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Discussion Starter · #1 ·
Hey all, first time posting and need some help. Running to fast in water and buried the front end of my 94 YJ 4.0L in water up to drivers seat in cab. Engine stalled, winched out and had 2 holes in the oil pan where I threw a rod. Someone has offered me an old Comanche 4.0L that ran when it came out of a 2WD Comanche with 240,000 miles on it. Would appreciate some thoughts or suggestion as to whether I should buy a crate 4.0L or use the Comanche and rebuilding it? Will the 2WD automatic even match up with the YJ 4WD manual?
Thank you
 

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If the engine is out of a 1991 or 1992 Comanche it will work. The older 4.0's use Renix fuel injection and the had intake and exhaust manifold are different and will not bolt in and run.

If it is a older Renix engine you could swap the head off the 4.0 you have now if the head is still good onto the renix bottom end and get it running that way. The only difference is the Renix block has a knock sensor int he side of theblock that will not be used with the 1991-1995 HO MPFI fuel injection
 

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Welcome to the Forum Swamp 94,

Too bad about your motor. Inhaling water is just as bad for Jeeps as it is for men.

I'd take what agalloch07 advises under serious consideration.
For me, I'd go with a re-manufactured long block from a company that I had confidence in. For such a purchase, quality would mean more to me than price. I'd want to have the Jeep back on the road as soon as possible.

If you have other vehicles and are willing to tackle rebuilding a motor, and take the time to do what's necessary, the cost will probably come out the same. When a mechanic or home mechanic builds a motor for himself, he generally spends more money for "better" parts than a re-man company would spend. Plus, a re-man company will have the necessary machines in house for the machine work that could cost a home mechanic a lot of money to have a machine shop do it.

What it boils down to is how much of a hurry are you in and what condition is your Jeep budget in. Assuming you have the skills and tools to rebuild a relatively simple motor.

Keep us posted on how it goes.

Good Luck, L.M.
 

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Discussion Starter · #4 ·
Thank you for your knowledge and advice. Thinking about just getting crate motor an doing swap myself. I have read some other threads that talk about making sure I mark and take pics of the vacuum lines but is there anything else i should worry about? Is this a task someone that is handy but never taken a motor out can handle? Appreciate candid responses, you wont hurt my feelings.
 

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Thank you for your knowledge and advice. Thinking about just getting crate motor an doing swap myself. I have read some other threads that talk about making sure I mark and take pics of the vacuum lines but is there anything else i should worry about? Is this a task someone that is handy but never taken a motor out can handle? Appreciate candid responses, you wont hurt my feelings.
Most folks that are handy and usually do their own maintenance can change a motor.
A lot depends on your situation. Having a big garage and the tools makes it a lot easier. I've seen guys change a motor outside with a chain hoist hung from a tree branch. You can probably rent a motor hoist from a U-rent place.

Changing a motor in a YJ isn't as difficult as many other vehicles. Start by having a plan. Talk to your buddies that have done similar jobs. Look on UTUBE. Get a Factory Service Manual. Taking pics is a good idea. Also have a system to label the vacuum lines and wires (masking tape and a magic marker works). The electrical connections usually have dedicated plugs that only fit their partners. Label them anyway.

While the motor is out you might find things that will need attention. Should you install a new clutch? Did you find a cracked exhaust manifold? Does the exhaust need replacing? How about the motor and transmission mounts? You might discover something that would be easy to upgrade while the engine is out that would be a pain with the engine in the Jeep.
Things that would be OK if they weren't disturbed might crumble (exhaust pipe or rusty bolts). Naturally you'll want to install new coolant. How's your radiator?
If you change the motor yourself and money is tight, when these things pop up, you can put the project on hold. If you have a shop change the engine and the mechanic finds anything that needs attention, he should call you for your OK to do the additional work. If you don't OK it, he'll proceed and note your work order that you declined the additional work. He won't want to wait for you to collect the additional money, he'll want to finish your job and get on to the next. Have a cushion in your budget for "just in case items".

When changing a motor in a YJ, it's easier if you have the grill panel off. I've seen where some guys even remove the fenders. With the fenders off, it's even easier. The hood folds back to rest against the windshield frame. Put a towel between the hood and the windshield frame to save any paint damage.

Other posters should have more suggestions.

Good Luck, L.M.
 

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Having a FSM makes the job way easier. I have one on my hard drive. I print the pages that I need and take them out to the shop. Then I can make notes on the pages for future reference.

Find a post by Got it at last. In his signature there's a free link to several Factory Service manuals and a couple Factory Parts Manuals.
Open that link and click on the manual that you need.
I suggest you review certain procedures like R&I (remove and install) the transmission and transfer case and make sure to have the necessary tools to do that portion of the job. It may not be necessary to remove the transmission to change the motor, but it's easier to fit a standard transmission to a motor when the motor is in the vehicle than fit a motor to a standard transmission when the transmission is in the vehicle. If you have an automatic transmission it may be easier to leave the transmission in place.

When you pull the motor, have an assistant around to hand you whatever tools you might need while you're under the Jeep and just in case there's an accident. Even a 9 year old can call 911.

Good Luck, L.M.
 
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