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Ticking/Tapping sound passenger side intake manifold 59 Coupe 390 (video)

Started by indetrucks, March 03, 2019, 12:01:25 PM

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indetrucks

My 59 developed a strange sound that I cannot pinpoint.
From what I have investigated, it's not the exhaust manifold.
Two videos below that I took to help diagnose.
First, cold start high idle:
https://youtu.be/ngdJebjro48

Second, at idle warmed up:
https://youtu.be/0zUEXB3kPx8

Brand new exhaust from manifold collectors back and rebuilt carb as well.
Car runs well otherwise, but the sound is quite loud under load/acceleration but at constant throttle it's not present.

While replacing the valve cover gaskets, I checked all the rocker arms while cranking and they are all moving as they should, as I thought maybe it was a sticking lifter?

Ideas?
C. Reedyhoff

indetrucks

After doing more reading on a possible cracked intake manifold, I decided to check underneath it with a mirror where the choke heat tube is and found what appears to be a fine crack/separation in the valley of the intake manifold (pics).  Not sure if this is a normal casting line or if it's an actual crack?
*Edit* it appears to be where the intake manifold mates to the block, so that appears normal.

Also, I removed the choke spring cap/cover and discovered exhaust soot starting to accumulate.  It wasn't a ton, but enough to cause concern seeing as I recently had the carb. rebuilt and imagine that area was cleaned out.

Does my intake look cracked based on that mirror pic?

Second pic with arrow is the crack in question.
C. Reedyhoff

indetrucks

Ok, it looks like that "crack" is just where the manifold mates to the block.  I checked the drivers side and it's the same.

HOWEVER, when checking the drivers underside of the intake manifold with the same mirror I discovered what looks like a hole?  Is this hole where the choke heat tube is supposed to be connected?  Other than on the passengers side existing the intake and going into the carb, I didn't see the hot air choke tube running under the intake manifold.  Is it supposed to be under there as well?

Pics of hole where I "think" that choke tube might supposed to be mating to.
C. Reedyhoff

Bobby B

Leaking air from any manifold will simulate a "Tapping" sound similar to a lazy/worn lifter. As the engine heats up, the noise will sometimes diminish due to expansion. Exhaust leaks are a little more visible since you usually see a trace of "white" around the crack. Easiest way is to throw a Vacuum gauge on the motor and you will answer your own questions. Good Luck!
                                                  Bobby


1947 Cadillac Series 62 Convertible Coupe
1968 Mustang Convertible
1973 Mustang Convertible
1969 Jaguar E-Type Roadster
1971 Datsun 240Z
1979 H-D FLH

indetrucks

Quote from: Bobby B on March 03, 2019, 02:37:38 PM
Leaking air from any manifold will simulate a "Tapping" sound similar to a lazy/worn lifter. As the engine heats up, the noise will sometimes diminish due to expansion. Exhaust leaks are a little more visible since you usually see a trace of "white" around the crack. Easiest way is to throw a Vacuum gauge on the motor and you will answer your own questions. Good Luck!
                                                  Bobby

I can confirm the car has low vacuum.
Where do I start as far as pinpointing if/where the leak is coming from?  Or is this one of those "gotta remove the intake to find it" sort of scenarios?

Thank you BTW
C. Reedyhoff

Bobby B

Christian,
  Hi, and you're welcome. A $10.00 Vacuum gauge can diagnose more problems than some modern day equipment. This should get you started....Good Luck!
                         Bobby

https://www.google.com/search?q=vacuum+gauge+reading+chart&client=safari&channel=iphone_bm&source=lnms&tbm=isch&sa=X&ved=0ahUKEwicvYSo7-bgAhUxZN8KHbC5An8Q_AUIDigB&biw=1658&bih=992
1947 Cadillac Series 62 Convertible Coupe
1968 Mustang Convertible
1973 Mustang Convertible
1969 Jaguar E-Type Roadster
1971 Datsun 240Z
1979 H-D FLH

indetrucks

Quote from: Bobby B on March 03, 2019, 04:04:25 PM
Christian,
  Hi, and you're welcome. A $10.00 Vacuum gauge can diagnose more problems than some modern day equipment. This should get you started....Good Luck!
                         Bobby

https://www.google.com/search?q=vacuum+gauge+reading+chart&client=safari&channel=iphone_bm&source=lnms&tbm=isch&sa=X&ved=0ahUKEwicvYSo7-bgAhUxZN8KHbC5An8Q_AUIDigB&biw=1658&bih=992

Thanks... I have a vacuum gauge and it is indeed low on vacuum. 
I also got the car up to warm temp and sprayed a fine mist of water around the intake and no change in idle was present.  I figure is there was an intake leak that would have discovered it.

Did you happen to watch the two videos I provided?  Any thoughts on the noise?
C. Reedyhoff

Bobby B

It's so hard to tell without being there. Did you take a long stick/pipe/screwdriver and hold it to your ear and probe it around while it's running? A mechanic's stethoscope is also a really handy tool for mechanical noises like this because even though it's hard to tell where it's coming from, you can usually pinpoint it with that. Just be careful the it's running....
                                                Bobby
1947 Cadillac Series 62 Convertible Coupe
1968 Mustang Convertible
1973 Mustang Convertible
1969 Jaguar E-Type Roadster
1971 Datsun 240Z
1979 H-D FLH

INTMD8

Sounds like a cracked choke tube in the intake manifold.

The tube runs through the bottom of the intake into the exhaust crossover area. Exhaust heat transfers to the tube which transfers to the choke.

So, one end of tube goes to the choke and the other is open to atmosphere. 

When the tube cracks exhaust gases leak out of the tube and sounds like your video.

I couldn't find the exact same size tubing so when I knocked mine out I drilled the holes out to (I think 3/8) and tapped in a 3/8 tube of the appropriate length to replace it.

Jon S

It sounds metallic to me; not vacuum. IMTMD8 could be on to something. He could be right or it could be a small metallic piece under the valve cover being shaken by the rocker arm. I would remove the valve cover and take a good look if any foreign Matter is in there possibly sitting in the oil.
Jon

1958 Cadillac Sedan De Ville
1973 Lincoln Continental Coupe
1981 Corvette
2004 Mustang GT

indetrucks

Quote from: INTMD8 on March 03, 2019, 04:33:08 PM
Sounds like a cracked choke tube in the intake manifold.

The tube runs through the bottom of the intake into the exhaust crossover area. Exhaust heat transfers to the tube which transfers to the choke.

So, one end of tube goes to the choke and the other is open to atmosphere. 

When the tube cracks exhaust gases leak out of the tube and sounds like your video.

I couldn't find the exact same size tubing so when I knocked mine out I drilled the holes out to (I think 3/8) and tapped in a 3/8 tube of the appropriate length to replace it.

In one of my pics on the driver's side, it looks like the open area of the choke tube.  How would I go about locating the spot if it is indeed cracked at the tube? Will I need to remove the intake manifold completely?
C. Reedyhoff

INTMD8

Yes, only way to inspect/repair is to remove the intake. 

You might be able to look -inside- the tube by removing the piece that goes from it -to- the choke but if it's cracked further down than an inch or so from the end you probably won't be able to see it.

Jon S

That heat tube to the Climatic control appears to be copper and copper would not break like the original steel tube could have.  I still believe there is something rattling around under the valve cover.
Jon

1958 Cadillac Sedan De Ville
1973 Lincoln Continental Coupe
1981 Corvette
2004 Mustang GT

INTMD8

The tube on the outside isn’t the one that breaks fwiw. (That one slides inside the one in the intake)

Jon S

Quote from: INTMD8 on March 03, 2019, 07:17:16 PM
The tube on the outside isn’t the one that breaks fwiw. (That one slides inside the one in the intake)

So, like a Ferrel or liner?   In any case I don't think that would be making the tapping noise I hear on the video.   My opinion is a loose metallic piece under the valve cover being hit by the rocker arm.
Jon

1958 Cadillac Sedan De Ville
1973 Lincoln Continental Coupe
1981 Corvette
2004 Mustang GT

indetrucks

Quote from: INTMD8 on March 03, 2019, 06:43:48 PM
Yes, only way to inspect/repair is to remove the intake. 

You might be able to look -inside- the tube by removing the piece that goes from it -to- the choke but if it's cracked further down than an inch or so from the end you probably won't be able to see it.

Great news! It is indeed the hot choke tube. I pulled it out (see pics) and it was pretty loose coming out of the intake.
When I pulled it out, I started the car up and the noise was very loud. When I plugged the hole where the choke tube goes, the noise totally went away.

Now how do I get that tube to properly seal when I wedge it back in the intake? Should I try flaring out the intake tubes end a bit?
C. Reedyhoff

INTMD8

You have to remove the intake manifold and tap the old tube out and replace it with a section of new tubing.


Daryl Chesterman

Christian, I hate to add to your problems, but in the picture that you posted (linked below) I see that the carburetor base gaskets are in the wrong order.  For the Carter AFB carburetor, it should be intake manifold, gasket, phenolic spacer, gasket, stainless steel shim, carburetor.  It is extremely important to have the stainless steel shim on the underside of the carburetor, to not only ensure proper idling, but to prevent erosion of the aluminum base of the Carter carburetor, due to heat from the exhaust crossover.  You can see the proper order in the picture from the 1959 service manual that I have posted.

     Your picture:

http://forums.cadillaclasalleclub.org/index.php?action=dlattach;topic=154318.0;attach=131909

     Gasket sequence from service manual:

http://forums.cadillaclasalleclub.org/index.php?action=dlattach;topic=134970.0;attach=73423

     Carburetor installation instructions from service manual:

http://forums.cadillaclasalleclub.org/index.php?action=dlattach;topic=134970.0;attach=73425

Sorry for the sideways pictures, but this is the way they were posted on a previous post that I copied.  You can rotate them with the rotation tool in the taskbar at the bottom of the picture.

Daryl Chesterman

indetrucks

Whelp, seeing as I have to remove the carb/connections to get the intake off anyway...guess the gaskets being on incorrectly isn't such bad news.

I'm mad at myself because I have a service manual and would have thought for certain I would have followed the order in the manual.
C. Reedyhoff

Roger Zimmermann

Quote from: indetrucks on March 03, 2019, 01:06:09 PM
Also, I removed the choke spring cap/cover and discovered exhaust soot starting to accumulate. 
That soot is typical for a cracked choke tube which is in the intake manifold.
1956 Sedan de Ville (sold)
1956 Eldorado Biarritz
1957 Eldorado Brougham (sold)
1972 Coupe de Ville
2011 DTS
CLCMRC benefactor #101