Raiderred

Hi All,

Thanks in advance for any input given here. I have a 1999 Jeep Cherokee XJ Sport, all stock with no mods 138K miles 4.0 inline 6. We recently had an overheating issue where the lower radiator hose blew. I've been told during the fix of that issue that they found water/coolant in the cylinder case so the head appears to be cracked. They did a block test because they smelled heavy gas under the hood etc. My mechanic has made a recommendation to install a used engine rather than fix the head at a cost of $4K and the cracked head cost would be $1600. One reason for this recommendation is there is also a large amount of rust build up coming form the engine block it appears. I've only owned the Jeep for 8 months and we noticed this right after purchase and put a new radiator on and flushed the system several times. We are still seeing large amounts of rust and probably what caused a possible blockage, causing the engine to overheat and hose to blow etc. He thinks the previous owner ran nothing but water through it for some time causing rust to form. My mechanic also recently went through this same scenario with another customer on a similar Jeep and they retooled the head rather than the engine swap. He said the block couldn't handle the new tooled head and cracked. This is part of the reason for his recommendation on the new/used engine as well. Any thoughts here? Is there that much risk on retooling a head on and old block? Is the rust issue something that could really be the problem and something I can only correct through the engine swap? What is the reliability factor of installing a used engine if done right?

Last, I'll add that i do trust my mechanic and he has amazing reviews locally. The Jeep itself is structurally/ electronically in very good shape for the age.

Thanks much,

Raiderred

Randy Bobani

The block couldn't handle the "new tooled head" and cracked? Are you out of your mind? That's the dumbest sh== ever. What is retooling anyway?

Do you even know where the head is cracked? If cracked at all? Has the head even been removed and inspected? Magnafluxed? It is almost impossible to see a crack in these heads without magnaflux. Why don't you clean the coolant passages? Get some tube brushes, chimney brushes, evapo-rust and some damn elbow grease.

jpz

I agree with Randy. The block not being able to handle a retooled head has to be the dumbest thing I have ever heard. It literally makes zero sense.

My guess is your mechanic will get more money, or finds it easier to change the engine vs the head and that is the basis behind his Doomsday prophecy.

DustyWagoneer

I'll pile on with RB.
WTF!!

You really have only three choices here.
A - Find a new mechanic that is honest.
B - Learn to work on it yourself.
C - Buy a newer vehicle that you can take to a mechanic, because most mechanics hate working on Jeeps.

exasemech

There are some real crooks out there......

The only thing I would add is:

1) a 99 with 130 k on it is a find. 99's are nice

2 by the sounds of it you don't even really know if the head is cracked. IF,BIG IF, given the crook factor , there was coolant in the oil it could be just a head gasket.
3) by the sounds of things likely the hose failed because it was 20 yrs old..

I would concur with the 3 options above

Raiderred

Much appreciate the feedback! I agree on the "retooled" comment. I only have a basic understanding of DIY maintenance, I'm definitely not a knowledgeable mechanic of any sort yet I found that comment odd. He basically feels the old block can't handle the pressure of a new head. I believe his direction is coming from his experience with the previous XJ owner he did the new head on, which may be telling here. He may not be the right guy for the job! Very good points on confirming the head crack, which hasn't really been done outside of a block test and visual inspection of the cylinders. His point is it's $400 to prove the crack then $1600 for the new head, so you're $2K into something that may lead to blowing the block in the end, so why not just do the engine swap. Anyway, again, I really do appreciate the feedback and I believe I'm going to get a second opinion.

exasemech

I'm still trying to figure out what the"block test" was. 🤔

Raiderred

New to me as well. It’s evidently a process to check for combustion gas in the cooling system. If you fail that test you’ve got a blown gasket, cracked head or cracked block. My 99 failed that test. Still doesn’t confirm the actual real problem, just that there is one which everyone has pointed to here. I also don’t think I want to deal with a mechanic that’s going to give me a very expensive solution without knowing the specific issue and confirming.

dmoe69

I've seen an XJ engine that has waterways caked with orange mud. If that's you - you either got to get it out, if you can, or I wouldn't put money into that engine. I'm wondering if maybe what your mechanic is telling you isn't getting translated as originally spoken (cylinder case...crank case?) Perhaps the mechanic is saying the piston rings might fail after the installation of a new head. If he's doing a combustion leak test, then he should be able to tell you if you have a crack, but it won't narrow it down to the head.

lawsoncl

The rub is that you need to pull the head to determine the cause. Retooling isn't the right word, imo. Resurfacing, re-machining, or decking is done to fix a warped head. They don't take off enough that it would affect the compression or stress the block. I'd guess the mechanic had a head resurfaced when the problem was really a cracked head or bad block to begin with. Keep in mind that a blown head gasket can pressurize the coolant system enough to blow off a marginal hose, so you could actually have cause and effect backwards.

Given the labor cost of pulling the head, determining and repairing the problem, it very well could be cheaper to just swap in a known good used engine. Even if it's just an obviously bad head gasket, I'd have the head inspected and resurfaced if needed.

Sig220

I picked up a 96 XJ for chump change that supposedly had a blown head gasket. I bought it thinking that if it were just a head gasket I would be extremely lucky! I pulled the head and found that the #1 piston had a hole about the size of a 50 cent piece and the edge of #3 piston appeared to have melted. Yep there was coolant in the oil when I bought it. Figure I would do a poor man's rebuild ( a inframe rebuild, replacing pistons, bearings, oil pump, etc) if the cylinders were not galled. At first it seemed like the #3 would be the likely damaged one but after I removed the pistons I found that aluminum from the #3 piston had been deposited on the steel cylinder walls and once that was removed it wad good to go.

So, I brought the head to a machine shop to check it for cracks, if it passed, they would machine the head and after that they would do a valve job on it and replace the valve guides. According to the machine shop (been in business for 25+ years) they had never seen a block that warped on a Jeep, always the head. So I am going to "redneck" check the engine deck with a straight edge and a feeler gauge and roll the dice!

I am now awaiting word on the how the head condition is before I buy any other parts. If it is trashed, I will buy a used block with a good head as heads alone are high. I keep my fingers crossed when I think about it while I wait on the phone call.

My advice is to find out what shape the engine is in, is it a blown head gasket, a warped head or is it cracked. Once you know what the problem is you can address it and not throw the baby out with the bath water! The most I will have in the head if it passes each step is 3 to $400 in it. I could have bought a reman engine for about $2500, but found a block for sale with a new head for less then $500. I will do all my own labor which is a big relief to my pocketbook. If my head is a piece of crap, I doubt my bill will be $200 for the test they did run.

Good luck to ya!

Sig220

Raidered, what happened to your SJ? Or did you abandon it and move on to something less trouble?

To close out my story, my head was determined to be cracked but the cost was $0 for that determination. I then purchased a used engine with a new head, swapped over my intake and exhaust, oil pan and other tidbits and installed it. Got it running and am happy with it. Cost me $400 for the engine. Since I have replaced the seats, and repaired the front end (damaged in a collision?), installed a trailer hitch and will add my home welded bumper this week! On a recently completed hunting trip, it got 18.6mpg combined highway/woods driving. I am happy.

tech

Ok I'm a mechanic , the block test will only show if there is exhaust getting in the cooling system and that is all , my guess would be that the head gasket is bad because of all the rust and for them saying that the block could not handle the retooled head that is a good line , if the block could not handle the head then it would loose the rings and start burning oil and that just almost doesn't happen with the mileage you have , the 4.0 engine is a very tough motor and will last a long time . I would remove the head and get it checked , when the head is off the block cooling passages can be cleaned and a new radiator can be put in the flush the heater core that way you will have a clean cooling system

User Unknown

I recently pulled my head and saw that almost all of my coolant passages were blocked. This seems to be common from many other owners from the forum threads and YT videos I’ve watched. I bet it’s from lack of performing coolant maintenance against the manufacturer recommendations. It’s not a bad thing to first spill and fill all new fluids for a new-to-you ride but it may be a lost cause if the damage was already done beginning with the first owner decades ago. Four grand is a lot but did I miss something? Is that a freshly overhauled motor or a used one?

Randy Bobani

None of your cooling passages are blocked. This is a common misconception. Look at the head gasket. The only passages that matter are the two cylinder head feeds in the very rear of block, the front water return port and the combustion chamber feed holes.