Sorry, but i did do a search and didn't come up with these symptoms.

2000 Limited 92k, purchased 1 year ago with 76k on it.

Assume it had a milkshake before I bought it, as radiator was new, oem.

For almost first year, it would have heat, as soon as the guage moved.

About a week ago, gauge was up, but no real heat. A few minutes later, heat.

Then I noticed the guage heading upwards while coasting, or stopped. Normal while driving normally. Fluctuation happens pretty quickly.

I had heard some gurgling for a few weeks, so I closed the switch for the rear heat. Not sure if it's related, but that night was when the guage really started to flucuate.

My previous 2000 had to have the electric clutch replaced on the cooling fan, when I was stuck in traffic for over an hour on 95 degree day.

If have another car, so I have some time. But, it has been snowing every third day here....

Any thoughts

If you heard bubbly noises inside the truck, it means you have air in the system. I would check the water pump or the rear heater lines. If nothing leaks, I would check for the head gaskets.

I was going to suggest rear heater lines also. They are known to get rusty and leak (which lets air in the system. The gurgling also is a clue.

Yup, my rear lines rusted and drained the whole system.

Little tip, the toyota coolant is delicious. Ask me how I know. But you won't feel well later. Plus the taste is a bit hard to get out of your mouth.

Thanks for the reponses to date !

Was with a friend last night that is a Toyota Dealer Tech.

He asked about noticing leaks. But, I haven't.

Given the duration of time I have been hearing the gurgling, he is guessing a real small/slow leak. Is providing me some coolant to add. Supposed to get it later today.

So, will add, and report back, probably top of week.

Prestone is a bit better on the stomach. Mine too have rusted out, i bought some rubber lines to replaced the corroded part though.

Got flu, and waited till it was warm here. Inspected all the lines I could see, no obvious leaks. Except, when I went to take the cap off the radiator, I was only paying about 50% attention. It could be that it was not on right, or is worn out. The hose to the overflow tank was loose, and covered with "stuff". Cleaned them up, and re-clamped the overflow hose.

It took about 9/10's of a gallon to top off the coolant. Heat came right up, and check engine light went out.

Ran for 10 minutes in driveway, then a ten minute ride around town. No visible leaks.

Will look at it this morning again.

Some drippage did develope.

Took the skid plate off, and found that the one of the lines (right) where it screws into the bottom tank was not tight. Shake it/wobble loose. Took about 5-6 turns to snug up.

No drippage since.

However, mechanic told me that the "china" replacement units have been known to be adversly affected by extreme cold. Begining to leak where two different materials are joined. Plastic at the fins in particular.

Am going to be watching for that for a little while.

Thanks again for your input !

I've think I'm having the same problem, I heard some gurgling sounds after I turned off the engine after an hour or so drive but I have no leaks. Over a 3 year period I had to add about 1 gallon of coolant. Would this be a good sign to do the head gaskets? Is there any other signs to look for that would point to the head gasket?