4.0L SOHC 4X4 WITHOUT Balance Shaft???

[hilltopfarm]

As many of you may know I'm replacing my worn engine with a re-man.

Upon removal of the cast oil pan the most notable thing was the absence of a balance shaft that I have read is incorporated into 4x4 models. The re-man engine that I got has the shaft on it.

Side view of balance shaft:

Top view of balance shaft:

So I'm just curious, does anyone have any ideas as to why the original engine did not have a balance shaft?? Also why is there even a balance shaft? What does it "balance"?

Thanks

 

[MastuhWaffles]

I think all the balance shaft does is eliminate vibrations, I thought only 4 cyl had them.

 

[Destroyer000]

my ole mans truck had a balanced shaft 4.0 was a 2004 4x4. i replaced it with a 2001 4.0 explorer motor WITH OUT a balance shaft. i was told only 2wd trucks came without the balance shaft.. guess not..

 

[gw33gp]

I am going out on a limb here because I am not positive I am remembering correctly. I thought I read somewhere that the Ranger 4.0 SOHC did not come with the balance shaft. Only The Explorer 4.0 SOHC engine came with the balance shaft. It could be the re-man engine came out of an Explorer.

 

[adsm08]

Some had it, some didn't, there are so many ideas about why it would or wouldn't be there and most of them seem to be wrong. I have seen both 4x4 Rangers and Explorers without them. I have seen one 4x4 Explorer with it. We don't really have 2wd Explorers around here.


It won't hurt anything either way.

 

[hilltopfarm]

Thanks for all the informative responses! I guess that this probably was the original engine and not a factory refurb like I had thought when I noticed that it did not have the balance shaft.