Coolant Loss......

[ChiefGunner]

Hey yall. I mainly lurk but I've come up with the possibility of the dreaded cracked head. It's a 2001 with 158k miles and a build date of 01/2001.

I bought it last August and changed out a bunch of stuff. I started fixing some cooling issues in December when I lost heat so I initially flushed the system and the heat came back good as new.

A month later my radiator cap started leaking so I decided while I was at it I'd change the thermostat as well.

No issues or leaks after that up until a month ago when I started having issues.

I noticed the temp started going up but figured it was normal with the warmer weather.

A week later driving home from work it spiked to 260 instantly so I threw it in neutral, shut it off, and pasted to a stop. Waited about 10 minutes and the Temps were normal again. Did it again a mile down the road and luckily right next to a gas station.

Let it cool down and open the radiator cap and it's bone dry. Filled it up and made it home 20 minutes later with no issues.

Get home and the radiator cap is cold and the overflow is full and looks clean. Fill the radiator again and have been adding a splash here and there every other day.

I don't have any of the tell tale symptoms aside from coolant loss. No milky oil under the cap, overflow tank stays at the same level, oil level was a bit low but not rising over the last 2 weeks.

I've searched 100's of XJ coolant loss and cracked head threads but cannot seem to match the exact same symptoms. My next step is to get a leak down done on her and see what's up.

The part that's screwy is the cold radiator cap and the coolant tank level are not changing at all. I can't even tell if the new cap I put on is bad because the coolant doesn't touch it.

Running temp stays at 200 driving 55 and doesnt get up to 210 when idling. Oil pressure was low but after changing the oil today it's back to normal(for me) 20-25 at hot idle and 45-50 driving 55.

Anyone have any thoughts or had the same symptoms? Hopefully I was thorough enough.

 

[Dragonlich1961]

Temp should drop while driving. Rent a coolant system pressure checker from a auto parts store to check for leaks. It lets you pressurize the system like it was running and getting hot. Just with out the hot part. I had a slow leak that turned out to be a heater hose. Only noticeable when cold. When hot the engine would evaporate what little came out. Did not cause a temp spike. But if forgotten long enough it could.

A cold cap suggests a failed closed t-stat.
I've had one fail open and was only 6 months old.
Also check spark plugs. A plug that appears different from the others indicates a problem in that cylinder. If the plug is clean and the others are dirty, it's coolant entering the cylinder

 

[mcnamaag]

Possible freeze plug leak. Searched for months trying to figure it out. Every time the wife would drive the jeep it'd get warmer than normal and you could smell coolant when she got home. I checked everything, but couldn't find a leak. I finally decided to let it idle until I tracked it down and after an hour of searching I noticed a rusty stain on the exhaust manifold and intake. Apparently the middle freeze plug was leaking and spraying coolant onto the exhaust. Wasn't bad enough to leave a noticeable puddle but enough to notice coolant loss after a few days. By the way, mine is a 2001 as well.

 

[Ecomike]

Non jeep, but I once had the suction side of the water pump gasket suck in air, and did not leak coolant ever, but it did fill the coolant bottle.

Found the very small head gasket leak on a ford not long ago using a 3 foot video snake tool they sell(about $79 now) that displays a 3x4 inch screen shot of the image, in my case it could see through the empty spark plug hole and see the green coolant dye traces in 2 of the 6 cylinders that did not show up on the plug. The snake tool is also great at snooping in and around and under hard to see locations One the greatest diagnostics tools I have now.