1994 Gs300 Overheating

[chadzeilenga]

Hello all,

I recently bought a 94 GS300 and am having some problems with it running really hot! I've been doing some other work on the car so I really haven't driven it much but it gets really hot when it idles.

So far I drained all of the coolant out of the block and filled it up with fresh coolant only to have it do the same thing. So I then drained all of the new coolant out and removed the thermostat and filled the car back up with straight water. I back filled the block until I had water coming out of the radiator and then started the car up and burped the radiator hoses until I couldn't get any bubbles to come out. Checked and there is definitely flow in the coolant from the water pump. The temp gage never gets much past 1/2 way, but the engine is way too hot. When I shut it off it bubbles and gurgles for quite a while until it has cooled off. The upper radiator hose is rock hard and I'm afraid of it bursting. I'm not quite sure what to check next as I thought the problem was a bad thermostat.

[hacker_720]

A lot of newer cars have a more complicated way to burp the system, a lot of the times there is a bleeder valve somewhere. I’m not familiar with the 2JZGE engine, but you may want to look into the proper method. The coolant shouldn't boil, that's a sign of air in the system or bad coolant, or a hot spot. Water will almost always boil though, and you said you were running pure water at one point. The only other simple solution is rad cap, I always change the rad cap and the thermostat at the same time. Other then that I would say do a compression test and hope it's not the head gasket. I know the 5MGE and 7MGE were notorious for head gasket failure. Also, is your rad fan coming on? It should come on when the car is parked, if not it can lead to overheating. If the fan is not coming on, then turn on your AC and see if the AC fan forces enough air past the rad to cool the engine.

Steve

[mlgs300]

That really is it in a nutshell. Do the simple things first. Put the right mixture of coolant/water in. Get a coolant hydrometer thing and check. To bleed fast you can take out thermostat, fill to top of that inlet, replace thermostat, button up, fill radiator, put cap on, fill overflow to hot level. Run car til thermostat opens and let temp get a little past that. Shut car down. You'll hear bubbling. Let cool down for a good 30 minutes to 1 hour, it will suck coolant down if there is air. Start car again and run. Definitely check for fan operation.

[chadzeilenga]

Hello mlgs300,

This weekend I filled and bled the cooling system. I left the thermostat off because I wanted to make sure that I had full flow into the engine. I topped off the radiator and started the engine, squeezing the upper & lower rad hose to burp any air out and left the heater on LO defrost. Once the coolant started to get warm I shut the engine off and let it cool. Then I topped off the rad and continued this process until I no longer needed to top if off. Then I added to the overflow tank and put the cap on and let the engine idle. The engine was definitely getting hotter than it should, but the temp gage only read 1/2 which I think is the normal operating temp. The fan spins with the engine since it is driven by the pulley. How does this kick on if it is pulley driven? What else could be causing the engine to run really hot, but not register on the temp gage? The rad cap seems to be working well and the thermostat was out of the engine so I would think it would be running cooler than normal. Any thoughts on what else I should investigate? I'm not very familiar with this car yet.

[djspawn00]

so its not overheating but you think its still too hot? did you plug in a OBDII diagnostic tool and get higher than average readings for your temperatures? You do know the temp gauge is normally slightly above half way on a lot of lexus vehicles right??? I assume you also know about stoichiometric points.... also the thermostat also helps with cooling... one half of the coolant gets hot while the other half gets cooled... no thermostat and all the coolant can just heat up....

[chadzeilenga]

So I have the cooling system all back together and I topped it off with a fresh mixture of 50/50 mix with a new thermostat. I started up the engine with the heat on lo and let it warm up. All of the air was purged out. I let it idle and then with a stick I tried to see if the fan clutch was working correctly. I was able to stop the engine fan at idle and also at higher RPM's. Does this mean that the fan clutch is failing? Also, my secondary fan in front of the condenser never comes on. AC is broke, so I can't check it this way. I unplugged the temp sensor at the bottom of the radiator and the fan came on and stayed on until I plugged it back in. My temp gage has always read just a little above 1/2.

[GS400junkie]

Hello all,

I recently bought a 94 GS300 and am having some problems with it running really hot! I've been doing some other work on the car so I really haven't driven it much but it gets really hot when it idles.

So far I drained all of the coolant out of the block and filled it up with fresh coolant only to have it do the same thing. So I then drained all of the new coolant out and removed the thermostat and filled the car back up with straight water. I back filled the block until I had water coming out of the radiator and then started the car up and burped the radiator hoses until I couldn't get any bubbles to come out. Checked and there is definitely flow in the coolant from the water pump. The temp gage never gets much past 1/2 way, but the engine is way too hot. When I shut it off it bubbles and gurgles for quite a while until it has cooled off. The upper radiator hose is rock hard and I'm afraid of it bursting. I'm not quite sure what to check next as I thought the problem was a bad thermostat.

hey man i had that same problem and it was the rad cap the spring was broken and it would just keep on gurgleing got a new one and it fixed it hope that can help you

[sakataj]

I let it idle and then with a stick I tried to see if the fan clutch was working correctly. I was able to stop the engine fan at idle and also at higher RPM's. Does this mean that the fan clutch is failing?

u stuck a stick into your moving fan? Y???????? :cries: well if it wasn't broke it might be now.....