95YJ 2.5l Blown Engine - Repair or Swap? - JeepForum.com
 
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post #1 of 10 Old 05-24-2021, 09:34 AM Thread Starter
Mclearg
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95YJ 2.5l Blown Engine - Repair or Swap?

Hi All, I've recently purchased a project '95 YJ with a blown head gasket.
My question is should I try and resuscitate it? or go with an engine swap?
I've swapped engines on cars in the past back home in Scotland so I'm familiar with the issues in general, admittedly not with a Jeep.
It came with a new head gasket kit so i'll probably take the head off and get it checked as a 1st task.
If it's a swap I would probably go with the 4.0l 6 cylinder as I've been reading that is a good direction to take but I'm keen to hear from any members that have chosen that path.
Thanks in advance,
Gordon

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post #2 of 10 Old 05-24-2021, 09:59 AM
gutthans
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Why did you buy it? What's your time frame? What's your budget? What are you wanting to do with the Jeep?

Even a total rebuild of the 2.5 will be immensely cheaper and considerably less time intensive than a retro-fit of a 4.0 (which may need work as well), and you have all of the correct plumbing, wiring, and accessory parts already. Now, if you have a donor 6cyl. wreck handy, that would greatly simplify things. Having a few buddies or a Jeep club nearby is also a serious plus.

Get it running and trade up for a project six if you really want one would be my advice.
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post #3 of 10 Old 05-24-2021, 09:59 AM
Waternut
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In order to get the engine out, you pretty much have to remove everything except the head to replace the head gasket. IMO, I'd just do the head gasket. It can be done in your garage after work one day. If you see something you don't like at that point, then maybe consider replacing the engine.

As for the 4.0... that's a full engine swap. It doesn't not bolt it and just because it's been done by a lot of people doesn't mean it's easy or straight forward. You need the engine, transmission, computer, wiring harness, driveshafts, and transfer case from the 4.0 donor. You can do it slightly differently by combining existing parts with donor parts but your transmission, transfer case will not work with the 4.0...or at least not without major modification. You also need to weld in new engine mounts because they are not the same. In short...the 2.5 to 4.0 swap is roughly 90% of the work and money as it would take to swap in an LS engine.


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post #4 of 10 Old 05-24-2021, 06:31 PM
Flyer58
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Since you have a new gasket kit I would install that and run it for a while to see if there's any other problems. I can be done in one day with no special tools. How many miles/Km's are on it? If it's worn out and needs more that that's a different situation. I bought one with a 2.5L with spun bearings and rebuilt it.
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post #5 of 10 Old 05-24-2021, 07:21 PM
Boojo35
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Why do you say it needs a head gasket? You said it came with a head gasket kit so I assume it was a diag by the PO. You also say blown engine in the thread title. Lets get down to basics. Maybe you have something even simpler.

Does it run? Does it knock, overheat, run like crap, blow smoke, etc. ???

If you cannot fix it with a hammer then it has to be an electrical problem.
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post #6 of 10 Old 05-25-2021, 01:57 PM Thread Starter
Mclearg
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Thanks for the input folks.

The previous owners mechanic made the diagnosis and I've no reason to doubt him. The oil being emulsified is a good indicator.
The engine does turn over but I've not tried to start it yet, will do as soon as I get a good battery in it and fresh fuel.

Mileage is stated as 138k so it shouldn't be too tired.

I bought it as a project with no real time frame in mind . . .more to keep me busy than anything else.

I'm aiming to go for a relatively stock appearance.

In my past I've carried out engine swaps including ecu's and total wiring harnesses, rebuilt cars and motorbikes that came in boxes, built kit cars and restored basket cases so I'm aware of most of the pitfalls.

Both my father and grandfather were merchant marine engineers before starting a car repair garage/body shop pretty much when I was born - some have a silver spoon in their mouths . . .I had a wrench :-)

As I said my initial thoughts are to check the head on the 4 pot and and go from there. If it is repairable i'll get the summer out of it and then go from there.

Once the heat of the Texas summer is over and it's a little cooler in the garage it'll be body off for body work/paint and interior.
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post #7 of 10 Old 05-25-2021, 04:38 PM
Boojo35
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If the oil is a milkshake it will really need to be rebuilt. That stuff trashes bearings. I am a mechanic for a living so I see when things are driven too long and put off and the ensuing damage. Having something that you can have machined and cleaned and rebuild yourself is the most cost effective way to make your Jeep run and be reliable. Then there are the swap options that may be desirable to you but have been pretty well covered already.

If you cannot fix it with a hammer then it has to be an electrical problem.
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post #8 of 10 Old 05-25-2021, 05:15 PM
steeve555
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Since you don't know history of engine I would do engine swap. I've pulled an entire 2.5 engine complete in 4 hours. If you take radiator and front grill off it pretty much comes out the front.
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post #9 of 10 Old 05-25-2021, 08:58 PM
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I have a decently running 2.5 4cyl in my '90. I plan to run it until it pukes so I would suggest you just replace the head gasket and see if it will be serviceable for you. Definitely easier than a swap. I plan on swapping in a late 90's S10 Blazer Vortec V6 with the 4L60E auto and transfer case. Yes it will be a lengthy process but if your going to swap, its just about as easy to get more power under the hood. Ive also located the donor vehicle for $100! Low 100K miles, the Blazer had an electrical issue they never figured out so I am hoping the rebuild of the driveline will be easy enough. Since my YJ is running, I have time to do all the rework and be ready for the swap when all of the Chevy stuff is done.


Look around for different options. The 4.0 is a good engine but there are other great options out there.
Good Luck!!
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post #10 of 10 Old 05-28-2021, 10:54 AM
denverd1
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How long has the oil been contaminated?

Probably looking at a complete rebuild, I'm sure the crank bearings are shot.

Easiest plan would be to rebuild the 2.5. Engine swaps suck

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98 XJ: 4.5" lift, 10K winch, F/R locked on 33's
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