• Mustang Forums
  • 1965 - 1973 Classic Mustangs -General/Talk-
  • Classic Mustang Specific Tech

Why Do My Plug Wires Keep Popping Off?

  • Thread starter Thread starter eleanor_350
  • Start date Start date Apr 18, 2005
E

eleanor_350

Member
May 20, 2003
92
0
6
Kentucky
Apr 18, 2005
#1
  • Apr 18, 2005
  • #1
Has anyone had trouble with their plug wires popping off the spark plugs by themselves?

I have a set of 9mm Ford Racing wires on my 351w that keep popping off while the engine is running. Usually, I just find one wire at a time that has come off. But, yesterday I was letting it warm up in the driveway and I raised the hood to find three wires had come loose.

Could the heat from the headers make them pop off?

Should I try crimping the plug wire ends so they clamp the plug a little better?
 

golf4283

Active Member
May 30, 2003
1,253
1
39
Orland Park, Illinois
Apr 18, 2005
#2
  • Apr 18, 2005
  • #2
I would not suggest crimping the wires because that might lead to a new set of wires if you mess up. Are you sure you have the right spark plugs and wires? Also do you press them on hard enough so they click into place? Sometimes I don't realize that I have to push really hard to get those suckers on.
 

coolblue65

Founding Member
Jul 26, 1999
1,224
2
39
Algonquin, IL
Apr 18, 2005
#3
  • Apr 18, 2005
  • #3
eleanor_350 said:
Has anyone had trouble with their plug wires popping off the spark plugs by themselves?

I have a set of 9mm Ford Racing wires on my 351w that keep popping off while the engine is running. Usually, I just find one wire at a time that has come off. But, yesterday I was letting it warm up in the driveway and I raised the hood to find three wires had come loose.

Could the heat from the headers make them pop off?

Should I try crimping the plug wire ends so they clamp the plug a little better?
Click to expand...


I don't know why it happens but it happens to me on occasion as well, to the point where I almost routinely pop the hood and double check each wire is on all the way before I leave.
 
E

eleanor_350

Member
May 20, 2003
92
0
6
Kentucky
Apr 18, 2005
#4
  • Apr 18, 2005
  • #4
That's a possibility, I guess. This is in a 65, so a few of the plugs are tough to get to. I be sure they are all pushed on really good.

Whatever the cause, the wire doesn't just come lose. Something is causing the wire to come completely off the plug. I watched one literally "pop" off the plug yesterday while it was idling.
 
G

geordie

Founding Member
May 10, 2002
576
2
19
Apr 18, 2005
#5
  • Apr 18, 2005
  • #5
Are the plugs snug and tight in the heads? If they were loose could this cause vibration and exhaust gas escape leading to the plug wires working themselves loose. Are the wires supported close to the plugs in some form of loom? I'm sure this would help.
 

Pakrat

Founding Member
Aug 6, 2000
3,843
0
56
Currently: NH Originally: Rhode Island (and all po
Apr 18, 2005
#6
  • Apr 18, 2005
  • #6
All I can say is I have to have my plugs well lubed with dialectric grease so that I can even get them off the next time I need to, I'm usually afraid to split the boot they fit so snug. I have never ever seen one pop off before like that but something is not right at all. You are positive you have the right wires or plugs? Do they feel the same as the fit on the other end of the distributor? Adding a wire loom on the tab of your valve cover may aid in keeping them put, but I have a feeling something is not as it should be.
 
E

eleanor_350

Member
May 20, 2003
92
0
6
Kentucky
Apr 18, 2005
#7
  • Apr 18, 2005
  • #7
Pakrat said:
All I can say is I have to have my plugs well lubed with dialectric grease so that I can even get them off the next time I need to, I'm usually afraid to split the boot they fit so snug.
Click to expand...

Mine don't fit that tight. The plugs I have are nothing special, just Motorcraft spark plugs from the parts store. I have Ford Racing wires that I bought from Summit (around $40-$50 for the set). I'm pretty sure they're 9mm. I'm running the later model large-diameter distributor cap. I havn't had any trouble with them coming off the dist. cap. Actually, they've been on the car since last July and I'm just now having this trouble with the plugs.
 
M

mustangdave

My rearend needs a stud and two nuts.
Founding Member
Feb 26, 2002
2,976
1
56
North Carolina
Apr 18, 2005
#8
  • Apr 18, 2005
  • #8
Check to see if your spark plugs, not wires, have come loose. Then use diaelectric grease inside all of the wires. This not only eases installation and removal, but seals the wire to the spark plug. I could be wrong but I think your spark plugs may have worked loose and the compression is blowing the wires off.
 
G

Gud T.B. Blown

Member
Dec 9, 2004
583
1
18
Apr 18, 2005
#9
  • Apr 18, 2005
  • #9
i had an f-150 with a 4.6 and it kept popping a single plug wire. turned out to be the spark plug. it either had a crack, didn't seat right or whatnot. once i replaced it everything was fine.
 

67coupe351w

New Member
Jan 31, 2004
424
0
0
Portland, OR
Apr 18, 2005
#10
  • Apr 18, 2005
  • #10
Did someone tell you the old "racers trick" of drilling tiny holes down the center of your plugs??



Sorry that was lame.
 
You must log in or register to reply here.

Similar threads

B
Electrical Why does my fox body keep frying eecs
  • brandyn200
  • Jun 20, 2026
  • Fox 5.0 Mustang Tech
Replies
8
Views
183
Fox 5.0 Mustang Tech Jun 25, 2026
AeroCoupe
M
Engine Unexplainable Exhaust Pop and Gurgle
  • Mrnissen122
  • Feb 14, 2026
  • Fox 5.0 Mustang Tech
Replies
12
Views
515
Fox 5.0 Mustang Tech Feb 18, 2026
Noobz347
Engine 1990 LX 5.0L EFI Mustang Fuel Management Problems - HELP!
  • 5.0LXStanger
  • May 25, 2025
  • Fox 5.0 Mustang Tech
  • 2 3
Replies
45
Views
2K
Fox 5.0 Mustang Tech Jul 11, 2025
5.0LXStanger
Drivetrain 83’ Glx convertible C5 Trans help!
  • JacksonJared2113
  • Dec 25, 2025
  • Fox 5.0 Mustang Tech
Replies
2
Views
354
Fox 5.0 Mustang Tech Dec 26, 2025
JacksonJared2113
Progress Thread Giving an abandoned 88 GT project a new chance at life
  • jaketractor
  • Jan 9, 2025
  • Fox 5.0 Mustang Tech
  • 2
Replies
27
Views
2K
Fox 5.0 Mustang Tech Jul 20, 2025
Noobz347
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1965 - 1973 Classic Mustangs -General/Talk-
  • Classic Mustang Specific Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?