Brad Cumby

Hey guys my 2001 XJ has been over heating lately. I've replaced the thermostat, water pump, and can clutch. My radiator seems to be in decent shape. I took it to a radiator shop this morning and without looking at it said it is probably my heads as it's a known problem with my model. The reserve water tank was boiling yesterday and the hose from the reserve tank to the radiator was extremely hot yesterday. Please help

PatHenry

Research the 0331 head. It's likely they're right and the head is cracked.

Don't drive it with a bad head - you'll leak coolant into the oil and it will ruin the bearings if it hasn't already.

https://www.cylinder-heads.com/cylin...ams-fits-2001/

SexyDexy

While the head being cracked is a high possibility. It's not uncommon for the original root cause to have been a stuck closed T-Stat or a weak Fan clutch. Once it overheats, it may have cooked the head gasket or caused the head crack, causing a secondary overhead issue.

Also mixing coolant types can cause what looks the radiator was filled from a mud puddle..and can clog up the radiator from cooling properly. If it were mine I would be flushing the cooling system really well (multiple times), then add Zerex G-05 coolant with distilled water.

PatHenry

I missed the part about them not even looking at it. You can confirm if the head/head gasket is bad with a test kit from the local parts store or an oil analysis (blackstone labs is a popular choice).

Keep an eye on your oil pressure. If you already have or start to see a drop in normal pressure, your whole engine may be hosed and require a complete rebuild. If you can correct the head problem before damaging the block, it will be substantially cheaper and easier. You can change out the head in your driveway with hand tools - swapping out an engine requires fancy equipment and a lot more time/energy.

I would start with checking your coolant for oil and oil in your coolant (visually) and if you can't see any cross-contamination, go get the test kit from the local parts store and order the blackstone labs kit (they'll send you their test kit for free, so you only pay when you actually submit a sample). If the parts store test doesn't show a problem, then submit the oil analysis. In the meantime (since the oil analysis process takes several days) follow Dexy's advice and flush the crap out of the system and change the oil. (Again, antifreeze in the oil will quickly ruin the engine)