Coolant Level (1 Viewer)

[jdotlim]

I've had my 98 LC since February this year. The past few months, I've been checking the fluid level on my car in the mornings once a month. Once a month, I've been having to refill the reservoir slightly about 1-2oz, or less back up to the full line. But this morning, I was a bit lazy and drove to work without refilling it. But when I got to work, the reservoir was well over the full line. Is this normal?

My radiator is always full. Car does not overheat, I've even did a pressure test in the cooling system with no leaks anywhere. Below are the details on what has been done to the car including mileage. Thanks in advance.

1998 LC, 146K (Currently, bought it at 140K)

112K, Timing Belt and Water Pump was changed by PO

Under my ownership since Feb, past 5K miles
Heater Tees
Thermostat
Radiator Cap

I also refilled about 1 gallon of radiator after changing out the thermostat.

 

[Eyedaho]

That reservoir is there to account for thermal expansion of the coolant when your engine warms up, so the level should be higher when the engine is hot versus when it's warm. Are you filling to the cold full line and then it's above the hot full line when warm?

 

[jdotlim]

That reservoir is there to account for thermal expansion of the coolant when your engine warms up, so the level should be higher when the engine is hot versus when it's warm. Are you filling to the cold full line and then it's above the hot full line when warm?

yeah, this morning was when it sat overnight, cold. It was slightly below the full line. But I did not refill it, I just drove it to work. Got to work, and rechecked it, and it was well above the full line.

 

[Ayune]

Fill & monitor the coolant level directly at the radiator. The overflow bottle level will change constantly, so don't go by it or you'll go nuts and end up with coolant being dispelled from the overflow bottle cap's hose. As long as your radiator is full your cooling system is full. The radiator will give & take from the bottle as needed to compensate for expansion.

 

[jdotlim]

Fill & monitor the coolant level directly at the radiator. The overflow bottle level will change constantly, so don't go by it or you'll go nuts and end up with coolant being dispelled from the overflow bottle's cap hose. As long as your radiator is full your cooling system is full. The radiator will give & take from the bottle as needed to compensate for expansion.

I think that is what is making go nuts. Radiator is always full when I check it. But reservoir isn't at this time. I guess this is normal. But I will keep monitoring the radiator. Thanks.

 

[katit]

I learned to fill to "Full" initially. But then after couple days drive I fill to "Full" when engine all way warmed up and in a morning it usually like couple inches above bottom. Get's to the MAX when warm. I guess with a volume of cooling system it expands so much

 

[jdotlim]

I learned to fill to "Full" initially. But then after couple days drive I fill to "Full" when engine all way warmed up and in a morning it usually like couple inches above bottom. Get's to the MAX when warm. I guess with a volume of cooling system it expands so much

I guess it is normal for the reservoir to fluctuate. As long as the radiator is full, the system is happy. I was pulling my hair out trying to figure this out.

 

[katit]

I guess it is normal for the reservoir to fluctuate. As long as the radiator is full, the system is happy. I was pulling my hair out trying to figure this out.

When engine cools off - fluid shrinks and sucks coolant through that hose in expansion tank cap back into radiator. When engine warms up - excess coolant pushed out to expansion tank.

Yes, it's normal. I myself was surprised there is so much but it does stay between low and high. I guess another option is to make sure when cold in a morning insure it's at MIN mark.

 

[jdotlim]

When engine cools off - fluid shrinks and sucks coolant through that hose in expansion tank cap back into radiator. When engine warms up - excess coolant pushed out to expansion tank.

Yes, it's normal. I myself was surprised there is so much but it does stay between low and high. I guess another option is to make sure when cold in a morning insure it's at MIN mark.

I am so glad this is normal. haha

Thank you everyone for your input.

 

[Eyedaho]

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• Eyedaho
• Dec 12, 2019

 

[Ayune]

The fluid does expand & contract with temperature, as does the overall capacity of the system (the ways, hoses, cavities, etc). Net result is approximately what's between the MIN and MAX lines on the bottle. SCIENCE!

 

[ZetheGSD]

I notice that mine varies from dead cold to operating temp the level will change 2-3 inches in the reservoir. It drives me nuts as well LOL

 

[jdotlim]

I notice that mine varies from dead cold to operating temp the level will change 2-3 inches in the reservoir. It drives me nuts as well LOL

Well after this thread, and noticing everyone is experiencing the same issue I have. I can sleep better at night. HAHA

 

[AlpineAccess]

You may also check at the coolant bypass tube underneath the heater t's. Not a common place to have a very slight leak, but myself and quite a few others have found a VERY minor leak there.

I have been losing about 1/10 a quart every 2k miles.

 

[jdotlim]

You may also check at the coolant bypass tube underneath the heater t's. Not a common place to have a very slight leak, but myself and quite a few others have found a VERY minor leak there.

I have been losing about 1/10 a quart every 2k miles.

I will check, my guess is to check when the car is running? I've done a pressure test, and nothing comes up as a leak. Would a pressure test not bring that issue up? Thanks.

 

[AlpineAccess]

I will check, my guess is to check when the car is running? I've done a pressure test, and nothing comes up as a leak. Would a pressure test not bring that issue up? Thanks.

You don't need to check while running, if there is a leak you will see built up crusty coolant at the base of that metal tube going up to the first of the heater T's from the bottom.

What pressure is your system holding? Sorry if I missed that.

I would be looking at the system charging to 20PSI and holding that pressure for a few hours without changing.

 

[jdotlim]

it was about 15-20psi, but I didn't leave it for one hour. I left it for about 10-15 minutes. I thought that was enough, but I can do it again. But I will check later today or this weekend about the bypass tube. Thanks!

 

[AlpineAccess]

it was about 15-20psi, but I didn't leave it for one hour. I left it for about 10-15 minutes. I thought that was enough, but I can do it again. But I will check later today or this weekend about the bypass tube. Thanks!

You got it. The reason this can be tough to find is that when this tube starts leaking it leaks VERY slow. It also has a tendency in my case to "self seal" up to about 16-17 PSI which is the radiator cap release pressure. Pushing it past there can sometime break that seal to identify the issue.

 

[jdotlim]

You got it. The reason this can be tough to find is that when this tube starts leaking it leaks VERY slow. It also has a tendency in my case to "self seal" up to about 16-17 PSI which is the radiator cap release pressure. Pushing it past there can sometime break that seal to identify the issue.

but obviously, if no crust. no leak right? haha

 

[Eyedaho]

but obviously, if no crust. no leak right? haha

Especially if you are using the red coolant. It leaves a really obvious visual indicator.