Tired 4.0L

[MWinland]

My '89 MJ is blowing oil from the valve cover gasket, the rear main, and there's oil on the spark plugs. What's a ballpark figure for a rebuild? I don't want to get complicated.

[Eagle]

Do you want a quick-and-dirty rebuild, or a decent rebuild? Are you doing the reassembly after having the block cleaned and machined, or are you paying a shop to do it?

 

The last engine I rebuilt on a budget was 25 years ago and it ran me about $600 with me doing the reassembly. That was for an AMC V8 that was NOT rebored, so I reused the original pistons.

 

Today I reckon it would have to be at least double that figure.

[Wildman]

I've see rebuild 4.0 going around $1100 plus.

 

Jasper's reman engines about $1600 plus.

 

Good used low milage 4.0 engines around $350-$450.

 

Rusted out XJ's with good engine, low milage $200-$500.

 

Humm........I'll take the last one, and the rest of the parts with the whole truck. I would put a good use engine in before I would spent the $$ for a rebuild. But that's just my opinion. If your building a show truck, diffrent story.

[jeepinjay]

Rusted out XJ's with good engine, low milage $200-$500.

.

I scored an 89 XJ that was rolled on it's side for $500.

Low milage Jasper 4.0L with good auto trans and transfer case. The front doors were nice so they went on my Comanche to replace rusted doors.

Discovered the D35 in the rear has a Trak-lok in it. The bucket seats also went into the Comanche to replace worn out bench seat Plus other odds and ends I can use. The engine will end up in our 89 XJ along with the axles. The pick up could use the tranny and transfer case.

[Wildman]

 

So.....Jeepinjay.......you think you got your $500 worth???

[chicofuentes0224]

I jusy checked jasper. They want 2230.00 for a 4.0 $315 for a deposit :eek:

[chicofuentes0224]

Ebay has some reman engines for 1200 to 1600. Look under "jeep 4.o engine" Let me know what you end up doing because mine feels like it's on it's last legs.

[Car RamRod]

my local machine shop wants 1100 for a long block reman, 900 for a shortblock. I have to swap over everything to the longblock them give them my old junk. I'm probably gonna go with that after seeing how much jasper engines are.

[jeepinjay]

:yeah that:

 

So.....Jeepinjay.......you think you got your $500 worth???

 

Got my moneys worth in parts, now I just have to get busy and start swapping things around. Good winter projects.

[ejndssn]

you can do the poor man stroker 4.5l there are few articles out there :brows: for you to get the exhuasted engine running strong again and you can do it at your leasure just do a quik search and you'll get a few hits just another option

[FxRacing282]

yeah i say stroker. do it your self and it would cost less and be much more engine. all you really need is a crank, cam, injectors and machining for the block(making sure its squared and getting the crank balanced). in your case you would also need to hone your cylinders and put in new rings.

itd be easier to go on craigslist or something along those lines and buy a 4.0. ive seen them for around $100

[offroader461]

i had a new motor put in the MJ and it cost me 1800 rebuilt and installed...took them way to long and when i got mine back i had to replace oil adapter o-rings, valve cover gasket and then fought the cooling system for a month...i should've done the install myself and saved the money but just didnt have the time to do it then...

[FxRacing282]

remember that it takes a patient mechanic to pull the bolts off the tranny :roll:

[ejndssn]

http://www.angelfire.com/my/fan/stroker.html

just in case you want some information or food for thought :brows: you can try dino's site as well

http://www.jeep4.0performance.4mg.com/

[Eagle]

Guys, just remember if you think you want to do a budget stroker -- you're looking at an engine that will absolutely need high octane gas, and even then you'll probably have pre-ignition problems.

 

The 4.2L crank is the same length as the 4.0L crank and has the same journal diameters, so it drops right into the block. BUT ... due to minor differences in piston design and deck height between the 4.2 and the 4.0, you have a problem. The budget route is to use the 4.2L rods with 4.0L pistons, but that puts the pistons a fraction closer to the head than they should be. VERY high compression. You need to deal with this. Some people have sought out the heaviest, THICKEST pistons they could find so they can dish out the top of the piston to reduce compression. Others do an aggressive cleanup of the combustion chambers in the head, enlarging them in pursuit of less compression. A stock cam won't work -- you have to use a cam with more overlap to bleed off some compression pressure. A couple of people have even tried running two head gaskets.

 

The other, and better, choice used to be to use the 4.0L rods, which are beefier than the 4.2L rods. The problem is, they are also longer, so to use them in a stroker you need custom pistons. The companies who make the stroker engines may or may not sell you a set of their pistons. The company I knew of in Baltimore that sold the pistons went out of business a couple of years ago. I have sort of dropped back from the strokers forum so I don't know what the current "hot" solution is. Carnuck might -- he was very active in that group.

 

But you have to do something, you cannot ignore the fact that the basic geoemtry will result in excessively high compression. That's the biggest reason why I advise NOT trying to do a stroker unless you really REALLY need the extra power. The "budget" stroker looks enticing at first glance, but it really isn't going to be as easy as it first sounds.

[Car RamRod]

A couple of people have even tried running two head gaskets.

 

ah the old big mac HG.

[Eagle]

I should also have mentioned that, IF you can find the custom pistons to use with the 4.0L rods (the pin height has to be relocated in the pistol to account for the "too long" rods), they will be forged, not cast hypereutectic. Forged pistons are strong, but they have a different expansion rate than cast hypereutectic pistons and so the engine will be noisier than an engine using stock pistons, especially when starting up cold.

 

The stroker engines involve a lot of compromises. It is NOT just a bigger displacement stock engine. They are great if you want/need the power and are willing to live with the necessary compromises. I have considered it carefully, and decided that I don't need the power and I am not willing to live with the compromises.