Exhaust Leak/Poor Mileage

[turboexplorer]

Will an exhaust leak make for poor fuel economy? Obviously my 2nd gen 5.0L manifolds are leaking really bad when it fully warms up it mostly goes away but it does leak. I have heard both ways that it does and doesn't affect it. Any thoughts?

 

[IZwack]

The exhaust leak will influence MPG because of the O2 readings. But regardless of wether it affects MPG, I would still fix the leak.
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[moosejaw]

You are losing power due to the exhaust leak. The scavenging effect is being comprimised. Power loss is a fuel economy loss.

 

[turboexplorer]

The exhaust leak will influence MPG because of the O2 readings. But regardless of wether it affects MPG, I would still fix the leak.
Posted via Mobile Device

True, just waiting to see if I want to take these crappy OEM manifolds off and weld the small cracks or go with the TMH's.

 

[Turdle]

Those "small cracks" is actually " broke in half"

lol

Welding is a waste of time. Differing expansion rates between the separate alloys will result in more cracking. Been there--twice. 3 times actually

 

[scottnh1970]

Will an exhaust leak make for poor fuel economy? Obviously my 2nd gen 5.0L manifolds are leaking really bad when it fully warms up it mostly goes away but it does leak. I have heard both ways that it does and doesn't affect it. Any thoughts?

It does.

 

[turboexplorer]

Those "small cracks" is actually " broke in half"

lol

Welding is a waste of time. Differing expansion rates between the separate alloys will result in more cracking. Been there--twice. 3 times actually

Lol, thats funny! Alright, Jon you made up my mind! Now to go convince the wife!

 

[turboexplorer]

I've decided to go with the later modeled manifolds. The cast ones from 99-01. Anyone know where to get them I have searched on ebay and things but can't seam to come up with any. Anyone have a link would be great. Probably need new exhaust manifold bolts to, and an new EGR tube Mine is cracked. Thanks guys!

 

[turboexplorer]

Jon, Are these the ones I want?

Cast Exhaust Manifolds

I put in a 2000 5.0L Explorer

 

[Turdle]

Yep those look good to me.

 

[turboexplorer]

Sweet Exhaust leak will be no more! Cast ones that are better are way less expensive than the worse tube style ones!

 

[turboexplorer]

I have the manifolds just waiting on the new EGR tube! That is all cracked to. They came with two new bolts with each manifold why only two? And are some studs and some bolts? That's what it looks like from just looking through the hood and looking at it?

 

[Carguy3J]

How about ceramic coated headers? They will be much nore effecient then any stock cast manifold, and the coating will help keep in heat, and maintain exhaust gas velocity, to spool your turbo quicker.

 

[turboexplorer]

So just a quick update, have had the new manifolds on for a few months. Really easy to change I was surprised. All I had to do was fab up a new bracket for the oil dipstick tube and all the rest was super easy. Anyways here are some quick pics. The first one is the Crack in the drivers side tube. It was under the heat shield. Second is of the way smaller exhaust ports than the cast ones because on these the weld is inside the tube. Third the collector, the cast ones are full and open not cramming everything in there. Then last to report between changing a primary bank 2 O2 sensor that was lazy and these manifolds my mileage has gone WAY up. Was at 10.5-11 around town, Now its at 13.5-14. 3 Better! Also freeway was 15-16 and is now 17-19 depending on wind! I love it and way worth the $100 for the new style cast manifolds! Thanks again to Jon for his help.

 

[bigalphaone]

I'm a newbie at this whole auto repair thing, and I want to replace my own driverside exhaust manifold..are there any tips you can give me on what to lookout for and the complexity of the job?

 

[turboexplorer]

Yours shouldn't have a problem. You have a 200 it looks like and so you have the Cast Manifolds already. If anything you just need to replace the gasket to reseal it back up.

 

[storlied]

I need bolt info on swapping over to the cast set? Sizes? Which ones of the old will work? Ect... is there a bolt kit I can buy? Also.. it seems getting the EGR off the pass side is gonna be a pain.. and the front bolt of the driver's side.... seems the A/C compressor is gonna be in the way a lil bit... Advice?

 

[turboexplorer]

Most of the bolts you can reuse. If I remember right there is just two new bolts on each side that you have to get new. What I did was put one of the factory bolts through the new cast manifold and see how much it sticks out of the manifold add that measurement to how thick the new cast sections are and that is your new bolt length. I got grade 8's for those bolts that where the same size and thread just longer. I torqued them down to the factory specs. All with a small amount of anti-seize on them.

The biggest issue that I ran into was that where the Oil Dipstick tube mounts with a manifold bolt on the tube style ones. The new cast ones run a thick section there where you need a longer bolt so you have to modify the dipstick tube mount to bolt to the new location which is just 1/2" or so more towards the outside of the vehicle. We came up will an easy way to do it and i can take a picture if you need.

Also as far as a specific kit i did find one from Ford but they wanted $11-15 a bolt so I didn't go that route.

New cast ones are great though! Well worth the little extra work. Thanks again to Jon for turning me onto the new style manifolds.

O and one more thing, its been awhile since I did it, but as far as the A/C compressor one goes I don't think the bolt can come all the way out of the hole before it hits the Compressor. So take it out of all the threads and just leave it there it will come out when you remove the manifold. When you go back together remember to put that bolt in the manifold before you put the manifold into place otherwise you will have to take it back out to get it in there. I used some ratcheting wrenches on mine and of course the TQ on that bolt is guesstimated but its real close.

 

[storlied]

I would like a picture of the modification, and thank you for all of that info. Any other tips or advice on this project will be greatly appreciated..
Also, Did you notice any performance/sound difference, even if minimal?

 

[turboexplorer]

K ill get a picture for you tomorrow. (Best as I can, tight in there as you know or will find out) And sound no difference but performance yes, mind you not TMH performance but yes some Also a little better economy, may have a slight amount on that due to no leak so my fuel trims are now perfect right between -1 through 1 for my long term trims
Also ill look for the pics of the two sitting together, old and new manifolds. Big difference. Laptop lost hard drive a while back but should be on my external. See the pics of my old ones in above post with the collector? See how the two pipes come together? That is all open and free with the cast ones. Also see pic of the exhaust port? The tube ones are welded inside to the mounting flange that takes up the size of the port. The cast ones don't have that weld so they are bigger there as well. You will see the difference when you swap them. You will be amazed at how much better and bigger the newer cast ones are.

Ill look for pics tomorrow

Sent from Android!