Lubrication problem???

[Hib Halverson]

Don't believe any of the BS about carbon buildup, or additives for your engine noise. It is PISTON SLAP and nothing but. I am a certified GM technician and competition engine builder (30+ years). The piston to wall tolerance is excessive. GM just doesn't want to pay for their mistakes.....

I can only laugh.
:L
Someone who was a GM tech and built engines would cite the piston-to-bore clearance specification for a Gen 3 engine in a discussion like this. Also, if a "certified GM technician" you knew this was "piston slap," he/she would also have some case information to post on all the engines he/she has disassembled and found excessive piston clearance. Please click reply and post that data.

C4C5 Specialist is correct and states the various causes of the noises.

Further, the noise--as long as it disappears when the coolant and oil approach operating temperaures is merely an annoyance and not a defect...at least not a defect in that it affects reliability or durability. There is no evidence to date that cold piston knock (if that's really the issue in the case that began the thread) in Gen 3s is a durability problem.

Anyone can say they are a retired mechanic and all Gen 3s with cold piston knock are defective. It's another thing to actually be a mechanic and have credible information proving the statement.

The position that cold piston knock is a defect will have some crebility with you whiners, here, can actually provide some evidence more than hearing some noise you don't like. Until then, your comments are really just useless static intended more to get attention and/or vent anger than be valuable information.

 

[C_Dogg]

I'll go along with that! ;worship

 

[madand043]

Just a couple of things: this 03 convertible makes this "normal" noise at all engine temps.

There are several other engines, by GM and other manufactures, that are both high performance and give economy that don't sound like ****.

Remember the only thing that improves with time is cheese and wine-------- not engine knock.

And finally maybe someone can set me up with GM to do a buy back as Ihave been working on this for 4 months and GM doesn't even want it back or maybe c4c5 you could buy it for a fair market value

 

[Rob]

Agree with BOB 1320 100%. Same problem with an 03 convertible with 6500 miles. I ran more additive crap than gasoline through it. GM doesn't have the melons to take care of their defective product. Just an interesting note: also own a 1997 with 65,000 miles that doesn't make a sound but the 03 sounds like a piece of crap. The service manager explained it as short skirt pistons.(HA HA). THE 1997 USES THE SAME PART NUMBER 88984245 PISTONS. THE SAME PISTON IS USED FOR 1997 THRU 2004 CORVETTES. SO, GM AND CORVETTE STEP UP TO THE PLATE AND TAKE CARE OF YOUR DEFECTIVE PRODUCT!!!!!

I'm kind of curious how you have determined that the product is defective?

Has the product broke on you or, are you basing your claims on sound alone?

What are the results of the engine oil analysis that you have had done in order to determine that the engine is failing internally or prematurely wearing? You have had an engine oil analysis done, haven't you?

Have you had the engine apart and properly tested each of the suspect components to determine if there is any abnormal wear occurring or if parts are in fact, defective?

 

[c4c5specialist]

Just a couple of things: this 03 convertible makes this "normal" noise at all engine temps.

HI there,
So there in itself, you have just proved that you do NOT have the piston slap condition, as you have just said it yourself.
Once again, normal.
And if I knew you better, personally, I would most certainly purchase it from you.
Allthebest, c4c5

 

[Rob]

I've been watching this thread develop and feel the need to share a couple concerns I have here.

If you have a problem with your Corvette, it is not enough for you to throw credentials on the table with no facts to back up your claims.

I don't care if you're a mechanic with over 40 years of exerpience. I don't care if you're a retired automotive engineer, a rocket scientist, or God himself. If you don't have the numbers, the data to prove your claims, then your claims, in my opinion, hold little value.

Now, I'm not, in any way, discrediting owners that complain they hear a particular noise in their Corvette. However, when someone comes out basically swinging at , and insulting GM on poor design and defects, then in my opinion, if you're going to do that, you damn well better have some data to back up those statements rather using your credentials to do the talking for you.

If you feel you have a legitimate argument, and your Corvette is defective in some way, whether it's engine, chassis - whatever, you will have far more credibility by tactfully proving your claims with some data rather than tossing credentials around and swearing your head off.

 

[Rob]

Case In Point

I also want to share a case in point here.

I own a 1990 ZR-1 that I've owned since 1994 when I bought it with 179 miles on the odometer.

The LT5 engine makes an obnoxious rattle upon startup that is known as "CCT Rattle" or "Cam Chain Tensioner Rattle". It sounds similar to a metallic rapping sound for the first 5 seconds after ignition. My understanding is that there is a valley or lack of a valley that does not hold enough oil when the chain starts moving.

When ZR-1 owners started hearing this, they complained to GM. GM stated it was not a cause for concern because there was no abnormal wear occurring, however they went ahead and slightly modified the CCT for the 2nd gen. LT5s. It was slightly redesigned to hold a little more oil, but some owners can still hear the CCT rattle upon startup. You can install the redesigned CCT on 1st gen., LT5s, but it's not a requirement.

I have routinely conducted engine oil analyses on my LT5 and all values have been either below or within normal ranges.

I currently have just under 28K miles now and I know many ZR-1 owners that have 60K-100K+ miles on their LT5 engines with no CCT failure or damage to the engine caused by the rattle.

The sound is obnoxious, especially when starting it up in a garage, but based upon the engine oil analyses I have conducted, I agree with GM - there is no cause for concern and there is no abnormal wear happening.

It is a characteristic of the engine that does not hamper its performance or reliability. Could they have designed a better CCT that even surpasses the 2nd gen. design? Probably, but it wasn't meant to be. Regardless, it's a slight annoyance that had not harmed the car in any way.

Another case in point is the ZF-6speed in the car. 1st gen ZF 6-speeds sound like cement mixers in first gear and when idling in neutral with your foot off the clutch. It's sometimes referred to as "gear rattle".

This reminds me of the old M-22 "Rock Crusher" tranny. If I'm not mistaken, that transmission was suggested for off-road use only. Why? Chances are, because GM knew that a lot of owners would find the sound and/or everday use unacceptable.

Owners cried so much about the gear-rattle sound of the ZF, that GM had the gear teeth slightly redesigned. As a result, the 2nd gen. ZFs are a bit more quieter, however, their torque capacity is also lower than the first gen. ZFs.

So owners got what they wanted: a slightly quieter transmission when they are not in first gear or idling in neutral (how many owners really sit in neutral or in 1st gear for extended periods of time???????), however in my mind, they also got a slightly weaker transmission.

If you want high performance, you have to be willing to sacrifice something somewhere along the way.

If you want a car that bathes you in luxury and quietness, then a sports car is not for you. If you place a higher degree of value on performance, driveability and fun factor, then you better be willing to sacrifice a little comfort/convenience somewhere along the way. Just my opinion.

 

[vettepilot]

Re: Case In Point

If you want high performance, you have to be willing to sacrifice something somewhere along the way.

If you want a car that bathes you in luxury and quietness, then a sports car is not for you. If you place a higher degree of value on performance, driveability and fun factor, then you better be willing to sacrifice a little comfort/convenience somewhere along the way. Just my opinion.

...and that has been the essence of the Corvette since day 1 I believe. The Corvette was never meant to be a luxo ride, it was designed to be a performer.
I for one think it does this quite well, and when driven for what it was mean't to be, the noises that annoy some either cannot be heard, or are ignored out of the sheer fun factor provided by the vehicle.
Just my opinion on the sounds of fun.
vettepilot

 

[madand043]

The fun and noise free performance has been accomplished in my 1997 Corvette Coupe. It's performance is as good as my 03 conv. gas mileage of the 97 is better than the 03, without any type of noise. I think it's only natural to expect at least as good or better product with 5-6 years of so called improvements. By the way, the 1997 is and always has been an excellent car and has never given any problems nor has there ever been any engine noise.

 

[Hib Halverson]

This thread has gotten, well uh...a bit testy and I'm part of the testiness but I want to get back to c_dogg's original question...this noise on start up.

I don't thing we really decided if this was cold piston knock or a valve train noise.

Not ****-off the Amsoil folks but, c_dogg, have you tried going back to a 10W30 Mobil 1 and a stock UPF44 filter then see what effect, if any, that has on the noise?

And...as for "piston slap", you ain't heard piston slap until you fire up the 460 in my 71. It's got forged BMEs with .007 clearance. Now THAT'S piston slap.

 

[C_Dogg]

I guess I don't get your point. Why in the world would I put in a lubricant that is NOT recomended by GM? According to the manual 5w30 synthetic is the ONLY oil for this car. After reading all of the threads, it is my opinion that is is piston slap, only because it goes away after it builds up some heat and has time to expand. And obviosly it is not detrimental to the engine as long as you allow it to warm up first. Like all of the rest of you guys, I have put in my share of carbon cleaners with little to no change. And to address your last point, there is no way in he11 that I would change my quality of oil. Your sugestion is absurd.

 

[motorman]

hib you can tell these people never owned a BBC corvette back in the 60s. i owned a 65 and a 66 both brand new and if these people heard the noise these engines made they would run away from them thinking they were going to blow any minute. my 02 has more engine noise when cold than either my 97 or 99 but it sure is quicker.

 

[Hib Halverson]

he11 that I would change my quality of oil. Your sugestion is absurd.

Uh C_Dogg, here's the sitch, pal....
I do not post absurdities to this forum. I have neither the time nor the credibility to waste doing so.

Reality is: the Owner's Manual is NOT the ultimate authority on this issue. The Service Manual is.

If you examine Page 0-42 and 0-43 of the 2001 Corvette Factory Service Manual you will find complete information on oil recomendations. For your convenience, here is an excerpt:

The recommended SAE viscosity is 5W30, however, if termperatures are above -18°C (0°F) 10W-30 may be used.

Bottom line: 5W30 is the recommended oil, but that recomendation is based mainly on GM's pandering to politicians and environmentalists with the fuel economy issue. Other than in very cold temperatures, best performance and protection will come with a 10W30 which, I might add, Mobil 1 makes.

Indeed, the noise is "piston slap" or, more correctly "cold piston knock" and that it is a pleasablity problem, not a reliability/durability issue. As for "carbon cleaners", the best carbon cleaner is driving the engine as it was designed to be run....hard once in a while.

he11

Darn...I just got that. An inventive way to get around the CAC's censoring of unacceptable words.

 

[Rob]

Darn...I just got that. An inventive way to get around the CAC's censoring of unacceptable words.
[/B]

Um, no. I think that was his own censoring. HELL

I'm not that much of a prude!

 

[vettepilot]

For what it's worth, to further support Mr. Halverson's information from the service manual, the operator's manual also gives the alternate recommended viscositys for temperature ranges. I don't have mine right here by my side but I do remember reading the section on recommended oils vs temperature ranges.

vettepilot

PS: I use 10W30 Mobil1 in my LS6, and used it in both of my previous Vette engines a 91 and a 93. Works great, lasts a long time.

 

[C_Dogg]

Well guys, your temp. point is well taken. Since I live in the cold great lakes area I'm using the correct viscosity. I still won't use Mobil. It's a blend, and I would prefer to use a pure synthetic for max protection. Everything I own that has a gasoline burning engine get Amsoil. To each his own!

 

[motorman]

as long as the oil you use meets GM4718M specs you are good to go,but some syn racing oils have a high content of a high pressure additive which will cause early oxidation of the oil. this is not a problem in race cars because of the frequent oil changes.

 

[Hib Halverson]

Well guys, your temp. point is well taken. Since I live in the cold great lakes area I'm using the correct viscosity. I still won't use Mobil. It's a blend, and I would prefer to use a pure synthetic for max protection. Everything I own that has a gasoline burning engine get Amsoil. To each his own!

Ah...now I understand, C_Dogg's an Amsoil user. Unfortunately, Amsoil is, IMO, a continual purveyor of disinformation about engine oil. Mobil Oil Corporation's "Mobil 1" is, indeed, a pure synthetic and not a blended synthetic or a "highly refined" petro-base oil like Castrol Syntec. It uses a different synthetic base stock than does Amsoil's, Royal Purple's or Red Line's products, but it is a pure synthetic.

Um, no. I think that was his own censoring. HELL

I'm not that much of a prude!

Ooops. Sorry, boss. I guess it was the Dogg's typo. We know you're not a prude. How could anyone speak so cruelly about a guy who is also the Bartender at the ZR-1 Net Saloon!? A prude wouldn't last 10 seconds in that job.

as long as the oil you use meets GM4718M specs you are good to go,but some syn racing oils have a high content of a high pressure additive which will cause early oxidation of the oil. this is not a problem in race cars because of the frequent oil changes.

Good point. Some, but not all, synthetic race oils do have that problem. In addtion, in some cases, not only might the EP additive packages cause "early oxidation," but virtually all the EP additive packages in true racing oils, also, will significantly decrease the lives of cataylitic converters.