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#1 09-14-2015 08:11:09

guy
Helper
Registered: 10-05-2008
Posts: 22

What causes this engine sound

This past heat wave was the final straw for the 4 point oh. Lousy sound with the camera that I used but I believe I have a piston that wants to vacate the block.

I'll know more as I tear it down. Got to figure what to do for a new motor...crate long block or JY find...

http://s74.photobucket.com/user/OldBlue … 1.mp4.html

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09-14-2015 08:11:09

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Re: What causes this engine sound

#2 09-14-2015 08:30:13

bluetrue
Newbie
Registered: 03-08-2009
Posts: 12

Re: What causes this engine sound

From what I can tell from the audio it sounds like a lifter/valve train issue.

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#3 09-14-2015 08:31:17

guy
Helper
Registered: 10-05-2008
Posts: 22

Re: What causes this engine sound

No such luck for me.  The top end is working fine.  I'm still leaning towards a piston or wrist pin problem.  Draining the oil and I'll drop the pan and take a peek in there that way.  Then pull the head, etc.

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#4 09-14-2015 09:10:51

evad
Enthusiast
Registered: 10-05-2008
Posts: 240

Re: What causes this engine sound

So you pulled the valve cover and everything looks good there including all of the push-rods that are straight?

Did you try shorting out the spark plugs one at a time to isolate which cylinder is giving you the problem?

Did you use an automotive stethoscope to listen around the engine? A long screwdriver might work too!

Did you make sure it is not a small crack in the exhaust manifold? Some heater hose might allow to pinpoint that noise.

Just uploaded a text file to the group "Diagnosing Engine Noises" which might help you locate the engine problem creating those noises!

Try to locate the problem before you tear everything apart!!!


Check out my Jeep XJ

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09-14-2015 09:10:51

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Re: What causes this engine sound

#5 09-14-2015 09:20:47

guy
Helper
Registered: 10-05-2008
Posts: 22

Re: What causes this engine sound

All the pushrods are straight and no broke valve springs.  I had that happen 2 yrs ago.  I had a cyl stop working and when the valve cover was pulled I had a bent push rod and a broke valve spring on the exhaust of #6.  It was on the way home from Chicago to Madison.  Never did figure out why it did that but the valve still sealed so the spring and the p-rod were changed.

Didn't try pulling the wire for each cyl but I did the big screw driver thing and I think its either #4 or #5.  With the way it smokes when it warms up I can't see it being anything else.

It has a header on it and other then a small gasket leak in the #1 tube it's not leaking out anywhere else I can tell.

The video I took w/my camera didn't do the knock justice.  It does sound like a bad lifter collapse in the vid but it's really hammering.  It's not missing on any cyl when I rev it but it knocks hard and it also idles rough.

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#6 09-14-2015 09:26:13

james
Rookie
Registered: 10-05-2008
Posts: 90

Re: What causes this engine sound

Yep ... that's the sound mine made when the skirt broke off a piston last year.

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#7 09-14-2015 09:30:55

guy
Helper
Registered: 10-05-2008
Posts: 22

Re: What causes this engine sound

Yeah, this is what I'm thinking it is too.  We'll see...

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