Engine Rebuild

[Waytec]

I am thinking about tearing down and rebuilding my engine 4.0L HO in a Cherokee this winter. I am consuming some oil and have over 300,000 km on it. I have read a lot on Scott's thread about cams but I am also thinking about stroking it as well. Jeff I think you stroked your 4.0L. Did you use a kit or assembled the parts that worked the best. I am looking for feed back on what has been done. I am also considering a super charger or a turbo but not sure if I will get the best bang for my buck.

[Immortal]

oh, Lord...
wait until it is really broken you nit-wit....

[hps4evr]

if you have the time, place, and money then an engine re-build and upgrade will be perfect. Jeff(gearhead) knows what the details of the stroker and head porting stuff. for the wheeling you do aaron i think hold off on the turbo or supercharger. rebuild and/or stroke the engine first. adding boost is not a cheap option, especially in kit form. i think the kits were hovering around 4-5ooo$ to start.
what year is your cherokee again?

[Waytec]

I have a 95 Cherokee.
I did not know the price on the turbos or SC. If they are that much forget it.  :)For Now

[Gearhead]

95 XJ , obd 1  right ?   ,  if so  , is a good thing.

Assuming the engine is stock and never been apart you're probably going to have the block bored +.030" (or more ) , due to milage / wear. The bores will be neither straight or round.   The crank will not be an issue , it gets ditched , the rods too , depending on whether you choose to go with custom pistons or not.

You will need a 4.2 donor to get a crank and rods. there are variations on these. 

There is a wealth of information to read on this subject , some good , some not , I did plenty of research before begining .

Don't be fooled into thinking this is cheap , any engine build , when done right and thoroughly is not cheap , there are a few additional steps / expenses when building a stroker , adding to the overall cost.

[Waytec]

I have been thinking about it. I am wondering if I should just pull it apart bore it, to true the cylinders and then put it back to gather with a high flow head and a more aggressive cam. Leave the bottom end alone, replacing what is needed. I don’t plan on going past 33’s for tiers.

[newfie]

Just throwing this out there
why not just buy a crate engine, you can get one for 4-5000$ out of the states can't ya?

just a question , was thinking of doing mine when it blows apart

[Gearhead]

I have been thinking about it. I am wondering if I should just pull it apart bore it, to true the cylinders and then put it back to gather with a high flow head and a more aggressive cam. Leave the bottom end alone, replacing what is needed. I don’t plan on going past 33’s for tiers.

Think about it , what kind of shape are your rod and main bearings ? , your oil pump ? , timing chain ? , cam bearings ? , to avoid inspecting any of this would be foolish after 300,000 km . Are the bearing journals still round or straight ?

Food for thought , my 88 came with a 4.2 , an engine that shares many design elements as the 4.0 l that replaces it , the 4.0 is based on the old 4.2 , with some tweaks to gain torque  / HP , fuel economy and extend the production life of the inline six. Once my 4.7 was built and ready to install , I pulled  into the shop and yanked the 4.2 , followed by a teardown / autopsy of sorts.  What I found was a surprise . This engine had 260,000 km on it , had what appeared to be healthy oil pressure , no abnormal sounds and was running as well as an 80's carbed could. As long as I have owned it,  it had regular maintenance and service.  The rod and main bearings had very little babbit left , mostly copper plating showing , the cam bearings were shot , a couple of them fell out of thier bores when I pulled the cam out . I had replaced the timing chain once and a few gaskets , other than that the engine was untouched. The oil pumps in these engines are known to have a service life of 150,000 miles .



When you are ready  we'll talk some more , I'm equipped to inspect , measure down to .0001" , and evaluate what you have .


Oh , if this engine has ever been overheated real bad  or swamped , there's potential for unseen issues that are not obvious till  , it comes apart for inspection.  Don't buy any hard parts till you know what size everything  is , only then can you make a shopping list. Believe it or not there are blocks  as delivered from the factory that can have more than one size of piston ! ,  mass produced variances are a reality in manufacturing , machining tolerances vary wildly too.

[Immortal]

WOW!! Good to know Gearhead...
I have a 97 XJ 4.0L with close to 400k on it (odometer says 390k, but bigger tires throws that off a bit.) The engine is still running strong, as far as I know. After reading that.... maybe not so much.

[Waytec]

Gearhead where would be a good place to start looking for engine parts. I mean everything for a worse case scenario. I need a ball park on prices. I am really thinking that I should tear this down and rebuild it. It has 300 000 plus and I don’t think it has ever been touched. I will be going to Mopac on Saturday because they are up the road from me and I like looking around in their. 

[Gearhead]

A suggestion , I've done this several times .....................

Find a core to rebuild , in the mean time you can still drive your vehicle. 

Tear down the core and inspect , make a plan based on the condition of your block , crank etc. .   When I do a rebuild , I buy all of my parts from the machine shop that is preparing my block n' stuff.  They supply the pistons rings , gaskets , oil pump , cam , lifters , timing chain / sprockets , pushrods , rocker arms and so on , in kit form  .    I do the assembly , they hot tank the block and head , check for cracks , bore the cylinders , align hone the main bearing bores , install the cam bearings and freeze plugs , size the rods , grind and polish the crank.  I do the disassembly and preliminary inspection , then drop off the parts needing machining , such as the block ,crank n'rods , cylinder head and so on . Any thing thats not useable goes in the garbage , the machine shop needn't see any of the the stuff that will be discarded ,  only the items that they will be working with .  They will draw up a work order and begin the process , at that time I advise them of the other parts I will be needing to finish up building the engine  and request that they be ordered. When the machining is done , the rest of the parts order should be there and ready for pick up at the same time .   

some prices..............

Hot tank block and head                                            $60
Bore 6 holes                                                                   $150
Deck block                                                                      $130
Resurface cylinder head                                            $75
Supply & Install cam bearings & frost plugs       $120
Align hone  main bearing saddles                          $185
Supply pistons                                                              $285
Arp rod bolts                                                                  $90
Rings                                                                                $105
Balance crank , rods , pistons ( stroker )               $300
Grind crank                                                                   $210
OIL pump                                                                        $114
Rocker arms                                                                    $84
Push rods                                                                          $48
Gaskets                                                                             $150
Rod bearings                                                                   $52
Main bearings                                                                $115





There's going to be some other expenses as well , water pump , hoses , thermostat , paint , doe's it need a harmonic balancer ? , tune up parts , how's the clutch ? , is the radiator  any good ? , and so on ...................... plan for addtional costs  and do not cheap out or overlook any thing that may contribute to early failure  or damage to your newly rebuilt  engine.

[Bnine]

Follow everything Jeff says.

Hesco is a good place to shop for some parts and get ideas on cost.

I recommend Keith Black for pistons if you go stroker. He does custom pin heights which allows you to retain your 4.0 rods. Makes a little more hp due to less angle applied to the roatating assembly.

Those pistons are 100$ a hole.

I'd recommend staying away from superchargers and turbo's at this time, unless you are willing to become a motor expert of your own.

[Gearhead]

An observant person   should notice , there are no prices or mention of cylinderhead work.  That would be an additional expense and varies  , .depending on what is done with the cylinder head.

I generally will not touch a cylinder head until it's been checked to see if it's straight , has been hot tanked and checked for cracks. A cracked head is of little use so no time is wasted messing with it till cleaned and inspected.