What OEM engine should I look for?

Number21 · December 16, 2021

I have a '00 1500 with the 5.3. Stupid thing blew a head gasket at about 180k. I'm either going to pay a mechanic to fix it or just replace the engine entirely. There are sooo many different 5.3 derivatives now. I'd like to find a lower mileage ebay pull, just a plain OEM engine. What is the most bang for my buck that will be easily compatible with my truck? I'd really love an aluminum block. Would an L83 be a good choice? Is there any reason that would not more or less bolt into my truck? Is there a better option?

I know I have to delete AFM on the newer ones and will probably replace the cam anyway. I don't want to have to do a ton more than that though. In the future, I'd like to lightly turbo it - and if the 4L60 goes I want to replace it with an 80. For now though I just want to get it running.

KARNUT · December 16, 2021

2 hours ago, Number21 said:

I have a '00 1500 with the 5.3. Stupid thing blew a head gasket at about 180k. I'm either going to pay a mechanic to fix it or just replace the engine entirely. There are sooo many different 5.3 derivatives now. I'd like to find a lower mileage ebay pull, just a plain OEM engine. What is the most bang for my buck that will be easily compatible with my truck? I'd really love an aluminum block. Would an L83 be a good choice? Is there any reason that would not more or less bolt into my truck? Is there a better option?

I know I have to delete AFM on the newer ones and will probably replace the cam anyway. I don't want to have to do a ton more than that though. In the future, I'd like to lightly turbo it - and if the 4L60 goes I want to replace it with an 80. For now though I just want to get it running.

Have you tried any stop leak or block sealer? I’ve seen that work quick fix.

Sharpz · December 16, 2021

If you didnt warp the heads, replacing the head gaskets is by far the cheapest and easiest way to go. It is really a straight forward process, and allows you the opportunity to do all sorts of things to give new life to your 5.3.

Number21 · December 16, 2021

I did use some head gasket sealer and it does seem to have helped, but who knows how long that will work. I want it fixed properly so I can trust it. Especially since I would like to do a bit of turbo in the future.

I know it's not terribly hard to take off the head(s) but I'm going to have to let a mechanic do the work, I'm too busy right now and don't have a place to do it. As far as I can guess it's going to be a similar labor cost to either fix the head gasket, or just swap the engine. (excluding the cost of the engine itself) But if I fix it, I still have a high mile engine, and it may have a warped head or something.

If I can get a low mile newer engine for around $2,000 I would be really happy. Definitely saving the old LM7 for future re-use. I really would like an aluminum block, it's just a basic 2WD truck so it is incredibly light weight, it handles surprisingly good for an old cheap truck!

swathdiver · December 16, 2021

3 hours ago, Number21 said:

If I can get a low mile newer engine for around $2,000 I would be really happy. Definitely saving the old LM7 for future re-use. I really would like an aluminum block, it's just a basic 2WD truck so it is incredibly light weight, it handles surprisingly good for an old cheap truck!

The L33 was the ultimate Gen III 5.3 motor. It's all aluminum with 243 heads. They were produced in 2005-2006. The 2007-2009 LMG, LY5 and LC9 are basically the same engine with AFM, same single pattern camshaft grind too.

Gen V LT motor is not going to work, neither is a Gen IV without adaptation.

shakenfake · December 16, 2021

LM7 or L33 are your only options. Anything Gen IV is not gonna work without a lot of cash and extra work.

Just fix the head gasket. Swapping the engine is the biggest waste of time and money for what you want to do. If you buy a used engine you will need to replace every gasket on it anyway or else you will hate your life. (Ask me how I know)

Sharpz · December 17, 2021

and dont forget, when you buy a used engine you are buying what you dont know. If you buy a new engine you will have thousands more into it and you will still have your hardware from your engine with all those miles on it, unless you replace all of that and then you are talking even more money. It takes 2 seconds to tell if the heads are warped once off, and they are not that big of a deal to get refurbished ones, and not that much money.

Bottom line if you have unlimited cash and dont mind spending it, go for a new engine with all the hardware new too......... might as well throw in a new tranny and torque converter at that time as well since you have the motor pulled. If cash is an issue, then go with the head gasket replacement, and look into upgrading some of the internal components from here. With the head gasket replaced, a new oil pump, and water pump kit while you have it apart, new intake gasket, new valve cover gaskets and a new oil pressure sensor and you should easily be able to get another 175 k out of your 5.3.

dgstarr63 · December 17, 2021

Don't buy any engine with AFM or DFM, too great of a chance of lifter failure. If you buy a late model used engine, buy one from a 2500 or a 3500. I would have your engine rebuilt or purchase a rebuilt one.

,

shakenfake · December 17, 2021

Quit talking about engines after 2007. He is not going to use them. No engines prior to 07 in Silverados had AFM.

Number21 · December 17, 2021

14 hours ago, shakenfake said:

LM7 or L33 are your only options. Anything Gen IV is not gonna work without a lot of cash and extra work.

Just fix the head gasket. Swapping the engine is the biggest waste of time and money for what you want to do. If you buy a used engine you will need to replace every gasket on it anyway or else you will hate your life. (Ask me how I know)

What is it you think I "want" to do? Long term my goal for this truck is big HP, but that could be 10 years from now. Or next thursday. I change my mind a lot.

I was of course not planning on major engine surgery right now, but since I do want to throw some more money at it in the future I might as well get the right "foundation" now. The L33 to me seems like a better engine in many ways, if I can find one for a reasonable price under 100k. Unfortunately it is getting harder to get the older engines with low miles...

Why can't I use a Gen 4? What modifications would be required other than the computer and the cam? I've also been thinking about using a stand alone computer anyway. Not a "necessary" thing to have again but neither are leather seats. The thing about newer engines is they are amazingly cheap often with very low miles.

I want an untouched factory GM engine because as long as it runs right, and the miles aren't too high, I can probably trust it. If I did this I would probably replace most of the gaskets (not the heads) and cam/timing chain/oil pump, however, this kind of work is much different than doing head gaskets in the vehicle or pulling the engine. I have a muscular problem that makes it very difficult to work on things that are not sitting nicely on a bench in front of me. I can't crouch under the hood and definitely cannot lay under the truck.

Since I have to pay a mechanic, it's going to become a very expensive game of "lets do that too while you're in there" if I fix the original engine, whereas I could do most of that myself on a stand.

Before it popped I already wanted to get a second engine to have and build on a stand to be swapped in later on. Yes, I know they can easily last 300,000+ miles, but I'd still rather have an engine with a lot less than that. The old LM7 isn't getting scrapped or traded for a core, and I'll probably end up replacing the head gasket myself, in the future. I already have 2 of these trucks, probably will end up with another. Always nice to have a spare engine laying around. I also have an old Jeep project that might like an LS too.

I've spent too long playing with turbo diesel trucks, where it cost $2000 to fix something just about every time I fart. That makes LS engines feel almost free in comparison!

Edited December 17, 2021 by Number21

shakenfake · December 17, 2021

Well I think you want to have a running/non-blown head gasket truck. I get it you want to have big HP, don't need a Gen IV to do that. Need to figure out what you want to do first and how you want to approach it.

You would need to do a lingenfelter box first of all to get the 58x crank to a 24x. Then you need, in the same kit, a 4x cam sensor into a 1x. These boxes are not super reliable and I have heard of a lot of failures but they do work. After that you will need to drill your knock sensors into the block. You will have to take it to a machine shop or do it yourself and drill larger holes for the knock sensors to get into the side of the block since there is no provision in the valley cover for them.

Obviously you need a full AFM delete kit so cam, lifters, front timing cover cause you can't use VVT (I have never seen anyone retain it and plus big cam = no VVT)

It isn't impossible but you may as well just buy a Gen III. There are literally no advantages of doing a Gen IV 5.3 swap. Now if you were talking a Gen IV 6.2 I would have a different opinion but it just isn't worth it just to do a 5.3. Especially when the Gen IV 5.3s are more costly than the Gen IIIs.

KARNUT · December 17, 2021

If my Avalanche at 172K started to fail and otherwise in excellent condition, it wouldn’t be put back stock. I expect the transmission to check out first. I would have it rebuilt to handle around plus 100HP over stock. The engine would be rebuilt or long block factory new GM. To maintain drivability I would probably go with a vortec type supercharger. These engines are easily tunable. I would price compare that with heads and cam upgrade to achieve the desired HP as long as drivability is maintained. Past projects have shown me that GM sourced engines are pretty reasonable. If the rest of the truck paint, front end is failing I’d ditch the performance upgrades. Of course I’d first try using bandage fixes on the engine while working on other areas. Taking in account it’s not my only ride.

newdude · December 17, 2021

Get a 6.0 LQ4 or LQ9 and build the trans up. 6.0 would give you opportunity to swap some great heads on it like some of the factory Gen VI heads from L92/L96 as well.

07+newer they made plenty of electrical changes and would require a good bit of work to swap in.

Edited December 17, 2021 by newdude

Supreme Pizza · December 18, 2021

I too agree that block sealer is a good start. $10 to $50 in parts.

Pulling the head to replace the gasket is not difficult, I just did one the other day. $50 to $100 in parts.

You can do the repair in the driveway, with basic hand tools and a torque wrench.

It would take a pro mechanic a few hours to do. A novice could do it in a couple afternoons of wrenching.

If you are really worried about warped heads, you could have yours machined and/or pressure tested.

Many shops will charge you $2500 to $3500 to replace the head gasket(s), but if you shop around, you can find someone to do it MUCH cheaper. Check online for mobile mechanics. Craigslist for instance.

If you hire someone to do it, don't pay in advance - and make sure they have all the tools and proper torque specs.

Once the repair is done, drive it around for a bit and make sure everything looks OK before you pay. (they need to agree to this before the job is started)

Sounds like you really want to drop a different motor in though, and that is your prerogative. Do what every makes you a happy person. As far as a replacement motor is concerned, I would get one on eBay. many sellers offer a warranty that INCLUDES replacement labor. Once you buy the motor and have it installed, if it turns out to be defective within the warranty period, not only will they ship you another motor for free - but they will also refund you like $1,000 to cover the motor swap labor. Obviously they test the motors thoroughly before they sell them, so that they don't have to lose money on the sale.

Edited December 18, 2021 by Supreme Pizza

Sharpz · December 18, 2021

what I cant understand here is you have all this money to pay someone else to do the work as well as a new motor etc, but you falter at the price of labor for a head gasket install? Do what makes you happy, if I had the money you seem to want to waste I would consult a professional shop and let them sell me on an engine. I wouldnt come to a free online forum with a bunch of randoms asking their opinion on what they would do. If you put in a high output motor, NO MATTER WHO OR WHAT IT IS!!!!!!!!!!!!!!!!!!!!!!!!!! you will need to upgrade your tranny too! So if you are willing to do all of this........... why are you here asking? Shouldnt you be speaking to the race shop or pro shop who will be doing the work?