Whistling 2F diagnosis advice needed (1 Viewer)

[mtksurfJ]

So this has been going on for some time now:

Drive for approx 10min and then a whistling (same pitch and tone as a human whistle) starts when I let off the accelerator (under load or no load) and will only go away when I apply a small amount of throttle under load (no load doesn't cure it). It also is unchanged in volume or tone based on speed. It occurs when motionless but goes away after a couple minutes with no motion.

I've tried to stop and open the hood and find the source but it seems to go away before I can isolate it.

It's loud enough for people I drive by to hear it.

I have an 81 2F with a webber and mostly desmogged. Can take pics of certain areas if that helps.

I've gone through the webber tuning instructions a few times and seems not to fix it.

Any ideas or suggestions?

Thanks!

 

[DAD2SIX]

Sounds like a intermittent vacuum leak. Check the carb mounting bolts or nuts are they tight? Check all the vacuum hoses ect.

 

[LAMBCRUSHER]

you has intake leak. it will be at the webber adapter assembly. you might have to trim the screws that hold the carb to the adapter....back when I had one( a webber), I found these screws to be pushing against the intake, lifting the base of the adapter ever so slightly- enought to let air get in after things got warmed up...HTH
another fix would be to PM trollhole and get one of his non US carbs, ditch that webber and adapter and bolt a real carb on...

 

[mtksurfJ]

Are these the 4 bolts in question?

How do I know if they are the right length?

 

[mtksurfJ]

Looks ok underneath?

 

[tyama]

Hiya, they're talking about the bolts at the carb base that holds the carb onto the manifold. Also check by spraying a fine mist at your carb base and around the manifold from a water spray bottle, and if you hear changes in the engine's rpm, you have a leak. Another place is the manifold itself where it bolts to the head. The reason it may go away is that the metal expands as your engine gets hot and stops it. If it's the manifold, you'll probably need to replace the gasket. It's a pita.
Best, ty

 

[Catching Neutral]

I had a similar noise. Sounded like a train whistle. It happened at speed with or with out accelerator on. I was convinced that I had an intake manifold leak or perhaps brake booster. Turns out it was an air leak on the upper left side where the hard top bolts to the windshield. Eliminated the noise by putting tape on that part of the window.. I take my hard top off seasonally and it just didn't seat properly when i put it back on that time causing the noise.

 

[DSRTRDR]

that windshield whistle at the upper left corner can even be there with a softtop or bikini - don't ask how I know

 

[kurtnkegger]

this looks familiar, might help you diagnose your problem??

https://forum.ih8mud.com/40-55-series-tech/277581-constant-whistle-noise.html

 

[mtksurfJ]

Thanks everyone!

Some thoughts:

It's not a windshield noise because it continues when I stop.

I think it's a webber adapter plate stud issue so I am going to order an adapter from MAF and see if it goes away.

 

[fjnifcat]

I had the exact same problem. I figured out that it was coming from the base of the carb. While taking it apart, i noticed that the bolts or fasteners holding the base and plate had come loose . $6 worth of gaskets and less then an hours work took care of it. Good luck.

 

[oregonfj]

I had the exact same problem too. Turns out there was a crack in the intake manifold bottom where the heat riser plate thingy used to be. Sealed it with jb weld and looks good 6 years later....

 

[LAMBCRUSHER]

intake leaks can be anywhere in the vacuum tract...I have had personal experience almost exactly as you describe and I went for the low hanging fruit...truth be told, all are right, you should isolate the offender and execute them-systematically. as mentioned, a fine mist of water sprayed at every gasketed mated join in the intake assembly should narrow down where your problem comes from. As stated, fine water spray start at manifold to head front to back top to bottom, then do the carb base, then the vacuum hoses. plug the line to your brake booster and see if that does anything, but based on the noise you describe, it is an intake leak, and my weber made the same sound at the base where it bolts to the intake- or actually where the adapter bolts to the intake, is where I found my leak. Found it by using a welding gloved hand and going over all the joints. at the carb base on the rear side, the noise went away. the intake had scoring marks from the screws of the webber to adapter bottoming out, and I could see dust tracking on the gasket where I thought I had found my leak...