Time for another swap?

[steelholder]

So I'm cruising around 75mph and notice the check engine light is flashing, I feel a slight vibration when accelerating. I pulled over and ran the OBD, I got the misfire 300 code. Very rough idle but decided to go on then boom, a super loud knocking sound that increases with acceleration.

I swapped out my engine once before about 3 years ago with some help from you fine gents. Is my engine gone? Could something else cause a misfire and that dreadful sound? This website has changed a bit since then, I hope all the informative threads carried over here.

 

[QUICKSILVER462]

Check to see if the flexplate is cracked first.

 

[Scottydoggs]

post a vid if you can. idle, then hold it at 3000 rpm and then just drop the throttle drop.

 

[steelholder]

Wouldn't I need to remove the engine to check the plate?

Here's a vid, rev to 3000 then let go
3.8 knocking - YouTube

 

[steelholder]

Also gives off the smell of gasoline.

 

[Fivefingerdeathpunch]

Jesus that is one huge exhaust leak.

Sounds like the rear manifold broke somewhere or at the downpipe connection.

 

[steelholder]

Jesus that is one huge exhaust leak.

Sounds like the rear manifold broke somewhere or at the downpipe connection.

Sounds like good news, hope you're right

 

[steelholder]

Going under later, any places to check besides the obvious?

 

[BillBoost37]

If that's an exhaust leak it should be very obvious and have a lot of carbon around the leak.

I'm not so sure it's a leak, but start there since that's as good as anywhere else.

 

[steelholder]

Thought it sounded like an engine knock plus the misfire code, didn't get a chance to check yesterday will do today

 

[Scottydoggs]

or it could be a busted rocker arm or bent or broken push rod and that sound is the valve not opening. hoping for the exhaust leak.

 

[steelholder]

or it could be a busted rocker arm or bent or broken push rod and that sound is the valve not opening. hoping for the exhaust leak.

I looked under, around the catalytic and could feel a strong airflow in my face coming from manifold/down pipe area but couldn't locate a crack or where it was coming from, it even tore up that fabric material (heat shield insulation?) around the down pipe area. It's raining hard so couldn't get a great look but it's def coming from behind the lower engine area, crossing my fingers for anything but a busted engine.

 

[steelholder]

One of the spark plugs had popped off somehow, screwed it back in and back to normal, thanks guys.

 

[SgtMarshal]

One of the spark plugs had popped off somehow, screwed it back in and back to normal, thanks guys.

that's crazy, i'm wondering how that would happen

 

[Scottydoggs]

damn i knew that was a odd sound lol

 

[Fivefingerdeathpunch]

If that's an exhaust leak it should be very obvious and have a lot of carbon around the leak.

I'm not so sure it's a leak, but start there since that's as good as anywhere else.

Bill, doubting me are you??

Hmmmmmmmmmmmmm. :hm:


Exhaust leak, spark plug blown out = same thing right?

I was damn close to real problem.