I have a suspected cracked head (2000 XJ, 75k on clock). Slow coolant leak, low oil pressure on idle (around 10PSI, but had a couple of check gauges lights recently when it went all together).

I've replaced oil sending unit, thermostat and fuel pump recently. Never overheats (runs between 200-210). I'm going to get pressure test done and have head inspected next week, but if it is a cracked head, can you recommend a good reconditioned engine supplier. I've found these guys:

http://www.rebuilt-jeep-engines.com/

Looks good, but trying to find cheapest (but still quality) option. Any help much appreciated.

 

Try autozone they have a 3 year unlimited mile warranty. Also you may just need a new head not an entire engine.

 

Just get a new cylinder head from Alabama Cylinder head

 

I am going to get it fully checked this week, just to see how much i need to replace. don't want to do more, or pay more than i need to, but been told the bearings have a bit of wear before.

If I just go for head, whats the approx cost of head and labour - not skiled enuogh to do myself...

 

The low oil pressure bothers me, though.

Few hundred, it depends on where you are and what the going rate typically is in your area.

 

that's why i am thinking it's going to need to be more than just the head. pressure is pretty low eh? and is that a sign of bad wearing on the bearings?

 

Typically.

 

What I find with pressure is typically 40 when I start up, holds there or just above
/below. After about 20 min driving may be down around 30. Idle is normally just on 10, but I have had 2 occasions in last month when it's dropped out complete in idle until I give her some gas and then settles on 10 again.

Coolant loss is from fill mark in bottle to right at bottom every 3 or 4 weeks...

 

Sounds very normal for a 2000 or 2001 4.0 to me. Yes, Im sure the bearings have been worn a bit. My own 2001 SilverStone Metallic Cherokees 4.0 is doing pretty good at 64,820 Hard driven miles, with no coolant loss, yet, and Hot idle low pressure of 25 psi. Moms 2001 Cherokee with 121,??? mile 4.0 starts out 40-45 psi cold, Hot idle lowest psi around 15-20. Co-workers 2001 13?,??? mile Cherokees 4.0 hot idle lowest of around 10-15 psi. Yes, it is worn, but still drivable, in my opinion. I would shop for a Good, rebuild, with out a core exchange, or build a 4.0, a Higher Compression 4.0 with .020 milled from the deck, and a .030 overbore. Thats what I did to my 99s 4.0 last year. Well, and Ported&Polished her Head for 24 Hours. Head Giver for 24Hrs.

 

When you say good rebuild, what are you talking about (sorry for my ignorance). as in engine? and if so, what's 'without core exchange'?

thanks for the reply..

 

so the head is cracked, and surprise surprise, it's between cylinder 3 & 4. the crack is very small, only shows up after a dye test with black light.

in light of what i posted earlier, if i don't rep;ace the long block (no money to do so at the moment), and maintain the XJ well - regular oil change etc and don't drive more than i usually do - which is about 40 miles a day, how long before i really have to change the engine, or is that an unanswerable question?

 

Well spec for this engine is 13PSI @ Hot Idle, 37(IIRC) and up above 1600 RPM. How long will it last? Unknown.

 

Agreed. It is impossible to determine how long the engine will last with coolant constantly in contact with the bearings. If you got a good deal on some really cheap oil (don't use expensive oil at this point!), and changed it more frequently, it might buy you some additional time.

If you can't afford a rebuild/reman engine at this time, how about scouring craigslist, salvage yards, want ads, etc. to find a used engine? Worth the time I think. I have had very good luck with buying/installing used engines. In 38 years of wrenching, I have only been burned once and have installed way more engines than I can even think about counting.

 

Thanks TJ.

The crack is apparently tiny - could only be seen with dye/black light, and I suspect most of the coolant is burning off before actually getting to bearings. Pressure is holding solid at what I said above. I will have a look at scrapyards and see what I can find as really cant afford to do much else right now (new baby...).

But if I can ask this - is it worth trying to replace just the head at this point, so to stop anymore coolant getting down to bearings as a temporary measure, or is that not going to really help? Oil pressure has been around the same for the last 4 months - it's not got any worse, and everything else seems to be fine - drives really well, no heat overheat issues at all. $$ is a real issue right now, but of course, I love my XJ, want her to run well, and need it to get around town...

 

My engine warning light is now on permanently and flashing intermittently. I've taking it to the shop tomorrow. I already know the head is cracked. I''ve been changing oil every 2000 miles, topping up coolant every week or so. I've noticed on the engine I can see a trace amount of coolant bubbling out (or at least I think it's coolant). At this point is the engine totaled or might I get away with just a new head?