LOUD engine noise

chromeGT · Jun 4, 2006

I replaced my intake manifold. When I started the car it makes a loud rapping noise (sounds like loose metal in a dryer) in the engine and idles real rough. The sound is so loud that I don't want to run the engine. I have every nut and bolt, but it sound like something fell in the intake port. Could it be something else? If something fell in the engine how do I tell where it is? Do I have to remove the head?

HELP!

Thanks

Kilgore Trout · Jun 4, 2006

Did you install a manifold that you tried to port and polish with bead blaster?

chromeGT · Jun 4, 2006

No, just stock.

chromeGT · Jun 4, 2006

I crossthreaded the last bolt in the back on the intake manifold. If it is not tight could that be the noise? (air leaking)

Kilgore Trout · Jun 4, 2006

Its always that last one, in the back

Mike97gt · Jun 4, 2006

ok sometimes what happens when you remove the manifold is you get a misfire due to small crap that might have fell in or for many other reasons..

at this point it will not hurt to run it and then bring the rpm's gradually and do not do sudden revs.. ( that can flood it and make it worse)

I have had this happen twice to me over the years and it cleared up after a few minutes.. it sure is scary when it happens...

but IF you did have somthing metal drop in there it will not clear up at all. you will have to replace that cylinder head.

chromeGT · Jun 4, 2006

So this misfire will sound very loud. It sounds like a broken rod. I am afraid if I RUN IT I will do more damage. At this point what is the worst thing that can happen if I let it run?

Mike97gt · Jun 4, 2006

chromeGT said:
So this misfire will sound very loud. It sounds like a broken rod. I am afraid if I RUN IT I will do more damage. At this point what is the worst thing that can happen if I let it run?

all the possible damage would aleady be done by now

DTNODYA · Jun 4, 2006

svttech76 said:
all the possible damage would aleady be done by now

Out of curiousity, what would the damage be specifically?

Mike97gt · Jun 4, 2006

well if a metal object like a bolt went down the intake you would see where the bolt impacted the heads during combustion .. 99 percent of the time the piston top will be ok as will the block, it's the heads and valves that take the beating.

BUT if this motor did ingest a bolt or somthing metal the cylinder head is alreay junk.

DTNODYA · Jun 4, 2006

When I changed my intake I was super worried about something falling in there. I used serious amounts of duct tape to keep em covered while it was off. Glad I did too ... So should he just keep running it or will that F it up worse, not knowing if something is in there or not?

BTW, for the thread-starter, I hope your engine is ok.

Mike97gt · Jun 4, 2006

DTNODYA said:
When I changed my intake I was super worried about something falling in there. I used serious amounts of duct tape to keep em covered while it was off. Glad I did too ... So should he just keep running it or will that F it up worse, not knowing if something is in there or not?

BTW, for the thread-starter, I hope your engine is ok.

all he can do now is run it and hope that it's what I said in my original post to this.. It looks like I am heading over to see the car myself tommorw anyways, he lives in the town next to where my dad lives.. And I really should go see the old man so I will swing by and look at this mustang too.

COramprat · Jun 4, 2006

When I pulled the heads off my old Cobra way back when I had an indentation of a bolt on one of the pistons (previous owner must have left it). Don't know where the bolt went but the car ran for a good 50k miles before I swapped engines. Never knew I had a problem till we pulled down the motor for S and G's after the swap.

DTNODYA · Jun 5, 2006

svttech76 said:
all he can do now is run it and hope that it's what I said in my original post to this.. It looks like I am heading over to see the car myself tommorw anyways, he lives in the town next to where my dad lives.. And I really should go see the old man so I will swing by and look at this mustang too.

Thats cool of you.

COramprat said:
When I pulled the heads off my old Cobra way back when I had an indentation of a bolt on one of the pistons (previous owner must have left it). Don't know where the bolt went but the car ran for a good 50k miles before I swapped engines. Never knew I had a problem till we pulled down the motor for S and G's after the swap.

That's crazy.

Stang|ess · Jun 5, 2006

svttech76 said:
all he can do now is run it and hope that it's what I said in my original post to this.. It looks like I am heading over to see the car myself tommorw anyways, he lives in the town next to where my dad lives.. And I really should go see the old man so I will swing by and look at this mustang too.

That's nothing short of awesome. You're a great person Mike! :SNSign: FTW!

the98stang · Jun 5, 2006

well if you dropped the bolt in there, you can always rebuild the eninge with forged goods and slap on a supercharger .

but really though, I hope the engine is ok.

chromeGT · Jun 5, 2006

I tried running it and it sputtered and stopped, now it won't turnover. It couldn't of seized after a few startup attempts, could it?

clarkjr · Jun 5, 2006

It might be an exhaust leak from the EGR. That would emit a very loud noise.

Mike97gt · Jun 5, 2006

chrome... sorry today was NUTS at work.. I could not make it out.. check your PM's

stng · Jun 5, 2006

I doubt that it is "Seized" but from the sound of things I think your motor is probably toast. At this point I dont think you have any option but to pull the heads.

"but IF you did have somthing metal drop in there it will not clear up at all. you will have to replace that cylinder head." No doubt that SVTTECH76 certainly knows a lot more than I do about these things, but the only time I have ever personally seen a bolt fall into a cylinder the bolt ended up being punched through the top of the piston, it looked like a golf tee sticking out of the piston...

If you want to rule out a "Seize" get a breaker bar on the harmonic balancer bolt and see if you can turn the engine backwards, my guess is something did fall in there and know it is jammed up between the piston and the cylinder head and thats why the car wont turn over.

At any rate I am very sorry to hear about your misfortune. If it is any consolation I have done some serious engine damage in my day from a simple mistake...(Long Story) but I can definately feel your pain. Good Luck!

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