swag

I have a 1968 corvette that likes to whistle at or around 3500 rpm. Not all the time.

Car can be warm or cold and it does or doesn't whistle.

I thought that I might have a vacuum leak so I got a carburetor cleaner and sprayed it near the hoses on each connection. I didn't notice a difference in the engine.

Also, per a suggestion from the local auto parts store, he suggested that my fuel line needed to be cleaned. I put some in the tank.

I am not sure if this is related, I was driving around the city on Saturday with temperatures around 100 F and when I was stopped at a light, then tried to accelerate when it was green, the engine was dead. Almost like it wasn't even on. so, I started it and pushed the gas even more to take off from the light.

Has anyone experienced either issue and know what the problem is?

fishslayer143

a whistle is usually a vacuum leak.. the stalling from a stoplight in 100* heat may be vapor lock

billschroeder5842

Swag- can you give more details on the "whistle" please?

Can you hear it in the car or do you need to be under the hood. Does it do it every time you reach 3500 or intermittently? Does it whistle only around 3500 and then disappear at higher rpms or does it start at 3500 and continue throughout the upper rpm range. Does it only make the sound under acceleration or only at cruise?

Details help.

Since it is intermittent, could you have a wind leak from one of the seals? I recently had a weird whistle/drone around 45-55 mph and I isolated it to a loose gasket on the T-Top. A bit of gasket sealer and I've had no problem since.

From the information you provided, like fishslayer, my thought is that it is a vacuum leak. if you isolate the sound you will find your problem.

OMF

I'd look again around the carb for a plug that has rotted away on the bottom and you just can't see it. Also, have a look at the rubber connections for your power brakes.
If that looks good, I'd pull the vacuum line from the intake that supplies vacuum for all the systems, and plug the intake source. Now see if that changes anything, If it does, it's a matter of tracing the faulty line or system.

swag

Thanks for the feedback everyone.

I replaced the pcv valve rubber grommet because I noticed a vacuum leak there. Instead of replacing it, the previous owner wrapped the pcv valve with a smaller grommet. I think she is good and sealed now.

I still have the "whistle at 3500 rpm"; however, I took it to advanced auto parts and the guy thinks the cooling fan clutch is going out. I'll fix that, and hopefully it won't whistle anymore.

Let you know what I find out.

PAmotorman

do you have the correct carb to intake gasket ???

swag

Yes, in fact, I had to replace it recently because it disintegrated in my hands when I was looking for a vacuum leak.

When I was playing with the throttle at the carb I could hear the same thing and it seems to be coming from the front part of the engine.

Here is a video/audio of the sound:

https://www.dropbox.com/s/ua5egtds28...30607.mp4?dl=0

billschroeder5842

Swag, sorry to parse words but after listening to your video you have a "squeal" and not a "whistle."

That is more of a metal on metal sound and not a vacuum leak.

Shoot up your fan clutch with some WD40 and see if it quiets things down. It will only be temporary but it might help you isolate your problem.

swag

No problem! Just glad I maybe found out what the issue was. I probably should have added the video earlier.

I'm kind of glad it wasn't a vacuum leak since they are hard to find.

I will give that a try. I'm going to see about getting that fixed soon.

swag

Hey, just an update on the issue. I did spray WD40 all around the fan clutch and it still screams. I ordered a new fan clutch and will have that replaced soon. Dang, those are expensive if I want an original fan clutch. I could have got a generic one for $40; however, the original reproduction is $150!

Peterbuilt

How old are your fan belts?

azza2u

On my 68 had the same thing from 3100 up. Mines an A/c car and I removed the belt for it as it isn't charged and wasn't doing anything. Problem is that left just the long alternator belt driving the water pump off the crank. At higher revs that slips causing the squeak. Put the a.c. belt back on and with the extra tension driving the water pump there was no more squeal.

Aaron

swag

Hi, I finally got the new fan clutch installed (with a new fan blade). The previous owner used a generic aftermarket fan clutch and blade.

Problem is that the sound didn't go away!

I should have replaced the fan belts when I was in there but from what I understand it is metal on metal squeal sound so that might not be it.

Big Block Dave

I wasn't able to watch the video. If you've got a squeal of some sort, the first thing that comes to mind is belts. Old, loose, or wet belts squeal. Try also looking for signs of a coolant leak... upper radiator hose, water pump etc. Make sure those clamps are tight.

swag

Thanks, I took the fan belt off (just uses one for fan and alternator) and it wasn't squeaking. Then, I put a new fan belt back on and the squeak went away!

I guess the auto parts guy was really wrong.

Well, just glad to get this fixed.

7T1vette

Auto Part store 'attendants' are not mechanics. Many of them mean well, but they are there to SELL PARTS. If you ask THEM what you need to do, they will gravitate to the most expensive parts that might be associated with your problem and advise you to start there. A GOOD mechanic would advise to start with the least expensive associated part and work upward from there.

Glad you found the problem. If you've never had any experience with these 'individual' drive belts, you wouldn't understand how many noises they can make and how to interpret faults. Lesson learned, I guess. Sorry it cost you so much.

You might consider joining a car club (one that relishes in working on their cars); those folks are a great "think tank" for asking advice on car-related problems. Their advice is usually pretty good...and it's FREE!