fatfartenson

Approaching 180k on my 01 XJ and the only thing I've been having trouble with is the wretched cooling system.

First started having some problems a year ago, noticed a leak, brought it in to the local shop. Things ran great for a while then the reservoir was empty out of nowhere. Didn't have any problems with the temperature however so I said screw it and drove on for another few months. Engine finally overheated one day. Dad and I ripped through it, replaced a few lines, and the water pump. Unfortunately I don't think we changed out the thermostat (can't remember).

Things were good for a while but the reserve tank started disappearing again. Overheated a few more times. I was in a pinch once and had to run a lot of water through the system. Everything must have froze overnight. Went to drive it the next day and there was an explosion of coolant/water/steam all over my hood after a few minutes in.

Limped it to the shop expecting the worst, a blown head. According to them the head was fine however, and they just replaced the radiator, flushed the coolant system.

got it back and it ran great for a few weeks. Reserve tank than disappeared all of the sudden. Been driving it empty for the past few weeks because I'm fed up with spewing propylene glycol all over the environment.

No problems with overheating but I have no idea how much coolant is actually in there. The engine always smells after use. A few times I spotted green stains on the snow where I've parked. But I cannot find the leak. Honestly, I haven't looked too hard though cause it's -5 where I'm at and I have no garage atm.

I put some coolant directly in the radiator cap today. When I opened it there was actually some fluid in there. In the past it's been bone dry. I was able to get about a half gallon of water/coolant mix in there.

I thought maybe it was leaking out of the reserve tank somehow or even the line which leads to the cap, which is why I put it directly in the cap this time, but that seems unlikely.

The car puts out heat on the inside, but not much. It takes about 20 minutes for the car to get up to a comfortable temp.

tjwalker

You gotta get a solid accurate diagnosis on this.

And that would involve both getting the vehicle up on a hoist and performing a thorough inspection for a leak. A cooling system pressure test would also help with this.

And with all of the overheating issues you have, and the possibility that the shop might have missed a cracked head, a cracked head is still an absolute possibility. Looking through the oil fill hole with a good light can sometimes (not always) show a crack if one is there with antifreeze seeping through the crack. Testing the coolant for the presence of hydrocarbons (block test) is another test. As is a cylinder leakdown test. A compression test is not an accurate test for a cracked 0331 head.

Good luck and keep us updated!

djb383

Sure glad tj post 2nd.......that gave me a chance to count to 100. LOL

fatfartenson

Thanks for the reply. So if the oil and coolant are mixing, then it's safe to say the head is cracked?

If it's as simple as testing the coolant for traces of oil, I can probably figure out a way to do that. I'm an amateur chemist.

jake7

Yes. Search 0331 heads. 2000-2001 have this issue.

Klutch

I just went through the cracked cylinder head issue. I was losing coolant and went to check the top of the head as tjwalker suggested above. When I removed the oil filler cap, it was milky on the bottom. I knew then it was the dreaded cracked head. Shining a light into the oil filler hole while the engine was running confirmed it. I could see coolant seeping into the top of the head.


FYI, my oil was not milky, but the level did go up. Thus, the oil had coolant in it, but not enough to make it appear milky. As I said above, the bottom of the oil filler cap was milky and, when I pulled the valve cover, the top inside of it was covered in milky oil.

Kalali

This may sound harsh or premature but you've been driving your Jeep with a cracked cylinder head for several months now and your engine is probably marginal at best. In fact, the "smell" you referred to earlier, is the smell of an engine being driven while overheating. And to make things worse, you stopped adding coolant or water to avoid getting coolant spewing out which explains long duration warm up and low heat. The last and final measurement is your oil pressure at hot idle. But then again with all the coolant in your oil, the oil pressure might be deceiving. Sorry but you should have caught this much earlier in order to be able to save your engine.

fatfartenson

How do I check the oil filler hole while the engine is running?

fatfartenson

Thanks for the honesty. If the engine is still overheating then why does the temperature gauge always check out ok? How do we know the engine is terminal? It seems to run the same as I did when I bought it with 140k - same meaning great.

Klutch

- Make sure the cooling system it topped off with coolant

- Install the radiator cap, start the engine and let it warm up to develop pressure in the cooling system

- Remove the oil filler cap, then very carefully reach over the engine (from the side to avoid belts and pulleys) with a very bright, portable light

- Shine the light into the oil filler hole and look for coolant weeping up into the top of the cylinder head

Did you check the oil filler cap for milky residue? Also, when I checked my engine, some steam came rolling out of the oil filler hole when I removed the cap; yet another sign of a cracked head.

fatfartenson

Ok thanks I'll do that. I didn't think you could take the fill cap off while the engine was running. Always thought it was under pressure

fatfartenson

Another thing I perhaps ought to mention, often times when I'm driving I will hear a whistling noise, similar to the sound a hot teakettle makes, though not as loud. It's as recent as all my coolant problems, so I'm assuming it's related.

johnfkellogg

2000 XJ Sport 4 door 4.0 fuel injection 91,000 miles:
engine heat sink problem after stopping/restarting at running temperature.

Restarting warm/hot engine on a too consistent basis results in vapor lock type hard starting/running (dieseling as if lack of fuel ... possible fuel boil off) requiring pumping gas pedal until return to smooth running engine with plenty of power. It seems like after shutdown the engine compartment overheats (it becomes so hot acting like a heat sink or I have an internal engine hot spot). When turning the key to restart I notice the temperature has climbed to above 210 to 220+. Please note engine consistently runs within temperature range (Below 210); thermostat opens at temperature, very rarely runs higher than normal temperature readings (summer in AZ while on RED trails) and I do not experience the above issue while running -- only after shut down.

What I have done:
Paid way too much for Jeep dealer to:
install new fuel pump assembly in gas tank; confirm 48lb constant fuel pressure - startup and when running at injector rail; new 195 thermostat; new water temperature sensor; engine fan operating at factory standard; Water pump operating at factory standard; No sign of cracked block or water/coolant in engine oil; new coil and spark plugs; Compression all cylinders at factory standard; installed new injector rail heat shield and #3 cylinder insulation fix; (I have added a 7" x 21" 2000 degree heat shield between all injectors and engine/intake manifold -- not sure if makes any difference) fuel injectors confirmed factory standard (?) fuel delivery all cylinders; New radiator; Back flush coolant system (including heater core); Fuel system and injector flushed -- this was done twice with emphasis on combustion chamber. Power train Control Module updated and operating at factory standards/ (I had previously replaced the Camshaft Position Sensor, Crankshaft Position Sensor and Oil Pressure Sensor all of which the dealer said operate at factory standard). I had, and on occasion have again experienced PCM readings for multiple cylinder misfires..however since above work by dealer the check engine light resets and the PCM resets eliminating misfire readings.
I have also driven XJ at over 3000 RPM per Jeep and local advise to insure valves are free. Please note for a couple years I used the XJ primarily on the highway and forestry dirt roads. For periods between 60 days and 6 months the jeep remained parked without any fuel additives possibly leading to combustion chamber build up/valve sticking and lack regular 3000 rpm exercise(Jeep TA notice).
Dealer advised $2700 valve job needed -- private party and local 4x4 shops disagree contending no valve job required.
XJ is in great shape and runs fine with the exception of the overheating issue. Most XJ owners and local 4x4 experts suggest I just quit complaining and obsessing over the heat sink issue and just enjoy running the back roads/trails.
????What might I do next????