Had my XJ for around 6 months now, the temp has always run 1 needle under the 210 mark.

I developed a squeal that seemed to match the symptons of a leaking intake gasket, so finally got around to replacing it. When I removed the intake a chunk of it fell to the floor Finally received a salvage yard intake for it yesterday and installed it today. All seemed to go well.

Then I went for a test drive. I soon noticed that it was running at the first tick mark above 210 mark. I kept an eye on the gauge and it didn't stray from that temp for a 15 minute ride to get oil and a filter. When I came out of the store and heading back home, it stayed at that temp for about 10 minutes then all at once jumped up to the third tick mark causing an audible alarm and the check gauges light to blink.

I pulled over and shut it off and looked to make sure the belt was on, it was. I then started it back up to look for any obvious problems and saw none. The electric fan was working. When I started it back up, the temp immediately dropped back to the first tick mark where it had been running.

I was close to home so headed on. This temp jump and fall happened once more on the way home and once sitting in the yard after I got home. An IR temp gun was showing up to 240 on the thermostat housing, somewhat less on the upper radiator hose and only around 190 on the lower hose.

Can anyone think of something I may have done to cause this? Or is it just a strange coincidence that this started immediately after intalling the new intake?

TIA

 

Sounds like air purging from the cooling system, normal.

 

But I didn't touch the cooling system.

 

IIRC, the sender for the gauge is located on the back of the head. You didn't bump it or anything, did you? I'd first try and verify actual temp with an infared gun type deal. Then go from there. Could just be a freak occurance after the swap. I've had those lol.

 

Just one sender for this year, on the thermostat housing. All I did to it was unplug it while replacing the intake. Cleaned said plug and wiggled it with no change. I did swing the rail out of the way that has the injector wiring and the leads from the sender in it. I was briefly hopeful that one of the sender wires had been damaged. But the following kind of dashes that hope.

After reading more threads on the subject of overheating, this seems to indicate that it is actually overheating. I guess it is a "freak occurance after the swap".

I have read a few times now that the wild swing in the indicated temp is from a steam flash over caused by a bad radiator cap. Going to try a new cap and top off the coolant as a start to the process.

If that doesn't fix it, I guess it's time for a full cooling system overhaul.

 

Two quarts of coolant added via where the radiator cap goes and a new radiator cap and all is good for now. Time will tell how fast the coolant level is dropping.

How does this happen with the recovery tank at the proper level? I thought the idea was that if coolant disappeared, the system would draw more out of the recovery tank to replenish it.

 

If the cap was bad, it wouldn't purge or recover properly

check the oil for coolant

 

Wait...are you losing coolant?

 

It was a strange coincidence.

Two days after changing the intake she blew a head gasket. Actually, I think the head gasket had been leaking for awhile. I don't drive it much, about 1200 miles in the 6 months I've had her. She's been missing at startup for a couple months when its been sitting for more than a couple days - it was coolant leaking into the #3 cylinder.

I went into it with plans of buying a new head given the 0331's track record. I couldn't see any crack visually and the head gasket blow out was very obvious so I cleaned the head up, checked it with a straight edge and slapped it back on. She's running by far the smoothest since I have had it.

Oh, the engine is pretty noisy as seems common and there was a lot of cylinder wall scoring. This helped me decide to just try putting the old head back on. If it goes like so many do, I'm not wasting money on just a head, I'm going to either do a complete rebuild or put a remanufactured engine in it.