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ghost engine knocks ??

6K views 46 replies 17 participants last post by  xoxoxoBruce 
#1 ·
Anybody out there, have something even remotely similar, to a rod knock ,yet, quieter ????
In my 05 R , just purchased in march, 49,000 miles, I have a feint knock in the engine. I have, just 2 days ago, changed the oil ,5w30 synthetic . The knock seemed to have gotten louder.

I took it to the dealer , in San Jose Ca, they do not have any readings coming from the block sensors, (didn't even know they had sensors),
they pulled the valve cover , on the nosey side, checked rockers,pushrods and lifters, (as best they could) and have now targeted the main bearings and the connecting rod bearings.

I have a $3000.0 powertrain warranty with the car , of which, all money is only usable by a chevy dealer. The dealer already ate up $1000.0 in troubleshooting ?
I am looking at a $10,000.0 new crate engine installed ,minus the 2-3k.

I get to pay 7-8k for my new crate engine installed ????? :(( for a truck I just bought. Not to mention all the work I have already done to her.

Severely bummed , is an understatement , (it should say severely burned) !

Bottom line is, I am looking for a bit of help with , what I call, ghost knocks ? They cannot be isolated or found with certainty. And are internal engine knocks.

I will scour the library and the site after my post.
Any help would be appreciated.

Thanks,
Chris
Black "R"
 
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#2 ·
What type of filter do you run some have said noise goes away with certain filters also piston are short now and could be piston slapping I know my sons Tacoma does this . Hey say coating wears off piston and could be making noise but I don't know if Chevy piston has coating. What dealer you at
 
#4 ·
do you have the OEM hood or is it aftermarket? I have an aftermarket and I get a knock when a part (EVAP purge solenoid vent tube) on the top of the engine, in front of the engine cover, taps on the bottom side of the hood. The sound differs if I have just braked compared to if I have just accelerated heavily.
 
#5 ·
My R is at Fremont Chevy.

They had ruled out piston slap because the knock is always there. I have driven the R so little , I cannot be honest about hearing it knock when hot? I will ask them to get it good and warmed up and then go take a listen.

I came across an article in Super Chevy, 2004, Re the upgrades between the LS1 and LS2. One of the upgrades was the full floating wrist pin. This was said to have eliminated the piston slap for the LS2 , in 05 , in the SSR and Vette.

I had my first oil change at pennzoil. Not sure of the filter type. Pennzoil??
Any recommendations on filter brands. Its an easy change !

Thanks ,
Chris
 
#9 ·
With regard to piston slap being fixed in the LS2 engine, the answer is no it was not. My former 2005 SSR had a bad case of piston slap and it was deemed "normal" by GM. In fact, current production engines such as the LS3 6.2L in the 5th gen Camaro and Chevy SS sedan still have occurrences of piston slap.

Usually, piston slap will only be heard when the engine is placed under light to moderate loads and usually only while the engine is warming up after a cold start.
 
#10 ·
Thanks abadssr,
I reached out to Jerry this eve.
Sorry you won't be around to see Dicktator.


Hi Shiftz,

This is good info, at least its some type of answer I can think on, instead of dumping a bunch of money and hearing it again.

I will put it thru the paces ,you suggest ,with a keen ear and a stethoscope. I believe you are correct in Re to hi RPM , although very difficult to hear ?

Thanks for the input. Very helpful and soothing to my ears and wallet.

Chris
Black"R"
 
#11 · (Edited)
Piston slap is normally loudest when the engine is cold, and will subside as the engine warms and thermal growth of the pistons occurs. The inverse is true of bearing damage, as cold oil moderates the noise and it gets worse as the oil warms/thins.

In the racing crowd, the first order of business would be to pull the oil filter and drain the oil. We would cut the filter open and carefully examine the debris - bearing flakes will be quite evident! Also, drain the warm oil through a filtering scrim and see what surfaces.

Because of the poor oil pan design, used in the SSR, in would not be unreasonable to suspect bearing damage!
 
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#15 · (Edited)
Sorry to hear about your engine noise. I think everyone has covered all the bases on this. But to recap and offer a couple more suggestions.... More then likely the old oil and filter has been discarded so cutting the new filter may not show you very much. If you were here I would pull a valve cover off and look for debris in the corners of the head where particles like bearing material can accumulate. If I found debris I would drop the oil pan and check the bearings and change them in chassis if the crank looked OK and measured up. Clean the head of any debris by vacuuming out the debris and flush the head down into the block, clean everything else from the underside by spraying cleaning solvent to rinse. Then I would get the oil pan changed to the C6 or get the stock oil pan suction modification Oil Pickup fix! Prevent starvation due to sloshing - Chevy Trailblazer SS Forum done and always run a quart more oil in either oil pan system. I run seven quarts in the C6 oil pan and 9 quarts in the C6 Topspin modified oil pan.

Some may think this is a hack repair but after seeing how good these engines are I think this light rod knock could be resolved by a simple in frame rod bearing change. Do not change rod bolts for stronger ones as this could cause more damage then it is worth.

Did the oil pressure change when hot? With my oil at 205 degrees it idles at 33 PSI on my stock 5.3 engine at 850 RPM and 198 degree water temp. 61.8PSI @ 6598 RPM.

The other option that you have if you don't find any debris in the corner of the heads is to button it up and run it. Worst case the noise gets louder and you deal with it then. If could be a lifter making the noise that comes and goes. Sure the safe thing to do is swap the engine and pay the price. But I would run it.

I have seen these engines torn down with more then 180,000 miles on them and checked for damages in the rod and mains before installing a new turbo camshaft, installing head studs and even reuse the old head gaskets after spaying with Cooper coat, never changed a single gasket, cam gear, timing chain, lifter, push rod and then put it in a race car and go pass after pass making over 850 HP and running in a 3000 pound car they can go fast and last a long time. We have some tough little engines in our SSR and if the oil pan issue is addressed they can give us a lifetime of fun.

All the best Jerry.
 
#16 ·
Hi Jerry,
First I want to thank you for your attention to detail in Re to this post.

I will check the corners of the heads tomorrow and see if we can see anything, like fragments.
The , in chassis , bearing change, is something I strongly suggested to the dealer , yet they are reluctant to do so. I do not know why? It is something I have done and do not see it as hillbilly/hack.

I cannot recall the oil pressure , yet will check it tomorrow. And see if it is much different. A last check.

I have deliberated the idea of "button it up and run it" and have come to the reality that , being a wrench, the minor knock would drive me crazy ! Its a curse and a blessing to know the stuff we know. Driving along, imagining the pistons , the explosions ,the crank , all spinning at 2-3000 RPM with hairsplitting tolerances, and all doing that after my hands have been inside that block ! Its nuts!! Yet it works.
The love of machines and their uses is bred into me. Part of me says , "just run it" the other part says, take as much as I can get from the $3000.0 warranty and bite the bullet , start fresh , and have a 3 yr. 100,000 mile warranty from chevy.

Again, Thanks for the help.
I will report back on this one . Hopefully with a happy ending , yet , definitely an ending, and a beginning, to be able to enjoy my Black"R" the way I want , top down and with a "Permagrin."

Chris,
Black"R"
 
#17 ·
Chris, I understand completely.

It is interesting to note that the TBSS guys seem to have a very very high engine rod bearing failure rate. My guess is that they are a younger bunch of hot rod, power adder guys that really beat on their engines so they have found the weak link and offer solutions to fix it. Anyway I never new about it until I build my LS427TT and was data logging oil pressure that I saw evidence of oil pressure dropping at 4000 RPM and up. I was very concerned so I did some research and found the TBSS solutions. So spend a little time looking at the information out there and you will see the compelling evidence to support reasons to make oil pan changes or pickup tube changes or simply add an extra quart or two of oil to the engine. My racing buddy Jason said just add more oil and it worked for me on my C6 modified oil pan I run 9 qts and my stock C6 oil pan I run 7 qts.

The SSR guys with blowers really need to look into this as well before they get the old rod knock.

I'm glad you posted about this subject. Chances are you have saved SSR fanatics thousands of dollars in repair bills.

Enjoy your truck to the fullest. We're not getting any younger! Jerry
 
#18 · (Edited)
My personal feelings are that the dealership is not the best place to have bottom end engine repair done, if they would in fact, touch it! Most of their techs have neither the knowledge, nor all the precision instruments needed, to do a proper evaluation/repair.

If you do have bearing damage, there's a lot of critical inspection that needs doing. Depending on the severity it may include removal of the crank for magnafluxing and checking for straightness. Careful and precise measurement of the affected journals is mandatory! Careful size and concentricity checking of any affected rods is ultra critical. These tasks are beyond the scope of the dealership tech!

Chris, I'm really against just throwing it back together and seeing what develops. Many times it leads to considerably more damage, sometimes catastrophic. I've seen too many LS2 blocks with holes through the sides, from people trying to live with the knocks - it rarely turns out well. Piston slap is one thing, but a bottom end knock needs to get dealt with, sooner rather than later. Again, checking the filter can tell you a lot as that's its job - to trap debris. It may never make it up to the cylinder heads, if you're not hammering on the engine. The only time it can bypass the filter is at full throttle when the oil bypass opens.

I don't know if this matters at all to you, but the original engine block is serial numbered to match the VIN#. So, in case you replace the engine it might pay to retain the original block, for the future.

As Jerry mentioned, damaged bearing are somewhat common in hard run LS2s, with our oiling system. It would not surprise me if that is the source of your noise. Good Luck!
 
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#19 ·
Jerry and Ken,
Thanks for the posts.

Any and all info from you guys is super important and critical to me, and, I hope, to all Fanatics.
These are costly repairs, and need to be taken lightly. Without your guys input, I would have not known about the little "bearing eaters" . (remember the 348 tri power?) Super valuable info , and will hopefully, save and push , some Fanatics out there, in the right direction, in Re to "MORE OIL." The bearings need it "especially at high RPM for extended periods and spirited driving." Head these words from Top Spin !! This simply means C6 pan if you own an "R" If not , get ready for a serious invoice you do not want ! Simply put , C6 pan installed , with supports installed, less than $1500.0 ...... New engine , $10,000 , installed (by you or whoever). Pretty simple , eh !
One night , I drove my C5 99 Vette , at 100-130 plus, back from Portland to SF Bay Area. A bit of extended driving time!!

Some of us , learn the hard way, yet , at least we learn... Whoa, to those who don't .

The matching VIN's was a very difficult decision as , You and I are well aware of , yet I feel I was in between a rock and a hard place on this one. (or a bearing and , a no oil journal). It does matter , a bunch , to me. Yet, so does a running car .
I come from a line of car nuts. And original /matching is important. I had to let the flipping penny decide that one for me. And a Permagrin is where I am going.

Thanks Much Guys,
Chris
Black"R"
 
#21 ·
Chris, I only mentioned the block so you wouldn't discard it as trash, if you ended up replacing the engine. It's definitely worth something to the owner of the SSR that it came from! Someone down the road could rebuild that engine, then re-install in it's original home, if so inclined.
 
#31 ·
Several posts say to run an extra quart of oil in the LS2 engine. I ran a garage in the 60s and have been to many auto schools and classes and was always told NEVER overfill your oil. An example a few years ago I had an Oldsmobile and was in a hurry so had the oil changed at a fast lube type place. After several days of the oil change the car started smoking terribly. I took it to the garage and had them check it over as it never smoked before. They asked me some questions and checked it over carefully and could not figure it out. Then one of the mechanics just happened to check the oil and said it was over full and that could be the problem. They drained some out and it never smoked again. They said overfilling it can also blow out seals, etc. Just wondering if anyone has some info on this overfilling idea.
 
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#32 · (Edited)
Ahhh, the good old days! Well, let's look at the differences between then and now.

In the old days the oil pump was usually an inefficient spur gear pump that was driven by the camshaft - which of course meant it operated at 1/2 engine rpm. Engines back then had lousy lifters and weak valve springs, so 5,000 rpm was about max rpm you'd see. The blocks had massive openings in the lifter valley, so oil drain back was real good, but unfortunately in rained down on the rotating assembly and was bad from a windage standpoint. Anyway my point being, the old engines moved oil slowly and drained it back quickly, so there was always plenty of oil in the pan - no need to over-fill!

On to the modern LS engines with their highly efficient gerotor oil pumps mounted directly on the crankshaft - spinning @ actual engine rpm. Roller camshafts with good lifters and increased rate springs allow the LS 2 to spin to 6800 rpm, from the factory - though it is computer limited to 6300 by the ECM. The lifter valley is sealed, with a few minor openings in the corners, so oil drain back is limited. This really helps to defeat windage, but again, oil return to the pan is a slow process. Down in the pan area the oil is well controlled in the sump by a baffle over the sump area. Additionally, there is a full length windage tray around the crank assembly, keeping oil away. So, this engine moves a lot of oil quickly, but drains it back slowly.

I measured the oil depth when I modified my original pan and there's plenty of room for the additional quart, with no danger of it getting near the crank assembly. The only danger is running the pan dry and starving the bearings!
 
#34 ·
Thank You Rodger, that's very kind of you! Man, I've still got boxes of those old car mags laying around - I just can't seem to part with them!
 
#35 ·
That information is good to know. Thanks. Adding some oil as we speak. Again thanks.
 
#37 ·
There are scenarios that could arise with any SSR where the extra quart could be a huge benefit. If you're cruising along @ 55 mph there's probably 3 or 3.5 qts. residing in the pan's front sump. If you kick down a gear and hit the throttle to make a pass, the oil will migrate to the rear of the pan and try to climb the rear wall. The pickup location is in the very front of the pan and can become uncovered relatively easily - that extra qt. could be the determining factor in whether the bearings remain lubed or suffer some damage! It could be the most expensive quart of oil that you never bought!
 
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