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Older vs Newer GenIII 5.3 Build Differences??? (99-04 vs 05-07)
I am on a quest to find a motor to work on as a winter project for my truck. I currently have a 2005 1500 4WD Crew Cab with the 5.3 and 180k on the clock. There isn't anything really wrong with the engine, other than it slowly sips coolant, but it runs good for the most part.
I want to semi-mildly build up a 5.3 over the winter, do some head work, bigger cam, pistons, and mainly have a fresh engine that I can drop in the truck in the spring when it starts warming up, have fun in, sound good, and add another 200,000 miles with onto the truck. When calling around to local yards and looking online, I can find a bunch of 99 5.3's for between $150-$250, but can't seem to come across very many 05-07 5.3s. If I do, they are asking an arm and a leg for them... I know in 05 they changed the piston and wrist pin to a floating design, is there anything other than that internally that's different? Are the connection rods and cranks the same? I am planning on dropping in new pistons in the engine anyway with the rebuild. In that case, would shelling out the extra cash for an 05 engine be a waste versus just getting a 99-04, if after doing new pistons makes them identical? That's basically my main question. Could I get away with just doing pistons/wrist pins, or would I have to do rods as well? Or is there more different internally than just that? The reason I ask is because when looking at pistons, some say fits years 99-04 and other will say 05-09. Assuming this is because due to the redesign in 05, would that mean I would need new con rods as well as pistons if I wanted to use the 05-09 style pistons in a 99 engine, or is there some reason they wouldn't work?
I have a 2000 Sierra with the 5.3 as well that I am planning on selling soon, but it has the dreaded piston knock/slap when it's cold. I enjoy my 05 not doing that, and I don't want to have to think about/hear that with the new engine which is the main reason for asking this question...
Last edited by TwiZtedZ71; 11-10-2015 at 11:17 AM.
Honestly they're so similar that it's really personal preference. I think if you're doing a whole piston deal as well I would just inspect/replace the bearings while you're going through the engine.
I'm betting that the 2005-09 engines have bushed connecting rods to accommodate the floating wrist pins. I've never had an engine that new apart to verify.
Cranks are almost the same, as are blocks, with exception of location of the knock sensors and i do believe the cam sensor.... At some point they went from a 24x reluctor on crank to a 58x may be gen 4 though, think the major difference in newer vs older pistons is the grooves for the rings...
Cranks are almost the same, as are blocks, with exception of location of the knock sensors and i do believe the cam sensor.... At some point they went from a 24x reluctor on crank to a 58x may be gen 4 though, think the major difference in newer vs older pistons is the grooves for the rings...
Being in different locations, will they still work with the newer style ECU (03-07 - P59) vs the 99-02 ECUs (P01)? I hadn't heard anything before about crank differences. Not doubting you, just new to me. May have to do a little more digging... I'm not in a super rush to get a donor engine as the winter months are just starting to come amongst us. But I'm kind of getting antsy, and want to make sure the one I get will work without too much headache. I'd hate to get a 99 donor engine and find out I have to swap out/replace most the sensors/internals/stuff to work in my 05 truck. Or, if I can get a 99, and just swapping out pistons/wrist pins, and maybe con rods makes it identical to an 05 engine (internally). That's what I'm trying to figure out, if that's the case, or there's more to it?
Originally Posted by Wolftrk99
When buying an engine be sure to check the heads for the 706 castechs and unless you plan on putting another set of heads on it stay away from it....
Whereabouts is this number located on the heads? Why is that, what's the story behind the 706 castechs?
Last edited by TwiZtedZ71; 11-10-2015 at 08:29 PM.
I did opposite 04 6.0 block in a 99 silverado.... Looked at my buddy's 06 tonight and apparently the differences started with the gen iv blocks.... His knock sensors are in sane place mine are...... The castech 706 heads tend to be porous and will leak coolant into neverland..... If you can find an lm7 grab it, just be wary of the 706 heads..... The casting number of the head as you are loking at the heads are on the right corner by the valve cover....if youre looking at the passenger side of the engine as it sits in the vehicle isbthe heads havent been pulled off you can see it plain as day...somretimes heads get put back on wrong side..... I can take a picture of it tomorrow when i get to work(have an lm7 sitting in the back room, that one of the guys i work with picked up for about $150 i think... As far as the rods go i am not sure as far as a floating vs pressed pins on 5.3s but i know that is the major difference between the lq9and lq4 along with lq4 having a slighg dish to them vs the lq9 being flat tops with floating wrist pins..... I had found an article by i wanna say engine tech somethingbor other magazine that had the differences in all of the different specs between 4.8/5.3/5.7/6.0/6.2 gen 3 and gen 4 from the ls1 all the way through an ls9, unless youre talking stupid hp/tq numbers you will never know the difference between floating and pressed pin pistons....
Specifically regarding your question pertaining to 5.3L from 99-07
The basic long block is the same for a Gen III 99-07 classic 5.3L with RPO LM7 and L59 engines. Iron Block, 706 or 862 Aluminum heads, -8cc dish piston
The LM4 is an aluminum block 5.3L with 706 or 862 heads, -8cc dish piston. Found in Chevrolet SSR 03-04 Chevrolet Trailblazer EXT, GMC Envoy XL, ISUZU Ascender 03-04 and Buick Rainier 03-04.
The L33 is an aluminum block high performance version of 5.3L with 243 or 799 heads, With flat top pistons from the 4.8L. Found in 4x4 Silverado extended cab 05-07
Be aware the 4.8L uses the same Heads and Block only. The crank and rod lengths are different on the 4.8L though so don't confuse the two.
The 5.3L cranks are basically the same an unchanged from 99-07 classic the minor change will be the balance throughout the years for the minor changes.
There were some minor changes throughout the years that you will need to be aware of.
99-03 had 3 different length head bolts, They are not interchangeable with the later 04-Up style which had only 2 different lengths.
99-04 will have pres pin rods and the LS1 rods. 99-02 will have non coated piston skirts.
05-up will have the LS2 bushed rods with floating pins.
As far as the heads go.
There basically the same between the 706 and 862 heads. The difference is in how they are cast. The 706 is Semi Permanent mold cast while the 862 is regular sand cast.
People fear the 706 heads because they are more prone to crack and there was a TSB regarding this issue, My personal experience is that as long as you maintain your cooling system and you have made it over 100,000 miles you're probably not going to have an issue. Maintenance is the Key. I have had 2 trucks, both with 5.3's and both have gone over 100,000 miles with no issues. I have seen several go over 200,000 miles and most of those had little to no cooling maintenance, again with no issues.
The early 862 has a notch cast into them, If you have these or are looking at purchasing a set, These can usually only be run with a fiber type gasket as they will not seal with a normal GM MLS type gasket.
I believe Felpro may have an MLS head gasket that will work on both notch and no notch.
As long as you stick with a Gen 3 engine it will be plug and play. The Gen 4 engine is different and will require some extension harnesses and a convertor box to convert the cam and crank signals.
There is far too much information if you want to know the difference between every signal LS based engine made.
Heres an idea of where the casting number will be the first pic is the driver side head on my camaro the second is the driver head on my truck, which trchnically i guess i put the heads on backwards..... Ooops....... Sorry i was so confusing on my **** storm of info earlier...... And fact i confused myself on this one lol
11-09-2015, 04:57 PM
Older vs Newer GenIII 5.3 Build Differences??? (99-04 vs 05-07)
lol