woodstockdrifter

Hope you guys are doing good. I'm new to the C4 and new to the LT1. Here are some noises that worry me. There are 2 noises, 1 video for each

FIRST a "wob wob wob" Took the video at about 150 F a couple minutes after start up.


SECOND is like a fast "tih-tih-tih" and first noise is gone from what I can tell. I took it after a 12 minute drive


I spent 4 to 5 hours researching this but I'm still trying to narrow it down. It could be dirty oil, dirty or bad lifters, dirty or bad injectors a bent rod or worn cam lobe?? The oil was changed 500 miles ago from 5W30 to 5W30 synthetic. Engine performance is good, start up is good.

The second noise seems to be coming from where I mostly had the camera. I just learned how to change brakes and I also just learned what a lifter is so I will end up taking it to a shop but Im hoping you guys can help me understand this potential problem better. I am learning as much about the C4 and LT1 as I can and want to take very good car of this car.

Is this true? If its a bad lifter, the lifter roller bearings can fail or even disintegrate which will obviously cause engine damage. Thank you for the help.

pifo1964

Maybe this thread can help and guide you on what to look at. The noise is very similar.
Today, 2000 miles after, my car runs even better but still hear the noise. I do not worry anymore and that´s good for my mental health....

https://www.corvetteforum.com/forums...ine-noise.html

RUU

It sounds similar to my LT4 earlier this year and it turned out to be a bad lifter. Use a long screwdriver or a length of dowel and put one end on a valve cover bolt closest to the noise and one end against your ear while the engine is running. Listen for a loud, distinctive ticking noise. Repeat for all the other valve cover bolts to determine if one area sounds louder than the others. That will determine if it is a valve-train related issue. Best case scenario is that it is a bad lifter, worst case is that a cam lobe is going bad.
From what I hear, you can probably continue to drive the car unless the noise starts to get louder.
If you're feeling adventurous, you can try one of the oil additives which claim to free up sticking lifters, otherwise, be prepared to shell out some money. The lifters themselves aren't that expensive, but there's a lot of labour required to get to them.

sluggballz

The first sound is exactly what my 95 sounds like at start up and until it reaches operating temp. When I first bought my car 5 years ago, I took it to show a friend of mine who is a very good mechanic. He heard it and said it was an exhaust manifold leak likely from a cracked manifold. He said he had seen quite a few of the right side manifolds crack, usually it's under the heat shield and you can't see it until you remove the manifold . It hasn't bothered me since and I've put probably 40,000 miles on it since I bought it. If I were to ever feel super froggy I might replace the manifold and go with headers. But that's not really in my crystal ball for the future.

woodstockdrifter

I think I remember seeing your thread as I searched. Thanks for the link. I think your second video and my second video have pretty similar noises but mine is at a faster rate. I think you should worry and look into it again because the more I research, the more I understand how the noise can be a sign of future engine damage. If its a bad lifter it can cause engine damage.

I know not what we want to hear but if its there we need to address it.

woodstockdrifter

Thanks for the reply. Sounds 1 and 2 are very different so that makes sense they aren't related and that it could be a manifold leak. I will work on sound 2 first since its probably a more serious problem but need figure out the first one too.

woodstockdrifter

You're right this can be costly. I saw a video of an engine pulled apart to try to understand how the lifter works and its like a full disassembly. I will try the screwdriver listening thing. Thanks

woodstockdrifter

After more research and reading threads like this one

https://www.corvetteforum.com/forums...licking-3.html

I realize I have 2 different problems from 2 different noises. I am going to address noise 2 first since it seems more serious.

I don't think its an injector because engine performance has been fine at all rpms. So it could be a bad lifter, bad cam lobe or bad rod. But I've been hearing more youtube videos and leaning towards a bad lifter. So here is my plan:

1. Try screwdriver listening method
2. Check oil for dirt and pressure
3. Possibly try oil additive
4. Possibly remove valve cover for further diagnoses
5. Take to a good shop

Is there any device I can use to help diagnose this like a OBD1 reader? If I take it to a shop will they do manual checks or hook up the ECM to their tools? And last thing, how does this happen?? Do lifters just go bad or does something cause them to go bad?

pifo1964

Thanks for the advice, but if you read my thread in detail, you´ll see that I really did everything possible to identify the noise. Also after that, I took the valve covers , ran the engine, and found nothing abnormal. The only thing left to do is to open the engine, but I will not do that unless it breaks. It has only 13.500 miles and since I bought it, 6800 miles ago, the noise never increased .
I can´t think what else to do but to enjoy my car.

woodstockdrifter

Evening bump

sluggballz

In the process of putting headers on and removed the old manifolds. Both drivers and passengers manifolds were cracked in two different places. They looked identical. This pic is after I cut off the heat shield.

Anyway, that's the cause of the burble sound you hear.
It's only taken me three hours to get the old manifolds off! Now the fun begins.

TorchTarga94

^^ Nearly every single LT1 manifold I have seen from a C4 will have these cracks.

ddahlgren

Does it sound the same at all temps?

Tom400CFI

I don't see any soot by those cracks so my first thought is that in spite of the fact that they are cracked...I doubt that they're leaking.

woodstockdrifter

The first noise, the wob wob wob goes away after the car's warmed up. The second noise, the ticking starts when the car is warmed up.

I'm looking into the ticking noise first. I will be taking off the valve covers soon I just havent had a chance to do anything with the car besides inspecting the oil filter.

Tom400CFI

Does the ticking noise change in volume with engine load (not RPM, load).

ddahlgren

Lash the valves then or use 20-50 oil. I use 2050W dino oil in my 91 for the last 8 years and no leaks and no problems. I doubt the injectors will get noisy from warm oil. If the lifters have leaky check valves they will as oil thins out. The 5 30W was all about startup smog stuff and fleet mileage. 20-50W will easily work with the temps 99% of C4 Corvettes are driven. If you use quality oil an additive is useless BTW. The big deal is keep it fresh and clean. The synthetic oils that allow high mileage between changes if me every 3K I would pull the filter and change it and add to allow for lost oil. Lashing valves and an oil change is about the cheapest test you might have on hand.

woodstockdrifter

The tick gets faster and a little louder under a small amount of engine load. But above 8-10 mph in first gear it goes away.

Engine feels very strong and sounds good overall but I havent pushed it past 3000 rpm since I first heard the noise. Someone on another forum told me it it wouldnt be a damaged cam because the engine is running too smooth and at least one cylinder would be underpowered. Checked the oil filter yesterday and no metal particles or flakes so probably not a damaged bearing. Well thats all I know when it comes to diagnosing the bearing stuff.

Since I have to replace the valve cover gaskets I will take a look at the rockers.

Tom400CFI

Well that wasn't as clear as I'd hoped, but how about this; does it go away under no load? (coasting down hill in 1st gear at lower speeds)?

If so, that would be an exhaust leak.

IMO; the noise that I'm hearing on the videos are;
1. induction/intake noise
2. valve train and injector noise that is typical for an LT1 -my car sounds about like yours does.

cv67

Not sure you have a problem at all