Clemson Vette

well a month ago i had my heads pulled and reworked due to a blown head gasket. it's running great now, but my radio has picked up a popping noise. it's pretty annoying and i need to fix it. you guys suggested that they broke a plug wire or something but i cant find anything. it runs like a top, and the radio will even play perfect with a cd in. it's only when using the radio for the antenna will the popping become known, and the popping's speed increases with engine rpms. so i'm stumped. please throw some options out there and what i need to do about em. does the antenna go thru the firewall and the mechanics busted it? help me out please. i'ts driving me nuts.


Stuart

mitymek

did you get new plugs and wires? if so they could be causing the interference.

skateparkdave

Climb under the rear on antenna side and look at the bottom of the power antenna. There is a ground strap that goes from antenna motor housing to frame over towards the spare tire. It's possible it has worked loose or they knocked it loose somehow. Usually engine noise is a ground issue or a frayed wire near metal trying to ground. Being that its only when the radio is on, and not CD, this ground strap is worth a look. Here's a pic of mine. It's the copper strap that my side marker light wire is wraped around (mines dirty). Make sure it's not loose at either end or broken or missing.

Clemson Vette

no didnt get new wires. they are brand new. only like a few weeks old when they had to rebuild the heads. and looks like my antenna ground strap is in good shape.

John Robinson

First of all do not assume that the new wires are ok

I know it was a long time ago but I had a 1955 Olds that I got a tune up done on. Left that night from Detroit to Parkersburg W. VA Car would not run over 50. When I got to Parkersburg I went to a tune up shop and we searched for over 6 hours to find problem. Finally I decided to start replacing all the new parts with the old ones that had been replaced. Low and behold when I replaced the new coil with the old one the car ran great. Since then I have not assumed that because they are new parts they can't be bad. Also Since you just had the heads done they could have left a plug wire loose on the plug.

Since the CD does not receive it's signal from the antenna and your noise is RPM sensitive you diffently are looking at an ignition related problem. Another thing to check is to see what plugs were installed when the heads were worked on. I don't know of a mechanic that would put the old back in. Perhaps they used a non resister plug

Clemson Vette

normally i wouldnt assume that, but i had the new wires and plugs on a week or two before the rebuild and it ran good then. so i know that they are good, unless they got damaged and the damage is invisible from the outside. i dont guess you can break the core of the wires without scarring the silicone coating can you? btw, these are taylor spiros.

John Robinson

Get out of the box. When the plug wires were removed they had to be pulled off the plugs. If done wrong they can be broken where they go into the plug cap. Secondly if you have a diagnostic done with a machine that checks all the plugs and wires you may find the problem. A good mechanic and I hope the guy that did the heads is good should be able to run a scope check to see if all the plug wires are good. He should do it for free to prove he did'nt do any thing wrong

skateparkdave

Ok antenna ground checks out, thats good. Now back to the work that was done. You say the plug wires were new a few weeks before head work, right?? Then it is still possible they mashed or nicked one when doing the heads and you just cant see it. Also, like John Robinson suggests, they may have installed a non resistor type plug which can contribute to ignition noise in stereo.

The thing that is most perplexing to me is I would think a plug or plugwire condition would cause the noise on radio AND cd. Unless the CD has some type of noise surpression that the radio doesn't. Or a seperate power wire or ground. You may want to pull your hush panel and see if you antenna wire is plugged tightly into the radio tuner module which is seperate from the radio itself. Again, Its most likely going to be some form of degradation in grounds or wire shielding or power wires. It's just a matter of tracking it down.

I think what I would do for starters is go and talk to the guys who did your head work and explain to them whats going on and that the work they did caused it and see if they have any insight as to what they could've done to cause it. They may have nicked a wire and taped it and know exactly where to go or something of that nature.

John Robinson

The CD is not dependant on the antenna You could remove the antenna and the CD would still play Think about it do you have an antenna on your CD player in your home stereo. The antenna is used to pick up AM & FM signals not CD or Cassette's. Therefor the antenna is picking up a high frequency interference from the ignition system. With high energy ignition the engine could run fine even if a plug wire is broken or a wire were not pushed tightly onto a plug because it has the voltage to bridge the gap. That same high frequency that is bridging or arking is being picked up by your antenna the same as it will pick up static on AM stations from Power lines along the road. One more thing. Back to the wires being new I had put a sit of wires on my daughters Chevette a few years ago and like you about 2 weeks later it blew a head gasket. Since I had just put on the wires and plugs. I reused them. Would'nt run right, Ran diagnostic's on ignition system and guess what bad wires.

skateparkdave

Duh!! I worked for a car audio shop for 2 years back in high school and have built several high end competition winning systems. In this case you may be correct but usually when ignition components are the cause of motor noise it isn't recieved just through the antenna only but rather fed through the system power supply also and or through any slight weakness in systems wire sheilding as well, and is heard throughout, CD or radio. But like I said, in this case you are most likely correct in that it is just being recieved via the antenna only. If so it may be resolved by simply purchasing a relatively cheap antenna wire noise filter that can be plugged into the tuner module where the antenna wire goes, then the antenna wire is plugged into it. That is if a bad plug wire or source isn't found.

John Robinson

Yes you are right but I am looking at this from the point of veiw before high output ignitions. The filter will work but it is a band ade for a bigger problem that was not there before the head job. Perhaps when they reinstalled all the pieces they had to remove they forgot to tighten a ground wire for some other componant or failed to connect something. Again a diagnostic check will show were to look.

skateparkdave

Totally! Hence my suggestion...

Clemson Vette

ok what is a diagnostic check? is that something that every mechanic can do? does it require special equipment? what exactly do i say when i go see him? i was just thinking along the lines, of " yea my radio is messin up, think you can check all the wires you took off?" i appreciate the help men. keep the input coming.

Stuart

skateparkdave

There are tons of diagostic machines out there and most good shops have at least one good one if not several.
What you need is a ignition diagnosis to see if there is an unseen loss of integrety with your plugs and wires.

You should take it to whoever did your heads and simply show/tell them what it's doing and tell them it didn't do it before they worked on it and politely ask them to check it out with the friendly attitude that they should find it and fix it with no hitches because they caused it. Dont even bring up charges, just let them check it with the attitude that it's part of the job you've already paid for. Only if they can prove otherwise should you be charged anthing at all. Remember, the old saying "Honey catches more flys than vinegar." Just be nice, yet firm in what you expect from them. After all, you are the customer.

Chris_G

Clemson Vette,

I tried installing wires and plugs in my 94 and was a
it's very possible they didn't seat the wires properly. You could start there. Don't ask how I know

Good luck,
Chris

mitymek

i agree with everything except the one post confusing primary voltage (read alt noise) with secondary voltage (read ignition circuit).if the noise was in the cd also then we would be thinking alternator iterference and suspecting things like the ground cable off the back of the head etc.
my moneys on one of the plug wires isnt seated.

Clemson Vette

well it seems that i have found the prob. i went to the mechanic and he was very understanding. he pulled the car around and started looking. hooked it up to a machine and did some testin of some crap. said" i dunno" and we both scratched our heads. he then started moving wires under the hood, and it got better, somewhat. where the coil is, he had routed the wires right on top of the actual coil wire going to the opti. he moved them and it got better. so he wire tied them up to the coolant hose. when i got home i unhooked em and re routed them over the hose so that they cant rest on the coil wire. the noise is 95% gone now. maybe the rest of the noise is just gonna be there. it is an old car afterall. but i'm very happy now. so if you got radio probs, first check to make sure wires arent clustered up with any high voltage wires, that can could cause interference.


thanks for all the info and help guys. your the best.

stuart

Justardnck

Check the ground wire on the engine one may not have been put back on by accident, I have always had problems with engine noises through radios on chevys and it is always been a ground wire on the engine.

skateparkdave

So it did end up being plug wires, but not a nic or mash, just poor routeing huh? I'm glad you took my suggestion about returning to the guy that did the work and approaching it as part of the job he did that you already paid for. That usually works.

As Justardnck suggests, you may still have a loose or corroded ground somewhere if you still have a small amount of noise.

The important thing is that it's alot better now and you're happy. Thanks for reporting back.