1991Jeep_Man

I had been considering getting a new rebuilt engine for my XJ. However, at only 200k miles, I dont think I should have to go that far. What I was actually thinking of doing is pulling the head and either having it refurbed or just buying a new one. So, my questions are these:

1) I imagine if you compared the durability of the two, the block and its components (pistons, rods, crank) are a lot more durable than the head and its components. Is this true?

2) What do you all think of this idea?

3) Is there any negative effect of putting a new head on an old engine?

1991Jeep_Man

And if someone has an opinion on one makers head over anothers, please share.

dweezer

I don't know what is stonger but my cherokee has 318,000 miles on it and there is more play in the main bearings on the crank than anything else. The only negative affect I can think, of right off hand, is that you might have a slight increase is compression, when installing a new head, and that could cause your piston rings to go out a little faster.

mike albo

my 87 has over 260,000 on it,still nice and tight

fishtaconc

Do a compression test, pull the oil pan and pull a coulple rod caps ,same for the mains if there is any sign that they dont look good put new ones in and do a rear main whille seal you got it apart regardless, as for the head if you can be without your ride take it off take it to a machine shop have a head job done most shops charge about $225-300 for this any reman head will cost at least $400 you have to take it off anyways to get your core back. My $.02

1991Jeep_Man

Well, the reason I was considering this is because I have been hearing this wierd sound. The Jeep still runs like a champ; great take off and acceleration. At worst tranny jerks a bit sometimes. I have a crakced header, and here lately I have been hearing this 'put put put' at random points at idle... and it's totally random and only lasts in short periods. And it usually goes away if I tap the gas a bit (in park or driving) and it goes back to that usualy desiel running sound. I figured something is up with the valves or something.

mike albo

they do make alot of lifter noise,that tic tic tic noise,also you might be hearing the injectors pulseing to,tic tic tic also

1991Jeep_Man

so if its running strong and not leaking, im pretty good?

hood81

as far as for new head or a new motor i started doing a new head when i warped mine,and when i got in to the motor it end ed up being a full rebuild(200,000) rods,piston,rings,new head(was cheaper over all) i did check around. id say if its running fine leave it unless its ur dd like mine.do what u can afford.

Caish

Word of warning.
I never put a head on a high mileage engine. Reason is its hard on the rest of the engine. More times than not I've seen engines go to using oil and smoking from the added stain.

If the engine broke I don't fix it. There is such a thing as PM on the engine, thats limited to a timing chain water pump, maybe bearings and oil pump. But never a head on a high mileage engine.

mike albo

yep

fishtaconc

4.0s came with factory installed valve noise

1991Jeep_Man

lol, well I figure if it's running well and just making noise I'm ok. Gonna get a new rad this wed and hopefully 'fix' my cooling problem.. considering you never really 'fix' anything on an XJ; you just delay it lol

TheJerm

I have 210K and put a head on it 20K ago. Runs like a champ, doeant leak or burn anything and i get 20mpg every tank.

If the motor has good compression and doesnt smoke too bad then just keep driving it, if it throws in the towel, stroke it

edit: i had like 2 or 3" of sludge covering my rockers but had to make a trip to school in a week so i just r/r the head

4jeepers

You just might blow the rings off the pistons by doing that, besides you will only be buying some more time before having to do the bottom end anyhow. I would either wait to do the whole engine or rebuild it now. Just a suggestion