Odd noise from engine
 

I've got an odd noise coming from the rear. As I start the car moving I hear an odd noise from the rear, it sounds like a hole in the muffler, as I can make out the normal exhaust sound and then a second similar sound. The noise is there in first and then after going into 2nd, as the rev's rise (say to 2500rpm) the noise disappears. While in 3rd no odd noise, even if I let the revs drop and then slowly accelerate.
When I'm beside another car it is more pronounced as I can hear the echo.

Parked I can rev it up and I hear nothing abnormal! With my head in the engine compartment or under it.

First worry was a failed or failing tensioner (I've got Carrera tensioners on my SC). I've searched on this issue and just don't hear anything (while still) that sounds like the noise of this.

In my best Jack Olsen impression I'm going to rig up a microphone and see if I can record the sounds while driving.
Until then any suggestions?

Jay

Does the noise go away in 1st if you press the clutch in but keep the rev's the same??

One thing to check...

My SC had the airpump hoses blanked off where they go into the exhaust ports, and while one was working it's way out it sounded like you described. Hee hee, when it blew it out completely it sounded like a diesel tractor.

I had a tensioner collapse (hydraulic) this past summer. It did not sound the way people described - chains being dragged over trash can. I still can't describe the sound, but it was not normal and at idle, was present, but when a little throttle was applied, noise disappeared. Even a Porsche mech, could not quit figure it out - he was with when I put my car back on the road.

It was a collapsed tensioner. It became more obvious when I put a "stethoscope" on each chain box. One was really loud and making the noises.

I wish you luck!

Dave

Thanks guys,

"Does the noise go away in 1st if you press the clutch in but keep the rev's the same??"
I'll try this and pay attention, the noise is there underload so I'll check.

Mine is an 82, don't think it had an airpump, not one there now.

"stethoscope".... I tried this by putting a piece of metal ( a shiskabob skewer ) on the chain covers and holding to my ear (other than feeling like a nut) I did not notice any strange noises. I'm going to go with the real "stethoscope" in the morning to make sure.

I drove it again a few minutes ago, its a deep "put put" sound that follows the exhaust.

Other dreaded thought, what does a broken head stud sound like ?

Jay

Yup the '82 had an airpump too.

I haven't heard the sound of a head leak due to a broken headstud but the discription I've heard is exactly how you describe the sound. Sorry.

-Andy

Subscribing for information purposes.

Good luck with this one.

1+, sounds like an exhaust leak.

Ah well (my fears that it is the head stud) but one more question. Shouldn't I hear a head stud type leak will the car is stationary?

Jay

Ok after some testing. I seem to get the noise only under load..... Say accelerating in first I hear the noise, can push in on the clutch, keeping revs constant noise goes away.

At a constant speed no noise.

Back to the chain tensioners, got a real stethscope. Testing on both of the tensioner covers gives me no scary noises.

Jay

I'm glad it does not seem to be the tensioners. Good luck!

Jay, I'm available to help you troubleshoot if you need it.

bluesky,

I may need to take you up on that. I'm just trying to find some more time to devote to it this weeked!

I'm in Germantown near Houston Levee.

Jay

The reason it only happens under load is that the cylinder pressures are much higher under load. The heads don't leak until the cylinder pressures rise enough to lift the head.

-Andy

Thanks Andy, I think. That unfortunately makes my guesses to accurate.

Jay

Hey Jay,

I would love to help you as well. I can't do much other than be another ear, but can offer a 3 rd set of hands... OK, I am selfish, I want to be their to learn form your problem. :rolleyes:

Seriously, let me know and I will try to come down.

Shane, I'll be sure and call when I need heavy lifting :)

Jay

Update, I've found a hole in the muffler, at this point I'm very happy to say this! I finally got the time to do more investigations tonight. I had the car running at idle and had my head under the engine to see what I could find. Had a hose up to my ear to check of leaks at the heads, exhaust ports, and all the joints on the exhaust. No sounds of leaking gases.
Got out from under the car and had my head in the engine compartment, reved it up and heard that poping sound..... but it appeared to be at my stomach. Got back under the car and looked at the muffler and there is a hole. Looks like a rivet? has come out.
http://forums.pelicanparts.com/uploa...1202438113.jpg

Any suggestions for a fix on this? (And lets skip the comments on the oil in the pictures).

Another angle.


http://forums.pelicanparts.com/uploa...1202438220.jpg

A sport muffler http://forums.pelicanparts.com/support/smileys/nuts.gif.