Engine knock/tapping noise, can't figure it out |
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Engine knock/tapping noise, can't figure it out |
Hammy |
Sep 26 2007, 08:19 PM
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#1
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mr. Wonderful Group: Members Posts: 1,826 Joined: 20-October 04 From: Columbia, California Member No.: 2,978 Region Association: Northern California |
My carbed 1.7 has a tap tap tap/knock knock knock noise at idle. It seems to disappear with engine speed but I can't tell if it's just the exhaust noise covering it up. I adjusted the valves using the Capn's procedure and set them all at 1 full turn past contact, engine has hydraulic lifters. Still the same knock/tap noise....
What is it? Is it fatal? This engine has been good to me and I just need it to last a little while longer until I get myself a FI engine hopefully soon... |
Brando |
Sep 26 2007, 09:26 PM
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#2
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BUY MY SPARE KIDNEY!!! Group: Members Posts: 3,935 Joined: 29-August 04 From: Santa Ana, CA Member No.: 2,648 Region Association: Southern California |
There are a few things on these engines that make tapping and knocking noises. Sometimes distinct, sometimes not. Valve tapping noises sound different than crank/rod knocking noises.
Injector ticking different than ignition ticking... etc. First you have to locate where the sound is coming from. I usually use a poor man's stethoscope (long wooden dowel or a long screwdriver with a big plastic handle) and put one end to the engine, the other to my ear. Go around the engine. Heads, case, etc. |
rjames |
Sep 26 2007, 09:35 PM
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#3
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I'm made of metal Group: Members Posts: 3,971 Joined: 24-July 05 From: Shoreline, WA Member No.: 4,467 Region Association: Pacific Northwest |
The noises from my car ended up just being a huge exhaust leak. I hope your's is something just as minor.
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Hammy |
Sep 28 2007, 06:40 PM
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#4
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mr. Wonderful Group: Members Posts: 1,826 Joined: 20-October 04 From: Columbia, California Member No.: 2,978 Region Association: Northern California |
I took a better listen today and it definitely seems to be coming from the passenger side head, and/or in the center of the engine/case...
I really only hear it at idle while sitting in traffic, and sometimes it's worse than at other times. If I were to get a video/sound clip up, could you guys help me diagnose? |
Rand |
Sep 28 2007, 10:01 PM
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#5
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Cross Member Group: Members Posts: 7,409 Joined: 8-February 05 From: OR Member No.: 3,573 Region Association: None |
I hope you get lucky like Robert. A piece of hose is a good way to listen for exhaust leaks... One end on your ear, move the other end around where the pipes bolt to the heads. Fingers crossed....
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rjames |
Sep 29 2007, 02:57 PM
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#6
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I'm made of metal Group: Members Posts: 3,971 Joined: 24-July 05 From: Shoreline, WA Member No.: 4,467 Region Association: Pacific Northwest |
You could also quickly just check your exhaust stud bolts to see if they are loose. If I had done this when I first heard the noise I could have saved myself the worry, and been driving the car instead of worrying needlessly about an engine.
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jaminM3 |
Sep 29 2007, 03:06 PM
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#7
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Member Group: Members Posts: 418 Joined: 23-March 07 From: SLC, UT Member No.: 7,619 Region Association: Intermountain Region |
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Hammy |
Sep 29 2007, 03:12 PM
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#8
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mr. Wonderful Group: Members Posts: 1,826 Joined: 20-October 04 From: Columbia, California Member No.: 2,978 Region Association: Northern California |
So an exhaust leak can sound like a knock?
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Rand |
Sep 29 2007, 03:32 PM
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#9
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Cross Member Group: Members Posts: 7,409 Joined: 8-February 05 From: OR Member No.: 3,573 Region Association: None |
LOL. Wel, it depends on your ear. But I have to say YES. In MANY cases, what was heard as a "knock" turned out to be an exhaust leak.
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So.Cal.914 |
Sep 29 2007, 03:56 PM
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#10
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"...And it has a front trunk too." Group: Members Posts: 6,588 Joined: 15-February 04 From: Low Desert, CA./ Hills of N.J. Member No.: 1,658 Region Association: None |
Back in the late 70's I built a 1385 (1200 block). The pistons I used were cast,
and at idle the skirt slap sounded like a tap...tap...tap. Not sure what you have in your engine but...Well you get the point. My .02. |
jaminM3 |
Sep 29 2007, 04:15 PM
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#11
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Member Group: Members Posts: 418 Joined: 23-March 07 From: SLC, UT Member No.: 7,619 Region Association: Intermountain Region |
This has happened to me a couple times with other cars and I always think it is valvetrain ticking or tapping, but when I bring it to the mechanic it ends up being an exhaust leak. And these cars have the exhaust stud issue that make it more common...
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Hammy |
Sep 29 2007, 06:38 PM
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#12
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mr. Wonderful Group: Members Posts: 1,826 Joined: 20-October 04 From: Columbia, California Member No.: 2,978 Region Association: Northern California |
Ok, so the popular opinion suggests an exhaust leak... I recently put in new copper gaskets, filed the tops of the exhaust manifolds down equally, and used the correct copper plated exhaust nuts...No spinning studs, all is tight. What gives? I know there is a slight leak at the gasket where the manifold meets the muffler, but the sound coming from that is not the sound I am hearing.
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highways |
Sep 29 2007, 08:14 PM
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#13
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Senior Member Group: Members Posts: 613 Joined: 18-June 05 From: Los Angeles, CA Member No.: 4,296 |
I'm going through the same can of worms. Convinced I hear a knock... pin pointed it to the passenger side valve cover.. (I believe it is the forward valve). Mechanic thinks I'm hearing exhaust leaks. He redid the copper washers and copper nuts (I didn't have copper nuts). There definitely was an exhaust leak... but the leak is seperate from the knocking noise.
Still knocking... some people say it's normal valve noise, some say drive it until it blows chunks. I wish I could fix it though. To me it seems like one valve does not hold it's adjusment- you set it, then it get's sloppy. |
craig downs |
Sep 30 2007, 04:33 AM
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#14
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Senior Member Group: Members Posts: 768 Joined: 25-November 05 From: mira loma ca. Member No.: 5,189 Region Association: Southern California |
If your engine was built using the aluminum head gaskets one probably burned thru.
These should never be used because of this. |
LetoAtreides |
Feb 15 2008, 08:35 PM
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#15
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Member Group: Members Posts: 86 Joined: 15-May 07 From: Half Moon Bay, California Member No.: 7,739 Region Association: None |
I have the EXACT same problem you're having, right down to the irrelevant exhaust leak at the manifold/muffler gasket and new exhaust studs/nuts/washers/rings. I even posted a thread about it. I've gotten suggestions ranging from a missing distributor spring to an exhaust leak.
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749142 |
Feb 15 2008, 09:12 PM
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#16
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Member Group: Members Posts: 254 Joined: 8-January 08 From: Bakersfield, Ca Member No.: 8,545 |
i agree with so cal 914. it maybe a piston skirt slapping in the cylinder. tolerances too lose. if your using aftermarket or used originals if they werent put back just the way the came out during rebuilding you will get that tapping noise from the piston skirt.does the noise quite a little bit when the engine is hotter? i have that noise but only when its cold. it gets warm and goes away. if it is piston skirt slapping one of your pistons is to worn or just wasnt up t o factories tight tolerances. you can start the engine. while running pull each one of the spark plug wires and put it back on. go around all four. if the tapping goes away when you pull one of the wires it is piston skirt slapping on that # piston. if it is this dont be hard on it and just let it try to wear to fit. if it wears to fit even tho that the tolerances maybe too lose it will quiet a little when it wears to fit.like i said mine only taps when the engine is cold. the noise is getting quieter. but its not gone when its cold.
steven |
749142 |
Feb 15 2008, 09:17 PM
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#17
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Member Group: Members Posts: 254 Joined: 8-January 08 From: Bakersfield, Ca Member No.: 8,545 |
also if the noise is a kinda deep knocking you might suspect rod knock. hope i helped
steven |
LetoAtreides |
Feb 15 2008, 10:30 PM
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#18
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Member Group: Members Posts: 86 Joined: 15-May 07 From: Half Moon Bay, California Member No.: 7,739 Region Association: None |
If you're hearing the same sound I'm hearing on my engine (and by your description, you seem to be) then you aren't hearing the rattle that is characteristic of a rod knock when revved, correct? Also, by your posts I gather that your engine is carbed? I'm sensing a trend...
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Twystd1 |
Feb 16 2008, 12:10 AM
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#19
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You don't want to know... really..... Group: Members Posts: 2,514 Joined: 12-September 04 From: Newport Beach, California Member No.: 2,743 |
Does the sound get louder with LOAD?
Going uphill or bogging the engine? C |
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