New - Rebuilding 91 4.0L for 92 STX (removing 2.9L)

[cooleyplace]

Hi, everyone.

I've been a member here for a bit, but haven't gotten serious...until now.

I've had a 1992 Ranger 4X4 STX with a 2.9L for (ten?) years now. The engine is running poorly and I want to upgrade it.

I found a 1991 Ranger 4X4 with a 4.0L at a local salvage yard and pulled the engine. To upgrade my truck's engine, to learn (I have never rebuilt any engine), and for a fun project with my 15-year-old son, we are rebuilding/renewing the 4.0L and plan to put it into my truck.

I've reviewed the great advice on this site about this type of engine swap, but I have no doubt I will have questions.

I have stripped the 4.0L down to the short block. Everything looks great, except one of the pistons looked too clean (see the attached photo - Cylinder #3 on the left). An uncle told me this could be because the head gasket was blown and the coolant leaking into the cylinder kept the carbon from building up.

ANY thoughts or help will always be welcome.

Steve

 

[RonneyJAyala]

Check your head gasket for depressions around the cylinders walls. I'm doing a head gasket replacement on my 4.0 due to a coolant leak in the combustion chamber.

can't really see it due to this was just a quick snap for progress matters, but it had two Pistons that were clean on this side(passenger-closest 2 to the front of the truck) and one in the back that was also clean on the other side (driver-closest to the cab)

Be sure to have your heads checked out, the 4.0's had a tendency to crack when they were overheated, since you don't know the previous owner of this vehicle id get them checked out. Costed me about $80 at my local machine shop, but they found my exhaust seats were set back 30 thousands up so that $80 turned to $480 lucky me! Haha, anyway, should be a good swap! The 4.0's are good for there size, countless times have I beat mine up a little bit and she came back just fine.

As you can see, I'm not always the nicest to her haha.


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[XLTbeater]

Nice project! I just dealt with a blown head gasket on my Ranger (4.0L).

The 4.0 always pinged on the highway since I got the truck 4 years ago. I tried all kinds of things without success. Then it started leaking massive amounts of coolant and oil; and the biggest clue was the misfire. Then I knew I had a blown head gasket. If I had the space, I would tear the engine down to see the aftermath. Probably got a clean cylinder or two as well.

XLTbeater

 

[cooleyplace]

Thanks for the tips! I will get the heads checked.

 

[RonneyJAyala]

How is the progress going? I just got mine all back together and damn does she run better than ever! I had a few mishaps, like putting the thermostat in backwards, but eh, it works now!


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