petethepug
Michael
Whoops fixed that
2007 5.3 year compatibility
- Thread starter tjoyce81
- Start date
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LOL, I misspoke about the reluctor wheel - I meant the cam sprocket (thought of it as a reluctor wheel - you can feel it through the cam sensor hole. No, crank did not break.
My oil pressure issue went like this.
First, I my dash gauge went to zero, and all kinds of warnings went off - but the engine never knocked or acted like it had zero pressure. It did this a few times.
This indicates a bad sensor. So I changed the sensor and screen that goes under sensor. The screen was a little clogged. It ran fine for about 2 weeks, but then the gauge went wackey again.
So, I set up 2, oil pressure gauges - one in place of the sensor, and one just above the oil filter (installed special bracket in place of block off cover). The gauges read different pressures, and they fluctuated (I forget what the pressures were) but the pressure was not zero. So, I suspected a bad oil pump or pump pressure spring OR oil pick up tube o-ring. So, I removed the pump and took it apart to inspect it. I did find 2 large burrs on the pump gears, so I just replaced the pump - along with the pickup tube oring (while I was in there I replaced the timing chain, cam sprocket and crank sprocket - of which as it turns out caused all my current problems). This actually made it worst. The dash gauge didn't work at all now, so I suspected an electrical issue with the dash - lol. I drove around with the oil pressure alarm going off for about a week - and the engine never knocked or hesitated.
So, I studied the oil system on the LS engine with the AFM system. The AFM system needs high pressure when it is activated - BUT when it is NOT activated the oil pressure needs somewhere to "dump" as the oil pump spring stabilizes the pressure. That is what the oil pan oil pressure relief valve does. It dumps excess pressurized oil into the pan - so the system is not over pressurized during the time it takes for the pumps spring to stabilize.
So - I removed the pan, and just deleted the pressure relief valve in the pan - and my oil pressure problem was solved. That was 150000 miles ago...
I didn't get the engine out yet - but I did remove the Valley cover - and every thing actually looks good of what lifters and cam lobes I can see.
I will update as I tear it down.
I can say with a high degree of certainty, that IF i did NOT change the timing chain stuff - I would still be driving my Tahoe today - with a fully functioning AFM system and 359000 miles on it.
Charlie207
Full Access Member
Admin/mods need to sticky this.
Dustin Jackson
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@tjoyce81 Thats a hard thought. Because you didn’t neglect the timing chain you are punished for it… might have been better off neglecting it.
I put a new melling timing chain in mine a couple years ago knock on wood.
I put a new melling timing chain in mine a couple years ago knock on wood.
There is growing consensus on the LS1tech forum over the past decade that the bowtie-style dampener is the better choice - at least when there is no VVT (I don't know what the risks would be of using the bowtie dampener on an engine with active VVT). Engine builders are seeing lots of failed tensioners:
LS2 timing chain Damper or tensioner? - LS1TECH - Camaro and Firebird Forum Discussion
Generation IV Internal Engine - LS2 timing chain Damper or tensioner? - Putting my SDPC LS2 413 CI together and putting the cam in and the timing chain on and the chain is loose . I got the damper with the kit .Use that or tensioner?:confused:
ls1tech.com
Edit: In doing more reading, it looks like the VVT guys are also preferring to use the bowtie dampener:
Ls2 dampener with vvt? - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums - Camaro5.com
Ls2 dampener with vvt? Camaro V8 LS3 / L99 Engine, Exhaust, and Bolt-Ons
www.camaro5.com
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My engine does not have VVT, it has AFM - 2 very different systems.
Well, here is the damage, and my opinion on what happened.
Chain tensioner bracket broke, causing the chain to break. Cam stopped but the crank didn't.
Just one exhaust valve bent, and that valves' pushrod and rocker arm have slight grind marks (where the rocker and pushrod meet). However, no pushrod is bent.
All other parts of this engine with 350000+ miles are in just about perfect shape.
AFM system never failed. Cam bearings show the milage, but Cam shaft is perfect.
ALL of the AFM and regular lifters function, and are perfect being ran for 350000 miles.
Main bearing clearance is .002, and rod bearing is .0015 - show no signs of wear.
One piston has a slight exhaust valve contact mark, but the rest of them are good.
One important thing that stands out to me is the valve seals. They are seriously worn.
After all this milage that is probably expected. BUT, can this be a lesson as to replace the valve seals every 100000 miles or so? Can doing so, save some of the tarnish build up inside of the engine? Also, can doing so help the function of AFM/DOD? Questions may be worth answering for somebody who just wants what the factory designed...just an extra thought.
In closing, IMO, and based upon my first experience with AFM -
All of the anti AFM/DOD system hype that is put on the internet may have hidden truths that may not be mentioned when AFM/DOD is trashed.
Are the systems that fail properly maintained?
Is the oil and filter changed 3000 miles religiously?
Is there an after market air intake system that can introduce air filter oil into the intake system?
These are just my thoughts on the AFM system in my engine. Of which I'm deleting (LOL) but never the less the proof is in what my eyes see.
My engine oil and filter has been changed every 3000 miles (since I purchased it with 95000 on it)
AFM system worked as it should with NO issues what so ever.
Filter is Purolator BOSS, Oil is Quakerstate Ultimate Durability (dexo stuff) full synthetic - green bottle with gold label. 5w30.
Thanks again to everyone! The knowledge here is more than I can ask for.
Chain tensioner bracket broke, causing the chain to break. Cam stopped but the crank didn't.
Just one exhaust valve bent, and that valves' pushrod and rocker arm have slight grind marks (where the rocker and pushrod meet). However, no pushrod is bent.
All other parts of this engine with 350000+ miles are in just about perfect shape.
AFM system never failed. Cam bearings show the milage, but Cam shaft is perfect.
ALL of the AFM and regular lifters function, and are perfect being ran for 350000 miles.
Main bearing clearance is .002, and rod bearing is .0015 - show no signs of wear.
One piston has a slight exhaust valve contact mark, but the rest of them are good.
One important thing that stands out to me is the valve seals. They are seriously worn.
After all this milage that is probably expected. BUT, can this be a lesson as to replace the valve seals every 100000 miles or so? Can doing so, save some of the tarnish build up inside of the engine? Also, can doing so help the function of AFM/DOD? Questions may be worth answering for somebody who just wants what the factory designed...just an extra thought.
In closing, IMO, and based upon my first experience with AFM -
All of the anti AFM/DOD system hype that is put on the internet may have hidden truths that may not be mentioned when AFM/DOD is trashed.
Are the systems that fail properly maintained?
Is the oil and filter changed 3000 miles religiously?
Is there an after market air intake system that can introduce air filter oil into the intake system?
These are just my thoughts on the AFM system in my engine. Of which I'm deleting (LOL) but never the less the proof is in what my eyes see.
My engine oil and filter has been changed every 3000 miles (since I purchased it with 95000 on it)
AFM system worked as it should with NO issues what so ever.
Filter is Purolator BOSS, Oil is Quakerstate Ultimate Durability (dexo stuff) full synthetic - green bottle with gold label. 5w30.
Thanks again to everyone! The knowledge here is more than I can ask for.
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strutaeng
Full Access Member
WOW! Just ... WOW!
The condition and bearing clearances is remarkable!
You are probably about DOD AFM being overblown; you only hear about the bad ones. I suspect some of those cases is after vehicle having multiple owners down the road and someone didn't do proper maintenance.
What are your plans for the engine? How do the cylinders look? Any measurements for diameter, taper, etc. on that? Maybe just ball hone for cylinders?
The condition and bearing clearances is remarkable!
You are probably about DOD AFM being overblown; you only hear about the bad ones. I suspect some of those cases is after vehicle having multiple owners down the road and someone didn't do proper maintenance.
What are your plans for the engine? How do the cylinders look? Any measurements for diameter, taper, etc. on that? Maybe just ball hone for cylinders?
The cylinders look perfect. Cross hatch is equally visible on all of them. No ridge, or vertical scuff marks. Rings are good, spin freely in piston. Piston skirt coating is rubbed off, but that is supposed to happen.
BUT, I never go by eye. I'll measure next week, then send it to machine shop for them to measure.
IF our measurements coincide with each other - I'll take it from there - but probably a light hone and a good hot parts cleaner wash cycle or two - some paint and away we go.
Plans are to rebuild this engine - but as far as it going back in my Tahoe - I may still swap a 6.0 into my Tahoe. That idea came from this thread. LOL
One thing that WILL NEVER happen too me again - is a Melling Timing Chain or Melling timing component will NEVER fail me again! I'LL NEVER LET THAT HAPPEN AGAIN!!
Dustin Jackson
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Having had the AFM lifter failure problem myself I can say that while the problem is very real the number of lifter failures is probably very slim in comparison to the number of GMT900s cruising around being driven be people that aren't even aware of what AFM is and they are passing 200,000miles easy and are going to sell the thing out of boredom and end up buying a 2024 Z71.
I think it's the same for the 4l60e, it gets a bad reputation for failing easily without ever accounting for the other millions that did their job
I think it's the same for the 4l60e, it gets a bad reputation for failing easily without ever accounting for the other millions that did their job
Measured all cylinders 3 times today. 1 has .0008 taper, 3 have .0004 taper, 2 have .0001 taper, and 2 have -.0001 taper. Having 2 being .0001 out of spec is ok with me - could have been a hair off with the measurement.
However, all cylinders are at least .004 too big (over worn). They measure (average ) 3.7845, These are my measurements, so Ill see what the machine shop comes up with. But, it seems just an extended hone perhaps to fit .010 over sized pistons and cam bearings is really all that this engine needs after 350000 miles.
I have to say, I've been thinking about your timing chain. I hope you have many more miles with yours, but from what I see with mine - being the same manufacturer - I would seriously consider changing it.
Thinking back on my chain replacement, I remember thinking how the GM chain seemed more stout - but then I thought - 'Melling makes pretty good stuff', so I didn't give it a second thought - until now.
I just got a new GM chain for $35 bucks, and now, seeing how good the rest of the engine is - as I tear it down to rebuild (because of Mellings' new parts) I would have loved to see how far it would have went....
With this particular situation, I think any timing chain would have failed. The failure of the tensioner was the probable root cause. Again, Melling makes many of the lifters and timing chains for GM. I have a Melling timing chain on the shelf and the box is marked Made in USA. I still have the timing chain I took out when I did my cam swap and it's indistinguishable from the Melling chain.
The entire timing set - chain, tensioner, cam and crank sprocket - is made by Melling. They were ALL changed at the same time. IMO It's highly unlikely the tensioner would break where it did, without the a broken chain catching it and snapping it off. Of course I could be wrong - and I understand Melling makes parts for GM. Looking further into this, a Melling timing chain measures more narrow than a GM chain. It's just a few thousandths or so, but it's what I've seen.With this particular situation, I think any timing chain would have failed. The failure of the tensioner was the probable root cause. Again, Melling makes many of the lifters and timing chains for GM. I have a Melling timing chain on the shelf and the box is marked Made in USA. I still have the timing chain I took out when I did my cam swap and it's indistinguishable from the Melling chain.
Melling is .048. GM is .049. Cloyes is .052. Does that make a difference, I don't know. But mine broke, along with and/or from a Melling tensioner. Parts of both ended up in the oil pan - but did not go through the system - which is wonderful....
Curious as to what the new Melling chain width measures as compared to the one you took out?
AND, for the record, I've installed MANY Melling parts into trucks and cars, for many years - but this is my first true failure of a Melling part. If that can be avoided in the future, it will be my last.
I’ll check the dimensions of both when I have a moment.
