V6 catalytic converter causes blown head gasket - F150online Forums

V6 catalytic converter causes blown head gasket

Old 06-20-2011, 10:08 AM
Thread Starter
Join Date: Mar 2010
Location: Greensboro, NC
Posts: 95
V6 catalytic converter causes blown head gasket

Okay, everyone, here's something you need to watch out for. My '99 4.2 blew a head gasket, let water into the right front cylinder, and bent a rod when I tried to start it.
I rebuilt the engine, and it ran like a top for about 3,000 miles. One day, I went to start the engine after it was hot and had been doing some shopping, and it made bad noises again. The same head gasket had blown again! Fortunately, it didn't bend a rod this time.
Turns out the right side catalytic converter was clogged. It caused excessive back pressure, and that caused the head gasket to blow.
If your truck has high miles on it (mine has about 270K), be aware of this and watch out for it!
To check it out, take out the O2 sensors on both sides, put pressure gauges (15psi) in each hole, and start it up. At idle, you should see little, if any, back pressure. Rev the engine - both sides should go up the same, and shouldn't go over 3psi. If you see more than that, replace the converter. It's a PITA, but it'll save you some real grief down the line!
Reply With Quote
Old 06-20-2011, 04:39 PM
glc is offline
Senior Member
Join Date: Dec 2006
Location: Joplin MO
Posts: 34,311
Muffler shops have infrared testers that can detect clogged cats without having to pull anything apart.
Reply With Quote

Related Topics
Thread Starter
Last Post
Pre-1997 Models
10-17-2015 03:21 PM
General Discussion
09-30-2015 10:06 PM
V8 Engines
09-30-2015 03:27 AM

Thread Tools
Search this Thread

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


All times are GMT -4. The time now is 02:20 AM.