1997 D1 Enginer Knock at Low End

mrbieler

Well-known member
Sep 15, 2004
71
13
Lost Angeles
New noise I'm trying to sort out. Right from start up. Knock at bottom end. 1997 D1 with a 4.0. Cylinder heads done under 10k miles ago. Definitely bottom end noise. Last year, someone tried to steal the cats which is the welds you see where they patched the cuts. Doesn't get louder on acceleration but it speeds up. Can't tell if it's speeding up at the same rate as the RPM.

Any thoughts?

 
Last edited:

mrbieler

Well-known member
Sep 15, 2004
71
13
Lost Angeles
with a stethoscope, it really seems isolated to the drivers side cat and the down pipe section just above it. Not from the exhaust manifold. No noise from the sump, bell housing, etc. The nuts on the down pipe weren't loose, but I gave them a little extra something which seems to have lessened the noise a small little. Tapping the cat gave a little bit of a rattle but nothing dramatic. I would think the 2nd o2 sensor would pick up the issue if the guts had shit the bed.
 

discostew

Well-known member
Sep 14, 2010
7,706
1,015
Northern Illinois
with a stethoscope, it really seems isolated to the drivers side cat and the down pipe section just above it. Not from the exhaust manifold. No noise from the sump, bell housing, etc. The nuts on the down pipe weren't loose, but I gave them a little extra something which seems to have lessened the noise a small little. Tapping the cat gave a little bit of a rattle but nothing dramatic. I would think the 2nd o2 sensor would pick up the issue if the guts had shit the bed.
I use a pretty big soft mallet.The deadblow ones. Hit it. Don't tap on it.
 
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