On to next problem! Tapping noise.
Thread Starter
Instructor
Joined: May 2011
Posts: 213
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From: Miramar Florida
On to next problem! Tapping noise.
I can hear a tapping noise that seems to be coming from either the valves or exhaust manifold. The sounds seems to be louder when I adjust the timing. I thought it might have been that the lash on the valves were not adjusted correctly after I replaced the head gasket, so I went back & set them again but I'm still getting the noise. Any suggestions?
Racer
Joined: Sep 2010
Posts: 327
Likes: 2
From: se iowa
I can hear a tapping noise that seems to be coming from either the valves or exhaust manifold. The sounds seems to be louder when I adjust the timing. I thought it might have been that the lash on the valves were not adjusted correctly after I replaced the head gasket, so I went back & set them again but I'm still getting the noise. Any suggestions?
Drifting
Joined: Dec 2007
Posts: 1,647
Likes: 4
From: Argillite KY
Did this tapping start after you replaced the head gasket? Take a piece of hose and stick it in your ear. Take the other end and move it around down by the manifold. This is a great stethoscope. Listen for exhaust leaks. Rule out the exhaust first. Then.....how did you adjust your valves?
Thread Starter
Instructor
Joined: May 2011
Posts: 213
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From: Miramar Florida
I adjusted the valves as explained in the manual for motors with hydraulic lifters. With motor at TDC, I used my thumb & index finger to twist the lifting rod as I adjusted the nut on the valve until there was drag in twisting the rod, then turned nut another 1/2 turn. I did this for each cylinder in firing order.
Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 412
From: WV
Next time you adjust the lifters move the pushrod up and down until all play is gone. This is much easier and more accurate for getting to 0 lash then twisting the pushrod. ...There's a guy on here named "Caldorone" that thought for sure he had a lifter noise. ended up being a small exhaust leak. Even in the video he made it sounded exactly like a lifter, so do like "1963SS" suggested and use the stethoscope method to find out where it's coming from....
..WW
..WW
Last edited by WW7; Nov 11, 2011 at 08:02 AM.
Drifting
Joined: Dec 2007
Posts: 1,647
Likes: 4
From: Argillite KY
I would go to the parts store and buy a mechanics stethoscope
They also have the regular old mechanical stethoscope for about 5 bucks.
Thread Starter
Instructor
Joined: May 2011
Posts: 213
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From: Miramar Florida
Ok, I only had a few minutes to work on the car today. I went & purchased a stethoscope as suggested & did a little probing around in the area where I suspected the sound was coming. It turned out that it didn't seem to come from the #2 or #4 valves as I suspected. I checked around the exhaust in that area also but nothing that I could tell. I listened to all four injectors on that side and they all sounded OK. The sound seemed to come from the passenger side but after checking today, I'm not so sure. I plan to do more checking when I have more time to work. Any other ideas or suggested areas to check?
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Thread Starter
Instructor
Joined: May 2011
Posts: 213
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From: Miramar Florida
I did some more checking today, and couldn't determine anything. I'm thinking that what I'm hearing an exhaust leak. I don't hear it so much while the car is standing and idling but I can definitely hear it when I'm driving. What do you think?
Former Vendor
Joined: Nov 2006
Posts: 2,482
Likes: 3
From: Carmichael ca
Exhaust leaks are usually louder when the engine is cold and get quieter as things heat up. An exhaust leak will also be louder when the engine is under a load and quieter when you let off the gas.
Melting Slicks
Joined: Jan 2005
Posts: 2,658
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From: Clifton Park NY
Thread Starter
Instructor
Joined: May 2011
Posts: 213
Likes: 0
From: Miramar Florida
I got the stethoscope and used it but I couldn't determine the leak with it. When I got it I thought it was a valve or injector that was making the sound but after I used it to check around the heads and injectors, it wasn't. Like I said before, the sound is not so loud when idling but I can hear it well when I'm driving.
Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
Did you have this noise before doing the head gaskets??
Did you have any "head" work done?
Did you "Torque" the exhaust manifolds & collectors, with clean, and lubricated threads. Did you install new gaskets?
You could also Pressurize the exhaust system, with the exhaust side of a shop Vac, and feel around for leaks. A soapy solution also works well for locating small leaks.
Did you have any "head" work done?
Did you "Torque" the exhaust manifolds & collectors, with clean, and lubricated threads. Did you install new gaskets?
You could also Pressurize the exhaust system, with the exhaust side of a shop Vac, and feel around for leaks. A soapy solution also works well for locating small leaks.
Thread Starter
Instructor
Joined: May 2011
Posts: 213
Likes: 0
From: Miramar Florida
Did you have this noise before doing the head gaskets??
Did you have any "head" work done?
Did you "Torque" the exhaust manifolds & collectors, with clean, and lubricated threads. Did you install new gaskets?
You could also Pressurize the exhaust system, with the exhaust side of a shop Vac, and feel around for leaks. A soapy solution also works well for locating small leaks.
Did you have any "head" work done?
Did you "Torque" the exhaust manifolds & collectors, with clean, and lubricated threads. Did you install new gaskets?
You could also Pressurize the exhaust system, with the exhaust side of a shop Vac, and feel around for leaks. A soapy solution also works well for locating small leaks.
No, head work was done, other than cleaning gasket face.
Yes, I torqued the bolt, now that I remember, I had a hard time getting to the bolts at the #8 cylinder. I need to re-check those. I used oil to lube the bolt threads. I installed a new gasket at the manifold but not the collector. Any idea what size gasket to use at the collector, everything is stock size?
Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
my LT1 collector does not use a gasket, not sure about the L98.
Go back and check all of the exhaust manifold bolts, I use high temp Anti sieze on my bolts, it won't burn up when it gets hot (rated 2400 f)
Go back and check all of the exhaust manifold bolts, I use high temp Anti sieze on my bolts, it won't burn up when it gets hot (rated 2400 f)
Thread Starter
Instructor
Joined: May 2011
Posts: 213
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From: Miramar Florida
I went through with the stethoscope again to see if I can identify anything but found nothing. I don't think the noise is coming from the engine, thank god! I'm almost sure its the exhaust. Not sure but I think its at the collector on the passenger side. I will plan on checking it this weekend. I don't have much time or daylight in the evevings now that time has changed.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
The bolts on my exhaust manifolds get loose about every six months or so. It's always #7 and #8. All the others stay tight.
The first time I had this happen, I would get a rattling noise when I accelerated up a hill. We finally found the problem when I put the car on a dyno so we could load the engine and listen for the noise. One of the #7 bolts was out more than 1/4".
The first time I had this happen, I would get a rattling noise when I accelerated up a hill. We finally found the problem when I put the car on a dyno so we could load the engine and listen for the noise. One of the #7 bolts was out more than 1/4".