Replacement Engine Question

nwoods

nwoods

Expedition Leader
Hey folks, thinking of dipping my toes back into the Montero world again. This time the hard way, by swapping motors from a donor into a nice clean 3rd gen platform for eventual use by my daughter as her first rig.

Do you know if a 1997 Montero sport 3.5L SOHC engine will fit in a 2002 Montero Limited? Same engine specs, but I don’t know of the mounts line up, tranny connects, exhaust manifolds will work, etc.... I have my eye on 2002 with a seized motor and am thinking of doing this motor swap. Never done anything like that before. Bit scary!

Anyway, this 1997 engine is very affordable and would make this hole deal a lot more attractive.

Do you have any idea how much LKQ “PickYourPart” wants for an engine? $2,350 for one with 80,000 miles on it, not including anything that bolts on, like compressors, pumps, manifolds, etc.... Yikes!
 
nwoods

nwoods

Expedition Leader
I guess alternatively, I could try a full rebuild of the existing engine, but not sure what is wrong with it. Seems seized up, maybe threw a rod? Was running down the highway, then abruptly stopped running and won’t start or turn over ever since. Tow service tech says “thrown rod” but that’s pretty rare for Monty’s, so hard to know for sure.
 
S

Salonika

Monterror Pilot
It will be a lot less trouble to rebuild the one you got than to try and stick one in there that you aren’t sure about. With all the work involved, do it right and have yours rebuilt. It will be better over the long haul. You gotta take it out anyway, let an engine shop give you their opinion before you dump that motor. I had mine rebuilt a few years ago, best decision I ever made.
 
nwoods

nwoods

Expedition Leader
My understanding of engine functions is poor, but if it’s seized due to a thrown rod, isn’t that the end? Doesn’t that result in a cracked block or a new window into the block that shouldn’t be there?
 
S

Salonika

Monterror Pilot
Whatever may be wrong, you won’t know for sure until you break the engine down and inspect it, which a rebuilder would do for you. They’d tell you if the block is junk. I know enough to be dangerous here, and I’d say #1, “thrown rod” can mean many different things to me. It might mean the connecting rod bearing is toast, or it might mean the rod broke in half.....”seized” is another generic term that doesn’t mean much to me until you get in there and look for damage. It needs to be inspected. Maybe you need a new crank. Maybe not. Maybe you have cylinder damage beyond practical repair....maybe not. Unless you had a catastrophic oil problem that caused damage on every internal moving part, it’s probably practical to rebuild.
 
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nwoods

nwoods

Expedition Leader
I plan on doing the tear down myself. Have done that a few times on my old 98 Monty. I’m comfortable with everything until I get to the pistons. At that point I quickly run out of know-how.

Oh, seized in this case means can’t manually turn the crank with a breaker bar. No rotation. At all.
 
S

Salonika

Monterror Pilot
In my experience, seized would mean a bearing on the crank failed, either a rod bearing or a crank support bearing (or several of each!). As long as the crank journals aren't severely scored it can be reused. Pretty sure there are specs too for measuring them.......again an engine machinist does this in their sleep. I think the worst case scenario is that you'd need a new crankshaft. I think rods and pistons are usually reused in a non-performance rebuild. I don't remember what they did with mine. But again I think the best plan would be to just rebuild what you have, and I would have it done professionally. With all the work involved pulling the engine and actually rebuilding it, and there is a lot of precision work that needs to be done, to me it isn't worth messing something up.
 
jeep-N-montero

jeep-N-montero

Expedition Leader
I would start by pulling up the part numbers on rockauto of a few questionable parts to see the interchange years, this will give you a very good idea of how easy or hard the swap might be. The engine itself is the same through 2002, only real difference I believe is the limited got the 5-speed transmission upgrade somewhere in there while the non-limited still had the 4-speed.
 
mezmochill

mezmochill

Is outside
Adapting a nonstock motor will almost always be more expensive, time consuming and have more reliabitiy issues reguarding electronics, vibration, clearances etc than OEM design.

Just keep that in mind.
 
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