mikecite7 Posted April 13, 2011 Report Share Posted April 13, 2011 I hope someone has some idea on this.... I have a 2003 SS 6.0... 85k miles with a procharger on the engine, "I've never seen this before but" I actually had both catalytic converters bust and clog up my exhaust at the same time, while trying to figure out what was going on with the miss in the engine, I then started getting blow by. After a tear down, the boost caused 2 piston rings to seize up on 2 seperate pistons. So I pull the engine go buy a rebuild kit take it to the local machine shop "that come to find out has never rebuilt a LS motor?" and have them rebuild with new standard size piston rings, cam and crank bearings.... nothing was done to cylinders except light cross hatching..... now everytime I start my truck it knocks like a diesel..... seriously. It gets a little better but not much after a while, i have noticed the oil pressure is alot worse than it used to be and it fluctuates up to 40-45 at best but stays around 20 psi at idle.... used to stay at almost 60 psi? btw I took the supercharger off and sold it thinking it was the cause of the engine blowing up... and it of course turned out to be the cats? Of course the engine builder is saying it is piston slap but my truck never had piston slap before so why would it have it now for one and for second.... I've heard piston slap and this sounds alot worse than anyones I have ever heard. I know this is not piston slap it sounds like a rod knocking solid and loud, but it is not getting any worse this is my daily driver and i have drove the crap out of it and it hasn't gotten any worse... I know I shouldn't be driving it but If I am going to have to pull it out and rebuild it again, why not..... If I pull it again what is a good resource to show me how to rebuild it on my own? I was hoping he forgot something small like the o ring in the oil pick up... but engine builder assures me he replaced it...? Truck also has as much power now as with the procharger...any thoughts? Quote Link to comment Share on other sites More sharing options...
eeekroar Posted April 14, 2011 Report Share Posted April 14, 2011 Man that sucks, I feel for you. First off did you get a warranty from the shop? I know the little shop that rebuilt my step dads truck, warrantied their work. I'm not by any way a engine mechanic so I can't help you there, but having more power NA than when you had your SC is VERY weird. The only thing I could think of to give you more power with the parts you listed replaced,is a different size cam. Hope you get everything worked out Quote Link to comment Share on other sites More sharing options...
Cramer Posted April 14, 2011 Report Share Posted April 14, 2011 (edited) I bet it's from the oil pump o-ring. I bet that it's pinched or torn, and that is allowing air to be pumped into the oil system aerating the oil, and robbing the lifters of full oil flow. If your needle is fluctuating, either you have a problem in the oiling system, or a more major problem. Did they use the original pump? And the original o-ring? If they used the o-ring that was on it, it is your problem for sure. If they used a blue one it is your problem too. The RED o-ring is the one for the trucks that will work if it's not pinched while installing. This is available at the dealer for like $5. Also take a piece of tubing or a long screwdriver and listen around the intake area for the sound you are looking for. If it's not there, listen to the bottom end to narrow it down. I am betting on the oil pump o-ring being the cause of this though. Let us know what you find out. Edited April 14, 2011 by sinr98 (see edit history) Quote Link to comment Share on other sites More sharing options...
Krambo Posted April 14, 2011 Report Share Posted April 14, 2011 ...more power now than with your procharger? I would have that discussion with another tuner IMHO. Your oiling or lack there of is going to kill your newly refreshed motor (if it hasn't already)! Like mentioned above, the O-ring is a common install problem. Quite honestly, a ported and shimmed LS6 oil pump is an inexpensive upgrade that will deliver much improved oiling. Quote Link to comment Share on other sites More sharing options...
misterp Posted April 14, 2011 Report Share Posted April 14, 2011 (edited) Stop the insanity! Mikecite7 - the motor went out because the cats failed; the reason they failed is from all the extra enrichment fuel in an aftermarket tune to support boost. Cats cannot take running rich, but the motor needs extra fuel during boost to keep cylinder temps down, the solution is to remove the cats, they should have been removed when the blower was installed. Your noise (I bet) IS piston slap from what you describe - a slow light knocking that improves as the piston warms and expands in the cylinder during the first few minutes of operation; the reason is because the machine shop honed the cylinders larger, but reused the factory pistons. The pistons are physically smaller when cold, and rattle until they expand to fill the extra machined clearance; the issue is that LQ9 pistons are specifically made to not expand very much. The oil pressure problem - it cannot be the O-ring; if it were missing or damaged or incorrect then the oil pump would not prime or suck oil out of the pan; you are getting pressure, just low pressure, and the chief culprit is loose bearing clearance. Probably, the prime suspect IMO would be if the machine shop "polished" the crankshaft, thus increasing running bearing clearance... I would change oil from 5W-30 to 10W-30 or even 10W-40 and see if that helps restore pressure of 30-psi at idle and 10-15 psi per 1000-RPM. Running with serious piston slap will cause accellerated cylinder wall wear, the 'rocking' of the piston in the bore will wear out the face of the ring too. This engine will have to come out and be rebuilt sooner instead of later, it's just a matter of time. Ask the engine builder to tell you exactly what the new piston clearance is (in thousandths of an inch) and what the bearing clearances are as well - this will tell you what viscosity of oil you will need to run in the engine, it is probably too loose to run 'thin' 5W-30 any more. When a motor is rebuilt correctly, it should fire and run/behave exactly like a new car on a showroom floor. My 2-cents. Mr. P. Edited April 14, 2011 by Mr. P. (see edit history) Quote Link to comment Share on other sites More sharing options...
Cramer Posted April 15, 2011 Report Share Posted April 15, 2011 Mr P I do agree on the bearing clearances, and the possible piston slap. But if the machine shop did a scuff up hone on the cylinders the material removed is minimal, done just to remove the glaze. This is a very minimal amount removed, and if the rings were gapped correctly there should be no problem with piston slap as the OP described. I have seen many motorcycles, cars, trucks, with re-ring rebuilds that actually are quieter than stock. On the oil pump o ring part, I had the same thing happen, and the description of the sound was almost the same as what I had. I only ran mine for 20miles, and at idle it was around 30psi, but got up to 45 or so and fluctuate when in the throttle. The issue was that I used the green o-ring that came with my ported LS6 pump, and it wasn't sealing totally allowing air to be sucked in along with oil. This was foaming the oil, but allowing the pump to still pump an amount of the oil with air mixed in with it. This gives pressure still, and some oil being pumped into the engine too. Now if it was installed without or the o-ring was torn or pinched enough, that would cause no oil pressure. I took my pump off, and put the red o-ring on and bam went to 55psi idle no lifter knock, and no other horrible noises. BTW I did remove the valve cover to verify that lack of oil was my problem and that I didn't knick my cam bearings on the cam install. This is my .02 from my experience of a wrong o-ring, and from discussing with a few builders about engine rebuilds. Quote Link to comment Share on other sites More sharing options...
misterp Posted April 15, 2011 Report Share Posted April 15, 2011 ... The issue was that I used the green o-ring that came with my ported LS6 pump... Thanks for the clarification, I have never run into this issue (yet) so I completely defer to your experience on using the wrong O-ring; if I hear of these symptoms again in the future I will certainly remember what you went through and discovered. Mr. P. Quote Link to comment Share on other sites More sharing options...
mikecite7 Posted April 16, 2011 Author Report Share Posted April 16, 2011 More power now because the cats were clogged up.... that was the real problem..... hindsight is 20/20.... I'm sure my 6000 dollar procharger system added alot more punch.... i bought the truck with it like it was and like i said it turned out the cats must have been clogged somewhat the whole time I had it before it blew... it is faster now. so I really regret selling the procharger? But I was pissed it blew and blamed the charger.... ...more power now than with your procharger? I would have that discussion with another tuner IMHO. Your oiling or lack there of is going to kill your newly refreshed motor (if it hasn't already)! Like mentioned above, the O-ring is a common install problem. Quite honestly, a ported and shimmed LS6 oil pump is an inexpensive upgrade that will deliver much improved oiling. Quote Link to comment Share on other sites More sharing options...
mikecite7 Posted April 16, 2011 Author Report Share Posted April 16, 2011 Yeah the engine shop said he will take it back apart and look at it but he will charge me for the parts/gaskets and not to mention all the trouble of pulling my engine out again ( im just still pissed i gotta deal with ignorant ppl thinking rebuilding an LS 350 isthe same as a old 350...They pretended to know how to rebuild one)..... and if he didnt know what he was doing enough to fix it rt the first time he will screw it up again.... Man that sucks, I feel for you. First off did you get a warranty from the shop? I know the little shop that rebuilt my step dads truck, warrantied their work. I'm not by any way a engine mechanic so I can't help you there, but having more power NA than when you had your SC is VERY weird. The only thing I could think of to give you more power with the parts you listed replaced,is a different size cam. Hope you get everything worked out Quote Link to comment Share on other sites More sharing options...
mikecite7 Posted April 16, 2011 Author Report Share Posted April 16, 2011 I think you are right the o ring that came with the kit was green..... I will go by the guys shop and ask him if he remembers for sure tomorrow.... Also can I take the center crossmember out from underneath the truck to drop the oil pan and make this repair while the motor is in the truck? I bet it's from the oil pump o-ring. I bet that it's pinched or torn, and that is allowing air to be pumped into the oil system aerating the oil, and robbing the lifters of full oil flow. If your needle is fluctuating, either you have a problem in the oiling system, or a more major problem. Did they use the original pump? And the original o-ring? If they used the o-ring that was on it, it is your problem for sure. If they used a blue one it is your problem too. The RED o-ring is the one for the trucks that will work if it's not pinched while installing. This is available at the dealer for like $5. Also take a piece of tubing or a long screwdriver and listen around the intake area for the sound you are looking for. If it's not there, listen to the bottom end to narrow it down. I am betting on the oil pump o-ring being the cause of this though. Let us know what you find out. Quote Link to comment Share on other sites More sharing options...
mikecite7 Posted April 16, 2011 Author Report Share Posted April 16, 2011 I have performed many modifications and rebuilds on many trucks, race cars, motorcycles, 4-wheelers and I also currently have a 67 Camaro with an 04 GTO LS motor (which doesnt have piston slap... I know the difference) and I assure you this SS truck does not have piston slap...It is a solid knock and it does get little better (not much) after i rev it up and the harder I run it... but if I putt it around it stays loud enough I have had ppl flag me down and tell me to shut it off.... alot louder than a powerstroke...lol . I have had at least two chevy trucks that had piston slap and this truck never had it before, cross hatching a cylinder will not cause this on a engine that was perfectly quiet before.... I was there when we took the engine apart. I am absolutely not new to rebuilding engines, I however will admit I know nothing about LS motors, but crosshatching and putting rings and bearings is the same deal....I was mainly looking for the differences in building a regular 350 and an LS.... Everything you are saying is right about piston slap, except along with the LQ9 piston not expanding(all Forged pistons) it is actually the short skirt style piston along with loose tolerances that causes the slap, learned that from pulling truck motors...(GM techs say it will not hurt the engine but I agree with you loose parts always wear out sooner)...the guy took three mos to rebuild and then slapped it together one day while I wasnt around? Again the builder assured me he put the new O Ring from the kit. I am sure it was not red..... I am not running thin oil I am also using lucas oil stabilizer..... actually it knocked less with the synthetic. I learned something new on the cats clogging up ... you are right because it gradually lost power, but in my defense the first thing I was gonna do was cut the cats off but the mufflar shop guy told me his truck stopped running right when he cut his off his exact same yr model 4x4 silverado.... I was skeptical but he convinced me... never again....I really appreciate all the responses Stop the insanity! Mikecite7 - the motor went out because the cats failed; the reason they failed is from all the extra enrichment fuel in an aftermarket tune to support boost. Cats cannot take running rich, but the motor needs extra fuel during boost to keep cylinder temps down, the solution is to remove the cats, they should have been removed when the blower was installed. Your noise (I bet) IS piston slap from what you describe - a slow light knocking that improves as the piston warms and expands in the cylinder during the first few minutes of operation; the reason is because the machine shop honed the cylinders larger, but reused the factory pistons. The pistons are physically smaller when cold, and rattle until they expand to fill the extra machined clearance; the issue is that LQ9 pistons are specifically made to not expand very much. The oil pressure problem - it cannot be the O-ring; if it were missing or damaged or incorrect then the oil pump would not prime or suck oil out of the pan; you are getting pressure, just low pressure, and the chief culprit is loose bearing clearance. Probably, the prime suspect IMO would be if the machine shop "polished" the crankshaft, thus increasing running bearing clearance... I would change oil from 5W-30 to 10W-30 or even 10W-40 and see if that helps restore pressure of 30-psi at idle and 10-15 psi per 1000-RPM. Running with serious piston slap will cause accellerated cylinder wall wear, the 'rocking' of the piston in the bore will wear out the face of the ring too. This engine will have to come out and be rebuilt sooner instead of later, it's just a matter of time. Ask the engine builder to tell you exactly what the new piston clearance is (in thousandths of an inch) and what the bearing clearances are as well - this will tell you what viscosity of oil you will need to run in the engine, it is probably too loose to run 'thin' 5W-30 any more. When a motor is rebuilt correctly, it should fire and run/behave exactly like a new car on a showroom floor. My 2-cents. Mr. P. Quote Link to comment Share on other sites More sharing options...
mikecite7 Posted April 16, 2011 Author Report Share Posted April 16, 2011 Thanks so much I bet this is my problem, I was guessing he might have pinched the o ring or srewed up the oil diverter reinstalling it incorrectly( dont know how that is possible) but I know for sure the o ring was either black or green (think green) but I will definately be getting a red one from dealer.... again I could do all this by dropping the crossmember giving me acces to the whole oil pan underneath truck.... Mr P I do agree on the bearing clearances, and the possible piston slap. But if the machine shop did a scuff up hone on the cylinders the material removed is minimal, done just to remove the glaze. This is a very minimal amount removed, and if the rings were gapped correctly there should be no problem with piston slap as the OP described. I have seen many motorcycles, cars, trucks, with re-ring rebuilds that actually are quieter than stock. On the oil pump o ring part, I had the same thing happen, and the description of the sound was almost the same as what I had. I only ran mine for 20miles, and at idle it was around 30psi, but got up to 45 or so and fluctuate when in the throttle. The issue was that I used the green o-ring that came with my ported LS6 pump, and it wasn't sealing totally allowing air to be sucked in along with oil. This was foaming the oil, but allowing the pump to still pump an amount of the oil with air mixed in with it. This gives pressure still, and some oil being pumped into the engine too. Now if it was installed without or the o-ring was torn or pinched enough, that would cause no oil pressure. I took my pump off, and put the red o-ring on and bam went to 55psi idle no lifter knock, and no other horrible noises. BTW I did remove the valve cover to verify that lack of oil was my problem and that I didn't knick my cam bearings on the cam install. This is my .02 from my experience of a wrong o-ring, and from discussing with a few builders about engine rebuilds. Quote Link to comment Share on other sites More sharing options...
BlownFogger540 Posted April 16, 2011 Report Share Posted April 16, 2011 if you cut the cats off, make sure to have them tuned out as you will only use 2 o2's now and not all 4 Quote Link to comment Share on other sites More sharing options...
Cramer Posted April 16, 2011 Report Share Posted April 16, 2011 You do not have to drop the cross member. You do have to remove the water pump, intake piping, dampener (pressed on to the crank snout, remove with a 3 jaw puller and your existing crank bolt, then use a longer M16 bolt to get it all the way off) and timing chain cover. To get the timing chain cover off you have to remove the bolts in the front along with two bolts that are on the bottom that also secures a wiring holder. You have to remove two bell housing bolts that go to the oil pan also. Loosen the oil pan bolts about a half an inch all the way around, and it should lower down far enough to get access to the oil pick up tube to pump bolt. The bolt is on the underside of the pump and is a PITA to remove and get back in. a trick I use is: use a 10mm ratcheting flexhead wrench, and when the wrench can't get to it anymore and your fingers are hurting take a piece of wire (bailing or hardwire of some sort) and put a 180* bend in the end with about a half inch of excess. Wrap it around the bolt threads and take some needle nose pliers and tighten the wire around the threads making sure that it is butted up against the head on the bolt. The bolt won't fall in the oil pan, and you can use it as a wrench. ( Stuff some rags in the front opening of the oil pan too just in case you drop something in there.) Now put your finger on the bolt head, and start turning the wire like a wrench till it's out. Now you can take the oil pump bolts that are going into the block out. Pry or push down on the oil pump pick up tube while rotating the pump clockwise and toward you. The pump will come out, and you will see the o-ring either on the pick up tube, or in the pump inlet hole. BTW when you get a o-ring from the dealer also get a new crank bolt. They are torque to yield bolts meant for one time use. Some have used them multiple times but some have had them fail too. They are cheap too. Quote Link to comment Share on other sites More sharing options...
sprayed99 Posted April 21, 2011 Report Share Posted April 21, 2011 (edited) Just reading some of your responses and none of the GM factory pistons are forged except for the LS9 pistons. Just thought I would add this. BTW you need to do a bit more interviewing before you trust someone with your engine again. And yes a clean up hone can cause piston slap if you use factory rings and pistons. The LS engines have extremely extremely tight tolerances. It is not like the good ol days when if it is close it is good enough. GM does not make a black o ring but it may look that way because they are just teflon caoted rubber. Also not all the trucks take the red o ring. Some of the older pick up tubes were built without the o ring recess and it requires the other oring. So you first need to verify which pick up tube you have to then figure out which o ring you need. Being your truck is an 03 that is the odd year for parts. Even some of the 2003 trucks had the older style windshield that GM installed to clear out old parts from the 99-02 trucks. I also hope he opened the oil pump relief valve and cleaned it out good. Over time the oil pump can build up residue and can cause that valve to stick. I have seen this happen in other members trucks even at low mileage (30K). The bearing tolerances are also very very tight on these engines. So tight you can run 0-30w and they run great. The biggest thing I noticed was the type of pistons you believe them to have. Hypereutectic pistons are made of an aluminum alloy which has much more silicon present than is soluble in aluminumm at the operating temperature. Hypereutectic aluminum has a lower coefficient of thermal expansion, which allows engine designers to specify much tighter tolerances. These are things this engine builder has to be 100% aware off before he even agrees to take on the job. Edited April 21, 2011 by Retired99 (see edit history) Quote Link to comment Share on other sites More sharing options...
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