Engine Coolant

[flanker271]

I started up my 92LS this morning and is ready to go to work when I noticed that my "low engine coolant" light is on. I went to Autozone during lunch break and added some Pristene anti-freeze coolant in my reservoir and the light went out.

I was wondering isn't the coolant system a closed system? What could be the normal cause for the engine to lose coolant besides leaking? Does temperature have any factors? I live in Arizona and recently there has been a rapid decline in temperature, around 20 degrees F lower than usual. Does this contribute to the lower coolant level?

Just wanted to know any possible causes before I conclude that my radiator or my water pump is leaking.

Thanks

[Lexls]

Same thing happened to me. When it started to cool down here the coolant level dropped. Strange thing.

[Em91]

The coolant is a closed system. If you are missing some it is either leaking out or being burned. My car was also missing coolant. I finally found the problem to be the rear cross over pipe. It was a real messy job but my leak is fixed. You are going to have to find where the leak is. Good luck.

[90LS400Lexus]

I agree- it should not be going down I would not think. It never went down at all on my 90' LS even when winter arrived. Have you noticed the temperature guage? Has it been staying on normal?

[flanker271]

Yes the temp gauge has always been in the normal range. Are there any symptoms if there is a leak? For instance, should I smell it from the a/c vents, etc.?

[Em91]

Hey Flanker, you are going to have to search for the leak. First things first, make sure it isn't mixing with the oil by just checking your oil dipstick. If that is fine then you will have to look all over for this leak. Check the reservoir for the coolant and check that it isn't leaking out of any of the hoses attached to it or even the sensor on top. Next check to see if you see any leak noticeable in the location where the water pump is located. Check the radiator and its hoses and in my case I got underneath my car and the leak was coming down the rear sides of the engine. My leak was coming out of the cross over pipe. Good luck searching.

[pgupta]

As its getting colder, I am having the same issue. With cold weather, heat is turned on inside the car. The car is probably heated using the engine coolant through a forced air to coolant heat exchanger. I noticed a plastic mechanism that probably controls the flow of the coolant to the heat exchanger in towards the cabin is showing a drip leak. It is located just under the passenger side wiper blade mechanism. The drip has eaten into some wiring/hose underneath as well.

Anyone has had similar problem? I am going to replace that part for starters. Any suggestions from someone who may have already done this?

[wwest]

In the twelve years I have owned my 92 LS400 I probably added as much as a quart of antifreeze, likely about a pint at a time. Liquids decrease their volume with temperature, so if your fluid was even close to the low mark during the summer, the onset of colder weather would likely result in a low fluid indication.

I finally changed out the factory fluid in mine just this past summer.

Oh, and it isn't really a "sealed" system. The radiator cap has a pressure release to allow coolant to flow backward into the expansion tank as the engine temperature rises, heats the coolant, and its volume expands. The expansion tank is in no way "sealed". As the tank "refills" due to engine heating, the trapped air, and the moisture contained therein, must be allowed to escape.

As the engine cools the coolant is pulled back into the radiator.

[glenmore]

As its getting colder, I am having the same issue. With cold weather, heat is turned on inside the car. The car is probably heated using the engine coolant through a forced air to coolant heat exchanger. I noticed a plastic mechanism that probably controls the flow of the coolant to the heat exchanger in towards the cabin is showing a drip leak. It is located just under the passenger side wiper blade mechanism. The drip has eaten into some wiring/hose underneath as well.

Anyone has had similar problem? I am going to replace that part for starters. Any suggestions from someone who may have already done this?

←

Yes, I have the same problem. The leak seems to be a fairly small one, leaving a small pile of red crust. Some has dripped to the wiring below. I had a small piece of sheet copper and just put it underneath there to catch the drips. I'll have to get to it one of these days.

glenmore

1990 LS400

[acflye]

In the twelve years I have owned my 92 LS400 I probably added as much as a quart of antifreeze, likely about a pint at a time. Liquids decrease their volume with temperature, so if your fluid was even close to the low mark during the summer, the onset of colder weather would likely result in a low fluid indication.

I finally changed out the factory fluid in mine just this past summer.

Oh, and it isn't really a "sealed" system. The radiator cap has a pressure release to allow coolant to flow backward into the expansion tank as the engine temperature rises, heats the coolant, and its volume expands. The expansion tank is in no way "sealed". As the tank "refills" due to engine heating, the trapped air, and the moisture contained therein, must be allowed to escape.

As the engine cools the coolant is pulled back into the radiator.

I have a 92 ls400 also and i am noticing a small puddle of antifreeze on the floor of my garage....where is the cross over pipe and how do i clean the reservior, mine is very dirty........

[Lex-ed]

Where should the coolant level be? If the car is cold, shouldn't the level show between the range of 'cold' fill lines? When I looked yesterday (the car was cold), I saw only about 1.5 inches of coolant showing in the bottom of the reservoir, so definitely below the cold fill lines. I added maybe 3/4 to a cup of red coolant, which took it up the the lowest fill line. I drove the car (which did not overheat) on errans, and then checked it a few hours later after it had cooled off, only to see the coolant level right back to that same low level of roughly 1.5 inches. Engine oil looks fine/normal. Doesn't this point to a leak? No fluid on floor of garage when I checked it the past 2 mornings. I would expect to see some fluid if it is leaking. I have not noticed any big puffs of white smoke when I start the car either. Tx. for any input.

[Lex-ed]

as a followup to my original post, the problem turned out to be a leaking radiator. after i realized the coolant leak was rapidly getting worse, i took it in for inspection. the reason i was not seeing any leakage is because the coolant was pooling in the protective liner that covers the underside of the front of the car, and it was blowing off during higher speed driving. the radiator was older and the the clamp (at the very top) had lost ability to withstand the pressure. moisture was visible all along the clamp. replacing the radiator was the right fix, as the coolant loss stopped immediately after it was replaced.

Where should the coolant level be? If the car is cold, shouldn't the level show between the range of 'cold' fill lines? When I looked yesterday (the car was cold), I saw only about 1.5 inches of coolant showing in the bottom of the reservoir, so definitely below the cold fill lines. I added maybe 3/4 to a cup of red coolant, which took it up the the lowest fill line. I drove the car (which did not overheat) on errans, and then checked it a few hours later after it had cooled off, only to see the coolant level right back to that same low level of roughly 1.5 inches. Engine oil looks fine/normal. Doesn't this point to a leak? No fluid on floor of garage when I checked it the past 2 mornings. I would expect to see some fluid if it is leaking. I have not noticed any big puffs of white smoke when I start the car either. Tx. for any input.

[pishta]

as a followup to my original post, the problem turned out to be a leaking radiator. after i realized the coolant leak was rapidly getting worse, i took it in for inspection. the reason i was not seeing any leakage is because the coolant was pooling in the protective liner that covers the underside of the front of the car, and it was blowing off during higher speed driving. the radiator was older and the the clamp (at the very top) had lost ability to withstand the pressure. moisture was visible all along the clamp. replacing the radiator was the right fix, as the coolant loss stopped immediately after it was replaced.

Where should the coolant level be? If the car is cold, shouldn't the level show between the range of 'cold' fill lines? When I looked yesterday (the car was cold), I saw only about 1.5 inches of coolant showing in the bottom of the reservoir, so definitely below the cold fill lines. I added maybe 3/4 to a cup of red coolant, which took it up the the lowest fill line. I drove the car (which did not overheat) on errans, and then checked it a few hours later after it had cooled off, only to see the coolant level right back to that same low level of roughly 1.5 inches. Engine oil looks fine/normal. Doesn't this point to a leak? No fluid on floor of garage when I checked it the past 2 mornings. I would expect to see some fluid if it is leaking. I have not noticed any big puffs of white smoke when I start the car either. Tx. for any input.

An easy test for a coolant leak is getting a pressure test cap from a parts store, usually loaned out per model. It attaches and you pump air into the system with a bike pump or something that will not exceed 16 lbs pressure and has a guage on it. You pump it up, look for any pinhole leaks and watch the leak down guage and see if it loses any pressure. Lots of people replace the radiator cap or other pressure sensetive caps in the system and have good results. always fill a cold system to the low point as coolant has a lower volume when it is cold.

[Lex-ed]

Ok, thank you. I have it a smidge..maybe 1/4 inch above cold line, and doesn't seem to give quite enough room for fluid to expand when heated. Shld. take out a small amount.

as a followup to my original post, the problem turned out to be a leaking radiator. after i realized the coolant leak was rapidly getting worse, i took it in for inspection. the reason i was not seeing any leakage is because the coolant was pooling in the protective liner that covers the underside of the front of the car, and it was blowing off during higher speed driving. the radiator was older and the the clamp (at the very top) had lost ability to withstand the pressure. moisture was visible all along the clamp. replacing the radiator was the right fix, as the coolant loss stopped immediately after it was replaced.

Where should the coolant level be? If the car is cold, shouldn't the level show between the range of 'cold' fill lines? When I looked yesterday (the car was cold), I saw only about 1.5 inches of coolant showing in the bottom of the reservoir, so definitely below the cold fill lines. I added maybe 3/4 to a cup of red coolant, which took it up the the lowest fill line. I drove the car (which did not overheat) on errans, and then checked it a few hours later after it had cooled off, only to see the coolant level right back to that same low level of roughly 1.5 inches. Engine oil looks fine/normal. Doesn't this point to a leak? No fluid on floor of garage when I checked it the past 2 mornings. I would expect to see some fluid if it is leaking. I have not noticed any big puffs of white smoke when I start the car either. Tx. for any input.

An easy test for a coolant leak is getting a pressure test cap from a parts store, usually loaned out per model. It attaches and you pump air into the system with a bike pump or something that will not exceed 16 lbs pressure and has a guage on it. You pump it up, look for any pinhole leaks and watch the leak down guage and see if it loses any pressure. Lots of people replace the radiator cap or other pressure sensetive caps in the system and have good results. always fill a cold system to the low point as coolant has a lower volume when it is cold.