A while back my wife was driving her IS 350, she called and said that smoke was coming from the front of the car while at the bank. I told her to stay put I will come take a look. When i arrived coolant had sprayed in the front area of the engine around the radiator and also the lower radiator hose and slipped off a little. I slipped the hose up and drove it home, it did not overheat. I ended up replacing the radiator, radiator cap, waterpump and thermostat!
I used a Denso radiator, beck arnley thermostat, OEM readiator cap and an OEM aisin waterpump.

Yet after replacing all of these the temperature guauge needle would get to operating temp but if the car was ran hard the temp guauge would drop down some and sloowwwlly climb back up to normal operating temp. So just 2 days ago I replaced the coolant temp sensor(thinking it was the sensor malfunctioning)

Each time i opened up the cooling system i attempted to purge air from the system using this method: leave rad cap off, bring car to operating temp(when fans kick on) let the fans come on 2 or 3 times then shut it off. I made sure the heat was set high. Fan on. I even tried with the fan off.

I have no clue what is going on with this piece of ****, can anyone help me as to why my temp gauge is doing this even though i have replaced everything dealing with the cooling system?

Lobuxracer I hope you can comment, you always seem to know when stupid **** happens to these cars what to do.


BTW i also own an IS300, it is my lil baby.

 

It could be your heads and gaskets blown. Are u loosing power when driving? U mentioned when driving hard. There's kits that can test. I believe lisle and u-view makes it.

 

So the ONLY "issue" you are experiencing now after all of those new parts is the temp needle dipping down?

When you had the radiator cap off to blurp the system, did you had more coolant as the level dropped? What you mentioned I did exactly the same thing to ALL of my Hondas; I only additionally added new coolant each time the level dropped when the fans kicked in. Yeah, 2-3 fan cycles was plenty too. '

GL!

 

My power is great, car still runs like a champ. Butt dyno says it is faster now lol.

I used a Lisle spill free funnel to fill up the car. AS the car heats up the fluid builds up into the Lisle spill free funnel. I then allow the car to cool and it sucks the fluid back down into the radiator cap. but yes Gville350 it is currently my only issue. I know something has to be wrong.

 

should I not allow that coolant to go back down into the radiator as the car cools? Is it to much coolant????

 

To be specific, I didn't use a funnel. I had a drop pan underneath the radiator to catch anything that would spill over. When the fan when kick on, I would fill the radiator to the top. When the fan stopped, I let the radiator bubble up and spill a bit of coolant out. I would do that 2-3 times. On the last time the fan kicks in, I filled the radiator up to the top...and put the cap on it. NEVER had issues after this procedure; but of course this was all done on my Hondas, not the Lexus.

 

I've done the same procedure as Gville350 mentioned on my IS250 after I had to replace my waterpump. No issues whatsoever. Gauge moves to normal operation temperature and never changes. Maybe try replacing the thermostat with an OEM?

 

spikes in temp like you mentioned could be a blown head gasket. I had that happen with a 2jz. ran great. but was loosing coolant. you might want to check If you are loosing any coolant. if you are, definitely an early sign of a bhg..

 

no leaks, not loosing any coolant either? I have driven it multiple times, parked in same spot and left the undercarriage panel off so I can look easily.

I feel like its air in the system possibly and I am just not doing something right to bleed it correctly.

If it was the headgasket my car wouldnt run as good as it does would it? Idle is smooth and power is all there throughout rev range.

 

true^ but back when I blew the hg on my 2j, the power was all there too..up until it lost compression and sputtered heavily at idle. honestly, I doubt its your hg. unless your wife overheated it, the hg should be fine. air in the system will cause spikes in temp as well. try to park on a steep incline on jack up the front of your car, turn on the heater on high, and use the lisle funnel. must have the front of the car higher than the heater control valve in order to burp it properly.

 

My driveway has a decent incline I was on it each time I tried to blurp it. Gville350 said he didnt use a lisle funnel and let it spill over. Could this be the trick? When I take off my radiator cap the coolant level is right there at the top and my radiator tank is at the full line. I then place on my Lisle funnel and as the engine heats up the coolant rises into the lisle funnel. Would it be best to allow that coolant to come out, is it to much in the system along with air, maybe?


oh yeah I even replaced each thing in the cooling system i listed above seperatley each time. trying to pin point the problem, starting with the radiator, then the cap, then the thermostat. and finally the waterpump(waterpump did have a small leak from weep hole). and lastly the coolant temp sensor

one more thing I did was open up passenger side of the block to drain coolant but couldnt get to the other side(drivers side was a *****). I know that allowed more air to enter the system

 

I agree it sounds like air in the system. TIS doesn't have anything magical in their fill/bleed instructions. The one thing I don't do is fill with the cap off. I've got the Lisle funnel, and I understand why it should work, but what I found with my Supra (had LOTS of playing with coolant but that's another story) was just filling the system, getting it up to temp, massaging the hoses, and letting it cool while being certain the reservoir never gets too low. Toyota say to do the same thing with the 2GR-FSE.

 

Lobuxracer, what do you mean, the one thing you dont do is fill with the cap off?

use the lisle funnel or dont?

break down how you would do it step by step, i am a little slow

 

I put the Lisle funnel in place, and add coolant. I then massage the upper radiator hose with the engine off to get out as much air as I can. When I have all I think I can get in the system, I remove the funnel and put the cap on. I fill the reservoir to the full line and start the engine. At this point, it's just a matter of getting up to temperature and pressure, then massaging the hoses again to get the rest of the air out.

It won't work exactly like this with the IS-F because the reservoir is pressurized too. I'm pretty sure the IS250 and IS350 are the same. You have a plastic cap on the reservoir and it is what actually holds pressure. I haven't had to do anything with my F yet, but if I were, I'd do pretty much the same thing - add coolant to the full line, massage the hoses cold to get out as much air as possible, fill to the FULL line, cap it and start the engine. One up to temp, massage the hoses again and let it run for a bit, maybe take it for a 20 minute drive somewhere, then let it cool enough to be able to safely remove the cap, add coolant (if necessary) and put the cap back on. At that point, I"m done and will only check the level after a week or so in case any small bubbles managed to purge themselves.

The problem with running the engine with the cap off is it's really hard to get the system to the right level. The cap is meant to pressurize the system, but with the cap off, that can't happen. So the coolant expands, you get some air bubbles out, and then cap it hot. Without any pressure, the self adjusting feature of the closed system doesn't work, so the level is wrong and there will likely be air in the system. Then you have to go through purge cycles and a bunch of other crap I hate to do, so I quit doing it that way a long time ago. It's even more important when you run a high pressure cap (as I do on my Supra) since the idea is to run a more water biased coolant mix and improve detonation resistance. To do this, you must have a higher pressure cap to prevent boil over because the boiling point is considerably lower even though the heat capacity is higher.

Anyway, I'd focus on massaging the hoses with the cap on and the system at normal operating temperature. I"m going to assume you are smart enough to realize it's a bad idea to grab a hose full of coolant at 180F with bare hands...

If you want to learn a lot about cooling systems from a reliable source, not just some shadetree wrench on the web, go to Stewart Components and get some really useful technical info on what to do and not do to your cooling system.

 

I use to own 2000 gts, had the same problem. No matter how much I bleed it, temperature kept spiking. Changed thermostat, pump even heater core still overheats. Came to one conclusion, blown head gaskets. Sure it enough it was.
On my is250, I've changed the coolant 2 times just drained and
refill, letting the car run and paying attention to the radiator cap and ull see when ur coolant cycles through the system. Do u see ur coolant cycling when the thermostat opens?
1. Try oem thermostat
2. Do a pressure test to see if ur loosing any, if so there's a leak somewhere.
3. Do a combustion test to see if ur gasket is really blown to eliminate this from ur check list. Since if the car was smoking meaning the car was driving when overheating.

Seems like u have done all the bleeding already and it is still spiking.