Whistling

[Lumpy Grits]

You can also use very soapy water in a spray bottle.
The bubbles get sucked in, and you can see exactly where the leak is.
Why not pull the carb and look for cracks and such?
LG

 

[Scout1067]

I did the test like Posi described and it looks like it is leaking from the firewall side of the adapter plate. I get off work early today so I plan on pulling the carb and plates this afternoon and replacing the gasket. Will let y'all know how it goes.

If I haven't said it before I will say it here. Thanks to everybody for sharing their insight and experiences with me on this site. I count myself a pretty decent shade tree mechanic but you guys have helped me diagnose a couple problems that were real head scratchers. I am sure I will need additional help going forward with my in operation rebuild.

 

[Scout1067]

Ok, I pulled the carb yesterday. I replaced all the gaskets down to the intake manifold and inspected the carb body. The gasket between the first and second adapter plates was pretty messed up and caked with rtv. I didn't see amy obvious cracks in the carb.

I cleaned everything up, put new gaskets on and put it back together with just the gaskets and no gasket dressing of any kind. I torqued the mounting bolts to spec.

When I took it for test drive, whistling started right when I would except based on experience. I'm now tearing my hair out trying to figure this out. The whistling still sounds like it's coming from somewhere near the carb.

Is it time for a carb rebuild? Or could it be the water pump? That is HH6's idea. I don't know when the PO put the Weber on, I got zero paperwork when I bought the jeep.

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[Posi]

I’m wondering if there is wear at the throttle shaft bore causing a whistle.
Is there any side to side play where the shaft goes through the bore?

 

[mriplaybass]

If you are convinced that you have a vacuum leak somewhere, you can do a smoke test. Just make sure that all vacuum lines are attached, except for the one where you are going to blow the smoke into, and take a plastic bag and firmly seal the carburetor intake with a rubber band or clamp, and do the same for your oil fill pipe if it's a V8. Then all you have to do is attach a hose to the disconnected vacuum port and blow some smoke into the hose. If you are a smoker, I have heard of people just using a cigar and using lung power to keep blowing smoke until they see the leak.

There are commercially available smokers, but for what they do, I think that they are over priced. I made my own using a canning jar, and a few parts laying around my shop.


I drilled 2 holes in the lid to accept a standard air tool nipple, and a piece of vacuum hose.




I use pieces of mosquito coil to generate the smoke, but what ever you come up with as long as it will continue to smolder will work. Paper does not work. The ash can be blown into the hose, plus, it burns too fast. The sand is to hold up what ever I use to burn.







I use a canning jar because it tolerates the heat, and won't crack like an ordinary jar. I hook it up to my compressor set at around 2psi, but you can also use lung power, and pump the smoke through the entire system. Just look to see where the smoke is coming from. Sometimes it's hard to see. You can use a laser pointer to better see where the smoke is coming from.

 

[Lumpy Grits]

Agree with Posi on worn shaft holes in carb. A small amount of clay putty can be used to seal the area as a temp test.
Check the carbs base again, with the soapy water this time.
Also-use a known flat-edge to confirm flatness of the manifold, adapter, and carbs base.
Replace the gasket between the upper and lower sections of the carb.
Take ALL the belts off, and give it a go..........
LG

 

[Scout1067]

Thanks for the tips. I figured it out. Two of the intake manifold mounting bolts were loose. One about a quarter turn and the other about a half turn. 30 seconds with a 9/16 wrench and my problem was solved. I learned a heck of a lot about the CJ7 vacuum system on the way figuring it out though.

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[Lumpy Grits]

Finally, you ck'd them.
Get the engine kinda warm, and check ALL the manifold bolts again.
LG

 

[cglax6]

Thanks for the tips. I figured it out. Two of the intake manifold mounting bolts were loose. One about a quarter turn and the other about a half turn. 30 seconds with a 9/16 wrench and my problem was solved. I learned a heck of a lot about the CJ7 vacuum system on the way figuring it out though.

Sent from my ALE-L21 using Tapatalk

Cue the Price is Right loser music...hahahaha.

Glad you got it figured out!

Kind of sad though...I always look forward to everyone else working through their struggles on their rigs. This was a good one. Glad it's not just me!

 

[Scout1067]

Cue the Price is Right loser music...hahahaha.

Glad you got it figured out!

Kind of sad though...I always look forward to everyone else working through their struggles on their rigs. This was a good one. Glad it's not just me!

I am taking the philosophical approach that I learned a lot and essentially have a new vacuum system now. I love my CJ because between this forum and my dad (who has forgotten more about engines than i will ever know) I am learning things all the time.