91 YJ motor question

[nappy_TJ]

My buddie has a 91 YJ with an inline 6 that is toast...he found a guy that has a 93 Cherokee that will give it to him for free. Are there any major differences like the bell housing or anything that we need to consider before we swap it. I know his YJ is manual and the XJ is auto.

 

[TreeClimber]

There are two basic 4.0 motors and one common 4.2 inline six cylinders common in the Jeeps. The Chrysler built 4.0 H.O. and the AMC built 4.0 Renix. If both motors are H.O. motors than he should be able to use the longblock and adapt over whatever exhaust, intake, and wiring to make it work just fine. My YJ came with a HO, but it was a 92. I don't remember what year the Jeep switched from one setup to the other. The 4.2 is carb'd and won't easily switch with the EFI engines.

 

[nappy_TJ]

OK thanks they are both Fuel Injected so I think we shoiuld be OK there...does the bell housing need to be swapped too?

 

[crash2]

I know the 87 xj's are the remix style...

The bell housings should be the same...

 

[TreeClimber]

Make sure one is NOT a Renix and one a HO. They are not compatable.

And yes, bellhousing will need to swap as one's a auto and one's a stick? Make sure to get a new bushing for the end of the crank and now would be a good time to put on a new throwout bearing and clutch too.

 

[nappy_TJ]

Make sure one is NOT a Renix and one a HO. They are not compatable.

And yes, bellhousing will need to swap as one's a auto and one's a stick?

will do....thank you

 

[crash2]

Make sure one is NOT a Renix and one a HO. They are not compatable.

And yes, bellhousing will need to swap as one's a auto and one's a stick? Make sure to get a new bushing for the end of the crank and now would be a good time to put on a new throwout bearing and clutch too.

So whats the difference between the HO and the remix?

Arent the 4.0's a 60 degree bellhousing?

edit by Tony - dammit, I'm not used to moderating tech yet. I tried to hit quote, and hit edit by mistake

 

[TreeClimber]

So whats the difference between the HO and the remix?

Arent the 4.0's a 60 degree bellhousing?

I'm not exactly sure, but I know that the intakes and exhausts will not interchange between them, which means that his applications it won't work. I believe the bolts are different. I do know that the wiring systems are completely different and I've heard that the cam profiles are different as well.

As to the 60*, I dunno

 

[nappy_TJ]

So, is the Renix 87 and prior? And anything after that is HO?

 

[crash2]

I would have to see a stock yj with a 4.0 so I can compare to joes I have in the shop...

 

[TreeClimber]

So, is the Renix 87 and prior? And anything after that is HO?

No, I don't think that's accurate. Junkyard Jim would know for sure. I do know that when Chrysler bought out AMC, they started switching engines in the models at different times. So the Grand Cherokees got the HO motor a couple years before the Cherokee, and so on with the YJs...

Ask (PM) Junkyard Jim, and he'd know. But I thing the two years you are talking about are both HO motors.

T

 

[nappy_TJ]

OK Thanks

 

[Six-Nine]

87-90 Renix

90-up Ho

 

[Cascade_Crawler]

the renix model just has a different computer system, along with a few little differences. Like joe said the 87-90 cherokees were renix, from 91 and up both the YJ and XJ had the HO 4.0s. 87 - 90 YJs were the carbed 4.2 bullshit

 

[Long&Low]

4.0 ltr HO's first came out with the 91's.
As said above get a new pilot bushing for the back of the crank / tranny input. The wiring may be different for the CPS hook up. but if you just swapping motor to motor, I'd bet it all plugs in without any needed mods.

If you need to change the exhaust manifold, yours from the 91 should bolt right up to the '93 motor.

I also believe the fuel rail hookup is the same too.

 

[Lokey]

87 to 90 was the first generation fo the 4.0. It used a Renix ignition system thus the link to Renix.

91 to 95 was the next generation of the 4.0 called (HO) with a new head design. You can use a block from the earlier 4.0 with a head from a 91-95.

In 97 there was a change to the head and block that prevents you from mixing and matching heads with earlier years.

From what I know I would not hesitate to get the motor out of the 93 and swap it in to the 91 YJ. True there will be a need to swap a few things between the blocks as you are deal with an auto and a stick but it is going to easy to make it happen.

 

[NotMatt]

To answer the original question... YES, the 93 XJ motor will go into the '91 YJ with the 4.0. However, you will have to swap over most of the accessories (alternator, pulleys, brackets, PS pump, fan pulley, etc) because they are different on the XJ 4.0's. I think you also may need to swap the exhaust manifold, but I'm not certain...

There were never any factory RENIX YJ's, because in 1990 and prior years, the inline six models were carb'ed 4.2's. XJ's came with the RENIX 4.0 starting in '87 and going through '90. Some LATE '90 models might have a 4.0HO (they're probably mfg'ed in '90 but are a '91 model year), the general rule is '91 and up XJ's are 4.0HO.

One thing to watch out for is manual/auto differences... The TPS may be different on the XJ if it's an auto and the YJ is a manual. Also, the XJ may not have a pilot bearing if it's an auto, so don't forget to put that in. Unless I'm forgetting something, it should be a fairly straightforward swap.

 

[nappy_TJ]

Thanks for the help....I imagine I will get stuck with doing most of the work...I have only worked on the 4 bangers so this should be a good experience.:beer:

 

[junkyard jim]

The bellhousing on the AMC inline 6 cylinders (232, 242 aka 4.0L, 258 aka 4.2L and 282 Mexican motor aka 4.6L) is the same from '72 till the end of the 4.0Ls. Flywheels and flexplates changed depending on fuel system (Renix/HO) and delivery (EFI or carb) '87 to '90 flexplates and flywheels have the same notches to run the Renix EFI.
4.2L got the same flywheel/starter after '87 but only some had CPS notches just before the EFI came along in YJs. The starters changed from Ford to Mitsu style and the offset of the flywheel did too.
904/998/999/42RE uses a different flexplate than AW4. You will destroy the trans trying to run with the wrong plate.
When they went from Renix to HO in '08/90, they changed the style of notches used to operate the CPS. Quick way to spot a Renix motor in the junkyard is to look for the EGR valve next to the carb. HO doesn't have one.

 

[zebraic]

the renix model just has a different computer system, along with a few little differences. Like joe said the 87-90 cherokees were renix, from 91 and up both the YJ and XJ had the HO 4.0s. 87 - 90 YJs were the carbed 4.2 bullshit

you would be amazed at what my 4.2 carbd bull **** can do