Newer chevy trucks

[TDunk]

Nobody has started a new thread in a while so i figured what the h3!!. I got a chance to tear into one a chevy's newer 4.8L (same as the 5.3 i think) and i have to say that it's almost as easy to tear down as an old carberated 350 SB. The guy overheated it pretty bad (thermostat stuck), had two quarts of antifreeze in the oil. We pressurized the cooling sytem, couldn't see anything dripping and the gauge was loosing pressure. OK, probably a cracked head/head gasket. Man, i'll tell ya what..... a wrench, four sockets and a ratchet is all you nead to tear the heads off that engine. The fords and the dodges you almost nead your whole tool chest right there just to do a tune-up. I have to say i'm impressed, it's faily clean (except for the "milk") no lip on the cyl. wall, and i had it down to the block in almost 3 hrs. I was dreding this job at first, but i have to give a hat's off to the engineers at chevys.

 

[RaisedByWolves]

Thats supposed to be one of the most ridgid blocks ever built.



Dont believe me, wait till you remove the 6 bolt main caps! Two strait down, two more down (straight or angled?) then one in from each side of the side girdle. the sides of the block extend well down below the crank centerline and the main caps span from one side of the girdle to the other, The oil pan is allmost flat! forming the most twist free block assembly to date.


Yes, your block twists under load......Erm, unless you have one of these motors.

 

[TDunk]

I've read all about these engines when they first came out, but this is the first major problem i've run into with them. And the only reason i'm tearing it down is because the owner didn't look at his gauges. The truck has about 135K on it and the engines shows very little sign of wear. Good stuff.

 

[spacemule]

Runs counter to the myth that newer vehicles are harder to work on, eh.

 

[chowdozer]

Thats supposed to be one of the most ridgid blocks ever built.



Dont believe me, wait till you remove the 6 bolt main caps! Two strait down, two more down (straight or angled?) then one in from each side of the side girdle. the sides of the block extend well down below the crank centerline and the main caps span from one side of the girdle to the other, The oil pan is allmost flat! forming the most twist free block assembly to date.


Yes, your block twists under load......Erm, unless you have one of these motors.

Yeah, a 6.0L stock block is worth in the neighborhood of 1000-1200 hp with a set of hairdryers on it. I've been thinking...

 

[2000ssm6]

Those "LSX" series motors are great! Easy to work on and tons of mods out there.

I don't think Ford or Dodge will ever make a motor comparable to the LS7(427ci). That is one hell of a motor!!

 

[RaisedByWolves]

Yeah, a 6.0L stock block is worth in the neighborhood of 1000-1200 hp with a set of hairdryers on it. I've been thinking...

The 5.3 is rated at 285 hp stock (for my year) and the rods were poo pooed when they first came out because they are sintered. Chevy rated them at 450 hp. They regularly see 650hp on Street/Strip vehicles with little problems.




Chevy HP ratings are rather consertvitave and do not mention that their HP ratings on parts are for continous duity (ie offshore racing, desret racing etc) over time. They usually test to 100 hrs, and while this may not seem like much at first thought, think about getting in your 400hp truck and driving WOT for 100 hrs!



I doubt that the average motor EVER sees 100hrs of WOT use.

 

[TDunk]

I heard that when they first came out in the trucks ('99) they had problems with something. I can't remember now if it was the rods or if they had a problem with the cyl. bore.

Now, i went to go look a tree job the day before yesterday after work and i see this older GMC single axle dump sitting in this guys yard behind his house ( i've been trying find one). The job i was going to look at was almost right accross the road. To make a long story short, i asked him how much he wanted for it, he said "let me see if it'll run first, then we'll talk money, see you up here tommarrow" . So i go up there last night with a battery, some starting fluid and a can of gas. Fired up after about 10 sec. SWEET. He jumps out of the truck and said "how $1500 sound" SWEETER. I was ecpecting to pay about $4/5000 for the truck. The body is in pretty good shape for an '83. But it's only got a 350 2brl. in it. I've biult up alot of engines for higher RPM, not torque. The engine in the truck only has about 15,000 on it (new GM long block) So my main qustion is what kind of cr@p do i have to do to this thing to get some torque out of it.

 

[DarylB]

I heard that when they first came out in the trucks ('99) they had problems with something. I can't remember now if it was the rods or if they had a problem with the cyl. bore.
.

I think it was either pistons, rings, or bearings that were out of tolerance when cold on some of the 1999-2001 gassers. They'd had an inherent "knock" when cold, some more noticeable than others. My dad's 2000 Z71 had the "knock". Do a search for the "knock" in that year range and you should be able to find some more info.

 

[DarylB]

So my main qustion is what kind of cr@p do i have to do to this thing to get some torque out of it.

If you're gonna change the cam put a Comp Cams 268H in it. Very good stocker, good vacuum and runs with a stock converter. A good exhaust and you'll have a good above avg 350. I'd definitely change out the 2bl with a dual plane aluminum intake, either a spreadbore type with a good rebuilt Q-jet or something like an edelbrock/holley 600 squarebore.

 

[Peacock]

The LSX motors ARE great. Other than some oil consumption and piston slap.

I'd say that they are easily the best light duty truck engines on the market.

 

[RaisedByWolves]

The piston slap issue was silly and overblown due to fear (rightly so) and ignorance among the (relitivly young) internet crowd.


My truck had it when new, but only when the temp was below 45* and the motor was reved above 1000rpm. Changing to 10-30 oil made a huge difference when cold, still does it if I get on it before warmed for a minute when its cold out, but it dosent really seem to be an issue.




The General redesigned everything about these motors recriprocating parts and one major change was the pistons construction. The older 350 (etc...) motor had heavy steel slugs cast into the pistons to control expansion when going from cold to hot.


The new design did away with the slug and uses Much better alloy in the pistons, but this alloy required a different shape to the piston to allow for expansion when the piston comes up to operating temp.


This design uses tapered pistons (all pistons are tapered, these more so) that are tighter in the bore when hot than previous designs. This had caused some noise in the earlier trucks, but once PPL got used to it not being an "Expensive" noise the whole issue died.


GM was giving 100k extended warrentys to those who were bothered (read complained) enough.



Think they had faith in their design? :hmm3grin2orange:



.

 

[RaisedByWolves]

Forgot to mention, I have 5k on my present oil chande and did not use any oil.


Im running Mobil 1 10-30 synthetic.

 

[TDunk]

The piston slap issue was silly and overblown due to fear (rightly so) and ignorance among the (relitivly young) internet crowd.


My truck had it when new, but only when the temp was below 45* and the motor was reved above 1000rpm. Changing to 10-30 oil made a huge difference when cold, still does it if I get on it before warmed for a minute when its cold out, but it dosent really seem to be an issue.




The General redesigned everything about these motors recriprocating parts and one major change was the pistons construction. The older 350 (etc...) motor had heavy steel slugs cast into the pistons to control expansion when going from cold to hot.


The new design did away with the slug and uses Much better alloy in the pistons, but this alloy required a different shape to the piston to allow for expansion when the piston comes up to operating temp.


This design uses tapered pistons (all pistons are tapered, these more so) that are tighter in the bore when hot than previous designs. This had caused some noise in the earlier trucks, but once PPL got used to it not being an "Expensive" noise the whole issue died.


GM was giving 100k extended warrentys to those who were bothered (read complained) enough.



Think they had faith in their design? :hmm3grin2orange:



.

Good post, i'd rep ya but i'm out

 

[Peacock]

Point is that you shouldn't have to change to a different oil to make it go away. It has been proven that piston slap doesn't cause any long term damage, but it still isn't acceptable.

Our '07 Avalanche doesn't have it though! My '99 Camaro's both had it, but you couldn't hear it over the lope and loud exhaust.

 

[DarylB]

Point is that you shouldn't have to change to a different oil to make it go away. It has been proven that piston slap doesn't cause any long term damage, but it still isn't acceptable.

Our '07 Avalanche doesn't have it though! My '99 Camaro's both had it, but you couldn't hear it over the lope and loud exhaust.

Couldn't agree more. Most "knocking" sounds from a brand new engine aren't good. If changing the oil only covered up the problem. I wouldn't have accepted it as "normal" now or then. I beg to differ that this was just internet crowd phenomena however. GM had a run of those engines where they had some tolerances off and they made noise.

 

[2000ssm6]

I have seen the TSBs and dealer only bulletins about these noises. I worked as a gm tech from '01-'04 and we did not see much if any of these complaints. Replaced one 5.3L with over 160K. None of the other dealers in my area did either. Our area must have had a good batch of motors. I think that issue was blown up too.

 

[RaisedByWolves]

Couldn't agree more. Most "knocking" sounds from a brand new engine aren't good. If changing the oil only covered up the problem. I wouldn't have accepted it as "normal" now or then. I beg to differ that this was just internet crowd phenomena however. GM had a run of those engines where they had some tolerances off and they made noise.

Good thing you edited that, I was able to actually make out part of some sentances.......



Changing the oil didnt cover up the problem, their never really was one, it only made me feel more comfortable jumping in the truck, hitting the key and throwing it in drive without letting it warm up a bit.....



How do you feel about brand new diesels?



Any way, the only ones who feel their is a problem with these motors at this stage are the Import tuner crowd. They worry wether a stock 5000lb truck will take them off the line or wait till it hits the top of first gear.



Imagine having 20k into a lil ricer only to get blown off by someone in a work truck that didnt even realise there was a race going on.



I also shamed a coworker in his "86" vette!


Granted, that years Vette only had 220HP, but I still smoked a Vette with a 4wd pickup!


.

 

[DarylB]

I love new-age diesels. I drive one Diesels knock anyway, morseso when they're cold, but that's in their nature. When a gas engine sounds like a diesel, you've got problems

 

[chowdozer]

Those "LSX" series motors are great! Easy to work on and tons of mods out there.

I don't think Ford or Dodge will ever make a motor comparable to the LS7(427ci). That is one hell of a motor!!

I must be old because whenever I hear LS7 I think 454 in a box.