neural

I'm looking at buying a used Z06, and would like to know what the more experienced owners might know about how to determine the overall condition of a Z06 engine on vehicles that have over 30k miles.
I sat in one earlier today and started it up. It has roughly 50k miles. While listening to the idle, I realized that I really don't know how the engine *should* sound if it was properly cared for.
Are there any known "sounds" (beyond the painfully obvious) that are tell tale signs of problems?
Are there any visual indicators on the motor itself that someone inexperienced such as myself should look for?

Buying a high mileage vehicle is probably the only way I'll ever obtain a Z06, and I'd like to get things right the first time.

Thanks

DaytonaFIC6

Listen for abnormally loud valve train noise. Also, the most obvious is to look for blue smoke upon start up and have someone rev the engine while standing behind the car to check for blue smoke. Check oil level, service history, carfax, tire wear pattern and rubber in the rear wheel wells(indication of aggressive driving). Those are the simplest things if you are really worried, you could get an oil sample and send it to be analyzed.

3LZZ06

The honest answer is no...

There "can be" very little notice of an LS7 going boom. On the other hand, in some cases owners have noticed obvious signs that there's a serious problem.

Bottom line...it's hit or miss so set aside a couple grand to have a reputable shop do the heads for piece of mind.

Best of luck with your future Z...

Gary '09 C6

^ good advice !

'06 Quicksilver Z06

Sad but true. We've had cars in here pop which were running flawlessly before.

One guy popped a motor just days before he was to have his heads fixed.

neural

Thank you for the replies. I had no idea you could have oil analyzed! Gotta love technology.
I'll definitely look for the blue-smoke issue. Burning oil is not a good thing, this is true.

spicytuna

The LS7 is one noisy engine!

When I first drove my car, I was almost convinced that I had an exhaust leak until I listened to several others and concluded that it was just a noisy valve train.

I just had my heads redone and it still sounds like a sewing machine which is about to go south.

siidman

I'm in the same boat so I'm having the car looked at by a shop that people on this site have recommended.
They're gonna check compression and put it on the lift to look at the undercarriage and put it on the dyno to see If the tune was done correctly. All about 400 and should be well worth it since I wouldn't be able to tell myself either.

Bill Dearborn

Sewing machine sounds are OK. Most LS engines will have a similar sound. Some people will notice a louder tapping noise and that could be a warning it is time to do the heads. Others don't notice any unusual noises until the engine just stops running. It will pull to 7K rpm just like it always did, it will feel just as awesomely powerful, observers behind the car may notice black smoke out the back when braking from a high speed and then getting back on the throttle but oil consumption will be normal for LS1 engines (about a quart per day at the track) and zero on the street.

Rubber in the rear wheel wells might indicate a car that has been drag raced but to see if a car has been tracked get it up in the air and inspect it from front to rear looking for chunks/strips of rubber strips lodged into the under body crevices, in the wheel barrels and on the upper and lower control arms. It seems to lodge almost anywhere a tire can throw it. I try to clean it up after every event but the next time I get under the car I will find some I missed.

Bill

Mark2009

One good check is to get it on a chassis dyno. Have the operator measure the air fuel ratio and data log the engine (timing, etc).

You are looking for:
1. Normal horsepower curve (good)
2. Stock air fuel ratio (good)
3. Ask the dyno operator to look at the PCM (engine computer) for programming changes from stock (changes = red flag).
4. Observe for smoke out the exhaust (bad)

You can pull an oil sample from the oil tank (I think) using a syringe or turkey baster or something. Do a web search on a company named Speedco and see if they have a location near you; they will do an oil analysis on the spot for $20 (you can just walk in). Normally they do trucks but I'm sure they will take your money

Look for any physical signs the engine has been removed or apart; scratches in the engine bay, bolts or washers with wear marks (like a socket has been on them), dinged up fins on the power steering cooler, etc.

jedblanks

If you have a mechanics stethoscope, listen to each exhaust manifold port. Compare all 8. Of you don't hear anything abnormal, best you can do is try for a warrantied car.
If what you hear makes you uncomfortable, move on.

I doubt anyone will let you pull valve springs to check, so really a stethoscope and your judgement is the best you can do.

JwT

All good advise from reputable guys here on the forum. You should take it. If you get a chance to drive the car, have someone follow you a have them watch the exhaust. Perhaps going up an interstate ramp, accelerating and changing gears. Have them look for any puffs of smoke between shifts. That's what let me know to take it real easy until the headwork was complete on my 07.

RWE 427

Thank-you for this tip! I have one near me and will definitely use them!