'69 Charger unknown engine compartment hissing/whining sound ....

[UH60L]

So, yay me, finally got the rear end rebuilt after almost 6 years.  The car is a '69 with a 440 and 727B.  I've started the car ever so often and even drove it out the garage and back in a few times to clean the garage.  It hasn't been actually driven since 2017.  Got everything together, brakes adjusted and bled, fired it up and ran it through the gears on the stand, then went and drove it to the gas station and around town a bit and back home.  All things considered; it ran great. 

But when I got home, my son said he could hear what sounded like a vacuum leak as I pulled into the garage.  Drove it again the next day and I could hear it, and it seemed to get a bit louder.  Whatever it is, it only happens when it's running and is fairly constant while driving.  Standing in from of the car it sounds like it's coming from the front of the intake manifold, carb area.  Standing on the right side you almost can't hear it.

Now on day 3, I have taken off the belt and eliminated the alternator, fan and water pump.  (I have manual steering and no a/c) I pulled out the PCV valve and no change, also the breather on the other valve cover, no change.  Spayed carb cleaner around the carb, no change.  Sprayed the vacuum adapter on the back of the intake, no change.  It has all new hoses from the intake to the headlight switch and the canister and headlight covers.

On my right hand exhaust manifold, the butterfly valve was half gone when I got the car, so I removed it and put in a bolt, washers and nut.  I'm gonna check to see if those got loose or fell off later today when it's not so darn hot... (but it doesn't sound like an exhaust leak to me, sounds more like vacuum or a bearing...)

I've also been told that it could be the harmonic balancer failing and half of it rubbing on the timing cover.  Guess I'll have to give that good looking at.

The car originally sat with the engine and trans installed from 2008 to 2016 waiting for me to get money and motivation.  Started and broke in the engine in 2016 with no issues and it was running great when the rear end ate itself back in 2017. 

I'm hoping it's just the exhaust or maybe the intake manifold gaskets.  I can't afford to fix internal engine issues.  Plus I just finally got it on the road again.  Was hoping to go to a car show or two this year...

Any thoughts would be appreciated.

[b5blue]

Use "starting spray" in small busts. (It will raise idle.) 68/69 use vacuum for headlight doors.

[UH60L]

I verified it wasn't an exhaust leak at the butterfly spot.  Also, I already checked the vacuum lines for the headlights.  Looked at the harmonic balancer, didn't appear to be separated or too close to the timing cover.  Drove the car a little more last night and other than the noise, it seemed to run fine.  Definitely sounds like vacuum.  When I shut the engine off, you can hear a little wheeze sound as it stops sucking or blowing...

[70 sublime]

What air cleaner do you have on the car ?
Take the air cleaner off and start it to see if the sound changes ?

[UH60L]

What air cleaner do you have on the car ?
Take the air cleaner off and start it to see if the nouse changes ?

I have the open sided mopar performance air cleaner.  Took it off. No difference.

[Dino]

Headlight vacuum pods are good? Any change in sound when operating the light switch?

[UH60L]

Headlight vacuum pods are good? Any change in sound when operating the light switch?

Yeah, all good.  Turning headlights on or off, the covers work fine and no change in the noise. 

I'm really scratching my head on this one...

[b5blue]

Take 3 feet of 5/8 heater hose and plug one ear with tissue. Put the hose to the open ear and move the other end searching for the hissing. 

[UH60L]

Well, after much searching and even trying the hose stethoscope trick, we still couldn't narrow it down exactly, but I think the consensus is that it's a leaky intake manifold gasket.  Hopefully won't cause any issues driving it that way for a while as I can't afford to pay anyone to do it and don't feel physically up to doing it myself...

Otherwise, the car is running great!  Thanks for the tips.

Clint

[UH60L]

Update:  After driving the car on and off this summer, I noticed the headlight doors were getting progressively slower at opening until they just stopped working.  Coincidentally the air leak noise stopped also.  AS I said earlier, all the vacuum lines are new and not leaking, but I puilled the small on off the canister and there was no suction coming from the canister.

Pulled the canister off and voila...  so first I have to add/note that the company that made this literally used a soup can with a plastic lid on the connection end (toward the rear of the car).  That said, right at the very top, hardest part to see under the battery tray, that plastic lid split along the edge of the can so I have about a 2.5 inch area that's wide open along the edge. 

I think I can do a sealant repair that will work short term, but long term that lid is gonna melt/cave in.  Does anyone make a replacement that doesn't use a plastic lid?

Also for the repair, a good two part epoxy sealant should work correct?  (I was thinking I should put a bead around the outside of the entire lid just to make sure as well)

[Dino]

Epoxy should work.

Part #2889965