five7kid

iTrader: (14)

My son has a 2001 S10 Blazer that he bought with a 5.3 punched out to 5.7 already installed. He's had it about a year & a half. Along with little things he's had to cope with and fix since getting it, a couple of months ago the Hughes 4L60E crapped out, and he had to have that rebuilt.

Today he called me just before quitting time saying the serpentine belt had come off and the damper pulley was loose. I headed out to where he was ( couple of blocks from home) and confirmed the damper bolt was loose. Went home and grabbed a socket & ratchet, tightened it up, ran it for about 30 seconds and it was loose again, so towed him home. He ran it long enough (after tightening the bolt again) to pull it up the driveway and into the garage. By this time the damper pulley was at about a 10 degree angle (and he said the PS wasn't working as he pulled in).

Pulled the bolt and the damper basically fell off. The sleeve past the front seal had broken clean off. I'm sure it wiped out the crank in the process.

So, if we get a rebuilt crank for it, think we'll need to have it rebalanced, or just put in a 5.7 crank and go for it? For sure the engine is coming out, only question is what goes back in.

dprest68

iTrader: (1)

Wow, that sucks! I think I would go ahead and have it rebalanced since the pistons are for a 5.7 bore instead of a 5.3 bore. Are you going to put a stock balancer back on it or go with an aftermarket one?

xpndbl3

iTrader: (5)

you could always pin it while the new crank is being checked out, and definitely look into the rebalancing as well since those aftermarket pistons would have different weights than stock.

dprest68

iTrader: (1)

Yes, that is what I meant!

five7kid

iTrader: (14)

Interestingly the 5.3/5.7/6.0 all show the same replacement crank p/n on the chain parts stores sites.

He's leaning toward going with a new crank and getting everything balanced. We honestly don't know for sure it was bored out to 5.7. For sure it is a 4.8/5.3 block. No idea if the shop that put it together balanced it.

The final decisions will be made after the engine is out and apart.

Also considering putting my "spare" 5.7 shortblock in, at least for the short term. That would probably get him up and running sooner, but would be more work if we put the 5.3 back in later.

Not sure about the damper yet. I'm planning on an SFI unit for the 6.0 when it goes in the '57, so he could have that one. I haven't heard a lot of talk about them being a weak link. I suspect this one either wasn't installed correctly (like bolt not properly torqued), or was damaged when they installed it. Hard to say, and we'll probably never know.

89ROC-Z

iTrader: (7)

Although the cranks may have the same number, you still have to watch for the type of rod/piston combo that the crank was on. LS2 rods are heavier than the earlier lq type rods, etc

Pocket

iTrader: (24)

If the balancer came loose after tightening the bolt a second time, especially on such a short interval, then either the balancer sleeve is split long ways or has spun on the crank chewing the interference fit to a slip fit. You're looking at a new crank and pulley at minimum

Next, you're in luck as 5.3/5.7/6.0 cranks are the same. GM only balanced the corvette bottom ends (drilled the balancer only), but car cranks were gun-drilled to lighten them. Manufacuring tolerances are much tighter on these engines, so using whatever crank (in good shape) with a replacement balancer will get your son back on the road with minimal fuss

If he's not running a blower, I wouldnt bother pinning the crank

Balancer failures arent unhead of on LSx engines. Usually its the outer ring flying apart, rubber slipping or excessive drag spinning it on the snout

five7kid

iTrader: (14)

The back end of the damper sleeve, the part that goes against the crank timing gear, is still on the crank. The damper broke clean from it. The part of the damper we have in our hands that goes over the crank is much bigger than it started out, and the crank snout is for sure chewed up. New crank & damper time. He's thinking he'd like to go through the engine at the same time, as it seems to like oil, too.

Good to hear the cranks are all balanced the same. That sounded right, but I hadn't had time to research it any further.

ZONES89RS

iTrader: (2)

How much did you tighten it? My lower pulley flew off on a test run, in the 6.0. Limped it home, threw a spare on and tightened it with a ton of force and neer had a issue again.

five7kid

iTrader: (14)

As tight as we could get it with a bar stuck into the damper spoke and jammed against the engine, and a 24" handle on the socket. It was already toast by that time, we just didn't know it yet.

86White_T/A305

Wow thats crazy.How common is this problem?

five7kid

iTrader: (14)

I had never heard of it. One of the reasons I posted about it here.

five7kid

iTrader: (14)

Well, I'm going to have to eat a little crow here. We pulled the damper off my 6.0 Saturday, and comparing them, the 5.3 damper didn't break off. It just spun on the crank snout. What looked like fracture surface turned out to be metal dust that cleaned right off. But, the part that presses onto the snout was really distorted and enlarged on his damper. The crank snout is roughed up, but a new damper would probably press onto it. We're not going to take a chance, since he wants to do rings and shave the heads while the engine is out. I'm going to be stroking the 6.0 and going to f-body accessories, so I'll give him my 6.0 crank and damper.

I think I've heard of people drilling the crank/damper and pinning them, maybe we'll look into that while it's apart. Cheaper than having crank and damper machined for a key, I'm sure. But, don't want to mess them up, either.

mw66nova

iTrader: (13)

the crank pin kit is pretty straight forward. get one from ati that has quality pieces and follow instructions. if my buddies with a procharger can do it on his 02 formula, then you'll have no problem with it (he's an economist that doesn't get his hands dirty, and he handled this)

five7kid

iTrader: (14)

$120. Not cheap. But, less than pulling an engine apart again.

Guess I'll get one, and some extra pins, and we'll do all our LS engines.

1gary

I'm learning from you 57 about the LS's. Kept the posts coming.