2.9 to 4.0

Farkhaed1 · Aug 3, 2014

I love my little ranger but the 2.9 isn't going to let me have as much fun as the 4.0 will. I am wanting to do a swap relatively soon and I need to know the storm I'm getting into. Motor Mounts the same? Fuel systems? Please enlighten me!

RonD · Aug 4, 2014

The 2.9l and 4.0l OHV share the same block so mounts and trans bolt pattern are the same, just a straight swap.
Fuel system is based on the year, fuel injected before '97 run 40psi with return line, '98 and up run 65psi with no return.

You do need 4.0l computer and wiring harness for the swap, and computer needs to be for automatic or manual trans, which ever you are going with.
Computers are also matched for EGR valve and Cam Position Sensor.

Best bet is a '90-'94 4.0l with it's computer and wiring harness
'95 was the OBD 1(EEC-IV) to OBD 2(EEC-V) computer transition year, and will add another layer of complication.

Good read here:
http://www.therangerstation.com/tech_library/4L_Conversion_faqs.shtml

Farkhaed1 · Aug 4, 2014

RonD said:
The 2.9l and 4.0l OHV share the same block so mounts and trans bolt pattern are the same, just a straight swap.
Fuel system is based on the year, fuel injected before '97 run 40psi with return line, '98 and up run 65psi with no return.

You do need 4.0l computer and wiring harness for the swap, and computer needs to be for automatic or manual trans, which ever you are going with.
Computers are also matched for EGR valve and Cam Position Sensor.

Best bet is a '90-'94 4.0l with it's computer and wiring harness
'95 was the OBD 1(EEC-IV) to OBD 2(EEC-V) computer transition year, and will add another layer of complication.

Good read here:
http://www.therangerstation.com/tech_library/4L_Conversion_faqs.shtml

Awesome! I've heard that using the tranny from a 2.9 may not hold up.. Anything I should be worried about? Also I was told that the 4.0 is a tad taller than the 2.9 and may require a a couple inches of body lift to fit it in.

PlumCrazy · Aug 4, 2014

This swap has been done on here 100+ times...do a search.

SenorNoob · Aug 4, 2014

Mounts are compatible, not necessarily the same. I can't see needing a body lift, but I haven't swapped my transmission out yet either and it's supposed to be the tightest fitting part.

Yes, the 2.9 transmission will work. How long depends on how hard you drive, which 2.9 transmission you have, it's condition when you started, and luck. My FM146 has lasted a year with me being as rough on it as I can with the 2.9 clutch. (It slips really easily behind the 4.0) I wouldn't recommend either to anyone. My transmission was supposedly rebuilt just before I got the truck too.

I'd recommend using a low mileage (regardless of year) 4.0 OHV and running it with the 90-92 (Ranger) or 91-94 (Explorer) ECU and wiring harness. You can go newer to get better features (OBD2) but it's more wiring.

Edit: I see you have '90. It can be done with minimal (maybe even no) wiring. Just change the engine harness and the ECU. Not sure what that'll leave you for starter wiring.

2.9 to 4.0

Farkhaed1

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RonD

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Farkhaed1

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PlumCrazy

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SenorNoob

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