 on: January 10, 2020, 02:52:35 PM »
Here's the CAT maintenance recommendations (form the CAT C12 manual):
Note the "check grounding stud on cyl head" task. I'll bet most are not aware of (or doing) this task.
- Mike

'05 Beaver Patriot Thunder 525, Vicksburg, CAT C13, Allison 4000MH, HydraLift
Orlando, FL

Dave Atherton

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Re: C-12 Valve adjustment
« Reply #11 on: January 11, 2020, 05:14:11 AM »
Jerry, if you look at what is posted and all of valve adjustments, you are fine at 30,000 miles.
The thing many do not understand there is a plus/ minus in setting of valves on electronic
engines and many do not understand the first part on valve adjustment it say check valve lash
adjustment and if a feeler gauge slides within that spec no adjustment is needed. It is rare with
The plus /minus that adjustment is needed. Than look at the next level 3 maintenance 300,000
mile valve check lash / adjustment is required.  Dave Atherton Retired Cat Mechanic
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