Noise in my 340

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wheelman21

Mopar noob
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Hey guys. I've finally got things sorted out with my 340 as far as getting it running. It runs great but I'm getting a noise. I can't seem to tell if it's mechanical or what. My buddy describes it as a slap. There is a small exhaust leak under the car, but i dont think thats the cause. What do you guys think? My grand dad didn't think it was mechanical. Just for info it has stock rocker arms. Below is a link to the video on YouTube. Thanks fellas.

http://m.youtube.com/#/watch?v=14QNfrnY6Ng
 
Hard to tell with that header leak , you try listening with a backyard stethoscope ?


[ame="http://www.youtube.com/watch?v=14QNfrnY6Ng&feature=player_detailpage"]http://www.youtube.com/watch?v=14QNfrnY6Ng&feature=player_detailpage[/ame]
 
Is the video jerry6 linked the one you tried to link? If so I vote header leak. I also have a header leak. I hear remflex gaskets are great. when I get a job I am buying a set to try out.
 
Take a length of fuel hose, put one end up to your ear, and search away. You can even stick it down into the valve cover openings with a little adapting (short piece of tubing, etc) and listen for loose valves, etc.
 
I haven't gotten a chance to stick the back yard stethoscope on it yet. The exhaust leak I know of is down at the header collector flange. I've checked all the bolts on the header manifold end and its all tight. I can pull a valve cover and see if there is anything obvious.
 
SirDan said:
Is the video jerry6 linked the one you tried to link? If so I vote header leak. I also have a header leak. I hear remflex gaskets are great. when I get a job I am buying a set to try out.
Click to expand...

yes , had a hard time finding his link so I put up a proper link . Hope you don't mind , figured others might not find vid so I'd make it easy .
Sorry if I should not of done it
 
had z
a sound like that after crank thrw malory that hit piston , ran but piston was out of shape made slapping noise . hope yours is just header leak .
still have the piston .
 
That's not an internal noise. Check the gasket below the #1 exh port. I'll bet it blew out. You want to check the header flage (the sealing flage) for flat ness, and whenever you torque them you staret with the center two bolts, then the inner bolts on the outer tubes, then the outer bolts. Tighten them. Fire it for a minute or so, snug them in that order again, the tihghten them the next day after it's been run. I use Mr. Gasket metallic silver gaskets. no prblems when the flange is flat and the torquing is don eproperly.
 
All i hear is the header leak. Dont hear a deep metal to metal knock. Fix header leak and then check back. I just fixed a header leak that sounded just about the same as your car.
 
That is a bad leak , after it is sealed I bet no noise , it would not run long if that was something lose or broken . Sounds like it is close to heads not collector
 
Take a soaking wet towel and slap it right down on the header pipes at the flange of the headers and under the pipes, bet the noise will change in tone. Just do it for 10 seconds or so, those pipes are HOT.

if the noise change you got an exhaust leak at the header pipes, doesn't matter how tight those little bolts are. what is needed is to pull the header off, clean up both surfaces with a straight edge razor and brake cleaner. Then put some RTV on both sides of the new header gasket. I even used those factory sliver color type gaskets if the ports in the middle are sealed off. They work really good, and I know, it says never to use those gaskets, lol but RTV seals them up.

Don't wiat for the RTV to cure, as soon as its all tight start the motor up but try not to rev it much, you just want it to get hot. After 30--40 seconds turn the engine off and retighten the header bots, you should get a 1/8 of a turn on a few bolts. You might need a few small open end wenches of different brands so you can tighten the bolts well.

Then let it cure for an hour or so and let it rip, fix should last awhile....be sure to use new header bolts so none break
 
I fired it up today and did some poking around and I agree it's a leak. Im going to get some good gaskets and be back in business.
 
New Fel-pro gaskets and we're good. Turned out the rear cylinder gasket had blown out underneath.
 
great but if those blow then get the dirt cheap factory style gaskets if you can find them with the divider in between the center ports. with some rtv sealer those gaskets will last a very long time
 
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