So I finally get around to it and looks ike it was due, because I'm pretty sure the valve covers haven't been off since before it left the factory - paint was still overlapping the gaskets, chipped off the excess before installing new gaskets. So anyway, the interesting part was it didn't really need any valve lash adjustment after 70k miles. About half the valves were right on spec at 10/20 and the other half were tighter - about 8/18!

So I guess either it was not setup correctly originally, or only half the valves managed to wear in about 2 thousandths more clearance in 70k miles. Dunno. So all I did was even them all up to 8/18.

 

Valve lash tends to close up as the valve recedes into the head so your experience seems normal.

Edwin

 

I did not know that. Still wondering why they seem to be doing whatever they are doing at different rates.

 

Well, you don't know how they were set to begin with. .002" is well within the statistical error zone. It's not something to worry about. ON my last adjustment I had a .006" spread. I just set them and go on.

The main thing is to not let them wear until you have zero lash because that's when you burn valves which is more expensive to fix.

Some guys set them to .008/.018" for a slight performance gain so you're running just fine.

Edwin

 

Mine are set a .006/.010 and have been for 20tho miles, I just check em every time I change the oil.

 

So, the valves are supposed to TIGHTEN as they wear? In my experience, esp with the 240K truck I bought a year ago (which I doubt they had been adjusted anytime), they were about 16 on the intake side, and .025+ on the exhaust. I have done valve adjustments for guys who had driven the truck 150K mi and didnt even know they needed adjusting. They were looser than spec, too, though only about .003-5 loose. Enough for a performance difference.

Ace- you need to drive your pickup more if it only has 70K- you barely have it broken in.

Daniel

 

It just depends on where the most wear is. The valves tend to wear down into the seats which reduces the lash while the rest of the valve train tends to wear looser. If you have insufficient oil somewhere and maybe good lubricity in your fuel you'll get things opening up. This isn't really a problem but it affects performance. The BIG problem is when the exhaust valves wear faster and you get zero lash and a burned valve. In a perfect world the valve wear in would match the rest of the valve wear out and you'd never have to adjust the valves but we all know how likely that is.

 

Sorry haven't been on in a couple days, is there a way to tell if your valves need adjusting? My truck seems to make a slight high pitched ting and I was wondering if the valves start to make some noise when they need adjusting? Mine haven't been done for about 135,000+, from the PO.

Thanks

 

I think since I'm running them a little tighter than spec I'm just gonna start checking them once a year from now on whether I think they need it or not. It's actually a realtively easy/quick job.

 

Depending on how picky you are, they could ALWAYS need adjusting. I would stick with the recommended 24,000 miles schedule to be safe. Fortunately the Cummins is easy to get to to adjust so you can do it more often if you like.

Edwin

 

Thanks it is on my list of much to do I do not like the ting sound though drive me nuts, but I think I'm crazy cause any little new noise I freak.