My 97 Expedition with 150,000 miles has exhaust manifolds leaking. The rear studs are broken on the drivers side.

Mechanic says $300 to change all manifold bolts if He can reuse manifold, but wasn't optimistic about using them again. He said they are usually warped.

I am trying to decide if I should go with new manifolds or Maybe just go with headers and try the install myself.

What additional exhaust items would I need to change to put headers in?

Estimates on total expense to complete Header install?



gg

 

Put in shorty headers if you want to replace old manifolds only. If you want power, performance, and volume, longtube headers. For longtubes you will need to delete your front converters and run rears only, but at 150k I would suggest buying brand new Magnaflow hi-flow cats to reassure you no catalyst burn failure after the new heat and force of LTs.

 

So any estimate on price?

Any mpg increase with either? Thing is only getting around 12mpg its a 4.6 4wd.

gg

 

I got a set of shorty's from Summit for $150, and saw maybe 1-2 mpg increase. If you're only getting 12 mpg, you may want to consider new COP's and plugs. After the few things I've done, I get 15-18mpg, but I still like putting the hammer down with my PHP tune.

 

It has had new wires and plugs recently. Luckily I don't drive it too much. I used to be able to get 17mpg on the highway. Now it seems 15 is the best it will get if its hwy only. I just figured it was from crappy gas now.


What about o2 sensors, Think that would make a difference?

gg

 

Replacing the front O2s could help. With 150k they get pretty carbon coated. They usually crap out completely by 200k. Did you also upgrade to any wider/heavier tires since? The winter blend could be hurting your economy too.

 

No same stock 17 " alloys and tire size.

The bad mpg was during summer months also. Luckily I don't drive it much I have a Jetta TDi as a daily driver.


gg

 

Well maybe try running a fuel clean out additive in with a tank of gas, some injector cleaner, clean the throttle body and MAF, and new front O2 sensors and you might get an improvement. If not well you solved possible problems that are soon to come regardless.

 

My mechanic just did an injector flush last week so I should know soon if that helped.

gg