'85 2.5L loud knock and smoke

My '85 2.5L has run decent until this point. More and more smoke the last two times out, had me wondering. This morning a loud knock started out of the blue, along with loss of power and rough idle! What could it be? The Jeep's a woods beater. I paid $400 for it, and have about $2,000 invested overall. Is it worth fixing? How hard to swap a newer fuel injected 2.5? Or possibly a 4.0? I have a 904 tranny, and the NP229 TC. Any help would be great.

i dont know about everyone else but i say keep it! so tottal you have 2400 in it . at least for the most part you know whats wrong with it.

i have less than $500 in mine and plan on keeping the 84 till the wheels fall off and then i'll just get new wheels.(then again i only paid 200 for the jeep and 300 to get it on the road.)

barillms said:

My '85 2.5L has run decent until this point. More and more smoke the last two times out, had me wondering. This morning a loud knock started out of the blue, along with loss of power and rough idle! What could it be? The Jeep's a woods beater. I paid $400 for it, and have about $2,000 invested overall. Is it worth fixing? How hard to swap a newer fuel injected 2.5? Or possibly a 4.0? I have a 904 tranny, and the NP229 TC. Any help would be great.

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Sounds like your engine had worn rod (and possibly main) bearings, together with worn piston rings and oil blowby. You could rebuild it for not too much dinero and get it running well again but if you want more power, you'll need more cubes. Since the XJ did come with a 4.0 engine from '87 onwards, it might make more sense just to buy another XJ with that engine rather than swap a 4.0 into your 20-year-old jalopy. A 4.0 swap will involve a lot of work and may be more expense than it's worth.

I vote keep it. It is a very good engine. If it is running that bad maybe your timing got off some how. If the engine is just about gone just look for another one for a couple hundred bucks. I just got done installing my third 2.5 and I only paid $240.00 for it.( two long stories on why its my third) Dropped it in, got everything together and in place, dumped some gas down the carb and it fired right up and all it took me was three hours by myself. It is a very easy engine to work with. If you have any questions let me know.

Kim.

I have a 93 2.5, ilove it. My 2.5 went last year when i was comming down the highway 100 miles from home. I found a nother one for a 200$ and put it back in and it runs like a champ. I have had to pull some of my buddies out of a mud hole and they all have the 4.0. I like my 2.5 i would keep it if i was you.

I have no engine work experience, I have no place to swap an engine in, and I really don't want to swap in another carbbed 2.5. If I did do a 2.5 I'd want to get the fuel injected 2.5. Not sure what to do! I've thought about parting it out. I found a '93 4.0 Auto about 45 minutes away for $800, runs and drive great. Needs a rocker panel, that's it. 177,000 miles but oh well. I can work on chassis stuff, but not engines! I don't want to spend $500-600 dollars on an engine swap when I can get a newer, better Jeep for $800 and use all my old parts and bolt ons to upgrade it.

"Their great I'm on my third 2.5" What kind of a Redneck recommendation is that?

langer1 said:

"Their great I'm on my third 2.5" What kind of a Redneck recommendation is that?

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No redneck here. Maybe you? I am on my third because the original was very tired and had alot of smoke and oil from blow by. So the second motor I purchased for $350.00 and had under 100,000 miles on it. That motor ran great until I let the rpms hit close to 6000 rpms for about thirty seconds than I had a very bad rod bearing knock so that motor was taken out for what is in there now which I only paid $240.00 for.
I did not want to wreck the original motor because I will be sending that motor in shortly for a rebuild. Yes, the second motor going bad is driver error but everybody learns from their mistakes, right?
These motors can be swapped in an afternoon and is VERY EASY. Just mark everything and don't lose any bolts. It doesn't take much for these motors if you have at least a little mechanical experience. Get rid of almost all vac lines and that is your biggest headache gone.

If you want to go to FI, than just get all the wiring and computers from donor vehicle and swap them in.

Kim.

85xjwoody said:

No redneck here. Maybe you?
Kim.

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:nono: Play nice Kim, he was only pointing out the appearant contradiction

If I remember the story right, it took you two engines to replace the original bad one with boo-koo miles on it. How did that story go anyway? Something about wrong manifolds or heads?

,Ron

No harm meant. :wave:

After the original went I got a good used motor and I wrecked that one. Then I got another motor that when I tried to put it in it had a stretched timing chain so I could not get the timing right. I returned that motor, got my money back, and went and got another one. That motor currently runs good thanks to the help of Langer1 and Zuki Ron. I just think that if you have some mechanical skills you could just get another 2.5 for cheap or just junk it and buy a cherokee with the 4.0 as he has already mentioned.

Kim.