Topic: 98 4banger in a 95

[Cnorth]

quick question, i am on the hunt for a replacement 2.5 for my 95 yj.  i have tracked down a 98 2.5.  This is my first engine swap, can someone tell me what issues, if any i will have in bolting this up to my 95 yj.  thanks.

[sharpxmen]

couple of members did that (both ways I think, TJ to YJ and YJ to TJ 2.5L swap).
get all the sensors from your engine, distributor, intake (including injectors and fuel rail), exhaust manifold and waterpump (i'm not 100% on this one but i think you need the YJ one). One issue you will have is with the water temp sensor close to the firewall in the cyl head (is the one for the gauge cluster), it doesn't exist on the TJ 2.5L, the location for the sensor is there (flat portion in the cast) but the hole is not drilled and tapped, you could get it done as it is a 1/8'' npt thread and use your old sensor.

another thing that i recall being different is the oil pan, apparently the TJ one has a different shape due to the exhaust downpipe routing, but i cannot say 100% it won't work, if you end up replacing it then you'll need the oil pump as well as the pickup is also different from what i remember.

[RNandKT]

The block is the same (and has been since like 1984, previous to that the 4 cyl was an iron duke chev block, stroke and bore was a little different in the 80's but your 95 YJ's I believe has the same as the TJ's, difference was basically the change from TPI to MPI) but the external stuff is different. Basically if you strip it down to the short block, you can move everything over from your current engine and then it will bold back in fine. Pretty much none of the sensors will match the plugs on your engine so you have to swap everything.

But this means doing a head gasket, but that also gives you a quick view into the condition of the engine. I have heard of people Drilling and tapping the TJ head for the temp sensor, but kinda risky as I have heard people say it can get metal shavings in your coolant.

It's a good idea if you do this to take your head down and have it dipped and cleaned at a bare min, and maybe pay the shop to do a quick valve job. It's not too expensive and well worth the results on these motors.

Good Luck

[grumpygy]

Instead of drilling the head could you not drill antd tap the thermostate Housing.



the flat round spot would be a great location.

[sharpxmen]

what he ^ said or just drill and tap the head, keep removing the shavings before you penetrate to the other side, when you're close keep the speed up on the drill and most of it will come off by the means of the bit spinning. put grease on the tap so it catches the shavings.  then blow air thru the hole you just drilled (thermostat housing removed) and you can also run water with a hose with the waterpump removed, i can't see having the head off making any difference with cleaning it off if you're careful, small bits will be blown off by air or  washed off with water (not saying a valve job will hurt in any way).

@RNandKT - YJs had MPFI since '91, the TBI which was up to 1990 had different head and pistons (not the Iron Duke, the AMC), bore and stroke are the same on all AMC 2.5L

[RNandKT]

My bad on the fuel injection you are right on that (crackhead typing, it's late, I actually had a 95 YJ with the MPI, but it is an OBD I as opposed to the TJ's OBD II and again none of the sensors will have the same plugs, they pretty much changed them all).  

I knew the bore and stroke and heads were different in the early years, but I have actually seen someone swap a short block on an early Cherokee (like 85 I think) to a later YJ (something like a 93) and the short block worked fine. Also I meant the pre 84 were the Iron Duke and it's completely different (actually a chev motor) but thanks for the clarify.

[Jeffy]

Since the temp sensor is only for the gauge, I wouldn't do any major work to get it installed.  I've seen some people put a T fitting into the ECM temp hole and do it that way.  Not perfect but gets the job done.  You could also do a collar with a tap and split the upper hose.  Drilling the thermostat housing would be a lot easier then drilling the block as well.

The big difference between the two engines is the cam.  Though I haven't hear of any issues using one or the other.

[SDWE61988]

Instead of drilling the head could you not drill antd tap the thermostate Housing.



the flat round spot would be a great location.

This is exactly what I did when I performed my swap.  The drawback to that is then the Thremostat sticks out and will be hit by the fan.  So I converted over to the electric fan.  (Good excuse to upgrade.)