just bought a 94 gs 300, and i did do the research, the same problem other member had, bubbling in the reservor tank..and 'flat' upper radiator hose!! someone told me is blown head gasket or maybe have to get the air out by press the upper radiator hose,..
here is a brief story. After a week, today it just act abnormal, the temp gauge show it went up to upper middle, i opened the hood and found out the upper radiator hose was 'flat', then i just unscrew the radiator cap to make the upper radiator hose 'fat' again, since like no air can go through. and there is bubbling noise in reservor tank...wat cause this problem? sigh, just bought the car with 160k and dont tell me it got blown head gasket
the previous owner told me he had changed the timing belt and water pump, and i can see the water pump is pretty new,
anyone can help a newbie like me? thanks alot
maybe time for me to change the engine, any idea how much the 2gzge motor ? and where to recomment to get it?

 

It is indeed possible that the head gasket has a leak. It would take substantial vacuum to suck that hose shut. A motor naturally creates vacumm at idle. Is the coolant strangely disappearing and is white smoke coming out of the exhaust?

My suggestion is that you do an oil change first. Check to see if there is anything white and milky floating on top of your oil. That would a kiss of death. Next, change your hoses. Coolant hoses deteriorate from the inside out. Then I would suggest is have a leak down or compression test done on the cylinders. If two or more of the cylinders leak down less than the others, break out the check book.

 

aww man.. hope not the head gasket failure..
there is two kind of radiator cap one is 13lbs and another is 16lbs, is that any problem to choose the certain one?
i will go to do the oil change, hopefully the HG is fine.. pray pray pray

 

The cap rating is to release pressure, not vacuum. You coolant should be a closed system under pressure.

What about the white smoke out the tail pipe and the coolant level?

 

no smoke dude, i pay attention and it didnt have any sign of smoke. i found out after i drive it for a while just now the coolant reservor tank just 'fill up more in there by itself' as i know i didnt top it that much...WTH?
i went to autozone and i search for the radiator cap, and they told me there is two different kind of radiator cap 13lbs and 16lbs. the current caps in my car is 14lbs, is that make any different? or should i contact lexus to make sure?
the car not overheat but everytime i shut off the engine, i heard the bubbling noise in the reservor tank not alot but double bubbling in btw 2 seconds. is that normal??
thanks for the patience, kaiser

 

Don't know if this will help much, but I had a similar issue on a VW and it was the radiator cap. Take it one step at a time, Kaiser seems to be giving you good tips. GL

 

Change the hoses and I get the feeling that will be it. Or at least a good start. There are some reported cases of strange overheats on this engine but it's usually the lower hose that goes first. The cap is probably fine.

 

okay, sounds more relax after knowing not much likely for HG failure
i been driving just now and the highest temp gauge went only till half a lil more, hope it wont climb up again and it move very slow.
there is no sign of leaking radiator fluid. 2 days ago i put the STP clean engine injectors, and improve perfomance some kind of oil in my gasoline, it wont affect the cooling system rite?
i will go ahead buy the lower radiator hose later in autozone ..... call the lexus just now but they also dont know wat kind coz they dont have it instock, stupid dealership~

 

I replaced my radiator cap rated at 13lbs same as my previous one. My coolant reservoir filled up 2 inches past the full line and I did not add any coolant at all. Does anyone know what this means?

 

maybe bought another 16lbs radiator cap just to try it?? i bought 14lbs and 13lbs... and the auto part store told me the computer list 16lbs too....well...i guess i gonna try 16lbs radiator cap see wassup, hopefully it help.
flush the radiator twice already still doing the same!!!!! bubbling reservoir tank ! hopefully nothing serious