Jeep Head

[MountainDon]

My Cherokee has been driving me nuts. It's been overheating since we replaced the water pump that was leaking bad enough to cause an over-temperature situation. The radiator did have some clogging but that was resolved with a new all metal 2 row radiator. Basically everything new in the cooling system except the rad cap and that tested out okay. Still it would over heat when worked mildly, as in steeper than usual stretches of upgrade.

The oil was fine; looked like oil, not a milkshake. Coolant looked fine. When it overheated it would puke two or three quarts. Then sitting on the driveway running the engine, A/C on to create load, electric fan disconnected in an effort to see what's going on, I discovered bubbling, boiling in the coolant expansion / overflow bottle. Going like a percolator.

Some Jeeps have a head that gives trouble. All is usually fine until one has an over heating event. Then many of these heads develop small cracks. Sometimes that causes water in the oil and vice versa. sometimes it does not. Sometimes it percolates like mine did.


So I have a reman head, almost completed the install. I lost a socket someplace in the garage (I suppose) or someplace. I can not find it! Had to get a new one. It seems most auto parts stores don't carry it. Due to head bolt design it must be a 12 point socket, 13 MM. The only place around here that has that in stock is NAPA. I know because when I was tearing it down I ran into the issue and had to buy one. I bought the only one the local store had yesterday. Then I lost it. So they are bringing one over from the warehouse in ABQ. I'll have it this afternoon. Perhaps SnapOn has them too, maybe Matco, but I didn't try to chase them down.

It's maddening though because you need a deep socket as half the bolts have a threaded top stud portion. OK, that's what I bought. it's a 3/8" drive. I wanted a 1/2" but all they carried was this deep 13 MM 3/8" drive. I can use andapter so it's no problem, right? Wrong. The rear most stud on the drivers side is close to the bodywork. Try as I might there was no way to get a deep socket plus an adapter and the wrench in there. OK, no real problem, just use a 3/8" handle, right? Well half right. That's fine for disassembly. (Oh this stud is one of the ones with a stud extension on top, so a deep socket is a must.)

For assembly a torque wrench is required. Have to hit 110 ft lbs. My 3/8" drive torque wrench stops at 75 ft lbs. Everybody around here has 3/8 drives that measure inch lbs. Well NAPA has some nice 3/8" drive torque wrenches but they are $180 and up. Still cheaper than having a shop do the head, but I have no other use for it. Ah, NAPA has a 13 MM standard length socket in 1/2" drive; that would fit my torque wrench. That's cool! Oh, but wait, the std length socket won't be usable on that head bolt (with the threaded stud top).  ....  This is one of the few such head bolts that actually makes use of the upper threads. The engine ground strap attaches to it.

After reflection, I cut enough off the top of that bolt. Just enough to enable use of a std length socket. Then I found some thin nuts to use for securing the ground starp and the bracket that secures a wiring harness.

More than likely none of the Cherokee owners here will ever be changing their head with the engine in the vehicle. But be warned, you need the correct 13MM 12 point socket(s) to do the job. I have never seen this issue on any of the Jeep forums but I only go there once in a while so may have missed, not found it.

Anyhow the new socket should be here in an hour or so.  I just had to vent a little.

[peternap]

You have my sympathy Don!

I never had to change the head on my Cherokee but I did on my wagoneer I made a lot of tools.

If you really want something to make you cuss, buy your wife a Land Rover. You have to pull the manifold to change the spark plug wires and that's one of the simple maintenance items.

[mgramann]

The optimist in me is glad it cracked in a good spot!  Had it leaked into the oil, you could have been looking at bottom end damage!  (Of course, had that happened, you would have had an excuse to put a 4.2 crank in )

As annoying as it can be to work on the I-6s, especially near the firewall, they sure do go the distance.  My 98 cherokee just rolled over 200k on Tuesday.

[MountainDon]

The optimist in me is glad it cracked in a good spot! 

  and the sockets were on sale too!   

[UK4X4]

"You have to pull the manifold to change the spark plug wires and that's one of the simple maintenance items"

arr you'l be talking about the Disco 2 spark packs ! cunningly situated between the engine and the bulkhead

remove secondary air tube- dislocate three fingers and wrist and its easy !

well actually I lay on the engine on cardboard and used a bent pair of snipe nosed pliers !

But yes I was wondering why the F an engineer would ever put a standard maintenance item situated in such a ridiculus place ! hopefully TATA have fired him

[CjAl]

hopefully you didnt loose the socket in the cylender

[MountainDon]

hopefully you didnt loose the socket in the cylinder

   No, I checked there.   

I did find it on the floor where it had rolled up under the tire.  Now I have a spare. 

Head's on, manifolds are on, starting on rehanging the P/S, A/C, etc. etc. in the AM

[Don_P]

I cracked a 360 similarly it sounds like. With the radiator cap off, romping the gas caused an exhaust powered geyser

[CjAl]

i have a friend with a cherokee with a very similar problem right now.  after new water pump, thermostats, cap and radiator its still running warm while driving but not idling.

i may have to be the bearer of bad news once again.

[MountainDon]

If the coolant and oil show no contamination there is a test that will reveal the presence of the products of combustion in the coolant.   In my case I found I could induce bubbling/boiling by put a sheet of cardboard in front of the grill, disconnecting the electric fan, turning on the A/C and running the engine at 2500 RPM or so for a few minutes. The overflow tank would start bubbling/boiling.

[mgramann]

I saw something on TV awhile back that may help.  A spark plug modified with an air hose fitting can test this.  It will also check the condition of the rings and valves.  Each cylinder should be checked at TDC.  Upon being pressurized, if the coolant bubbles, it's a head gasket or head issue.  If air comes out of the crankcase oil fill, the cylinder rings are likely worn.  If air comes out of the throttle body, intake valves aren't seating correctly.  If air comes out of the exhaust, the exhaust valves are a problem.

[Tinga]

Makes me glad that I just picked the parts out and had our shop do it for us. 
We *DO* have alot of the reverse TORX bits, but I don't recall having any deep socket ones.

[MountainDon]

The lives!!!  Started right up. Test drive later.

I may grumble about the weird stuff I run into when doing mechanical work, but it beats paying the shop. Sort of funny, I did not begrudge them the cost of replacing the belt idler on the Honda... couple hundred bucks or so. But I was going to feel really bad if I forked over the cash for this job. It also helps that there was no time crunch to get it completed. ... I also replaced the fan shroud as it fractured into 4 pieces when I went to reinstall it. The plastic gets brittle after many hours of heat. The local dealer had one in stock so it must be fairly common.

[CjAl]

i am done buying new vehicles. i sold my 2010 dodge ram and i am sticking to my early 90's vehicles except for the 04 wrangler. i can rebuild them almost indefinatly and do it all myself. thats gold in the age of $100+/hr shop rates.

a friend of mine works at toyota as a tech. do you know you have to disassemble the entire front end of a prius to change the headlights? ya, thats good engineering

[UK4X4]

Since I was 17 I think I only ever paid a mechanic once- for a BMW engine rebuild after a catostrophic head gasket failure at about 125 mph

He 'repaired' it,  then it dropped a valve during the test drive....writing off another bunch of parts.

eventually got a second engine from france and swapped that in.

Still now when really I can afford to pay some one else I still tend to do things myself, it gets done right and I find tinkering enjoyable.

Things I wont touch are auto transmissions, and major engine repairs, even head gaskets these days on the V style engines can be a pain in the rear with so much electronics involved.

Loved working on my wrangler 6 cyl - simple robust engineering- good luck on the test later today !

[CjAl]

motors are what i prefer to build. auto transmissions are not too bad they are just intimidating, lots of parts to keep track of. i have rebuilt two but admit that my 220k mi suburban makes me cringe every time the tranny does something out of the ordinary.

[peternap]

motors are what i prefer to build. auto transmissions are not too bad they are just intimidating, lots of parts to keep track of. i have rebuilt two but admit that my 220k mi suburban makes me cringe every time the tranny does something out of the ordinary.

You should have a 95 Bronco. They made that transmission just to give me ulcers.

[MountainDon]

... I'd of probably put a couple of 300 grain hollow point 45's into it by now! 

It still overheats and bubbles/boiling occurs in the expansion/overflow tank, when working hard on an upgrade. *#&%@!!   

Tomorrow I'm leaving it at Quanz (one of the few places I have faith in) for their opinion and some testing. Then we're heading to the cabin for a few days in a borrowed F150 4x4. There's not much left to suspect and there's one I don't care to think about.

[CjAl]

thats not good.

[flyingvan]

Hey Don---this reminds me of our old Dodge Coronet 500 3-on-the-tree war wagon me and my brothers all learned to drive in.  It would idle fine but overheat with any demands put on it.  We tried advancing the timing and putting more expensive gas in, in case it was pre-detonating-- Dad tried everything to increase the coolant flow to no avail----it wasn't until he put in a more restrictive thermostat that impeded flow a bit that made it run cool again.....The coolant wasn't spending enough time in the radiator. 

[rick91351]

Radiator cap been pressure tested, thermostat also makes sense.   

[NM_Shooter]

That's weird. 

Any chance the impellor on the water pump is slipping on the inside of the pump?  What if you completely remove the thermostat?  Hmmm... hopefully Quanz will figure it out.  I usually don't use them because they seem to be a bit high priced.  But I don't mind paying more if they get it right the first time.

[CjAl]

you guys arent taking into account the pressurozed cooling system. that means compression from somewhere. if its not the gasket and not the head then it has to be the block. i have seen many small hairline cracks that were initially missed because they were so small but once it heated up it would expand. so hopefully they missed something in the head. bad head is bad but still better then a bad block

[OlJarhead]

Crap Don that sucks!  How many miles on the rig?

I solved my problem on my last trip by cleaning my K&N filter -- no joke! 

But I still have some O2 sensor problems or a bad catalytic converter (PO171 code I beleive)....

I carry a code reader everywhere I go so I can check the 'check engine' light if it comes on and since I'm out of work will be doing my own mechanicing now to.  First up will be replacing the rad and fan shroud and skid plate...then we'll see if she heats up under load.

Also I plan to replace the O2 sensors.

Anyway, again, I'm sorry to hear about the issues....can't imagine what might be the problem since you replaced everything!  One thing to check though is the dizzy (distributor).  Seems on older jeeps as they wear the dizzy can loosen up and cause timing issues.  There is a mod that can be done to resolve this, or a new (er) on can be installed.  If the dizzy causes the timing to advance a little too much, or to retard a little too much then it's possible to cause overheating -- so too can leanout caused by too much air and not enough fuel (clogged injectors or clogged fuel filter) -- might check those to.

[NM_Shooter]

BTW, the most likely socket in my collection to go run off with a measuring tape is 13mm too.  Something about that size just has a wild hair.