5.3 dod/afm delete

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Oct 1, 2018
San Diego
I know this isn't an offroad/ prerunner type thread. This is my experience with a d.o.d. delete that didn't last as long as I thought.
Back story. I got rid of the displacement on demand system on my dads saab 97x "read trailblazer s.s." about 40000 miles ago. Ls7 type lifters are noisy again. I cannot find anything other than weak lifter springs and carbon in the lifters. I have pulled the heads and have disassembled the lifters one at a time. No problem found other than carbon and trash in the lifter. Cam appears to be good. I have the engine down to a short block and plugged the a.f.m. oil galleys last time I did this. I know about the oil bypass in the block. I'm looking at every part as if I was building a competition type engine. I've taken all of the lifters apart and cleaned them. No problem found other than carbon buildup.

I'm looking for someone who has experienced lifter knock.

I don't want a bunch of speculation and bullshit. I'm an a.s.e. master along with g.m. and Chrysler master certs. If you have practical knowledge please chime in.


Senior Member
Sep 8, 2010
Phoenix Az
Your a master certified tech, Bert? How the fuck can we compare?

Run a synthetic oil. Sounds like oil coking like you get in turbos if it’s carbon in them. Could be too long between changes, shit filters, oil pump dieing (common).

How about total miles on the engine, what oil is used and so on
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I are smarts
Mar 21, 2007
Flagstaff, AZ
I usually don't hear about people having problems with ls7 lifters. I also don't pay too much attention to it though because I plan on keeping what ever 200k mile ones come with the long block. Unless I do buy a DOD motor then I'll replace them, some pac 1218 springs, and an elgin 1840p cam.

If you're on facebook, post it up on the Sloppy Mechanics Public Page. You'll get some shit comments but I guarantee there will be a few to point you in the correct direction.


Oct 1, 2018
San Diego
Thanks for the replies. Oil is 10w30 synthetic. Usually mobil. But sometimes its whatever is cheap. This thing has me stumped. I agree with the lack of complaints regarding ls7 lifters. Most of the failures I have read about are due to heavy springs and giant cam lift. This cam is tiny. 490 lift duration is about 200 degrees.

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