100,000 mile valve adjustment

[Steve St.Laurent]

Winter finally broke here in Michigan (70 degrees today - was snowing last week) so I finally was able to get around to adjusting my valves since I have 100,000 miles on the truck. Here's what I found - intake valves were from . 012-. 015 (optimum is . 010 - spec is from . 006-. 015) and exhaust valves were . 021-. 024 (optimum is . 020 - spec is from . 015-. 030). I was blown away that they were still within spec after 100,000 miles - and I haven't been exactly easy on the engine . I set mine slightly tight at . 008 on the intake and . 018 on the exhaust. A note to anyone adjusting theirs - there is a lot of play in the Y from the camshaft to the valves on the 24v engine. I adjusted mine and then cranked the engine over and then rechecked them - it took about 6 times of adjusting them before the numbers were consistent on the next rev (I've adjusted TONS of valvetrains over the years BTW). I continued to adjust them until I was able to get a consistent reading for 2 revolutions after I adjusted them.

 

[Rob Thomas]

Steve,



Thats good to hear, another 47,000 miles I'll have to adj. mine.







See ya, Rob

 

[LSMITH]

Steve, glad to hear yours were still in range. I have read about several that were in and several that were out at 100K. Mine were out. I set mine to the same numbers as you did.

 

[KatDiesel]

a few of mine needed adjusting at only 28k



Just an FYI for others out there.

 

[rcaldwel]

Valve adjustment procedure

Is there a write up on how to adjust your valves. I have the factory manuals but I like how TDR members supply information that depicts hands on experiences and that might even show pictures. To me it is a comfort to read this additional information before undertaking something I have never done before.



thanks,



Bob Caldwell

 

[americana]

did you re-torque the head

steve,



did you re-torque the head bolts? i do this on my motorcycles and mustang before i adjust valves. wondering if it is something you do when adjusting the valves on the mighty cummins.

 

[Steve St.Laurent]

No I didn't. Since the head bolts are torque to yield bolts I don't think that's a good idea. Bob - I just went by the factory instructions with the exception that I used the a wrench on the alternator nut and turned the engine backwards rather than using a barring tool.

 

[Don M]

I know that 12 valve head bolts can be re-used. The Cummins manual shows the criteria to re-use or not. Head gaskets come with a gauge to check the length before re-use.

Generally torque to yeild head bolts stretch a bunch when used once and are no good anymore. Cummins and others have re-used the head bolts many times during recon or rebuilds.

IMO, the practice is safe if the guidelines are followed.

As far as re-torque goes during valve lash adjustment... you dont need to do it. Once it is cinced down, its cinced down.



Don~

 

[americana]

still learnin'

thanks, didn't know that about my head bolts. but don't know about that comment about "once it's cinched down. " always undid head bolts a little and re-torqued. you'd be surprised how loose things got after break in. maybe cummins took care of that problem with the yield bolts. mind you i'd retorque my toys when newer (or rebuilt)... first valve adjust then every other one for a few times. like i said... . the experience i'm drawing on is gas motorcycle engines and gas 60's hot rod engines.

 

[Mad Max]

If you're messing w/ torque to yeild type head bolts like that, you're flirting w/ loosing a head gasket and potential Hydro-lock.



You motor, your $'s, but look into what an overhaul or a shortblock costs before taking that risk, YOU WILL BE SHOCKED HOW MUCH OUR LIL 5. 9 Short Block's go for.



Max

 

[Don M]

To clear up any mis understanding... the head bolts are not the torque to yeild type and can be re-used if they are not stretched past the gauge Cummins supplies.

Changing valve springs is a good example on the 12 valve. You loosen several and re-torque them back to spec.



Torque to yeild head bolts are designed to be used one time only.



Don~