Well, my 96 F150 xl turned 100,000 miles last week! Runs excellent, other than the hellacious exhaust leak, and the stupid check engine light, which is now on again, its the fourth time ( IIRC) in less than a year! The truck still runs fine, and everytime my shop pulls the code, it comes up with restricted flow in the cat, but everytime the check it, they find a bad vacuum line, or lines,replace them, and reset the computer. This time it took about 6 months for the light to come back on, so I'm hoping its another bad vacuum line, my shop told me its hard to get cats for my truck, and they're about $800! Shouldn't the cat last pretty much the life of the truck, unless there is some problem with the engine IE: running lean or rich, oil burning, or something else? I'll be taking the truck into the shop in a few weeks for the check enigine light, and to have the exhaust leak repaired, thats going to be a nice bill! They quoted me $500 to remove the manifold, replace the gasket, check the manifold to see if it warped, then bolt it all back up again. Also, is it possible that a leaking exhaust manifold gasket could be causing the truck to boil over? Maybe by letting hot exhaust gasses into a coolant passage somehow? Every once in awhile, more frequently during the summer, obviously, when really taxing the engine, by climbing a hill with a load, the coolant would boil over, the temp guage would read normal, but coolant would coming out of the reservoir. The engine is the 4.9 straight six, btw! Anyway, sorry for the long post, just wanted to say how great the truck has been for me, even though it needs some repairs right now! I need to get my 04 into service, and use the 96 as a back up, it deserves some rest after years of excellent service!

 

Ya Cats should last as long as the truck but as a owner of a 88' (185K) I can tell you that you have outlived quite abit of the stuff the truck was designed with. Regretably you still live in that communist state of Cali and have to Smog the truck or I would tell you to just take the cat off.You may find a new one at a junk yard and then put it in yourself. If you do this you may want to put a diversion tube in. After you leave emisions you can bypass the cat and get better mileage and also not heat the engine as much. If you are going to have new exhaust manifold put on it may be cheaper to go with a aftermarket header instead of a stock one from ford. With the straight 6 can't you get into the manifold yourself? It's just a couple bolts and you should have plenty of space. It is a bolt on part so there really is no special knowledge or tools needed. And the last one I have for you is overheating, It happens to trucks in the sumemr that have smaller engines and have to go up hill. Try living in the AZ desert and then we can compare overheattin issues. Good luck.

 

The exhaust leak could be the cause of your check engine light, particulary a leak that is before your O2 sensors. Converters are designed to last 50,000 miles, not the life of the vehicle. It is a filtrate and like any other filter it gets dirty, clogged, plugged, or burns out the inside and stops working. With ideal running condition a converter may last a lifetime.