4.0 from xj into yj rio grande

[jakejeeper]

i have a 95 yj rio grande with 2.5 and want to swap the motor from a 95 xj with a 4.0. i have the whole xj that runs and drove befor i took the axles out i want to know what i will need to to the swap whats compatable and whats not
any info would be helpful thanks​

 

[superj]

Google will tell you it can be done.

 

[Bounty__Hunter]

You will need a transmission from behind a 4.0L as well. If you use the XJ auto you will need to wire in the TCM (transmission computer) located under the dash. The XJ transmission also clocks the transfer case lower than a YJ transmission, so you'll lose ground clearance unless you redrill the tailhousing of the transmission to clock the transfer case up a bit.

You will also need to cut the motor mount perches from the frame and fab up some for the 4.0L engine, not much the same between the 2.5 and the 4.0. It's often the same amount of work or easier to transplant a better powerplant than the 4.0L engine.

 

[Gennybro]

I had read on this forum at one time that the AMC inline 6 would bolt up to the yj that had a 4 banger in it with no modifications.

 

[superj]

all i know is the 95 4.0 in the xj was a great motor. we had one of those and it was a hot rodding high speed drag racing monster. my wife killed mustangs all the time with her little cherokee and all it had was the factory tow package 3.73 gears and 2 wheel drive.

 

[jakejeeper]

the xj i have has the ax 15 i belive. for the transfercase wont mind losing the cleance unlees the skidplate/ cross member wont work inwitch case i will redrill
and as far as the mont do i fab up a perch for the xj motor mounts if they are in good shap or should i get motor mounts for a yj 4.0?

 

[paddywagon]

It can be done with the time and effort...yes it is as much work as it would be to put in a v8 but the 4.0 was engineered for these vehicles. If and when something breaks you will save yourself time and aggrevation being able to walk into the parts store and get something right off the shelf rather than have to wait to have something special ordered, or have the sales clerk give you the deer in the headlight look. Bottom line is the 4.0 is a great motor and not everyone wants or needs a v8.

 

[jakejeeper]

the 4.o is for sure what im going with mostly cuz its in my back yard but thing im still unsure of is how do i locate the new motor mounts? where do measure from . mabey the tramison crossmeber or do i go to the rear axle?

 

[Bounty__Hunter]

I had read on this forum at one time that the AMC inline 6 would bolt up to the yj that had a 4 banger in it with no modifications.

This is wrong. Not sure if you read it wrong or if you read wrong information.

You will need to fabricate new motor mount perches and use OEM 4.0L motor mounts for a YJ. Check out a 4.0L YJ and get some measurements on where the motor is located side to side and from the grille and the firewall.

True statement that not everyone wants a v8 Jeep, but on the same note not everyone wants a run of the mill 4.0L Jeep with a hacked up install. Why not go with more power on the street and trail?

 

[superj]

i want a v8 wrangler and i have a 4.2 or 4.0 (still not sure exactly what is in the block on this monster)

 

[paddywagon]

If one can't install a 4.0 without hacking it up I would venture to say their install of a v8 would be equally hacked. Just my opinion

 

[superj]

a v8 would have to be though, wouldn't it? since hte wiring harness isn;t made for a v8 sensors?

the 4.0 should be easy since its all drop in and plug in with all factory parts.

 

[jakejeeper]

that helps i just need to find someone with a 4.0 yj
also i read that both the 2.5 and 4.0 both have a fuel preasure of 33 but i will still need to swap the fuel pump for the 4.0? im going to check parts numbers later on today to find out.

 

[superj]

Ok. Sounds good to me

 

[jakejeeper]

the fuel pump and presure regulator or the same part number so same part acording to atozone so the artical i read must have been wrong now just gotta find another yj to measure!

 

[superj]

What measurement? From the fire wall to the mount or from what

 

[jakejeeper]

ya according to bounty hunter from the fire wall to mount and from grille to mount would work

 

[Bounty__Hunter]

When i say 'hacked up install' I'm comparing it to the hundreds of thousands of factory 4.0L Jeeps out there.

Don't advise the 4.0L is plug and play as it isn't nearly that easy.

 

[paddywagon]

I never said it was plug and play. It is the same amount of work that a v8 is yet everytime the topic comes up there are statements about why it would be a waste because you get more power out of a v8 and a 4.0 would be a hack job. The point I was trying to make is that if the person installing the 4.0 in place of the 2.5 did a hack job on it then it would reason to think that their install of a v8 would be a hack job...simply because you have to do the same work. I do believe the 4.0 would be an easier (no saying easy) install because that is a motor that was engineered to be in the vehicle...ie less things that have to be fabricated, custom or special ordered...probably more cost effective too.

Bottom line...his vehicle his choice. respect the mans choice. I for one would take the 4.0 over the v8 any day...but thats just me.

 

[jakejeeper]

alright i swap in the 6 cly over the weekend i made new perches had to modify the transmission mount. I didnt have any clearence problems with the transfercase and cross member but had to switch a peice of the shifting linkage. the problem i am having and am not sure what to do about is the wiring. i used the harness for the 4.0 but the one plug under the dash was different and had diferent wires. what could i do woth that?