aec
Senior Member
Joined: Apr 2016
Posts: 315
Likes: 0
From: Central Wisconsin
You need to give just a little more information about your truck.
As an example I drive a: 2003 F150 XLT FX4 4x4 5.4L 4R70W transmission
There are several engine options, transmissions and drive trains available so it makes it easier for someone to offer you some help if they know exactly what you are driving.
Other info that would be helpful is: was it always doing this, when did you discover the problem, etc.
Why was the cat disconnected? Have you checked for codes? Does it have a mechanical fan or an electric fan?
If I was ONLY TO GUESS I would wonder if it IS a mechanical fan, is the fan clutch bad. Meaning the fan moves fast enough to cool while at idle rpm (650-700rpm) but doesn't maintain speed as rpm's increase. Without some more info that would only be a guess though.
Just my two cents
As an example I drive a: 2003 F150 XLT FX4 4x4 5.4L 4R70W transmission
There are several engine options, transmissions and drive trains available so it makes it easier for someone to offer you some help if they know exactly what you are driving.
Other info that would be helpful is: was it always doing this, when did you discover the problem, etc.
Why was the cat disconnected? Have you checked for codes? Does it have a mechanical fan or an electric fan?
If I was ONLY TO GUESS I would wonder if it IS a mechanical fan, is the fan clutch bad. Meaning the fan moves fast enough to cool while at idle rpm (650-700rpm) but doesn't maintain speed as rpm's increase. Without some more info that would only be a guess though.
Just my two cents
Senior Member
Joined: Jan 2002
Posts: 5,994
Likes: 221
From: Wilmington,NC
Running Hot Causes? (that I can think of)
Not enough coolant
Bad fan
Bad thermostat
cooling system clogged up
bad head gasket or cracked head
One other thing that is a slight possibility - ignition timing way off. Is this a V6? the Harmonic balancer keyway slot has been known to wear and throw the timing off on those.
Not enough coolant
Bad fan
Bad thermostat
cooling system clogged up
bad head gasket or cracked head
One other thing that is a slight possibility - ignition timing way off. Is this a V6? the Harmonic balancer keyway slot has been known to wear and throw the timing off on those.
