rebuilding the 4.0

[kunar]

well i have a '93 4.0 from a navajo thats on a stand in my garage. i would like to swap it into my ranger, probably not till next spring/summer. long story short, im getting free labor for a full rebuild. i certainly plan on new rings and bearings and of course gaskets. is there anything else that i need to do while its apart? i know it depends a lot on what kind of shape everything's in. it will all be mic'd and checked for proper clearances. i dont want to replace the crank, rods or pistons if theres nothing wrong with them. im just looking for suggestions on what to check or what to replace. lifters? timing set? etc etc...

btw, i bought the engine without hearing it run, and have never had it installed. its got 125k miles on it with an otherwise unknown history. the vehicle it was pulled from was wrecked in the rear.

 

[MAKG]

If it needs a rebuild at 125K, something went very wrong. Expect bad news.

The engine should easily last twice that, with NO repairs.

You'll need the order of $200 in GASKETS and head bolts to rip this thing apart and put it back together again, so I'd check it out assembled first.

Try a leakdown test, then remove the oil pan and check all the oil clearances. If those are good, replace the oil pan gasket and put it in. They SHOULD be good at 125K.

 

[Adreenaleen]

Dude Rebuild it the right way. That way you'll be happy and wont have to go back into it. do it right the first time.

Adreenaleen

 

[kunar]

Dude Rebuild it the right way. That way you'll be happy and wont have to go back into it. do it right the first time.

Adreenaleen

so tell me... what is 'the right way' ??

 

[rickcdewitt]

if anything pull the rocker shafts and replace the rocker arms and push rods that are bad.i had several bad ones in the 50,000 mile motor that was going to go in my truck.and use a ford lower intake gasket.

do the leakdown anyway if the heads won't come off.

 

[kunar]

Read what I wrote, thats the right way.

i've read it and i appreciate your input. it never hurts to get as many opinions as possible though.

if anything pull the rocker shafts and replace the rocker arms and push rods that are bad.i had several bad ones in the 50,000 mile motor that was going to go in my truck.and use a ford lower intake gasket.

do the leakdown anyway if the heads won't come off.

it will be completely disassembled. the parts that are to be replaced are entirely my decision. i had wondered about the rocker arms and push rods. is there an aftermarket for these parts or should i go to the dealer?

 

[Bird]

i've read it and i appreciate your input. it never hurts to get as many opinions as possible though.

it will be completely disassembled. the parts that are to be replaced are entirely my decision. i had wondered about the rocker arms and push rods. is there an aftermarket for these parts or should i go to the dealer?

If you will try and do a search, you'd be amazed at the information available to your questions - these same questions keep coming up time and time again.

Bird

 

[Yellowsplash]

For the rocker arms, go with deltacam.com's rocker arm kit. They have hardened cups to prevent wear, and therefore, premature failure.

I think I remember them offering the hardened pushrods, but I'm not 100% sure on it.

 

[kunar]

If you will try and do a search, you'd be amazed at the information available to your questions - these same questions keep coming up time and time again.

Bird

ha... you telling me to search. ive looked, found some stuff... and am still better off doing it this way. you act like im new here or something...

For the rocker arms, go with deltacam.com's rocker arm kit. They have hardened cups to prevent wear, and therefore, premature failure.

I think I remember them offering the hardened pushrods, but I'm not 100% sure on it.

i just checked the site and its under construction. ive still got a few weeks before i need the parts, ill check on it again later. thanks

 

[rickcdewitt]

i used rockers from another motor,i'm not spending any money on the junk 4.0 i have unless its necesary

 

[woodyedmiston]

Well, what is it you are trying to do? MAKG is right - a 4.0 with 150k, good compression and good rocker arms will go another 150K miles. However, 150 is about the time the rockers start ticking. You might consider getting new ones if they have worn semi-circles where they hit the valves. I resurfaced my rocker arms with a belt sander and it's doing fine 12K later. It's a mule longblock I'm using as I rebuild my 99 motor that had 240K until I cracked a head when I lost all the coolant. The rockers are from the 240K engine. (The Delta Cam pushrods are hardened just for those who are interested)

I agree with you that complete disassembly and checking everything twice, grinding, polishing and all that is the right way to do a rebuild. If however, your goal is to be driving your truck with a 4.0 in it. You may be wasting a lot of time and money for nothing. Besides you could be driving it by next week.

 

[NBRanger]

Funny you should ask...

Just got done installing a 4.0 in my '92. It was a replacement for an existing 4.0. I got it out of a Explorer. I got the same story about 125K miles and nothing wrong when I picked up the used long block. I tried to do a quick and dirty R&R with the used motor. Didn't work out. I ended up with two used motors. I used the best block (cylinders in good shape) and checked the cam. These are roller cams and can take a lot of miles. I cleaned a set of lifters. Lifters are very pricey for these motors. I found a set of completely rebuilt heads and bought new rockers and push rods. I also made a set of rocker spacers to replace the springs (see Sven Pruett's suggestion in the Tech Section). From what I found between the three motors, is that the bottom end will take way more than 125K miles but with the oiling problems these motors have in the valve train, I would not reuse any push rods or rockers. I would also suggest rebuilding the heads. Even in the motor with 125K a couple exhaust valve seats were toasted. On the original motor with almost 300K, all the exhaust valve seats were gone. I've left a bunch of other stuff out. I dropped it in this week and it purrs like a cat...we'll see.

 

[Ranger44]

From what I've heard, once the seats are toast, there's no fixing it. There is litterally no room to grind them out any further.

 

[MAKG]

You can't put hardened seat inserts in a 4.0L? Why not?