Where was it and what is it now? At full operating temp you should be from 20-40psi.

 

Yes can be higher,
Also search typewriter noise for duramax in search bar, mine does it sometimes after a fresh oil change

 

It has basically always idled at about 23-24 PSI when warm, going up to about 50 or so under load. Right after the change it was idling at 40 something and would shoot up to 70 under load. Now it is back to where it always has been.

 

Thanks for the typewriter advice. I tried searching ticking and bent valve and everything i could think of and really didn't find what I was looking for, but that is exactly my problem.

Is it harmful to run it with the tick or just annoying? It would seem that it might be prudent to switch the oil out? Thanks a lot guys.

 

will not hurt it at all. just about every duramax does it, including mine.

 

Oil filter? What did you use when you changed the oil?

 

The oil pressure being high after oil change is normal. It will slowly settle down the more heat cycles you put on it.

The typewriter noise is normal and happens in every dmax. :thumb

 

Oil filter was a Mobil 1.

 

I guess I just never noticed it before. How much of a difference would removing the foam-ish insulation from inside the engine bay (on the firewall) make sound wise? When I had my truck getting trans work done the guy test driving it smelled smoke and noticed it was getting kinda charred so he yanked it off (turned out it was a huge crack in my downpipe that got worse after I dropped it off). I just keep reading about how expensive it is to re-build a motor for these trucks and I don't want to have to do one with less than 200K on it. Sound is more of a sewing machine noise than a typewriter, very faint.

 

The increase in pressure is from the new oils viscosity. The old oil you drained has been thinned by heat and pressure. The viscosity index improvers which are added or "blended" into the base oil have been shredded up and have lost their structure. Pouring in fresh oil replaces these, hence the increase in pressure.

As far as the noise, yes it could be the Dmax tick, but I've noticed some engines are picky with oil filters. My LMM doesn't like certain filters. It's just plain noisier on some. Had a Toyota that was the same way. The AC Delco seems to be a great filter for the Dmax. I run bypass filtration, so the fact that the delco doesn't filter as well as the Mobil 1 is of little concern. I just want a quiet engine!

 

Did you go from a synthetic to a conventional dino oil?(Molasses in winter)

Typewriter tick
https://www.youtube.com/watch?v=iyng0E9mUyM&feature=youtube_gdata_player

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