engine swap or rebuild?

[MJ.rusty]

FINALLY! i have found a garage for cheap right down the street. i have many plans for my truck- flat bed (if someone needs the original six foot let me know) body work , etc. all of these i know something about.

 

bear with me now I'm not a mechanic nor a gear head. still learning

 

now while I'm in the garage i want to do something with my motor. i have a 1990 4.0l eliminator with manual trans. i think it has 150k on it and runs ok. i think it has some blow by due to the oil splater on the passenger side of the engine and hood (think it might be blowing out of the dip stick. not sure) pretty sure i need to replace the rear main seal cause it leaks oil from somewhere and ends up dripping of the oil pan.

 

when i first bought it i had compression tests and all that good stuff done and it all came back good. i plan to replace most of the bolt ons. and was wondering if it would be worth it to get a rebuild kit or to get a rebuilt engine. i don't want to replace a good motor for the sake of it. i bought the truck to learn. but i also don't want to rent a garage for the rest of my life to fix the existing engine.

 

any and all feedback would be greatly greatly appreciated

[MJ.rusty]

FINALLY! i have found a garage for cheap right down the street. i have many plans for my truck- flat bed (if someone needs the original six foot let me know) body work , etc. all of these i know something about.

 

bear with me now I'm not a mechanic nor a gear head. still learning

 

now while I'm in the garage i want to do something with my motor. i have a 1990 4.0l eliminator with manual trans. i think it has 150k on it and runs ok. i think it has some blow by due to the oil splater on the passenger side of the engine and hood (think it might be blowing out of the dip stick. not sure) pretty sure i need to replace the rear main seal cause it leaks oil from somewhere and ends up dripping of the oil pan.

 

when i first bought it i had compression tests and all that good stuff done and it all came back good. i plan to replace most of the bolt ons. and was wondering if it would be worth it to get a rebuild kit or to get a rebuilt engine. i don't want to replace a good motor for the sake of it. i bought the truck to learn. but i also don't want to rent a garage for the rest of my life to fix the existing engine.

 

any and all feedback would be greatly greatly appreciated

[Wildman]

:hmm:

 

i don't want to replace a good motor for the sake of it.

 

I think you said the right thing :roll:

 

If you had a compression test done, and the reading were in the good / spec range, why even think about rebuilding the engine???

 

We are talking about a '90, 4.0L, with 150k on the clock........right???

 

I hope guys with close to, or even over the 300K mark on there 4.0 will chime in here ;)

 

Yes, I can under stand you want this to be show room perfect, but, if the engine was not neglected over the past 18 years, I'm sure you will get another 18 years and 150K out of the engine you have now :D

 

Yes, change all of the seals and gaskets, you right bank oil leak could be from the oil filter adapter leaking, common. Nothing wrong with changing all the gaskets, changing the accessories, to upgrade, or make fresh. And even do the fuel injector replacement (see Taz's info on that) And you will spend less time in the rented garage, and enjoying driving the MJ sooner :yes:

 

That's just my 2 cents.

[Wildman]

:hmm:

 

i don't want to replace a good motor for the sake of it.

 

I think you said the right thing :roll:

 

If you had a compression test done, and the reading were in the good / spec range, why even think about rebuilding the engine???

 

We are talking about a '90, 4.0L, with 150k on the clock........right???

 

I hope guys with close to, or even over the 300K mark on there 4.0 will chime in here ;)

 

Yes, I can under stand you want this to be show room perfect, but, if the engine was not neglected over the past 18 years, I'm sure you will get another 18 years and 150K out of the engine you have now :D

 

Yes, change all of the seals and gaskets, you right bank oil leak could be from the oil filter adapter leaking, common. Nothing wrong with changing all the gaskets, changing the accessories, to upgrade, or make fresh. And even do the fuel injector replacement (see Taz's info on that) And you will spend less time in the rented garage, and enjoying driving the MJ sooner :yes:

 

That's just my 2 cents.

[project88mj]

the PO of mine took good care of my truck and my 4.0 runs great @ 230,000

 

(i get a modetate amount of blowby but nothing too much to make me worry)

 

i still race hondas and own the off the line then up to about 45-50 i get cought. i think some

4.10 -4.56 gears will change that :brows:

[project88mj]

the PO of mine took good care of my truck and my 4.0 runs great @ 230,000

 

(i get a modetate amount of blowby but nothing too much to make me worry)

 

i still race hondas and own the off the line then up to about 45-50 i get cought. i think some

4.10 -4.56 gears will change that :brows:

[MJ.rusty]

thanks for the two cents wildman. if you know of any good write ups on replacing gaskets and seals let me know.

[summerinmaine]

I hope guys with close to, or even over the 300K mark on there 4.0 will chime in here ;)

 

 

:waving:

 

300K and counting here! Compression is still 150# across the board (don't what OEM would be, but it's a low compression motor, right?).

 

Oil pressure is 40# when cold, 20-25# when hot @2500rpm. Main seal leaks a bit, and a slight amount of oil blow by into the air filter.

 

Everytime I think about a rebuild, I stop myself. :yes:

 

Keep running it and build yourself a stroker in your spare time. Then you'll REALLY have a reason to change the motor.

[Pete M]

I would do a new timing chain and call it a day for the internals. :thumbsup: