speedrace

I need opinions. I just bought this car and it was driving and running fine. I decided to do some preventive maintenance and flush the cooling system. Drained it first from the petcock on the radiator with engine cold. Left the petcock partially open, and using a garden hose in the radiator filler neck I started the engine--with the hose running. So far so good. I did notice what looks like that ****ty Aluminseal paste --- on the radiator cap seal and got worried.

When the water was running clear, I shut down the engine and let it cool for about a half hour. Added a bottle of Redline water wetter, and then filled it with distilled water, and started it up --also turned the heater on high temp.

Burped it for about 5 minutes and then cleaned off the cap and put it on.

Everything seemed okay around town, but as soon as I got it on the highway the temp started to climb. I had turned the heater off before the drive, but now cranked it back on to the Hot setting, and sure enough there was no hot air blowing. ****!-- I've got a stuck thermostat. So this morning I replaced the thermo, and started the whole water-wetter/distilled water thing again.

I thought I had it, but did notice that with it running and letting it come up to temp for a longer period this time to make sure all bubbles were removed, the water was starting to erupt out of the filler neck, instead of just normal flow and slight overflow as the engine ran. But-- I capped it, made sure there was the right level in the overflow tank, and went for another drive. This time on the highway it ran fine --heater blew hot air, and I start to relax. But the damned thing did it again this afternoon!. And just like last time, when it started going towards the red zone, I checked for hot air from the heater, and there was none.

Now this time (as I sat waiting on the side of the road for it to cool down), I checked a couple of other things. First -- the radiator fins were hot at the top (only for about an inch or so) and the very bottom was only warm. The whole center section was stone cold. Thermo housing was hot. So-- maybe a clogged radiator, I'm thinking. But when I had replaced the thermo, and had the lower hose with therm housing un-connected to the water pump, I had done a check and ran a hose into the top of the radiator, and the water seemed to be flowing through the radiator and out the thermo housing just fine.

I've already suspected the HG, but there is no "milkshake" color on either the engine oil filler cap, or the dipstick, and no white smoke or steam out the tailpipe. I had the oil changed yesterday, and asked the guy to check the drained oil for signs of coolant, and he said it looked like dirty oil-- no water.

So it appears I have a flow obstruction somewhere that is only happening at highway speeds. The give-away is the heater air temp dropping off as the temp gage climbs. I'm assuming a couple of things here. One is-- the water flows through the system from the bottom of the radiator--to the top-- where the cooled water is returned to the cylinder head. Second -- the reason for the "eruption" when the engine gets warm just idling is that the flow obstruction is making the water in the cylinder head and upper hose start to boil, and backup against normal flow direction until it erupts out the filler neck of the radiator.

My questions are....... In my experience a water pump only fails when the bearing gets sloppy, then the shaft seal goes, and it finally starts to leak coolant from the weep hole. My isn't. Is there another problem with these pumps that causes them to lose the ability to move water?

I've heard of pump impellers on other makes actually eroding to the point that they won't move enough water through an engine.

And last-- I thought the clutch fan was supposed to lock up progressively more as the temp went up, in other words, at crawling along traffic the fan would engage more positively to draw more air through the fan shroud. At highway speeds it moves more toward free-wheeling as the ram effect of the air at highway speeds means its not required. Well-- mine freewheels all the time! ---cold or hot.

This is got me stumped. Any ideas from you guys?

W1d0wMaker

the fan shouldn't ever completely freewheel, it should always be moving. so if that fan ever stops moving completely, its bad. check for obstructions in your airdams that would restrict airflow to the engine bay. also, check to make sure your radiator cap is holding pressure. its supposed to hold 14psi, pressurising water makes its boiling point much higher and alows it to dissipate heat faster. I have personaly experienced this problem. bet you couldnt guess how long it took me to figure that one out. I dont know what watter whetter is, but im assuming it is some kind of ati-freeze. if not you realy do need ati-freeze. it does the same as pressurising the sistem, it has a higher boiling point and dissapated heat faster. a 45/55 is the best mix. check to see if all your belts are good and snug, the centrifugal force while driving highway mite be throwing it out and not spinning your water pump like it needs to be.Oh yes, does your car have an underdrive pulley set?

speedrace

Water Wetter is made by redline, and it increases the heat transfer in the cooling system. Some claims are that it lowers the water temp as much as 20 degrees. It is formulated with additives to lubricate the water pump and has anti-corrosive additives, so that it is okay to use it with water alone in a cooling system as long as you don't live in a climate where you need the anti-freeze properties of normal coolant. I don't -- I live in Northern California.

when I talk about the freewheeling of the fan blades, I'm talking about with the engine off I can easily rotate the fan by hand. Viscous coupling fans have a fluid in the hub that is supposed to "lock up" the fan when the air temperature gets hotter and the fan needs this direct coupling to draw more air through the radiator when in traffic, and at low speeds with high air temps.

If you shut down a engine with a viscous fan and the engine compartment is at normal temp, you will feel some resistance when trying to turn the blades. If it was colder outside, the fan should turn more freely. But my fan easily turns all the time-- even after a drive in hot weather just around town. This is why I suspect it.

So-- the latest is that I let everything cool down again, noticed the system had pulled all of the coolant from the overflow tank back into the system. So I removed the radiator cap, very very slowly poured warm water into the radiator neck until it was full. Then I filled the overflow tank to about the 3/4 full-mark and started the engine. I turned the heater back on with the setting at full hot, and held the rpm at about 3000 for a good ten minutes. After about 5 minutes the heater was pumping out great heat, the temp gage was holding at the midway mark, and then I shut down the engine so I could fit my hand in front of the fan and check the radiator temp from top to bottom. Surprisingly --- it was now hot all the way down.

So now I'm off for another drive and I'll post the results.

speedrace

Car drives great with the gage in the middle around side roads, going through the gears, and probably no more than 60 mph. Take it on the highway and it's all good for about 10 minutes (heater blowing warm all this time). Then when cruising about 70 mph in 5th gear, the heat starts going away, and almost immediately the gage starts climbing.

I pulled over and raised the hood. The coolant was boiling in the overflow tank. So-- I waited 30 minutes for half of it to be pulled back into the system, and limped it home again. Interesting on the drive back that the temp stays manageable as long as the rpm is under 2000.

Oh!-- I also checked the radiator on the fan side when it first overheated on this test drive. It was again-- hot on top---hot on the botton ---cold in the center.

It's starting to look like radiator replacement time. Strange though, how it doesn't create a problem until I'm at a sustained freeway speed. I would think blockage would be a problem no matter what speed you are driving.

Any other help out there?

I'd appreciate suggestions.

Steelwheel

Assuming the fan/radiator/water pump were in good working order, I would guess it is not fully burped and/or the water is boiling in certain places when it get hot enough around the cooling channels. This can happen a little bit easier with water since it boils at 212F at atmospheric pressure which is slightly lower than antifreeze/h20 mix. If your radiator is holding pressure properly (14 psi or so) then the water will require a higher temp to boil (around 250F, antifreeze water 50/50 is around 267F I think). If your system (radiator cap) is not getting up to pressure your boil point could be low and with a better than original heat transfer which might cause boiling when the engine is producing more heat (higher rpms). Boiling in coolant channels can stop flow of coolant causing all to boil.

BTW, water by itself has a better heat transfer capacity than antifreeze/water mix (and with water wetter it is even a little better), but antifreeze/water has better freeze and boil points and should give better chemstry.

I've ran water/water wetter mix in a drag car with great results but would not run in my daily driver (not that you can't or should not, I just would not) since most daily drivers are designed to properly cool with antifreeze/water.

Good luck and let us know what you find.

speedrace

Thanks steelwheel!

Your post got me thinking, and then I also observed something else tonight after yet another cool off session. I slowly filled the radiator again with hot water (just to make sure I didn't thermal shock anything deep in the motor) that wasn't fully cooled off.

I started the car after again making sure the overflow tank was 3/4 full and let it just sit and idle. After about ten minutes I checked the temp gage--- and it was sitting right in the middle. But then I noticed that the coolant in the overflow tank was boiling!

Just maybe I have a defective radiator cap that is not even holding the 14 psi spec, and with your statement about water (even with water wetter) having a lower boiling point it got me thinking. Is it possible that a weak cap--coupled with the lower boiling point-- could be the source of my problem?

If I don't have the vehicle under any real load around town--- but then load it even with steady state highway speeds by pushing air and using more throttle, maybe I am just not maintaining enough system pressure without boiling in the water jackets.

I'll go buy another cap tomorrow. And if that cures it, I'll also mix in some anti-freese to raise the boiling point. I thought I read a post here somewhere where a guy was running just distilled water and Water wetter on a Forced induction SC300 with no problems.

Thanks again. Let me know what you think of my logic here. I'm looking for any and all possibilities. This car has me stumped -- but I admit I only gave the cap a quick look over and it seemed fine.

TheMole

iTrader: (13)

It's probably that crappy seal around the radiator cap seal. The previous owner must have done a cheap fix on it.

Also, checkout this thread since they experienced a few of the same symptoms you are experiencing:
https://www.clublexus.com/forums/sho...d.php?t=144931

Steelwheel

Yeah, if the system is not holding the pressure, it can boil regardless of whether you run antifreeze mix or water only. Like SC300max and widowmaker said, definitely check for proper pressure in the system.

In a properly operating system staying above 32F, distilled water along with anti-corrosive additives should be fine. However, the lower boiling point can set the margin of safety lower if it loses pressure.

Running this kind of mix can be an advantage if you require better cooling due to mods, but you will have to be aware of the extra precautions.

Hope that new cap does the trick.

speedrace

Thanks again guys! I drained the distilled water w/water wetter at the radiator petcock this morning. Added a gallon of antifreeze, more water wetter very slowly -- then burped the top radiator hoze by squeezing it to force out some air bubbles. Put the new radiator cap on and let it idle for about 15 minutes.

I drove it around town for about 20 minutes, not exceeding 60 mph, and watched the temp gage like a hawk-- with the heater set to 85 degrees. All seemed fine, so I took it out on the highway for a couple long 30 minute stretches up to a sustained 80 mph and the temp gage never flucuated from the halfway mark. Hot air from the heater never varied.

So --- I'm thinking its good to go. The lesson learned here is to listen to those that say check the little things first. I bypassed the whole idea that I had a bad radiator cap. Hell! the thing was running fine before my drain and flush. But maybe my pushing the boiling point by just running distilled water and Redline water wetter after the re-fill highlighted the weakness of the old cap.

Now the next thing is to deal with a starter issue. During all of this, a couple of attempts to start the car resulted in a binding noise coming from the starter--- almost as if it was loose on the mounting flange and the starter pinion gear was binding on the flywheel ring gear when I would turn the key. It was a much uglier sound then just the "Click" when you have a bad armature. So-- I ordered a Denso-remanufactured starter. But.....it has not done it again with a dozen more engine starts. Anyone had starter issues like this?

Anyway-- thanks to the group for giving me pointers on the overheating. I'm pumped to be able to drive and enjoy the car again. I just bought this 5-spd SC300 about 2 weeks ago. A previous owner had fitted it with Tanabe springs, Tokico struts and some massive sway bars. It has 17" Lexus IS wheels and Bridgestone Potenza tires. It sits about 2 inches lower than stock, and I have to say it handles pretty good through the twistys considering its weight and tire/rim size.

I just threw in a K&N replacement filter element today and tomorrow I'll be able to do my first gas mileage check when driving it to the San Francisco airport on mostly highways--from the East Bay . I'd be jazzed if I got 25 mpg --- but maybe thats too optimistic.

Regards to all

speedrace

Took all of one 120 mile trip before the temp climbed again. I guess the HG is blown after all. HG replacement?---or used motor swap?.....as this one has 170K and has gotten pretty hot a few times now.

TheMole

iTrader: (13)

Have you checked the oil to see if there is any discoloration/coolant in it?
Is the waterpump still good? At 170k there's a chance that it has never been replaced. A new waterpump/radiator can't hurt since it will be a good idea to change it when rebuilding the engine or doing a swap.

If the engine does have a failed headgasket, will be a good time to get a thicker headgasket if you are going turbo. If you want it stock, either rebuild or get a low mileage swap. 2jzge swaps are alot cheaper than their turbo versions obviously.

Hope things work out for you.

speedrace

This morning we put a cooling system pressure tester on it. Pumped to 20 psi. It actually only dropped 2 psi over 30 minutes. BUT-- that was long enough to fill a cylinder, and so the engine hydraulic-ed when trying to re-start. The final death nail was when I pulled the engine oil filler cap and it was coated with mocha-colored gel (yesterday it was clean).

I'm not gonna screw around with repairing this engine. I've found a $495 Japanese import with 50-60K on it that carries a 6 month unlimited mileage warranty on the long block. I'll fit this engine with a new water pump, timing belt, clutch disk (as long as I'm there),and maybe a rear main seal.

Im hoping to be back on the road next week. For me-- the lesson learned is that I'll never buy a high mileage car like this again without doing a compression and/or leak-down test even if I have to pull the plenum to get to all the spark plugs in order to get the true picture. If the owner doesn't want to screw with that--- I'll walk away.

Later........