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Time for a new engine.

P

Pat94xj94

NAXJA Forum User
Location
Camp Pendleton
Did 2 head gaskets on my 94 cherokee within 500 miles of each other. I didn't cheap out on them either. Got new head bolts, fel pro gaskets, and head refaced both times and I'm going to assume now that the block is screwed. The motor has 233k so its time for a new one. I have the majority of the tools but no place to work on it to swap the engine. My question is how much is a new 4.0 engine, which used 4.0 will fit a 94, and what are the prices for both? I got quoted 450 labor for a shop to do it and the best engine I've found is $1200 with 81k on it. What is your opinion on what I should do and prices?
 
What made you pull the head in the first place? A cracked head can be similar to a blown head gasket. Block problems are rare, piston slap and noisy lifters are more common. The 4.0's can go a LONG time without any major bottom end work. Mostly what they need is valve work and gaskets every 160,000-180,000. The bottom enIf you decide to go with replacing the engine, local areas can differ in prices but I wouldn't think a junkyard motor would cost more than $500.
 
i got the head inspected and they said it was fine. i bought the jeep from a dude who had a shop rebuild the engine. turns out the shop was garbage. I pulled the head in the first place due to coolant leaking out between the head and block next to the dip stick. it wasn't that bad but after I replaced it, it got worse. The oil before didnt show signs of a blown head but leaking from there it had to be the problem. Now the oil looks like straight coffee
 
So, tell me again, exactly why do you think the engine is shot?
 
the engine has already been rebuilt already and it has 233k. I've had overheating issues with it and the cooling system has just about been completely redone. Im by no means a master mechanic but I'm pretty handy, so I feel like i did a good job with the head gasket. I don't feel like paying a mechanic to fix the problem when i can drop a new one in for about a grand.
 
So you are going to replace the engine because of overheating issues?
 
Pat94xj94 said:
Now the oil looks like straight coffee
Click to expand...

OK, let me get this straight, you say you are getting coolant in the oil? Right?

In all my years, I have never seen coolant in the oil that didn't appear as a whiteish frothy mess, not straight (black) coffee.

Are you getting oil into the coolant? If so, what does your coolant look like?

Having the oil appear black isn't that uncommon and is related to getting the carbon in the engine mixed with the oil. Even if you put new oil in an old motor, within a day or so it usually looks quite dark.
 
Gar-head has been checked by a reputable machine shop
old_man- when i said coffee i didn't mean black. its like coffee with a lot of cream in it. i haven't had a chance to check the coolant. i will when i have time tomrrow

could i have just messed up the head gasket job? i cleaned off the head, didn't use gasket seal because the fel pro gasket said not to, refaced the head, and got new head bolts. Thanks for the replies guys
 
What can happen is that the heads pass a cold test but when heated they fail wide open. I think you should explain to a machine shop the problem and see what they tell you. The best machine shop I've ever used for problem stuff is Mark DeGroff in Northidge. He is legendary and would take the time to talk to a customer. This was about 10 years ago so I don't know if he's retired.

Also there is a 3-4 step sequence in torquing down the head starting in the middle and working out to the edges. Are you referencing the factory service manual?

If this is your first head gasket job then you may be doing something wrong without realizing it or explaining it to us.

Normally you make sure the block deck has no old gasket material on it. None. Then you put the gasket down right side up and then lay down the head. No sealers or sprays are used. Are you using the normal Fel Pro gasket? Or the MLM one?
 
Not trying to be an ass, just trying to be thorough and not have you waste time and money.

Ask the people who checked out the head if they magnafluxed it.

Personally I use the metal head gaskets and use coppercoat paint on the gasket before assembly.
 
old_man said:
Not trying to be an ass, just trying to be thorough and not have you waste time and money.

Ask the people who checked out the head if they magnafluxed it.

Personally I use the metal head gaskets and use coppercoat paint on the gasket before assembly.
Click to expand...

+1 on the Magnaflux, I have seen a machine shop guy look over a head & check it for flat then call it good, I told the guy he should seek employment as a shoemaker!
 
md21722- I did all of those things you are talking about, torqued everything in sequence all to 110lbs and the front right bolt to 100lbs.

oldman- I wasn't worried for a minute you were being an ass. I appreciate your time in trying to help me.

When the engine was rebuilt the head was replaced with a new one.
 
How severely has this engine been overheated? Coolant in the oil tells me a cracked head or cracked block if the gasket has been replaced a few times.

Where did the shop source this "new" cylinder head? I know guys with 0331 head problems have had issues where they get reman'd engines that still have the crack prone head and the head fails a second time.

I second the idea of a good used engine. You can find them on Craigslist for a couple hundred bucks, often they are still in the Jeep and you can hear them run.
 
I got a question can a 99 XJ 4.0 be used in a 1992 XJ? I know the block are essentially the same, I thought the cylinder head may some difference for a temp sensor or something.

Ours has close to 300k on the original motor, I found a 99 motor near by and thought of but it a building a replacement before we need it.
 
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