Hi, I'm new to the forums and looking to get my first Corvette. I'll try not to make this long. I have always wanted a C5 Z06 and I finally feel like my financial situation will allow the purchase. I am looking at 02-04 models.

Question
Most of the cars I am looking at range in mileage from about 25K to 40K. What kind of issues should I expect at this mileage? Assuming the car wasn't tracked should I expect suspension bushings to be worn? Shocks? What about electric components (sensors, fuel pump, etc.)? I know the column lock problem is common.

Intended Use
I want a reliable fun car I can drive to work everyday or take on trips (assuming no snow) and throw around in the back roads. May do some autocross events with it but nothing initially. I have an E36 BMW 328is that I've had since high school. This is currently my daily driver and autocross car. With over 240K miles the car has its share of issues. Sometimes it can be nerve-racking trying to get the car running before work the next day. So really looking for something I can depend on everyday within reason. I understand this is a sports car and its not perfect. I have a 95 Volvo 850 for winter running.

Maintenance I intend on doing on any car I buy
I plan on doing plugs, belt, and all the fluids. Also will get the car inspected prior to purchase. I've always had cars that were over 100K miles so I just went into it knowing I had to do a suspension overall or another big job. Euro cars have really taught me to do preventative maintenance and that is what I intend on doing on the C5Z as well. I know each car is different but just looking for some general wear intervals to expect or things to keep my eye on with these cars around this mileage.

Thanks!
Vishnu

 

At 40k I wouldn't worry about much. My car had 50k on it and didn't need anything notable other than column lock(!!) in the first year, though the diff did start going out in that timeframe. OEM diffs crack the bellville washer/spring that preloads the clutch packs sometime around 50k miles and they start eating themselves and eventually start to whine. If you find a car with a rebuilt diff, consider that as a $2000 bonus. Everything else is pretty rock solid but I do agree to change stuff that can go out with time as much as miles like rubber belts, fluids (especially orange dexcool coolant). Its also common for people to sell these lower miles cars with original 20 year old tires which you should consider as a $1000 hit to the sale price at least throw them out and get a new, quality tire. As far as intervals, these cars don't have anything unusual.

 

Thank you so much! Makes me feel much more comfortable going after a car that has near 40k miles. Will the whine be apparent on the test drive or does the fluid have to be hot after a long drive for the whine to develop? I just don't want to miss it on a car that I test drive. Is there any preventative measures you can do to prevent the washer from breaking?
Funny you mentioned the tires. The thought/fear of 20 year old tires crossed my mind especially when I consider travelling for a car.

 

It depends on how advanced the wear is. When I first noticed mine I had to turn off the radio and HVAC and I was still not confident that I wasn't going crazy. After a couple years it was so loud I couldn't have a conversation in the car on the highway. The noise will get progressively louder and higher pitched with wheel speed and go away completely when you let off the gas. Depending on the exhaust it may be easier or harder to hear. Mine is loud but I can hear it at cruise at 60+ in 5th or 6th. Lower gears I can't hear it well. For reference I replaced mine around 70k and put a diff it from a wrecked car with 84k on it and now I'm at 102k and this diff is starting to whine louder all the time as well.

 

Replace the fuel filter.

 

I would flush the fluids, (diff/trans/brake/clutch/coolant) and replace spark plugs and wires more due to age than miles. Fuel filter is a good idea too.

 

change valve springs.

 

Thanks for all the replies! Forgot about the fuel filter. So I will add that to the list. New wires makes sense too.

@oharal Thank you for the detailed explanation of the diff symptoms. I used to have an 89 BMW 535i 5 speed that developed the exact same whine in the diff. First it started out very faint but it progressively got louder. The day I knew it wasn't in my head was when my friend was following me and he could hear it from his car. I'll keep an ear out for the noise when testing the car. I know it all too well now!

So I keep hearing about the valve spring issue. I had planned on doing it but how common is the issue really? What causes the failure? Is it high-rpm? Using the wrong weight oil? Not letting the car warm up? If I'm opening up a can of worms here I can start a new thread

 

Funny you mention about others hearing it. Mine was already very loud but I always assumed only I could hear it. A friend of mine from work passed me on our commute home and texted me right away asking "are you aware your car is singing?" Bear in mind this was 80mph on the interstate!

I should have mentioned the valve spring issue as I did my springs right away after buying the car at 49k miles. 2002 is the main year for issues but 2003 has some as well. There's a big thread out there with a lot of info. Basically in 2002 they used a spring that had material issues that didn't show up until they somewhat randomly break while the engine is running. The issue is with the yellow springs. Which may be kinda brown now. In 2004 they changed to a blue spring which is more reliable. That's what I used. It has nothing to do with the oil, warming up, age, mileage or anything. It's purely random. The job is easy enough to do with some fairly inexpensive special tools and well worth the peace of mind that you wont drop a valve and grenade a perfectly good engine.

 

visvette, you might be able to determine if valve springs on an '02 or '03 have been changed. Remove the oil filler cap and peer inside the valve cover using a dental mirror and a small flashlight to redirect the light toward the closest valve springs. Look for mustard yellow or yellow-tan coloring on the closest valve spring ("iffy" ones) or blue (replacement GM).

I bought an '02 Z06 that was produced in January of 2002, which just (by a few weeks) preceeded the time-frame of the notoriously "iffy" valve springs run. I decided to replace the valve springs with the blue GM springs and used that as an opportunity to replace the valve seals at the same time. Doing the valve springs requires a bunch of bits to be cleared away, which makes it a no-brainer to replace the spark plugs, spark plug wires and valve cover gaskets during reassembly. Now, I have full confidence that the valve springs are reliable.

The parts costs to replace the valve springs are fairly reasonable...figure about $75 for the blue GM springs and about $50 for the intake and exhaust valve seals.

 

[QUOTE=M.Y.02Z06;1600927931]visvette, you might be able to determine if valve springs on an '02 or '03 have been changed. Remove the oil filler cap and peer inside the valve cover using a dental mirror and a small flashlight to redirect the light toward the closest valve springs. Look for mustard yellow or yellow-tan coloring on the closest valve spring ("iffy" ones) or blue (replacement GM).

or easier yet. just take the rocker cover off

 

[QUOTE=walleyejack;1600929181]Not easier. He's looking at buying a car, and this would be the least invasive way to check the valve springs. I wouldn't allow a buyer to pull the valve cover on a car of mine...maybe a shop.

 

@oharal Yup, same situation. My friend heard it from his 240SX that had a built motor and exhaust. At the time my car had an exhaust leak and was quite loud. The diff was still louder!

@M.Y.02Z06 @walleyejack Thanks for the advice on the valve springs. M.Y.02Z06 is right. Since I'm looking at buying a car I probably can't go there with tools and start taking the valve cover off. I will go there with the dental mirror and check to see which springs it has. I have a lead on an 03 but it is in California (I'm in Illinois). The car should survive the approximately 2000 mile trip home right? Should I risk the 2k mile trip home if my inspection on site reveals it has the yellow springs? The seller admitted to me that he never did the springs but was thinking about doing it.

 

https://www.corvetteforum.com/forums...-failures.html

 

Check the build date - it should be on the upper left corner of a white GM tag located on the door jamb end of the driver's side door just above where the door striker is located. If the date is before Feb. 2002 the car's valve springs are supposedly lower risk, and any date after is supposedly higher risk (based on owner reporting data about failures). The date range starts around the 2nd half of 2002 production year and into 2003. The production cycle started mid-calendar year...so January is transitioning into the 2nd half.

Personally, I'd drive it back home but play nice-nice with the engine...a nice warm up period when started, don't nail it (unless necessary), check engine oil, etc. [By the way, none of these precautions supposedly matter.] The valve springs matter should be treated as a housekeeping item on any 2002 or 2003; don't let it keep you from buying the car if it checks all of your boxes. If you are worried about driving it, then have it shipped.

My understanding of the valve spring matter: the yellow valve springs reportedly could experience failure due to metal fatigue; the failure is reportedly due to a manufacturing issue; failure is supposedly not dependent on driving conditions, such as a cold engine versus warmed up engine, rpms, etc. As a recent buyer of a Z06 (bought mine in Dec. 2019), I can tell you that there is a lot of easily accessible information here on CF about the valve spring matter. Best to review it and arrive at your own conclusion and action plan.

My car was built in Jan. of 2002...supposedly lower risk group...but I decided to change them anyway just to eliminate uncertainty. It was a personal decision...maybe overkill, maybe not...but now I can drive it for personal errands or take it to the track for warp-speed enjoyment and not worry about a valve spring randomly toasting (just everything else).

 

laurent z06, thanks for the thread link. The car I'm looking at was built 09/02 so literally at the borderline of the high risk group. Great...

M.Y.02Z06, I agree with doing the valve springs no matter what! I plan on taking care of this the moment I get the car home when dumping the fluids and doing the other maintenance items previously discussed. I'm definitely worried about it making the 2,000 miles home but hoping everything goes okay. The car has about 16K miles. Maybe the lower mileage buys me more time?

I'm with you on avoiding uncertainty. I would hate to drive the car just worried that it could blow a spring any minute. Especially since I'm looking to more or less daily drive this car.

 

I have posted this in the past and linked to the topic. The original owner of my '01 lost a valve spring. The car did have some HPDE time. If I were to purchase an '01-'03 Z with factory springs, I would replace the springs. It isn't a bad job or an overly expensive to do yourself and then you know you're car isn't at risk.

At the same time, the spring issue wouldn't stop me from buying another Z in that year range. When the car came home I'd pop the valve cover and take a look. C5s aren't difficult cars to work on. Further ease of mods and maintenance was a factor in replacing my C4 with a C5 nearly 20 years ago. The C5 is easier to work on than late C4s. A spark plug and wire change is easier on my C5 than my 70 Chevelle SS396 with AC. I am also not a mechanic but a cube dwelling bean counter by trade.

 

Add to maintenance list: change PCV valve (inexpensive, easy and preventative).

 

Will add the PCV system to the list, thanks!

93Polo, funny you mention you're a cube dweller. I am one too. A geologist mostly shackled to the office now. Honestly it's a miracle I've come this far in cars (with the guidance of good friends off course). I will say my rock hammer has come in handy for a few jobs over the years
I do appreciate your perspective comparing the C4 and C5 on maintenance. The C4 was the first Corvette I really wanted. Still love the body and some colors just make it pop. However, I thought it would be better to get the C5 since my other cars were from the 90's. Might as well go for something slightly newer and more capable. Plus I think the Z06 looks great.

Been doing a lot of reading on the valve spring replacement and looking up as many DIYs as I can. I plan on doing the TDC method as laid out here: http://www.ls1howto.com/index.php?article=23.
So in this case I would do Cylinder 1 TDC which also places 6 at TDC. Then you take all the rocker arms off and do the springs for 1 and 6. That makes sense. The guides then say rotate the motor until the next two cylinders are at TDC. So in this case 8 and 5. Does that mean the cylinder is physically pushing the valve up as you are rotating the crank? There's no damage caused by this? So it's safe to rotate the crank without the rocker arms on? Or do you bolt the rockers back on, rotate crank, unbolt rockers, change springs? Sorry if this is a novice question.

 

https://www.corvetteforum.com/forums...ressor-at.html

We used compressed air. TDC should keep the valve from dropping and you don't want to torque down the rockers when the cam is in position to have the valve open as you torque the rocker down it will push the rocker arm in the direction to open the valve which due to pressure won't open resulting in the push rod being pushed into the lifter. It can increase chances of stripping the threads. It'd be best to do TDC and compressed air. You shouldn't have to use thread sealant on the rocker bolt with stock castings. Ported heads will sometime have the rocker bolt hole exposed to the intake runner.