coloradoboy

so i have a 1991 jeep xj engine, i would like to be able to put it into a 1990 jeep xj, however i was told i couldn't because the 1990s have a remix engine and you cant swap the engines, does anyone know if this is true.

Please include details

cruiser54

Don't listen to those people anymore. They are flat-a$$ wrong. Use your intake and exhaust manifolds, an intake/exhaust gasket for your 90, your flexplate/flywheel, distributor etc. Piece of cake.

One warning: The 91 block will have a plug in the driver's side that you need to remove in order to screw your Coolant Temp Sensor in. Make sure you get that handled before installing the engine and it's manifolds. The square drive to remove the plug is 5/16".

jakbob

or what you could do (so the coolant temp sensor gets a more accurate temperature, from what im told) is do all of the above that cruiser said, but instead of worrying about the plug on the block, take the water outlet housing off of the 91 and put it on the 90. the temp sensor would move into that housing, and all you have to do is shorten up the wiring for the sensor. im looking at doing the same thing on mine.

but cruiser def knows his stuff

cruiser54

Good idea. I never thought of that. Pull the plug on the block. Take a 5/16" allen and grind the edges til it works on a square female plug.

freegdr

dont forget the renix also uses a knock sensor ...

freegdr

the temp sensor will get more accurate engine temp being mounted in the block

jakbob

ive seen accounts of the sensor in the block being 15* under true temp, same sensor mounted like the HO's, it was maybe 2* off. the guy took pics, and used an IR gun.

and also, if it was more accurate in the block, why would they move it to the water outlet housing?

cruiser54

Yes. And the 91 block is threaded for it.

cruiser54

It's for cold start-ups. And besides, the difference isn't gonna be that great. Put it where ever you want. It's not a Formula 1 engine.

jakbob

makes sense. im still going to do it because i dont like all of that wiring going under the manifold... gets too hot. i had a knock sensor that literally turned to pieces when i tried to take the retainer clip off... seemed like it was little pieces of glass....

Caish

The problem with sending unit in the thermostat housing, is that its on the wrong side of the thermostat.
It will not get an accurate reading till the thermostat opens.
Its better in the head than the T-stat housing.

jakbob

its not in the head anyway. its either on the thermostat housing, or at the bottom of the block.

unless you are thinking of the temp sender (for the gauge in the dash). then we are comparing apples to oranges. AFAIK, the temp sender has always been on the back of the head.

milehigh94xj

Is the 91 engine complete or short block?