I have a 2000 f150 4.2 v6 and I think I have an exhaust leak (different sound lately) but does that motor need a certain amount of back pressure. The motor feels like it is hesitating, now I am thinking it is an exhaust problem and not a motor problem. does this sound about right????????
thanks

 

4.2 v-6,how many miles on it???my experience has been anything over 75,000 miles your living on borrowed time with this engine,ford told me that they fixed the problem on them, i don't know.my son has a 97 150 with 4.2 and around 89,000 the bottom end fell out of the engine he put a 3.8 in it.every time i buy a ford that is not a v-8 i have trouble with it.

 

Ford had a couple of issues with the 4.2 in the F and E seires for the 1997 & 1998 model years that was resolved (TSB 99-20-7). I've seen numberouse 4.2's with well over 100,000+ miles on them that still run top notch. My 4.2 in my 04 Freestar is at 86,000 without a peep.

The engine doesn't need back-pressure per-say, but requires the exhaust to be intack for proper exhaust flow to ensure that the cylinder is emptied of the spent air/fuel charge and a vacuum is created to ensure a good fill of a new air/fuel charge in the cylinder. Exhaust leaks will hinder this and cause the engine to loose some performance.

Easiest way to check for exhaust leaks is to raise the hood on a cool morning and fire the engine up. Then look in the engine compartment and under the truck for steam coming from the leak. The steam is from the moisture in the air turning to vapor from the combustion cycle. If you don't see any, then you'll have to use your ears and hands to listen for and to feel the exhaust pressure from the leak.

 

the motor runs fine except for the hesitation on hard accelleration. this time of year will be hard to check it the way you said---too warm in mornings, but I will crawl under this weekend. (it's been this way for a year and it passes inspection--- can't be too bad) as for mileage 160000 and it's a 2000 from what i hear Ford fixed the issues after 98 so I think i'll hold onto it for a bit longer.

 

On your "hesitation on hard acceleration", are you refering to a lack of "Giddy-up An Go"? Does it downshift properly. Does it do this at any and all speeds when you get on it? At 160,000 miles, it could be the catalytic converter getting tired (partially plugged) and not allowing proper exhaust flow under hard acceleration.

Driveability symptoms such as a drop in fuel economy, lack of high speed power, rough idle or stalling are classic symptoms of excessive backpressure due to a plugged converter. Checking exhaust backpressure and/or intake vacuum will tell you if there's a blockage.

 

it seems that it might be the cat, would my shift rpm change, used to be able to get int 5th at 50 or soe now it seems that 60 65 feels better. you say check exhaust back pressure--how?
thanks

 

about a month ago i had a rattle when i started the truck, it sounded like a loose heat shield, could that be related. but it went away after a couple of days.

 

This truck seems to have 4 cat conv on it, would there be any downside to removing the 2 that look like elbows or the 2 strait ones?

 

The forward units are the PRE-Converters and the rear units are the MAIN Converters. You need all of them for the rear OBDII O2's to work properly. However, you can replace the left and right side PRE & MAIN converters with a single universal unit on each side.