# bad gas mileage on rebuilt engine



## Tlovell (May 2, 2010)

Hey, I hope someone can help with my 91 Jeep Wagoneer. I just had the 5.9 Liter engine rebuilt. It runs great most of the time but it now gets about 7mpg. Before it was rebuilt it got about 12. I love the vehicle and intend to keep it but can't keep filling the tank every other day. 

Anyone have any ideas of what it might be? 

Thanks


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## sulaco (Jan 15, 2009)

A rebuilt engine is "tight" meaning new rings will create some drag during the breakin period,but that may or may not be excessive....how many miles on rebuild?you may give it some time to break in and see if your mileage comes up.......and dont forget to change your oil....I would personally drop that breakin oil at 500 miles, oil is still somewhat cheap:smile:


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## wolfen1086 (Oct 4, 2007)

I had the same problem mines an 01 with a 2.5 I swapped the bad engine of e crate motor and it took about 4000 miles for the mileage to start going back up, I was getting 17 withe th old engine, I have 500 on the new one and I'm up to 12.5 mpg now, so I'd say give it a couple of thousand to break in.
I've been rebuilding engines and installing new ones for a long time and every one I do does the low mileage for a while thing.

Look at the bright side though you can get to the next gas station faster than those of us with 4L and 2.5's


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