New to forum; new to Corvette ownership
Just bought a 1996 C4 LT4 manual coupe; put in shop immediately for routine maintenance; replaced serpentine belt, oil change, etc.
Picked up car today; has knock in engine. Help?? I know nothing about auto mechanics... Anyone know a good mechanic in Birmingham area for Vettes?
What are the possible causes of this? Solutions?

 

Sorry man, don't know, but here's a bump anyways. I'm kind of surprised no one has responded yet.

 

Already took it to a "shop" or a "dealership". Take it back and ask for an explanation of "knock in engin".

 

"Knock in engine" is kind of vague. These engines will make all kinds of noises. With the hood open, can more or less isolate what part of the engine the noise is coming from? Is the noise a loud deep knock? More of a click or clack? Check the pulleys when the engine is running and look for vibrations.

What kind of shop do you take it? A dealership, Car-X, Midas? What kind of oil did they put in? What exactly was the "etc."? Plugs, wires?

The recommended oil is Mobile 1 5w-30 full synthetic. The key word being synthetic. These motors, especially the LT4's have very tight tolerances and operate at hot temps which is why synthetic oils are used.

Also keep in mind that the transmissions in these things are prone to gear rattle when in neutral and the clutch pedal out. Piont is unless you can a little more insight as to the nature and location of the noise, an online diagnosis is impossible.

Now, about shops. There are two ways to go. 1) and probably the best bet, is to join your local Corvette club and ask around. These folks will probably lead you to a good, honest, knowledgeable technician. 2) Take it to a Chevy Dealership. There is likely to be one or two techs that have been there awhile and seen one or two of these things. They will have all service manuals and info at the fingertips specific to your car. But they will not be the cheapest option.

Welcome to the madness and good luck

 

Hi, this is Pappy's wife responding...The noise is more of a clicking I guess. You do not hear it when the engine is idle. When you rev it up, you can hear it. When you drive it, you can hear it as you accelerate. The mechanic I took it to replaced the serpentine belt, replaced the valve cover gaskets, hoses, coolant system flush, acc drive belt replaced, oil pressure switch replaced, brake cleaner, carb cleaner, oil filter, synthethic oil, thermostat replaced, new battery. The problem is that I did not hear this noise before I took it in for a check-up. I really do not know what to do. If it is a rod, what are my options?

 

I'm not trying to be an *** but from a mechanics perspective this is very vague. There a lots of clicks and ticks that come from fuel injected engines as they operate. It could be just fuel injectors operating or it could be a loose rocker arm, etc etc. If you have no mechanical inclination or experience you are gonna have to take it to a good mechanic and ask about it. Its all you can really do. No one on any forum can diagnose a problem like this without being around the car.

 

Try to guess exactly where the noise is coming from, listen in a quite place, you can rev the engine from the engine compartment easily, the throttle is in the front where the air intake is connected. If it is a rod, I think a rebuild is in order, who did you buy this from? If a dealer, they may help you out if it is a rod, but I don't think it is, these motors are pretty well built, but I don't know what kind of abuse it has suffered.

 

Rods make deep knocking noises - not clicks. I have been in service my entire profesional life and I have found that the first question to ask is "What was done/changed/fiddled with immediately before the problem occurred?" Obviously we can't hear it, but unless you are hearing injector clicking, I would have a professional listen to the noise and advise you. Otherwise, online people will only be guessing (unless the description is subperb and the problem is common)

It could even be as simple as a serpentine belt contaminated by coolant or oil. Good Luck!

 

You have to get it to a competent shop. Everything here will be speculation. It is probably something minor

 

If you could narrow down the area the sound is eminating that would give us a better idea of where to concentrate our efforts.

There's an ole' mechanic trick of using a long piece of rubber hose, (some use a broom handle) about 3 feet in length and 3/8" ID should work. Place one end of the hose against your ear and use the other end to locate the sound.

Just move the non-ear end of the hose around the engine, listening for the sound and try to locate where that sound is loudest/most pronounced; that'll be the area. Of course, BE CAREFUL with the hose around the moving serpentine belt/pulleys, etc.

Let us know what you find.

Jake

 

Pappy's wife here again: I got in touch with the local Corvette club. They gave me a mechanic's name that they all take their cars to; specializes in Corvettes. I called him, and he is going to look at it next week. He told me not to drive over 50 mph until then. Thanks for the replies. I hope it turns out to be minor but I will let you know.