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Comprehensive List of Technical Issues w/ C4s?

pgtr

Well-known member
Joined
Nov 20, 2002
Messages
324
Location
CST
Corvette
96Cpe
I was wondering if anybody has compiled a comprehensive list of typical, predictable technical issues w/ C4s? I'm not looking for 'expected' issues like brake pads which obviously wear. Nor common wear items that given enough miles always wear out like alternators. (unless there is a premature failure issue)

These would be technical issues that are somewhat predictable based on not just personal experience so much as seeing sufficient identical/similar issues say on this forum or elsewhere such as professional experience, magazine articles, research, TSBs, etc...

These would be issues that are a function of mileage, time, design flaw. etc.

The info might be handy to a new buyer or a long time owner to 'know what to expect' or 'what to watch for' over time. Or maybe to get out ahead of as preventative maintenance.

How about a format such as:


Descriptive Title
YY - YY (years affected)
Paragraph expanding and justifying it as a common, typical or predictable issue.


Here's a few I came up with... (but what have I missed?)

Opti-Spark Failure
92 - 94; 95 - 96*
Opti allows moisture in from water pump leak and causes ignition failure. *Improved and arguably fixed in 95. Occurs based upon miles accumulated and amount of exposure to water. Upgrade options exist for earlier versions.

Headlight Motor Gears Failure (headlights don't raise/lower)
84 - ??; ?? - 96
Earlier versions had problems w gears stripping. Later (improved) version had problems w/ internal gear stops shearing/disintegrating. Both result in essentially same symptoms and are a function of usage over time. Discussed on this forum and in magazine articles.

Digital Dash Display Failure
84 - ??
Digital display can fail over time/usage and has to be sent out to be rebuilt/restored electronically. Discussed on this forum and others.

Headliner hangs down
?? - 96
Foam material disintegrates w/ time and heat causing loss of adhesion, sagging material. Various replacement kits/techniques to use adhesive on new material. Mentioned online, commonly available kits through catalogs.

Warning Chime Intermittent/Fails
?? - 96
The warning chime for leaving headlights on etc. in (late?) C4s can fail over time due to miles/vibration. Apparently a crack in some solder traces due to vibration causes the intermittent failure. Must open up dash and remove to repair or replace. Discussed on this forum.

Weak or poor illumination at night on the road
84 - 96
The OE plastic lens headlamps provide poor illumination (always or with age?) further hampered by the inherently low headlight position on a C4. Virtually any standard halogen replacement results in improved night visibility over the OE lights.

Bose amplifier failure(s)
?? - ??
I'm not sure what years this affects but I've read about it for years. The unique to Corvette, Bose amps (capacitors specifically?) placed at the speakers can and do fail over time/usage. Various solutions including repair or replace w/ aftermarket system.

LTPWS Failure
?? - 96
I don't recall when this option was first offered but the Corvette's first generation low tire pressure warning system (LTPWS) does incur problems with age. Since being developed the industry has gone on to other technologies for use in tires and the Corvette sensors are generally not serviceable. Some people simply remove the bulb from the dash. Others seek out known good used sensors. Many just ignore it.


What else did I miss? Corrections/clarifications to the above? (remember the paragraph isn't intended to provide a complete detailed fix-it solution - just a couple sentences to point someone in the right direction is all)
 

Tom Maine

Well-known member
Joined
Mar 30, 2005
Messages
64
Location
Minneaoplis
Corvette
1991 Yellow Converible
I can help on the BOSE system. Sound repair in Fl. says the Bose is essentially a very good system, ahead of its time. THey can repair the system and make it much better using todays technology. They repaired mine and did a fantastic job on it. Price was more than reasonable and turnaround time was great. They also have on their site how to get the radio and such out of the car in a step by step process. They indicated that if I went aftermarket they would liketo have the old system. It is very good once you get it fixed.
 

vetteoz

Well-known member
Joined
Jan 20, 2004
Messages
1,561
Location
Not in Kansa anymore
Corvette
1990
What else did I miss?

Where do you start?
There are well documented probs from the factory as well as age related ones; common wear and tear.
Example

Tachometer failure
1990 - early 1991
Tachos commonly have eratic readings or peg out.
Nearly always need the tacho unit in the cluster rebuilt.

Tachometer failure
1984 -89
Faulty tach filter /bad connection.
Tach filter is silver cyl mounted on top bellhousing bolt hole Drv side .Has 2 white wires to it.

Relay Connectors Failure
1984 -1988
The non weatherpak relay connectors used in early cars lose the insulation on the wires giving shorts and faults.

4 +3 Trans
1986- 1988
O/d operates correctly but can not be controled by shifter mounted button . Replace switch at base of shifter with Radio Shack # 275-1549 ($4) or similar.
MUST be "momentary " contact ; not off/ on switch
.

*Edited to comply with format started by thread originator. - Jane Ann
 

XLR8

Gone but not forgotten
Joined
Jun 23, 2004
Messages
6,662
Location
Mississippi Gulf Coast
Corvette
2003 AE Convertible, 1998 LCRM Convertible
Vetteoz, I edited your reply slightly to stay with the format started by pgtr, making the issue bold to standout during searches and skimming by readers.

Excellent idea for a thread, by the way. :thumb
:wJane Ann
 

Schrade

Well-known member
Joined
May 2, 2009
Messages
1,315
Location
Not in CF; BANNED!!!
Corvette
'90 LT 5
Door panels/weatherstripping.





(hope that's good format)
 

pgtr

Well-known member
Joined
Nov 20, 2002
Messages
324
Location
CST
Corvette
96Cpe
Where do you start?

Indeed! This thread - if enough members contribute may help. Not looking for detailed solutions. If indeed people post 'common' or 'known' or 'predictable' problems then there certainly will be plenty of past threads, articles etc. out there w/ all the detailed solutions and options available.

The two samples you cited are perfect - thanks
 

Brian Smith

Well-known member
Joined
Aug 20, 2009
Messages
46
Location
Flower Mound, Texas
Corvette
1993 Viper Red Coupe
One would mention: Engine temperature control to include fan operation, fan relays, the two sensors, thermostats (I can help with that);

Weatherstrips (C4s are aged enough now to require replacement easily - I can help with that);

Basic A/C issues to include R134 installation (likewise just did that); CPU error codes (some expereince there also) and window adjustment (another maddening experience-took the drivers door panel off more times that I care to share but did get it right).

I am so looking forward to learning how the seat movement mechanisms work this fall. The bolster inflators and the seat track motors etc.

Carpeting? This fall also.

Figuring out how to redo the surface of the interior trim pieces (like the console part that goes up to the radio) that have that rubberized texture on it. Significant wear and not willing to spend a ton for cosmetic replacement of structurally sound pieces. It has to look good too.
 

vetteoz

Well-known member
Joined
Jan 20, 2004
Messages
1,561
Location
Not in Kansa anymore
Corvette
1990
I am so looking forward to learning how the seat movement mechanisms work this fall. The bolster inflators and the seat track motors etc..
Drive gears in track assembly strip .
If bladder pump runs but no inflation commonly the diaphram in the pump is perished.Easily fixed by cutting a new one from a rubber kitchen glove.
 
S

seajayiii

Guest
Fuel Injectors

'89-'91 stock Multec fuel injectors are prone to failure.
 

sstearns2

Well-known member
Joined
Feb 14, 2008
Messages
95
Location
Camarillo, CA
Corvette
1990 convertible, red/tan/tan, 6 speed
Bose stereo system failure(s)
All years with option available.
The amps are built into the speakers and prone to failure. CD failure is common. All the components can be serviced and rebuilt for about the same price as new modern components. The Bose system has a unique architecture making it difficult to use aftermarket components together with the original Bose components. It is generally recommended to replace the entire system with modern components for sound quality, use of modern formats (CD-R, USB, Ipods, etc.) and cost issues.

Fuel Injector Failure
85-94
The ethanol added to gasoline causes the fuel injectors to fail over time. The fuel injectors should be replaced as a set with modern units as they will all eventually fail. Don’t bother only replacing the one or two that will go bad first. Rebuilt modern fuel injectors are available for about $250 as a flow matched set.

Clutch Slave Cyliner
89-96 (maybe earlier years too?)
The seals in the clutch slave cylinder go bad, even on low mileage cars. Check the clutch master cylinder fluid level and the slave cylinder for signs of leakage frequently. Weak clutch hydraulics can lead to difficulty shifting and damage the transmission over time. It is recommended that the master and slave be replaced as a set and that both units be disassembled and checked for metal burrs and correct seal orientation prior to installation.
 
Joined
Oct 7, 2007
Messages
719
Location
Amherst, NY
Corvette
1989 Red Coupe
Incorrect MPG reported on Digital Dash
1985-1989
MPG jumps all over, or shows way off values.
Resetting ECM or using rest button does not help.
Serial data processor defective in ECM, replace ECM.

Flickering Digital Dash
1985-1989
Check battery voltage with load and in drive.
Clean grounds, especially on transmission bell housing.
Check alternator (diode ready to fail???, this was my issue)
Internal issue with connections, solder joints, or power supply (search for more info)
 

air1jpg

Well-known member
Joined
Jun 4, 2007
Messages
393
Location
Louisville, KY
Corvette
1996 Polo Green LT1 Coupe
Brake saftey Switch for the Automatics
???-1996
Some will develop a problem with this switch in front of the gear selector. When inop, you will not be able to press the release button to get the transmission out of park while depressing the brake pedal.
Replace the switch per the FSM.

Automatic Antenna
1984-1996
Overtime, either the gear in your automatick antenna will wear out or the plastic strip that is attached to the motor will break.
Take the drivers side tire and and the wheel well linning out and replace the antenna assembly.
 
C

cotton

Guest
list of issues/

great thread : does anyone know how long this info is stored on
this forum : can see right now will be looking this up for
period of time while I go thru a learning curve: thanks
 
C

chuck121566

Guest
Leaking fuel pressure diaphram

I recently replaced the fuel pressure diaphram in my '88 and have sine learned that this is a fairly common problem with the L98 equipped cars ('85 to '91). A small hole in the diaphram will cause a flooded/hot start condition that is often misdiagnosed as leaking injectors.
 

vetteboy86

Well-known member
Joined
May 26, 2003
Messages
2,760
Location
IN
Corvette
1986 Black "Indy 500 Pace car replica"
great thread : does anyone know how long this info is stored on
this forum : can see right now will be looking this up for
period of time while I go thru a learning curve: thanks

It will be around for a while :thumb
 

air1jpg

Well-known member
Joined
Jun 4, 2007
Messages
393
Location
Louisville, KY
Corvette
1996 Polo Green LT1 Coupe
Bose stereo system failure(s)
All years with option available.
The amps are built into the speakers and prone to failure. CD failure is common. All the components can be serviced and rebuilt for about the same price as new modern components. The Bose system has a unique architecture making it difficult to use aftermarket components together with the original Bose components. It is generally recommended to replace the entire system with modern components for sound quality, use of modern formats (CD-R, USB, Ipods, etc.) and cost issues.

The original Bose head unit can be re-biult to play the CD-R discs. Also, you can use one of those "old fashion" cassette to CD adapters to play your Ipod or other MP3 palyer through the Bose system. :thumb
 

bill5674

Well-known member
Joined
Dec 14, 2003
Messages
183
Location
li ny
Corvette
1990
climate control..... prone to vacuum trouble leaks,bad modules and bad head units.also leaking heater cores have been known to be less than pleasant to change.
 

pgtr

Well-known member
Joined
Nov 20, 2002
Messages
324
Location
CST
Corvette
96Cpe
Great info - keep it coming!

Most of this info is dead on to what I was envisioning. Those problems unique and specific to C4s. Perfect info for owners or would be buyers.

Again - common/obvious problems like carpet or air conditioning - any car can and will get this and quite apparent to any owner or buyer. Too long of a list and not much value in cataloging the obvious I suspect.
 

Superc63

Active member
Joined
Mar 10, 2004
Messages
37
Location
Franklinville NJ (South)
Corvette
1993 Ruby Z07 x2, 1988 Dark Blue Z52
1984-1996, Automatic Transmission Output Bushing/Seal Wear and front Driveshaft Yoke Wear

Symptom is leaking transmission fluid out the back of the tranny and driveshaft vibration with speed. This problem may apply on manual trans too.


1984-1991 engine compression ring failure

Symptom is excessive blowby followed by oil leaks from valve covers and excessive oil consumption. This is easy to spot by pulling the dipstick out and starting the car. Hit the gas and see if a lot of steam or oil blows out the dipstick tube. I once bought a 1988 without first checking for that problem...ended up selling it for 3k less than I bought it. I also just (3 hours ago) looked at a real sharp yellow 1990 with the same problem at a used car dealership.
 

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