4.0 Reliability


Sultan

15+ Year Member

Joined
Apr 29, 2009
Messages
229
Points
3,101
City
Sultan, WA
Vehicle Year
1986
Transmission
Manual
Hey I was talking to a mechanic the other day and I told him about my plan to buy my son a 89-90 B2. The plan includes swapping to a 4.0. He told me that the 4.0 has the same issues and finding a solid one for a swap was difficult.

So is this guy on to something or just a lugnut?

Thanks for your time and input. RS
 
Some of the early 4.0L motors had some issues, IIRC it was usually the lower intake gasket leaking.

But they certainly do not have the head cracking problems that the 2.9L motors are famous for.

Any OHV 4.0L will swap in an 89-90 BII without much trouble, but it would be best to use a wiring harness from a 90-92 Ranger when you do the swap.
 
While they do carry some of the same issues (oiling, cracked heads) they have them with substantially less occurence. The 4.0L is the improved version of 2.9L, and are very reliable as far as engines go. If your going to be using a higher mileage engine, I'd take a good look at the rocker/rods for wear as they are usually the first thing to show substantial wear on these engines.
 
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