Rebuild vs New Engine

McGriff21

New member
City
Dover
State
NH
#1
So we are just underway on rebuilding our 81' Scrambler. We have discovered that our timing belt is worn out. It has about a 150,000 known miles on it. We are debating about rebuilding the engine vs a new straight 6 replacement. Does anyone have any insight/history into which way they went? We are planning to keep this Jeep in the family for generations to come so matching numbers aren't critical. Does anyone have a recommendation on where they have sourced replacement engines? Thoughts on rebuild vs. new? We are in NH if that is critical at all
 

Ron84cj

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
West Bend
State
WI
#2
The 258 has a timing chain. Other than that what's wrong with the engine? Does it have bad compression? Burn oil? If it's still healthy just run it. Don't rebuild it just because of miles. If it truly does need a rebuild I would get some quotes from a reputable machine shop in your area. Depending on where you live those numbers are going to be all over the place. By me you would very realistically be about $2,500-3,000 into it for the 6. For me it was actually cheaper to swap in a low mile 5.3LS. But there too, it depends on where you live. Salvage yard prices are all over the place too. Check out your options locally and if you have any questions I would be happy to help.
 

93_Fummins

CJ-8 Member
CJ-8.com Member
City
Edmond
State
OK
#3
If you are speaking strictly 258 I-6, even a "new" engine will be a rebuilt engine. The main difference would be (hopefully) that all the seasoned parts are already inspected and within good tolerance on the "new" rebuilt engine, versus opening up your engine for a rebuild and finding out that something is beyond serviceable use.

And it is typically NOT cheaper to "just swap in a 5.3 LS" because that comes with a myriad of nickle and dime changes to the entire powertrain and chassis plumbing to make it work reliably.
 

don87401

Scrambler Junkie
LIFETIME
CJ-8.com Member
SOA Member
City
Farmington
State
NM
#4
I agree with the above. Do the diagnostics and see if you need to go that far. 258's are know to run for ever if well taken care of. If it checks good go with the timing chain and drive it.
 

Ron84cj

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
West Bend
State
WI
#5
If you are speaking strictly 258 I-6, even a "new" engine will be a rebuilt engine. The main difference would be (hopefully) that all the seasoned parts are already inspected and within good tolerance on the "new" rebuilt engine, versus opening up your engine for a rebuild and finding out that something is beyond serviceable use.

And it is typically NOT cheaper to "just swap in a 5.3 LS" because that comes with a myriad of nickle and dime changes to the entire powertrain and chassis plumbing to make it work reliably.
Well, everything all said and done I have about $2,000 into the entire swap. I have been driving it daily for several years now very reliably. Any problems I had were not related to the swap. Rebuilding my six would have been more expensive by $500. As I showed in my build thread it is way more expensive if you just buy absolutely everything from novak or advance adapters instead of just using mostly off the shelf parts like I did.

Either way, people get way too caught up on miles. I've seen engines with 70,000 miles that are trash from neglect. I have also had engines apart with well over 400,000 miles and are still well within spec. If the engine is still healthy, replace the timing chain, gaskets, seals, and run it!
 

Belizeit

CJ-8 Member
CJ-8.com Member
City
River Ridge
State
La
#6
I had the 4 cylinder. At 140,000 miles the timing chain was worn out. Put a new timing chain on and got another 100,000 on the engine and was still running strong. At that point even running strong still, I decided I wanted a 6 cylinder and found one and rebuilt that. If that had been in the Jeep I would probably still be running it. Just decided what condition the engine is in and go from there.
 

Mancunian

Lifetime Member
LIFETIME
City
Bridgeport
State
WV
#7
My timing chain was toast too, its a fairly easy replacement if you go that way, just be sure to put it in TDC for #1 before you rip it all apart. Do you have a manual to follow?
 

Belizeit

CJ-8 Member
CJ-8.com Member
City
River Ridge
State
La
#9
If the timing chain and sprockets are worn, replacing will make it run a lot better. Mine would actually stall at stop signs. The timing was out of whack because it was jumping around.
 
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