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Quick Coolant Question


intellivised
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To all the great knowledgeable Lexus forum regulars I pose this quick question:

Radiator light popped on for the first time in 1.5-2 years. I have a slow leak/burn off in my cooling system *somewhere*. Not too worried about it, the temp. gauge is doing fine and there are no real red flags, I'm guessing a hose got loose somewhere or I need a new cap.

My question is: What ratio of water/coolant should I use to top off my overfill tank to get the light to go away? 50/50? I actually have a big container of the official Toyota stuff and a few gallons of distilled water I picked up at lunch. I'm going to do this after I get home from work. Regarding the ratio: I live in Wyoming @ 7000'. It's always cool at night and winter comes in October and it is brutally cold up here.

Strongly considering a flush when I get my snow tires put on before winter starts.

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You loss of coolant was the first symptom I had that the water pump was going. It became a steady drip after about six months and was a lot less in the winter. I'd take a look under the car and wipe off all the grime behind the crankshaft pulley and take a flashlight to the spot after coming back for a spirited drive. I bet you will find the coolant is coming off the area around the waterpump bearing/shaft. Better to plan for the repair if that is the prob IMO.

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You'll know if you need a new cap. Just look at the top of the expansion tank around the cap. If it's leaking there, you should be able to see signs all around that area. If your warning light came on, then you must be leaking a fair amount. I would find the source of the leak before you pop a hose or sieze the pump and wind up stranded somewhere you rather not be. Don't let it ride or your ride will let you down.

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Update: I added a little coolant, went to the movies, came home. Still the light coming on. So! I added some more (not a whole lot) and started it up in the driveway. Still coming on. Added a bit more (I've added about .5 L total, I bought a plastic container with a spout and measure marks) and took a quick drive out across town and back. The car doesn't seem to be overheating, it doesn't seem to be doing anything really out of the ordinary.

The light just randomly popped on. Is this something that maybe getting the system flushed would fix (at least temp.?)

Any thoughts as to what/where I should check? My reservoir is impossible to read - its borderline opaque! Should I add more fluid?

Cap seems golden, no leaks. I'm kind of worried as I might be driving back east soon and want to make sure everything is as tip top as possible before I do!

The plan right now is to let the car cool and watch The Simpsons re-runs and go back out and see where the fluid is at.

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Check your heater. Set it at max temps and see what it blows. If it's hot, and the temp on the guage is steady and you have no further drop in coolant level, then it's likely an electrical connection/voltage supply to either the bulb or the sensor, or the sensor is on it's way out. You should have the coolant pressure checked as well.

If, on the other hand, you continue to loose coolant, then you have to find out how. Can you see the leak from a hose anywhere on the engine, from the rad, from under the car as IS400 mentions, white smoke coming out the exhaust, or can you spot coolant in your oil? These are all possibilities that mean different things. Keep an eye on that reservoir level.

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eatingupblacktop:

Thanks for the great tips. I also love your user pic!

I think I may have overfilled the reservoir since I have such a hard time reading it (the capacity is 1L and I think I'm in for .7). I ran the car for about 3 minutes @ 2000-3000 RPM and when I was done it looks like the system had dumped out my fresh overfill. The reservoir doesn't really seem to be going down at all, but again, it's hard to read. And I'm inexperienced. I over did it, I think. I saw the sensor and went into OMG NEED TO ADD mode.

As far as the other signs:

White smoke? No.

Leaks to engine? No.

Radiator? Need to check.

Oil? Will check in AM.

Under the car? Besides the overfill, the only leak I have is some minor sweating from the P/S system (need a solenoid cleaning)

Will check the heater thing right now. I'll then pull it into the garage and let it sit and see where the coolant is at.

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Update:

I let the car idle for a bit (called a friend that I needed to catch up with) and then drove stop and go around the block for 10 minutes with the heater ON full blast. The heat gauge never went beyond the 3rd hash mark (below half) and tended to stay there, just below it. Let the car sit to cool off a bit, checked the reservoir with a flashlight behind it and it looked solid red. Standing up over the reservoir and looking into it you could def. see fluid (some of it had a green tinge to it, or maybe even yellow). Started the car up and the warning light came on AGAIN.

I'm stumped. I want the light to go away (hopefully cheaply!). Are there any simple things I can do to possibly fix this before exploring the possibility of taken it in to get looked at? Should I not be driving my car until I do get this fixed?

Also: The light comes on after the car has been running for 45 sec - 1 minute, it's not immediate. I don't have anyway of getting under the car - and I've not noticed any leaks besides my overfill spill.

Summary:

Coolant level fine.

Temp. gauge near constant (below half, right on that closest hash mark)

Light comes on.

Any suggestions? My main concerns are: How do I fix this and Should I be driving my car?

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Tomorrow morning check the level again with the flashlight. It should be closer to the lines marked on the reservoir. There should be some empty space above the fluid. Until you can get it in to have the warning system checked (fairly simple test for a good shop), I would keep an eye on the temps and levels. If you notice an increase in the temps, then there are other concerns - water pump as IS 400 mentioned, air bubble in the system, etc. But for now your symptoms don't sound that serious. The yellow/green you describe is interesting though. Are you sure it's not just discoloration of the plastic? It should be a light red. I know there's a code for coolant temp signal, not sure if a "low coolant level" warning light would throw a code, but you might check anyway. If you haven't done this before, it's pretty simple, here's a link:

http://www.lexls.com/tutorials/intro/codereading.html

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how about the sensor located in the coolant overflow reservoir? that could be bad, also u say u have a leak in ur system, i suggest having a shop put a leak tester on the car, coolant leaks are nothing to fool around with, they only get worse....so unless u r only doing in town driving...have it looked at

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Actually the "leak" was just me accidentally overfilling the coolant reservoir, and a little p/s sweat.

This morning I checked the oil (light brown, no traces of coolant) and actually disconnected the battery to clear any codes that might be going on (took off negative lead, counted to 10). My clock reset but my radio buttons were still intact, wonder if I need to do it longer - I was in a hurry to get to work.

Reservoir tank looked unchanged. The fluid in it looks orange, not red (age?). I'm still having an impossible time reading the level. The tank is near opaque and even lighting it from behind, everything just reflects and it looks like a red mass. I'm just checking by standing OVER the overfill and looking down in.

Called the local Toyota place (they're honest, if not a bit $. Only people in town that have an Lexus working experience) and have an appointment in for Friday. So I have until then to get the light to go away on my own. It's driving me nuts. Any further suggestions? I'm not looking forward to paying for an hour of labor.

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the temp on the guage is steady and you have no further drop in coolant level, then it's likely an electrical connection/voltage supply the sensor, or the sensor is on it's way out.

Good to hear everything checks out. Have your coolant tested or do it yourself with coolant tester you can buy cheap anywhere. Make sure you idle the car for about 5 min before using the tester. Check when your coolant was last replaced. It should be every 30k or 24 mths, and remember to use only distilled water for mix. As I mentioned here, you can jiggle the connector to the sensor to see if that makes the light go out. If you have a meter, you can check the voltages, to ensure there's a supply to the sensor.

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I'm going to jiggle some wires later. I'm actually quite sick today, so getting the gumption to gout and do anything has been difficult.

What's "normal" for a cruising around town engine temperture? It's about 70 here, and it got up to about the hashmark below 50%. That'ss about when I ran out of energy and had to come in.

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You're in the ballpark. Lexus temp guages aren't very responsive. They generally settle in at the midpoint and don't move much unless there's a spike in the temp. They have way too much built in tolerance for variations for my liking. Imo, gauges should display precise measurements with a somewhat attenuated response to fluctuations, something similar to a vu meter as opposed to a digital scope. The Lexus guages do neither, they just sit there making you wonder if they're on the verge of shooting out of the comfort zone and into trouble territory. Get better soon, your car is waiting.

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I'm hoping to get healthy soon - this cold is NO fun. I tried again to get a REALLY good look at the level and got nothing, even with borrowing lamps from the house. It's just not easy to see. I let the car idle at 2000 RPM for a bit and once the temp. guage started moving I cut the power and made sure my coolant reservoir was fine. Jiggled some wires. Tank is at it's neck (expecting a bit of overflow to pee out tomorrow) so it's most def. not the

Last question before the sudafed takes over: How hard should the cap be to get off? Mine's pretty easy given the fact that I assume its supposed to be a 'under pressure' situation.

VU meter? I work audio and video... that's something I can get behind!

I have a date with Toyota on Friday, we'll see what they say. Hoping it's something simple/silly.

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Update:

The problem seems to have gone away. Air? Lack of pressure cap? Wacky sensor? Who knows? The actual coolant level seems fine.

I have to go on a little drive this evening out the edge of a town. I'll bop on out to the highway and back on during my trip. As of right now, I'm going to cancel my appointment @ Toyota and actually have the system flushed (it could use it) soon.

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Trip around town confirms so far: No light. I'm going to add "checking the coolant overfill" to my weekly chores.

When I sat down and REALLY thought about it: the light went away when I dropped my friend off at the grocery store. Important thing to know is that up here in the mountains sideroads have BIIIIIG dips for 'rain gutters' since it's all hardpan and they direct all the flashflood waters to storm drains/resevoirs. If you take it any faster than 10 your going to loose some fillings. It's made me think maybe there was an airpocket in there and I just burped it. Or that jiggled the sensors just right. As of right now, my roommate is taking credit for it. Overflow level is fine. I'll keep an eye on the temp, get the radiator flushed before it gets scary cold and have whomever cleans the solenoid screen let me know if they see anything down there.

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*AUGH*

It's back. Just went out to the store and back, and the Parthenon of Doom light has reappeared. As soon as I pulled into my garage I gave it a few to cool and checked the overfill tank. To the brim! The pressure change even kicked on the overflow valves and it peed a little on my garage floor.

This is actually the first good look I've gotten at the old coolant. It's orange. Orangey-greeny. Not the light 'robotussin' red you'd expect. I'm thinking maybe previous owner didn't put the right stuff in.

Any thoughts? Everyones been awesome so far helping this relatively new guy figure this out.

EDIT: I just ran the car, radiator light *ON* while looking (top down) at a VERY full coolant overflow tank.

Any help would be appreciated.

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not a mechanic, but sounds like you just have a bad sensor on your overflow tank.

mine was doing the same thing- put in a whole new tank and sensor unit, and it is fine now. - about $300.

question- for someone- is there any other sensor that would effect the coolant?

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I do not know about the Lexus specifically, but most water pumps have a "weep hole" that lets a little bit of coolant escape when it is on its last legs; i.e., is the water pump's way of saying "replace me". Can you tell if the leaking coolant is coming from the water pump?

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And the survey sez:

Sensor! After trying for a week+ to find something mechanical wrong with everyone here's awesome help, I took it up to Toyota. Paid 1/2 hour of labor and the said my sensor has a circuit closing issue. Which is exactly what my former band mate (he's a Lexus tech in MI) said - he had replaced my timing belt before I drove from MI to WY and he said my water pump looked strong, and that was less than 10K miles ago (I don't drive very much out here, Laramie is small).

I'll probably replace the sensor when I get the coolant flushed late next month. Looks like Toyota when they were investigating reseated the connection so it's less likely to stay open for now, so the Parthenon of Doom isn't glaring at me for now.

Thanks again everybody for great input and answers!

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