New engine - low MPG

[RedTRex]

Morning,
2 Questions:
1) I have 300 miles on rebuilt engine. On my drive which is 60% hwy I am averaging 15 mpg. Soes this seem normal?
--- 02 Liberty 4x4 auto. New tires, 89 RON, 150k miles on chassis.

2) I replaced the fan clutch (she has HD cooling package) with Autozone part as it seems like the original was about dead. Sounds like jet engine when taking off from stop. Is that normal? and could it be causing mileage drop (I think it contributes).
Thanks
Rick

 

[tommudd]

First a new engine takes a while to break in, with only 300 miles on it its not broke in, won't be for quite a while.
Second I wouldn't trust anything from *utozone except wax, are you sure they even sold you the right fan?

 

[RedTRex]

First a new engine takes a while to break in, with only 300 miles on it its not broke in, won't be for quite a while.
Second I wouldn't trust anything from *utozone except wax, are you sure they even sold you the right fan?

True. Guess I will revisit that question in a month or 2.


I work at Autozone part-time (2nd Job) - so yes I know it's the correct part.... well can't guarantee the right part was put in the box .... but it matched up to the old and installed fine.

 

[Mangate]

My original cooling fan has sounded like that since new. Makes more noise than the engine for the first 2 or 3 minutes.

 

[uss2defiant]

yeah mine doesn't sound like a jet engine.
well as long as it pushes air like a jet engine it might be okay.

 

[TwoBobsKJ]

I agree with Tom - the engine is too new to be concerned yet about mileage. Be sure to vary the RPM's when you're on the highway - older engine designs like the 3.7 break in best when the engine load and speeds vary frequently while driving it for the first 1000 miles or so.

As for the HD fan... The viscous fluid is actually engaging the fan on first startup even though it's cold, which is the opposite if the way it will operate when the engine warms up. On cold startup the fan is fully engaged and spinning at the engine speed; after a few miles the viscous fluid will "relax" and the fan will spin much slower unless/until the engine gets hot enough to fully engage the fan. At that point you'll also be hearing the electric fan's noise. Since you're hearing the mechanical fan on startup it would appear the old viscous clutch was shot and not able to get the fan moving.

By the way, did a local shop rebuild the engine or did you buy a rebuilt/remanned unit?

Bob

 

[CzarKJ]

I agree. My mechanical fan is quite loud until my engine warms up. Then you don't hear it unless I'm in 4x4 or on super hot days.

 

[Hedsic]

Get in the zone... Autozone :thumbsdown:

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