canucklehe

My 93 ES300 has been sitting for a few months. I moved it and let it warm up at idle. The dummy gauge on dash showed normal operating temp. The fan was moving slowly, not fast. Based on that, I assume I wasn't overheating.

Upper rad hose was hot (not excessive, but hot), lower rad hose was cool. Shouldn't that lower rad hose be same temp as upper? It was cool outside. And car was only idling. Would that make a difference? Do I need to rdrive and run it at higher RPM to get a better read on coolant cirulation/water pump?

Can I crack open the engine coolant cap when cold, to see if water pump is circulating coolant ? (I only have one cap on top of motor...I have the sealed rad set up= no rad cap).

anything else I can check? It's not noisy, nor is it dripping coolant that I've noticed.

LeX2K

The lower rad hose is supposed to be cooler, coolant travels from the top down in the rad and cools in the process.

lluahs

Not much you can do to see if it is bad without getting in there. Check for leaks, listen for strange noises coming from the timing belt/water pump area, and monitoring for overtemp. If you suspect the car overheating, a false read in the temp gauge, then I would check your temp sensor with a multimeter( you can find the specs in the owners manual or online).

canucklehe

I may be paranoid because of similar issues with my Ford 6.0L diesel truck. I have good aftermarket coolant gauges that tell me temps and my oil and coolant both overheated while idling and lower rad hose was cold.

I think my lexus is probably OK. I'll drive it and see if lower rad hose feels a bit warmer under normal driving conditions. Maybe just idling like that wasn't a good way to make this diagnosis. I don't think my dummy gauge is faulty. I recently had cluster re-done by Tanin. I could also check temp on upper rad hose to get a ballpark idea.

lluahs

Does the fan run at full speed at operating temp ? if not, you have another issue...ill post the link if it isn't

canucklehe

just checked it now when I got home from 30 minute city drive. temp gauge sitting in normal position, upper rad hose warmer and too warm to hold onto for long but I wouldn't say "hot" relative to an overheated engine hot.

lower rad hose warm and I can hold onto it warm. so cooler than upper, but still warm.

fan was spinning and I could barely see the outline of fan blades as it spun, so not spinning super fast (as in: when fan spins fast, the blades look like a blur). I put my hand to them and could stop blades from turning.

I dunno, I think that all means it's working. If it was getting hotter, I assume fan clutch would kick in and really spin the fan.... but since it's not getting that signal, it doesn't need to spin fast. Does that make sense?

LeX2K

That's more or less how it works. This is the only radiator fan system that is infinitely variable that I know of (the LS400 also had the same setup). It does make the fan very quiet in most conditions, I guess that's why Lexus went through all the trouble, although I can't imagine many people complaining about rad fan noise.

canucklehe

did you happen to view my latest post on my replacement steering rack issues? I'm trying to pin down if this is a defective reman rack, sensor, or might work itself out.

milirx450h

Being that your car is 20 years old I would think that a good radiator flush, new hoses and a thermostat might ease your paranoia. But then again, if you aren't having problems it might be better to keep checking everything periodically than throwing parts at it.

lluahs

If you take a paper clip(or wire) and connect e1 to op1, does the fan spin so fast you dont want to touch it? If it still runs at the same speed you probably have the same issue as I did a while back.

canucklehe

car running, or in "on" position? or will this work when shut off?

lluahs

Well the fan is run off the power steering pump, so I would suppose it would only work with the engine running(thats how ive always done it anyhow).