Jump to content

2018 L83 DoD Delete = Running great, then no Compression

Kubs

By Kubs
in Engines & Drivetrain

 Share

Recommended Posts

Kubs Enthusiast

Kubs

Posted
Posted (edited)

I just got done doing the DoD delete on my '18 L83 Silverado.  I replaced the cam with a BTR L86 cam (very mild) new lifters, lifter trays, dod delete plugs, all new VVT gears, chain, tensioner, oil pump etc.  I also added a 6.2L intake manifold and TB during reassembly.

 

The dots on the cam gear and crank lined up perfect, and engine spun by hand no problem on reassembly.  Once back together I held the throttle down and cranked to build oil pressure before starting.  Foot off the throttle it fired right up as soon as I hit the key. Idled beautiful without a miss, hesitation, lifter tick (reason for the tear down in the first place) or any odd noises.  After a few minutes of idling while I was checking for leaks and listening, the truck just shut off.  No bangs, rattles, smoke, nothing.  Just stopped like someone turned the key off.  Now when I crank the engine spins like it has no compression.  Very free.  No codes or check engine light either.

 

Feeling defeated I called it night cause it was like 10pm and decided to tackle it again today.  Im going to pull some plugs and check compression, and also pull a rocker cover to inspect, but what would cause it to lose compression all of a sudden?  How could it start and run great, and then not have anything?  Im at a total loss really.  Anyone else experience this?

Edited by Kubs
rlcole321 Enthusiast

rlcole321

Posted
Posted

I did the same thing, your push rods are too long, once the oil pressure built up, it keeps the valves open, on my 2018 L83, it never had compression, had too measure the push rods I needed (with an adjustable pushrod tool) and get shorter ones. Hope you have a HPTuner, you'll need to "Retune"!

  • Like 1
Kubs Enthusiast

Kubs

Posted
  • Author
Posted (edited)

So pushrods wasnt the issue.  Rotated the engine to where cyl 1 had both intake and exhaust valves closed.  Then I thought if I loosen a rocker I should see the spring move a little.  Nothing.  They are closed.

 

I got it the rest of the way apart over the weekend. The cam bolt backed out and the gear spun on the cam a little making it out of time and lacking compression. It also destroyed the pin to the point I cant get it out so Im out $400 for a brand new cam also...

A little background. I took the engine apart to replace the VVT after a P0016 code. I did a new cam gear/phaser, new bolt, tensioner, etc at that time. When I got it back together it developed a lifter tick right off the bat. I suspect it had been going out for a while and sitting with no pressure in it finally did it in.

I then took it apart again to do the DoD delete with LS7 lifters, new trays, cam, valve springs and seals. I reused the cam gear and bolt that had 2min of run time. GM says if you re-use the cam bolt the new torque spec is 47ft/lbs + 50° instead of +90°. I dont think this is tight enough apparently.

New cam, gear and bolt on order, and hopefully this is the last time I put this engine together. 😒

Edited by Kubs
UrbanRage Enthusiast

UrbanRage

Posted
Posted

Damn, that sucks you're out $400, but at least you know what the problem was. Hopefully, everything will go smoothly with the installation of the new cam.

  • Like 1
  • 4 months later...
Kubs Enthusiast

Kubs

Posted
  • Author
Posted

Reviving this.  I had to step away for multiple reasons.

 

I had the heads re-done with new valves as when the cam jumped time it bent all the intake valves.  Its back together and starts and runs, but will idle rough.  Along with the new cam I also changed to the L86 intake and TB.  It might just need a tune now.  I cant datalog though because I am relying on the AFM disabler in the OBD port to allow me to test fire until I can get it to the tuner.

mikeyk101 Senior Enthusiast

mikeyk101

Posted
Posted (edited)

Not sure if this will help but you can get splitter cables for the OBDII port to allow 2 devices to be connected. I have done this with a Range Disabler and an OBDII reader to monitor various engine functions. It has worked out very well. Not necessarily recommending this one but if you search on Amazon, there are many to choose from.

 

https://a.co/d/aLK2tUV

 

 

 

 

Edited by mikeyk101
  • Like 1
  • 1 month later...
Kubs Enthusiast

Kubs

Posted
  • Author
Posted

Truck is currently at the tuner.  The rough idle was a dead driver side O2, but we are now getting fuel trims about 15% different side to side.  Pass side is taking a lot of fuel out and cyl 4 spark plug was BLACK.  I think I have a hung up injector.  Hopefully that clears it up and I can finally drive this again.

  • Like 2
Kubs Enthusiast

Kubs

Posted
  • Author
Posted

Closing the loop on this, replacing the injector allowed the truck to run well and be tuned.  It made 304hp and 333ftlbs on the rollers, with a 33" tall A/T tire and 93 octane.  Unfortunately I dont have a comparison to before all the work but it feels pretty healthy.  Very close to some 6.2L trucks I have driven.

  • Like 4
  • Thanks 1

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing

  • Latest Articles

  • Posts

    • teamjnz
      Stabilitrak conversion to Z71

      By teamjnz · Posted

      Sounds like converting will be a bigger endeavor than I was thinking. This truck doesn't have 2Hi like the Suburban did. The Tahoe has 4Hi and 4Lo and a button to turn of traction control.   From what I understand the Stabilitrak uses open diff in the front and rear. When wheel speed is not the same the stabilitrak uses the ABS system to slowdown the spinning wheel(s) to transfer power to the slower non-spinning wheel(s). I thought the transfer case was open too. Being able to transfer power either more to front or rear depending on wheel spin. Maybe I miss understood some information with you saying and power transfer is 50-50. Thanks
    • PunchT37
      OCI, not when but why?

      By PunchT37 · Posted

      My brother has a 2007 Avalanche with afm 5.3. It`s got 176,000 miles. Runs like a clock. Never been apart. Co worker has a 2010 Tahoe with afm 5.3. 230,000 miles. Never been apart. Runs like a clock. So, even though cyl deac is a weak spot, they can go the distance.   BUT, these engines had the oil changed regularly, AND had 5w30 as spec. I wonder if they would have lasted this far on 0w20? I`ll bet not.
    • Chuck FB
      OCI, not when but why?

      By Chuck FB · Posted

      I certainly could be wrong but I hear of pickups far newer than that 2007 cutoff which may not be going to the wrecker but are having engine work done and be that a reman engine or new engine or trying to repair the existing engine. Some of it would be design issues as per the cylinder deactivation system that GM has and one of those lifters wiping out the cam and the question of oil changes moving the needle or not on that whole mess, or in the case of Ford pickup engines that have the long timing chains and wearing them out and the roller followers and phasers and some of that certainly goes back to oil change intervals. But in those various cases the truck has all sorts of life left in it and so the unfortunate owner and may be original owner or used market owner that is pouring money into repairs so the truck is not seeing the salvage yard yet but damage is happening by infrequent oil changes. A friends son had bought a 2018 I think it is half ton GM and it had some sort of extended or used dealer warranty on it and of course the lifter issue bites and its rattling and so the dealer had to swallow the bill and was at least 7000.00 and I think they only replaced what they felt they had to replace so yeah, I can see that being a ticking time bomb in the not too distant future. Would frequent oil changes cure all these engineering "marvels", probably not but some engine designs have shown that they do much better if the oil is changed a lot more often then if the manufacturer service claims are followed. New trucks cost so much that there is an incentive to keep the existing truck on the road by repairing. 
    • davester
      Tranmission stays in Low

      By davester · Posted

      get a good code reader, and find out what problems the truck has noticed by reading codes. cheap ones can only get basic engine codes, you may want to get one that can get codes from all the computers in your truck.
    • asilverblazer
      OCI, not when but why?

      By asilverblazer · Posted

      This is sort of my point, salvage yards aren't overflowing with all these 'poorly' maintained trucks - excellent/good/servicable condition otherwise, salvaged only as a result of a bad engine from poor oil change regiment.    In my area, there are no 2007 to newer gm trucks/suvs in any salvage yards. A few are in the 'recyclers' with very obvious reasons for being there - wrecked.

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...