I am certainly not a wrench or a seasoned xj owner even but one thing I often see on here never makes sense to me. It is the advice that once you get to a certain point, maybe if you need to replace vs grind cam, you should just go get a junk yard engine and install it instead of rebuilding your own.

The big thing that lights off in my head is what makes the junk yard engine in any better shape than the one I have now? Who is to say it wasn't abused, run with antifreeze in it etc? The only way you will know its condition is either to install it and see what happens or rip it apart to the rebuilding stage to check cam bearings.

I guess if the engine you are rebuilding has 300k on it that it would make more sense to me but if it has maybe 100k, 150k ?

Am I just not taking something into consideration?

 

Igeeky2!

So wazzup? Knocking, low oil pressure?

"The big thing that lights off in my head is what makes the junk yard engine in any better shape than the one I have now? " Well, if the rear-view mirror is pressing on the shifter, and the odometer says 80K, there's that...

 

It's all about cost effeciency. For instance, my 90 motor with 300k was beat up, hydrolocked twice, overheated, low oil pressure, the whole 9. So, I could either rebuild it (comes out to bout 300$ in parts alone) or get a jy, late model motor with better headers, intake and Tb, for 165$.

 

$165 for a jy motor? wow that's an awesome price, here they start at about $400 w/high mileage and go up from there, I've seen them at $1000.

 

You can't use everything on that later JY engine on your Renix.

You can use the long block but a lot of externals are different.

That being said, it still sounds too cheap for a good engine. Maybe you can do that in your area, but not mine.

 

Well, this is the fourth motor my buddy and I have bought from this guy, we have done a few swaps for various customers.
And my 90 to 99 swap went swimmingly, pretty much only difference is using a 91-92 fuel rail, 're wire for the map and tps or custom mount the renix tps...and add a 3/8 npt tee on the thermostat housing and Tada, renix remix

 

I got lucky on mine at picked it up for a 100 bucks on u pull , customer appreciation day. I did a full gasket head surfaced, injectors, exhaust, brakes and upgraded a few parts too . Was into it about 900 into a 500 jeep that was sold for 3200.

It's just all depends how bad the motor is check crankshaft play. Timing chain slop. Carbon deposits on pistons and if a ridge on the cylinder walls.

 

A junkyard motor will almost always be a crapshoot, but it doesn't take much to pull the head(s) to check it out before you buy. (If it's a U-Pull). I have ran junkyard specials in the past, but usually just to keep whatever I'm running it in roadworthy while I do a rebuild on the original. That being said, there's nothing wrong with running one long term, especially if you luck into a lower milage replacement. A junkyard swap might even be a cheaper fix depending on what else needs to be replaced when you crack the old one open. I usually spend twice the amount I anticipated after I replace/upgrade all of the extra stuff "while I've got it apart".