Spark Plug Knock ??

[maggitmay]

I was reading some posts from last year talking about spark plug knock on 99-00 Mustangs with 3.8L engine. It sounded exactly like the problem I've been having with my 2000 Mustang. There is a knock, or maybe a clicking, sound from under the hood only on acceleration. It is worse in hot weather and a little better if I use a higher octane gas (higher than 87). There was a tech bulletin out that said the problem was caused by a faulty valve cover baffle, and that the valve cover needed to be replaced with a newer version.

Has anyone had this done, and did it solve the problem?

I called my local Ford dealer (there is only 1 in my area) and they apparently hadn't heard of the problem. Being a woman, I don't think they really took me seriously. I finally just asked them to give me a price to replace the valve cover.

If you've had any experience with this problem I would appreciate your opinion.

Maggitmay

 

[merkur87]

Usually a spark knock is caused by any one of several things. Advanced timing -not likely on your car. Low gasoline octane rating - sounds like you improved the situation with the higher octane.
The prime suspect on a spark knock is usually a problem in the EGR circuit. This could be caused by a loose or split vacuum hose, clogged up passages because of soot, or a fault with the EGR valve. I am not familiar with the valve cover problem you cite as that sounds a little strange to me anyway. I would have the EGR system checked.

 

[Burner79]

That little nock

That little nock you are hearing seems to be common on 99-00 Stangs. Not trying to scare you or anything but everyone I have talked to that has this problem has a cracked/leaking head normally its the driver side one. My car has this problem as well. Do you also get the engine surge at idle speeds or stop signs?

 

[maggitmay]

No engine surge, and no other problems with the car. Could it just be caused by carbon in the combustion chamber? I was thinking of running some carbon cleaner through it.
Maggitmay

 

[marvinmycat]

I have a 98, and I know about the valve cover baffle problem. They improved upon the baffles to help prevent as much oil from going through the PCV valve and into the intake. Time to find another dealership as the ones you've been talking to are most likely inbred idiots.

 

[DanM]

Yes, there was a TSB for 99-00 V6s relating to oil seepage through the PCV system resulting in knock under load.

Ford's official fix is to replace the valve cover (expensive). Most guys around this community either delete the PCV system (cheaper, but not emissions-friendly), or install their own custom filter in the PCV system (not the easiest thing, if you're not garage-savvy).

All of those are good solutions and will fix your problem. Before you do those, however, there are a couple easier/cheaper fixes you can try first.

The first is to use a decarbonizer, as you said, to try to clean deposits from your combusion chambers. The second is to replace your PCV valve and see if that helps the problem a bit. Both a can of decarbonizer and a new PCV valve are about $5 each, and easy to use/install, so if you're not comfortable deleting your PCV system, installing your own filter, or forking out $40 for a valve cover, I'd try those first.

Good luck!

 

[marvinmycat]

See my how-to on this site for creating a PCV valve bypass system. It is fairly easy with just putting in a filter.

http://www.stangnet.com/content/view/20//

 

[maggitmay]

Thanks guys for the replies. I think I'll try the decarbonizing and maybe replacing the pcv first. I've read that Seafoam works pretty good for getting the carbon out.

If that doesn't work I may take my car to the nearest bigger town and have the valve cover replaced. I'm not too sure about bypassing the pcv, but thanks for the info. I may need it.

Maggitmay

 

[marvinmycat]

Hmmm...

Valve cover off?

Roller rockers...

But, that's just me.

 

[atlblue2000]

I removed the PCV from my car, put a breather in both VC and capped off the opening on the upper. Too simple, and no more oil where it does not belong.

 

[marvinmycat]

I removed the PCV from my car, put a breather in both VC and capped off the opening on the upper. Too simple, and no more oil where it does not belong.

How is the smell? That is one reason I didn't just go with breathers. The other being that it wouldn't pass emissions.

 

[atlblue2000]

How is the smell? That is one reason I didn't just go with breathers. The other being that it wouldn't pass emissions.

Funny you ask...maybe I am wierd or something, but I seem to be the only person who has deleted the PCV and not smelled any oil. And I know for a fact it was faulty in the first place b/c when I pulled the upper off for the inj install the rear runners were coated. Ah well...

As far as emissions, I live in TN. We don't believe in emissions I suppose, at least not in the northeast.