oldfogey47

As everyone knows, projects have a habit of prioritizing themselves. That being said, I (maybe) have a new project.

I recently purchased a 2006 Silverado 1500, with an LM7 5.3 engine with 174,xxx miles on it.
The engine runs fine and I understand these motors may go 220,xxx+ miles and still have more.
The truck is a (almost) daily driver, so I need to keep costs down, and reliability is most important.

I’m thinking of rebuilding it and my choices are:
1. Continue to drive it and leave well enough alone.
2. Rebuild it.
For option 2, I’ll lay out my plan and you look for “problems” with my logic, etc.

Machining: Bore block, grind crank, rebuild heads (706’s)
Parts: new pistons/rings, new bearings (cam, mains, rods)

Question 1: Is there any problem cutting and upgrading the Intake valves to 2.00”?

Question 2: I was considering using an LQ9 cam/lifters, as I have one from my LQ4 with only 18K miles on them.
I read that: “The 01-up LQ4 6.0L used the 12561721 cam
The 02-up LQ9 6.0L also used the 12561721 cam”.
OR, is there a better choice?

That’s enough for now. Thanks…

G Atsma

2 questions:
1) Does it use any oil? Or blow blue smoke, etc.
2) Have you done a compression check?

If no oil use, and you know compression is good, run it a while longer!

To answer the other ?'s- You can upgrade to 2.00 valves, but you might consider finding some 243/799 heads that come on most late 5.3's and have better ports AND the larger valves you want.
The LQ9 cam is a good one, so if you have it, use it!
AND, a shameless plug for a sponsor/vendor of this forum; give WS6store a call for a good deal on parts and great customer service!

oldfogey47

Thanks G Atsma , I was hoping for a reply to tell me to just run it (lets me move to my LQ4 project from another thread).

The 5.3 in the truck runs fine, with no noise or smoke of any kind. The maintenance records I got with the truck indicated that it has received regular oil/filter changes and other parts as needed.

It does have the check engine light on so I checked and its the P0332 (knock sensor) problem. I'm planning to swap new sensors and wire harness soon.

Thanks again...

tech@WS6store

iTrader: (2)

Our complete rebuild kits are $699 shipped.

The 706 heads arent bad as long as they are not castech...so check.
For ls7 lifters add $90. The 6.0 cam will really only be different if its from 04+ otherwise its no change.
If youre going to build it, bore it out to a 3.898 and make an iron 5.7 out if it. Parts are same price.

Id doesn't sound like you are one way or the other on the projects, but sometimes peace of mind is priceless, PLUS make better power and upgrade all those parts with new improved and heavy duty parts for the best value around.

00pooterSS

iTrader: (40)

If it has no issues to speak of I can't imagine why you would consider rebuilding it.

If it has solid maintenance and you continue to maintain it properly it should go beyond 300k no problem.

I've had many with well over 200k come in with zero issues. Mine is at 190k now and hasn't changed a bit since I got it with 80k on it. It doesn't use any more oil than it used to, doesn't smoke doesn't make noise etc.

Also consider this, if you rebuild it, plan on having issues sooner than if you had just left it alone. Nothing seems to last like a well maintained OEM engine. Once they are opened up it never seems to be the same, it can be, just doesn't happen as often as we would like to think.

wph351

iTrader: (3)

These motors are so cheap and so plentiful, why waste 1 minute rebuilding It? You can pick up a running 5.3 for 500 bucks. Pizza and beer for a buddy, and youll be up and running sunday afternoon.

tech@WS6store

iTrader: (2)

Because you only want to put it in once? (thats what she said)
Plus you cannot buy an iron 5.7 and is pretty hard to find a flat top 5.3l.
There are many reasons to do both...but with a rebuild (with better than stock parts) you get way more dependability and potential power output without worrying about cold knocks, blow by, and needing to run a catch can to save it from knock etc.

wph351

iTrader: (3)

That's a matter of opinion.

tech@WS6store

iTrader: (2)

Well after being in the industry for this long and seeing every way to do a project, its a clear fact.
The stock assembly line lifters suck, castech heads like to crack, stock rings and pistons LOVE to agitate pcv issues and blowby. Alot of stock truck springs like to break also.
Ignoring those things and brushing them aside as normal isnt right either.
Like i said, do it right once, you wont have to do it again. Doesn't mean all forged etc etc etc either.

00pooterSS

iTrader: (40)

All of that is a case to do a top end and a catch can using the money you would waste on rebuilding the bottom end that holds up fine.

For what it's worth, keep your environment in mind and the problems you will see in it. The issues you mention happen but aren't really very common considering how many have issues and how many don't. I've been a tech since the LS came out. I have multiple LS powered vehicles roll through a day, some days I'll have 2 or 3 in my bays and several will roll through quick service up front. With those thousands of vehicles I have seen, I have seen 1 truck with a lifter issue. And in all that time and on all those cars I have yet to see a valve spring issue or the castech head issue. Even my personal truck with the heads in question with the rev limiter at 6500 from 80k miles till today with 190k miles has had zero issues.

I will say I did break 8 valve spring tips in the camaro though with the 6900 rpm rev limiter on stock springs at over 150k miles lol. Oddly it broke the last 1/8" of the spring winding off of each one and caused no running problems. Just kept finding little pieces of metal on the drain plug.

For a budget/mild power build I would do heads cam springs and catch can over rebuilding the bottom end. And it's starting to get hard to build a case to do the bottom end even for high power builds with all these SBE guys.

tech@WS6store

iTrader: (2)

The reason for the catch can is because of a bad bottom end. It is only a bandaid for most applications and doesnt fix the issues with the bottom end.
Wouldnt you rather have an engine that doesnt use quarts of oil for hundreds of thousands more miles vs having a low oil light before your next oil change?
Quite a bit less than a crate, and lots more options than the jy.

00pooterSS

iTrader: (40)

I don't know man, I use about a quart every 5k and that won't stop if I rebuild my bottom end, plus I have a small oil leak that contributes. By the time it's time to add oil it's time to change it, so no issue really. Every car I ever owned burned oil though, doesn't bother me. More than a quart every 3k would get annoying though.

tech@WS6store

iTrader: (2)

An oil change at every 3k though right?
Depends on what parts are used...but low tension oil rings DEF dont help.

00pooterSS

iTrader: (40)

No, double that or more in the truck, I do around 5k oil change on dino oil and 7-8k roughly on synthetic. Manufacturers have moved to 10k+ oil changes on todays oil so I moved my mileage up and it's doing great. I used to change my oil in the camaro at around 3k. In the truck I just use the monitor except last week it said there was about 20% life left and I was around 8k on the oil. I've always changed it early except with the truck, I was curious how it would do using the monitor. Any time I've gotten the oil light it was past time to change it (not by the monitor but by mileage I'm comfortable with) so I just change it rather than adding. So I may use a hair less than a quart every 5k.

I surely thought I would have a nasty motor running oil so long but I did valve covers on it last week

wph351

iTrader: (3)

And that's why they are opinions. People see different things to form their own opinions. There are both success and failure stories on BOTH sides. That's a fact. To say a rebuilt motor is going to be "way more dependable" than a well examined drop out, is false in my personal opinion.

tech@WS6store

iTrader: (2)

I had a friend 3 weeks ago run a well examined 6.0. Helped him tune it but something was off. Couple days later 0 oil pressure and motor was done. Of course the other side of the table knee jerk reaction is "well he didnt inspect it good enough". Then the question is what is good enough? He heard it run before pulled, he checked the oil. Didnt make any noise. Not the first time thats happened either.
Years of perosnal and professional experienc by me and the others around i know and help say that rebuilt is more reliable than used.

G Atsma

I think when you buy a junkyard pullout, unless it has under 100k miles, if it runs well AND holds up for good while, you are LUCKY. It does happen a bunch, but don't cry if it doesn't. Just be prepared to go through it. I would at least pull the pan and maybe a head for peace of mind. Otherwise it could be a Pandora's Box.

wph351

iTrader: (3)

I understand that, and appreciate that it does happen. I wont bore you with one of my rebuilt motor failure stories. My opinion is based off the same things yours are.

00pooterSS

iTrader: (40)

That's funny, I've had the polar opposite experience. I know you're credible and not making up stories. Again i'm a tech so we install used and rebuilt engines. I have never had a problem with a used engine in my personal cars, bikes, or customer cars. But all the bad experiences with rebuilds make me cringe hard at the sound of the word rebuild. I just passed up on a boat earlier this year because it had a rebuild and opted for a very well cared for boat with a 26 year old engine, and I do not regret it one bit. It's flawless.

The level of rebuild is everything in this situation.

I recently installed a rebuild that was sourced from LKQ, that ATK built. I'd vote for that rebuild all day. But the motor cost over 6k, most opt for a much lower cost rebuild, and in that situation the used motor is a better bet.

I've seen several rebuilds not even make it out of the shop..

N/ALS1

My ___ is bigger than yours!!! Lmao