A few weeks ago I had an older experienced auto mechanic redo my whole exhaust from front to back and reset the timing and the carb and reran some hoses, replaced the pcv valve and replaced the breather with a tube thats connected to the air filter. Since he worked on it there has been a rattle that started as an occasional rattle I would just slightly hear when I first accelerated. After awhile it got worst and sounded like the pipe wasn't connected in front correctly, I brought it back and he said he didn't see any issues and he adjusted the carb a bit cause it was idling low. A couple weeks past and the rattle was starting to get worse so I brought it back, he said he moved some brackets that he thought were rubbing and it was good. It instantly got worse over night and turned into a constant rattle that stops occasionally for a few seconds and you can't hear it when idling. I brought it back and he turned the timing down a bit and said try sea foam which did nothing, I told him I didn't feel like it was a lifter and the sound is from underneath. He used a stethoscope type thing and said he didn't hear it in the valve covers much but more underneath them. Since then it struggles to start a little and the car has gone from instantly peeling the tires with no effort to I could slam the gas and not get a squeel :/ The car will almost die for a second when giving gas and then pick back up but only from a dead start or in early speeds. That night the brakes got a vibration feeling and there was a whining noise coming from the engine. I pulled over and shut the car off. When I started it back up the whining was gone and it ran fine, I figured there was air from a leak? So I'm thinking the rattling noise could possibly be an exhaust manifold gasket? Could that be causing my problems? I need some advice please, this guy is getting to expensive and not helping much. I don't have the funds now to try another guy so I want to do it myself. I appreciate any help you can give!

 

Is the rattle coming from the engine bay?

When you say the car has no power, does the engine produce the same rpms?

Is it an automatic? If so, how is the fluid level.

The wining noise could be a loose intake manifold bolt causing a vaccum leak.

You could check the exhaust manifold bolts...it can't hurt.

Check all connections since you don't really know the history of what has been done.

 

Do you still have the stock exhaust manifolds? Is so the heat risers could be the culprit. Does it still have a cat? They can rattle. There are flimsy metal covers on stock exhaust manifolds on 81s that can rattle a bunch. Also metal spark plug wire covers under the valve covers bolted to the block. I suggest crawling all over and under it tapping on everything until you find the noise. You could have a valve train issue as well, which means you may need to look under the valve covers for a rocker or spring issue. Did he do any work on the distrubutor? If so the Dist may need something tightened up under the cap, and that would affect performance too. Just some things to check, good luck!!

 

Are the original carb and distributor (and the ECM system) still operational on the car? If so, does the "repair guy" know anything about that system and how to set it up?

 

The rpms drop too, down to like 400 almost feels like its about to die. Only does it sometimes though, not every time i drive, it's weird. Still not a lot of power though, rpms go high and car sounds loud but no power to go with it at all. I need to check the bolts and stuff, I have free time Wednesday night so I'm hoping to play around then. Wanted to get opinions first.

 

The cat was removed before I purchased the car and the rattle is definitely coming from the front of the car, sounds like its coming from underneath the engine to me. I check the fluids on a weekly basis because of the valve cover gaskets leaking, was going to change them Wednesday night and look at the lifters and such then to make sure but it doesn't sound like a lifter at all. He did move the distributor when changing the timing but he tightened it up in front of me.

 

Did he remove the 4 wire plug that goes into the dist. before he timed it.

 

I too vote timing. The *rattle* that you hear at almost any speed is too much advance. If you do not unplug the 4 wire connection into the dizzy, then it already is too advanced. Set it, once free of all computer / sensor to 8 BTDC and you will be happy. No more *rattle*, power will be there in the lower band (rpm) and you will enjoy the ride again.

It's the timing. That's where I place my bet!

 

I know when I stopped there he played with the timing again and it seemed to change the rattle a little but it didn't go away. He unplugged one of the tubes and asked me to press my finger over the end, is this what you're talking about? I just know the rattle didn't start til after he worked on my car and it's gradually got worse over 2 weeks or so.

 

You really need to know if the stock carb, distributor and ECM are still hooked up on this car. They all work together. There is a 4 wire connector on the dist that controls the timing advance. Take a few pics of your engine and post them up and we can help you get it right. Its a whole different story depending on stock 81 setup or modified to regular distributor and carb setup

 

I spoke with the guy and he said since its not an electric Carb that he didn't think disconnecting the 4 wire plug would change anything or cause a rattle noise. He had it set advanced to 10you and the last time I was there he changed it back to 6 to see if it helped. Never unplugging the 4 wire from the distributor. The Carb is a Holley. The Carb has electric choke but and since setting it down to 6 the choke doesn't even kick in. Thoughts?

 

I think he has the distributor to far advanced like some others have said. Did you add gas after you left his shop. Maybe you got a bad batch of gas and the advanced timing will make it even worse. Go put some premium in it.

 

The 81 has and ECM that controls timing advance. You can set inital timing, but that's it. The rattle that most are thinking you're hearing is from the initial timing being to far advanced. Does it rattle at all when it's not in gear? If you "power brake" it, that is hold your foot on the brake and add throttle at the same time, do you hear the rattle then? If so, it a timing issue, no matter what the mechanic says.

The tube he disconnected sounds like a vacuum line. If that's the case, and the distributor has a vacuum advance, it's been changed, the 81 didn't have vacuum advance. If that's the case, that the distributor has been changed, well that brings to mind a bunch of other questions....

 

It really didn't bring up other questions. The guy adjusted the carb and the timing. It has to be one of them. Look up the timing specs and retime the car. I have never heard of a carb adjustment making a motor ping.

 

He said he can only hear it in 2 of the cylinders but its not in the valve cover, that he hears it in the exhaust manifold more and that if I got an cast iron manifold it would help to not hear the noise. He said that I might not have heard the noise before because of the exhaust pipes being loose and rattling. But after he fixed them the rattle wasn't bad and after he did the timing and carb the next week it has slowly progressed. When in park the rattle will come and go, but when accelerating it definitely gets a lot worse. Not sure about doing a power brake cause I'm at work, I could try that later. He didn't disconnect the 4 wire when setting the timing at all and it was a vacuum line that was being plugged when setting the timing. The whining noise was there for 2 seconds today when I started the car and then it went away. I've ran premium in the car every time since I've purchased it so it's not that.

 

Your last comment is dead wrong. Running premium in an 81 is asking for a carbon problem, go back to low grade quickly. The rattle could very well be carbon rattles knowing you ran premium all the time. Dump a can of seafoam in it to decarbon everything. These low compression motors only need low octane. Period. Your car is not a diamond making machine, carbon is bad, and I have heard rattles from carbon banging around on a piston from running too high octane.

 

From someone who has made the same mistake please for all glories sake simply slide under the car and have someone roll the throttle in and out. I had the same sound when I installed a new starter because I installed the FLYWHEEL COVER incorrectly. If you did swap the starter it will rattle no matter what! Those tabs on the cover have to be slid in perfectly as well the bolts fairly snug. Also you may need to trim the cover to fit the starter.

 

Lets see he didn't have the rattle then he had the guy to adjust the timing and the carb and he redid the exhaust. Unless the car is starting to fall apart after this guy did the work why would you look elsewhere.

 

You know, the stock 81 with stock exhaust manifolds has air tubes going into each of the "header" tubes, and they're prone to cracking....might check these too... It's difficult diagnosing a sound when you can't hear it....

 

When I had my exhaust done, the shop used paper gaskets. Which blew out first time it backfired, lol. Which created space for the nuts to slowly back off...which did two things. It rattled, plus I had an exhaust leak, and the worse it got, the less power it made down low. Simple check, simple fix.