Jeep Head

[peternap]

I don't know if you have emissions tests Don, but if you don't...rod out the catalytic converter.

I second the idea of leaving the thermostat out. I do that anyway on my 4WD's (Not the land rover).

[Gary O]

 Dang, Don, take all those new parts and wrap another Jeep around 'em.

My '99 Wrangler has been giving me fits.
Intermittent problem.
For months, every 2-3 tanks of gas it'd loose power, just chug, cough, spit under load, then snap out of it.
All gauges were dead nuts normal, no 'check engine' lights on, nuthin'.
Thought it might be the fuel pump, or hopefully fuel filter.....nada.
This morning, she sputtered again,

But

The 'check engine' light went on........finally!
Something to register on the ODB.
The 02 sensor
$50
20 minutes
Runs like a top
Hand cleaner
Dinner
Fat, dumb, and happy again
Now, after reading about your woes, if she ever overheats, gonna take the ol' gal on a rock climb...one way.

[MountainDon]

Peter, we live a few miles outside the nearest "emissions test area". However for years there has been talk about including us as there are loads of folks who drive from here on the high mesa to the polluted river valley that consists of a large portion of ABQ which is the reason there is an emissions test area. Anyhow that is not a problem as the cat passed the restriction test with flying colors.


Thermostat vs no thermostat. Well on the trip up to the cabin with the drilled stat, the Jeep pverheated more or less right where I anticipated. Once at the cabin, with 2 more stops for dribbling cool water over the rad exterior, I dumped the load of water in the cistern and let the engine cool. I decided to remove the thermostat for the trip back. I don't view this as a solution, just a crutch and a sop to my curiosity. The trip home showed some lower than usual temperatures as it is mostly downhill and the 830 lbs of water was left behind. Tonight though I pulled the #3 plug again. Instead of the light brown it has been it was more black. Not sure if I'll try a loaded trip with the stat removed?     I've already hung too many new parts.  Scary thing is that a search for overheating XJ Cherokees in late model years (95 thru 01 more or less) brings up lots of guys with the same problem. Some threads seem to have been resolved with new rads, fan clutches, etc. But there are a number that simply stop with no stated resolution.  I think for some reason the engine is producing more heat than it used to. It's very discouraging when after so much work and so many new parts that the XJ can not perform the same tasks it did for years. There is a hidden reason; well hidden. Normal about town driving and highway travel with no heavy loads can be done with little fuss. At this point I am weary of chasing the solution. There are a couple of local recent year Tacomas that are looking more and more attractive.

Looking for a RR X-ing to stall out on.... 

[rick91351]

Speaking from experience!  Do the railroaders a favor and don't do that!   

I am sort of wondering alcoholic - gas be a problem?

Long time ago we had a F-600 it started over heating we never found out why.  We peddled it off and they put a new short block in and is running today.  Can the block get garbaged up and not allow for proper circulation?  After the F-600 I have alway wondered that.   

[OlJarhead]

I'd seriously consider the oil pump screen Don.  If it's getting restricted, which can happen with age then it won't be able to provide the cooling that oil provides.  Oil actually does more to cool the engine then water/coolant does though most wouldn't believe that.

Just imagine what cools the hottest places in the block (friction heat in the bearings).  It's the oil.  Which must be circulated well and efficiently and in enough volume to carry away the heat while lubricating the parts.

I haven't ever dropped the pan on an XJ so I don't know how tough it would be to drop the pan and remove the screen and clean it of sludge and crap but I'm willing to bet it would make a difference.

One way to check though would be to do this:  Buy SLICK50, do an engine oil change and add the SLICK50...run your test again.

If it runs cooler with the SLICK50 when you're under a load I'll lay dollars to donuts it's the oil screen in the pan that's clogging up and reducing flow since the SLICK50 will be providing more friction reduction then normal the oil will be better able to cope with the temps.

I once drove a Ford Escort across the US pulling an MGBGT.  When I first tried doing this (leaving Camp LaJuene after getting out of the Corps) the Escort just couldn't seem to do it.  It would cut out and stutter and fail every time I tried to get up to speed in 4th gear.  I changed the oil and remembering something my Dad told me from his sportscar racing days I added a quart of SLICK50 and whaddya know the dang stuff worked!  I pulled that B across the USA at 70mph no problem!  Never got hot either.

I left the B at my cousins in Eugene and went to work in Portland....some 10,000 miles after adding the SLICK50 and changing the oil etc I went back to get the car and pull it the 200 miles to Portland...and I couldn't do it!  No way was that Escort going to pull that B again...stunned I unhooked and had to have my wife drive the Escort while I drove the B (with an open header) the rest of the way.

Got one heck of a head ache but loved the ride!

Anyway, something to try right?

[peternap]

All I can say Don...is that you have far more patience than I do!

[diyfrank]

I'd seriously consider the oil pump screen Don.  If it's getting restricted, which can happen with age then it won't be able to provide the cooling that oil provides.  Oil actually does more to cool the engine then water/coolant does though most wouldn't believe that.

Just imagine what cools the hottest places in the block (friction heat in the bearings).  It's the oil.  Which must be circulated well and efficiently and in enough volume to carry away the heat while lubricating the parts.

I haven't ever dropped the pan on an XJ so I don't know how tough it would be to drop the pan and remove the screen and clean it of sludge and crap but I'm willing to bet it would make a difference.

One way to check though would be to do this:  Buy SLICK50, do an engine oil change and add the SLICK50...run your test again.


If it runs cooler with the SLICK50 when you're under a load I'll lay dollars to donuts it's the oil screen in the pan that's clogging up and reducing flow since the SLICK50 will be providing more friction reduction then normal the oil will be better able to cope with the temps.

I once drove a Ford Escort across the US pulling an MGBGT.  When I first tried doing this (leaving Camp LaJuene after getting out of the Corps) the Escort just couldn't seem to do it.  It would cut out and stutter and fail every time I tried to get up to speed in 4th gear.  I changed the oil and remembering something my Dad told me from his sportscar racing days I added a quart of SLICK50 and whaddya know the dang stuff worked!  I pulled that B across the USA at 70mph no problem!  Never got hot either.

I left the B at my cousins in Eugene and went to work in Portland....some 10,000 miles after adding the SLICK50 and changing the oil etc I went back to get the car and pull it the 200 miles to Portland...and I couldn't do it!  No way was that Escort going to pull that B again...stunned I unhooked and had to have my wife drive the Escort while I drove the B (with an open header) the rest of the way.

Got one heck of a head ache but loved the ride!

Anyway, something to try right?

I haven't seen much sludge around pick up screens unless the engine was badly neglected and it would have sludge through out the engine. If the valve cover was fairly clean it most likely will have a fairly clean pan and screen.

[MountainDon]

I know the oil does much of the cooling. But I believe as diyfrank said, there would be traces of crud eldewhere too. The valve cover inside and the head top were pristine looking. Not a trace of any deposits or crud so I really doubt the plugged screen theory.  Oil pressure reads good so there is flow. Oil filter reads okay temperature wise when the cooling system goes boinkers.


Rick I have been wondering the same thing... some loss of coolant flow through the block or a loss of ability to transfer heat from the iron to the coolant. But I draw the line at pulling the block. And even though I had little faith in it I tried a bottle of water wetter by Redline. Snake oil.


(and just kidding about the RRX. Decades ago in a blizzard back home I saw a car abandoned on the RRX. Always wondered if it was intemtional or what. Train never did hit the car.

[MountainDon]

Peter, I guess I do have some patience, but it's not inexhaustible. And I have said a few blue words.  This started out as a simple problem. Then it became a challenge. Now it seems to have turned into a gamble; "You got to know when to hold 'em, know when to fold 'em." 

[Tinga]

Might be time for a new head?? Some of the older 4.0 heads would get hairline cracks in 'em. Supposedly the 2000+ heads stamped TUPY were better.


Course if you were pulling the head, might as well spring for a rebuild while she's down..

[MountainDon]

It's got a newly remanufactured head with the "good" casting number 0630, not a 0331 which is susceptible to cracking between #3 and #4. Thanks for the input.


FWIW and FYI, late '99's can have the 0331 head, 96 thru earlier 99 have the the 0630.

[NM_Shooter]

Don, do both heads read the same temp with the IR Gun?  What about the exhaust manifolds?

Measure the radiator inlet and outlet temps too.  Check the differential... too bad you don't have another jeep to compare it to.

It was mentioned before.. but I wonder how it might be possible to check the fuel mixture.   

Has your fuel economy changed at all?

[MountainDon]

It's an inline   

There is a temperature drop from radiator in to out. I forget the numbers but Quanz, Moneysworth and Walton all measured and state it's fine (when it's sitting there.)

It uses pretty much the same amount of fuel for a trip to and from the cabin as always. That's not a very accurate measure.  An old meter I have from the EFI CJ days indicates the mixture is within allowable limts. Quanz also ran a probe and said it was okay. Plus the OBD is clean as a whistle.




Missed out on one Tacoma TRD today   but there's another I'll be checking on tomorrow. A little older than my ideal but then it is also cheaper. And it has the factory tow package = 6500 lbs tail. 


In the meantime I may rig the chemical sprayer I used to use as a misting, evaporative cooler for my personal comfort (don't worry it was brand new, never saw any pesticides, etc.)  in the old CJ as a misting cooler for the XJ radiator for a trip to the cabin.

[Huge29]

Don,
What a frustrating experience!  First of all, you need to get a better tool set; I just have a $300 Crescent set that is about a 275 piece set and I have a 12 pt 13mm in 1/4 and 3/8, oh, but none in deep 12 pt....Sounds like a good excuse to upgrade!
I don't understand your concern with removing the thermostat; there is nothing to possibly be damaged.  Their original function was only to provide heat to the cab, but in recent years has been a way to keep emissions lower by always having the engine temp hotter, but running without one for a short time won't damage anything, just take longer to heat up. 
On the oil pickup screen idea, hanging on to this as the only thing I can see as plausible, it could be dirty/clogged while there is no sign elsewhere of crud as something may have possibly come down the filler, unlikely but possible, into the case with as goofy as Jiffy Lube techs are.
You can't sell it; you need to hang on to it just to give us closure on this.  Can you feel the flow through the hose?  Does the IR gun show much cooler temps on the lower hose vs top (signifying flow)? 
Before I say my next line, I have a Dodge with 140k miles with only a water pump and a new ignition cylinder in 8 years of ownership, pretty dang good vehicle, but in my 10 or so years of working auto parts the Chrysler stuff had by far the most number of people swearing them off to never own one again...I am sure that is all much better now that Obama and the UAW are principle shareholders, I can't think of anyone better than the fox to guard the hen house!

[OlJarhead]

Have you tested the T-Stat?  Boil tested it?  Or did you replace?

http://www.summitracing.com/parts/BRA-1747/
Some say this is the way to solve the problem.  High volume/flow water pump. Some claim it will keep the 4.0 running 195 all day long in heavy conditions -- folks that had overheating issues previously like yours.

http://www.lunghd.com/Tech_Articles/Cooling/BurpAirMod.htm
Some say that it's often air bubbles caught in the head that cause the problem.  Have you burped the system?

I know the feeling on thinking about selling.  I was seriously considering a Ruby a few months back but I'm glad I held off in the end because the XJ is running well today and I have a truck for cabin trips where I need to tow

[peternap]

Well Don....

I'm still thinking it's a simple problem. It's a simple engine and I swear mine is probably still chugging along or the fellow I sold it to.

The only suggestion (and you've done it on the way back) is pull the thermostat out, don't worry about the blackened plug (I always go up one heat range or so on the plugs after I take the Tstat out)....and see if it overheats with a load like it did before.

That will at least narrow it down if you don't want to leave the thermostat out.

[MountainDon]

The thermostat opens. Starting from cold I can watch the gauge climb and then tick back a notch. This coincides with the top rad hose getting hot all of a sudden, followed by the radiator heating up. The 'stat is removed at present, and I'll see what happens. I can already see it runs much colder about town on the typical short trips here. The computer doesn't like it as seen by the indication of a rich mixture. Maybe I'm being stubborn but it ran perfectly well for the 11+ years we've owned it. Until now. With all the new parts it should run the way the factory designed it.

Flowkooler water pumps are great for slow crawling. That is where they shine. Flowkooler themselves states that the flow is much greater at idle rpm's. By the time engine speed rises to 3500 rpm's the flow has slowed back to normal specs. I don't know how that is done, but that's what they say. "At idle our pumps pump more than twice other pumps and we outflow "performance" pumps by 20%.  At 3,500 rpms, the gallons per minute flow rates level off to standard flow rates. " My issues are happening at the higher rpm's; 3000+ when it's working hard. I'm usually running 3000 rpm;s up the approach to the high point. After enough of that the gauge jumps to hot as the alarm sounds. Water flow from a Flowkooler is pretty much in the factory pump range at those speeds.  Hesco also has a HD pump; I'm not sure of it's flow rates, but it even more money.


Back to the thermostat and burping. I used to loosen the top bolt on the t-stat housing when refilling the system. I could hear a pffft- pffft as air escaped. Since trying the hole drilled in the stat trick loosening the bolt only gets fluid. The hole does pass the air. There are some stats available with a factory made venting hole.  FYI, I usually work on cooling systems on the section of my driveway that permits parking with a distinct nose high tilt. Ideal for assisting in burping through the front end. Some 4.0's have the sensor fitting in the head at the rear. Mine does not; it is factory mounted in the t-stat housing at the front.

It's never knocked or pinged. Never seen any indications of pre -ignition from plug readings, ever. Been looking for that now but, nothing. I pulled the distributor a while back and it checks out on a test bench. Followed the factory installation from the factory service manual. The ECM does all the work after that.


So yes I agree that the solution might be a simple one, but a simple one that is very elusive. Right now it's a lot like a girl friend or wife who has let you down, cheated on you, stolen some cash or whatever. I have lost my trust, my faith. Unlike a girl friend or wife the XJ is an inanimate object; it can not love me back.  I have no brand loyalty. I know, "Jeepers" will all gasp collectively at that blasphemy. But really, it is just a machine. I've owned over a dozen different brands of automotive machines in my lifetime, some more than once. There are very few I truly miss for one reason or another.

[MountainDon]

'06 Toyota Tacoma TRD Off Road package (includes locking rear diff, skid plates) and the factory towing package.

[rick91351]

To pretty to take four wheelin' or even to the cabin 

[peternap]

To pretty to take four wheelin' or even to the cabin 

Yep!

I wonder what the difference in gas mileage will be. I think it was you Rick, that commented about it getting to be a major expense. Me too. Round trip about $60.00 now.

[MountainDon]

FWIW, the EPA figures for the Tacoma is 1 better on the combined and the highway side, 2 better on in town.     Jeep highway 19 and Tacoma highway 20.  The trip to CA in early June returned an average overall of 18.9; maximum highway speed about 65 mph.  The Jeep weighs more than the average XJ  one because of the bumpers, tire rack, skidplates, larger tires and so on. (gearing change corrects to be very close to stock as far as engine rpm's per mile.  I've talked with one Tacoma owner who has a shell on the bed like ours and he says he gained nearly 2 mpg when he added that.  So we'll see.

[rick91351]

The shell did help my old 78 F150.

[MountainDon]

To pretty to take four wheelin' or even to the cabin

Not as pristine as the first impression.

[peternap]

Not as pristine as the first impression.

If you're saying that's not pristine Don...I'd best not show any pictures of my Bronco.

[MountainDon]

Now I have the dilemma of what to do with the XJ. It's not right to knowingly offer it for sale without mentioning the issues it's having. Now that I have wheels that work again perhaps I'll have to pursue a solution a little longer. Or accept bottom dollar for a vehicle with known problems.