What engine for a 91'

[RTownsend]

I posted in another thread about a problem I'm having with my high mile 4.0 91'. I figure it may be time to get a new engine or one from the junk yard.

If so then what years should I look for? I assume I should look for the newest one I can find. Will one from a Wrangler work? Would I be better off with one from an engine rebuilder or even rebuild it myself?

 

[asatxj]

I just swapped in a 97 and there are a few issues
1) The coolant sensor if you have factory gauges
2) The AC and PS brackets (used the 97)
3) The 97 intake is a little different and requires some grinding for the PS pump.
(If you want pix and more info let me know. Most of this applies to post 96 motors according to info I've found)

BTW I have a running 91 that has a rod knock, you can have it cheap or for barter and then make one good from the two.

If I can be of more help let me know
ASATxj

 

[Eagle]

The easiest, most direct swap for a '91 will be an engine from a '91 thru '95. Wrangler or Grand Cherokee should be just as good as a Cherokee.

 

[RTownsend]

Thanks ASATXJ

Is the sensor in a different location?
Is the block different or just the brackets?
Could I just use the block and head and avoid any problems?

Eagle

If I use an engine from a 95' then I would think I would be better off to spring for the extra money and rebuild my current engine. I called a junk yard today and they had a 95' with 70,000 miles for $600 plus core. I couldn't help but think that to have that low of miles that it had to have been sitting a long time.

 

[Eagle]

Not necessarily. Not everyone drives a lot of miles or takes XJs off-road. In your situation I'd snap that dwal up. Most yards give a 90 day warranty that any used engine will have decent oil pressure and won't use oil. Ask.

My '88 XJ has 237,000+ miles on it, but my '88 MJs have 104,000 and 118,000 respectively. Neither one uses any oil and both have better pressure than the XJ.

 

[asatxj]

the temp sensor for the guage isn't used on the 97+ the computer gets it's feed from the one on the tstat housing. Therefore you have two choices 1) drill and tap a hole in the head in the same location as the one on your 91 (easy with engine out) or relocate it to the Tstat housing by drilling and tapping there. I've read on JU where people have removed the sensor on the tstat housing and put the gauge sensor there but I'd think that causes other issues so Id' poo-poo that idea.
The block is the same, the brackets all will swap and the "grinding is very minor and takes about 10 minutes, I'd do it agian if I were swapping for someone else-very easy.
The price they quoted you isn't too bad! I got a 97 with 47k for $500 but that was a VERY special deal!
Eagle is right, the 95 swap is easier but the new motor isn't a big problem, just a couple of tiny issues. Keep us posted!

BTW Eagle, is it possible to run the factory temp gauge off the sender on the Tstat housing? A chap on JU pulled his and put the gauge sender in there but wouldn't that cause the computer to run rich and the electric fan to not come on?

 

[Eagle]

Eagle is right, the 95 swap is easier but the new motor isn't a big problem, just a couple of tiny issues.

Well, I don't know if the issues are "tiny," but they certainly aren't insurmountable. The basic engines are the same, and with a later engine the best route is probably to use the brackets and manifolds from the vehicle. That still leaves the temp sender problem to deal with. Personally, I like to keep things as straight-up as possible because you never know when an outside shop will have to work on the vehicle, and it's a lot better if they don't find a lot of surprises.

BTW Eagle, is it possible to run the factory temp gauge off the sender on the Tstat housing? A chap on JU pulled his and put the gauge sender in there but wouldn't that cause the computer to run rich and the electric fan to not come on?

I don't know enough about the new computer to answer that. I'd guess there should be a "Check Engine" light triggered, for one thing, because there would be a PCM circuit that's not receiving any input.

This is why we don't pay any attention to tech advice from JU.

 

[Spudboy]

I couldn't help but think that to have that low of miles that it had to have been sitting a long time.

Ask to see the rig it came from if they still have it. I bought an engine from a '91 with 75,000 on it last year. When I went out to look at the XJ it came from, there was no question - that thing looked new!

That's a pretty good price IMO. I paid $650 with no core required. Good thing since my old engine had a 4 inch hole in the side of the block.

 

[asatxj]

Thanks Eagle! I tend to side with you on the JU issue. I have a plan for the sensor and a backup if that isn't effective. More news as it happens.
Sorry for the hijack, I'll get back on task now!

 

[RTownsend]

Thanks for the help guys

It's hard to decide what to do. Everytime I decide to just fix my engine I start adding up the cost and quickly come close to the cost of a used engine. I will go look tomorrow at the used engines and see what they look like. I do know that I want to keep my engine for parts if I get another one.