Misfire cylinders three and four, head gasket replacement

2004 FORD F-150
245,000 MILES • 4.6L • V8 • 4WD • AUTOMATIC
Avatar
BANSHEE JOHN
  • MEMBER
  • 2 POSTS
Number three and four cylinders misfiring. Spark plugs have fouling but not from oil. Can I replace just that side head gasket or should I replace both?
Sep 2, 2018 at 5:11 AM
Advertisement
Avatar
ASEMASTER6371
  • ✓Experienced Mechanic
  • 52,796 POSTS
Good afternoon.

It is always suggested to replace the pair.

How did you determine you have a failed head gasket? Did you do a compression test?

Roy
Sep 2, 2018 at 6:38 AM
Avatar
BANSHEE JOHN
  • MEMBER
  • 2 POSTS
My mechanic made that determination. He thinks it started with the o2 sensor in the converter went causing it to call for more fuel. Anyway new converter passenger side, two new o2 sensors, coils, plugs. Three and four fouling, plugs have a liquid on them not oil. I got almost 250,00 miles on the truck. I am going to fix it and sell it.
Sep 2, 2018 at 9:49 AM
Avatar
BANSHEE JOHN
  • MEMBER
  • 2 POSTS
Thanks for the information. Should I put new head bolts too?
Sep 2, 2018 at 9:51 AM
Avatar
ASEMASTER6371
  • ✓Experienced Mechanic
  • 52,796 POSTS
Yes, that is a good idea.

You are welcome.

Glad to help.

Roy
Sep 2, 2018 at 10:05 AM
Join 2CarPros for free, one of the most advanced car repair communities on the internet. From first-time drivers to seasoned mechanics, everyone is welcome to reply, share details, and get better answers. You can add a temporary image or video first; uploads are limited to 20 MB.
Ask a Free Question
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.