Coolant level goes down

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I'm trying to find information out on this as well. I've read a couple of threads and it seems to be a common problem.

A little background its a 99 LX with 193k. I brought it with low coolant but car ran and drove fine with no CEL and temp gauge on the dash is good, so I put coolant in it after I brought it. A couple days later I drove it 1300 miles round trip from GA to DC and had to stop and put coolant in it on the way back home.

I have no visible leaks, no coolant in the oil (which from research I've done shows that is not always a determining factor of blown head gasket in these cars), replaced heater Ts and rad cap with OEM and I'm still losing coolant somewhere. I'll go check the hoses but I'm not seeing any spots in the driveway and I have my skid plate off. Any other suggestions before I brought it to a shop? I guess I could try a compression test or the other test - pressure test? But I'm not savvy with how to use those tools although theres always YouTube.
 

2001LC

 
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Did you top as outlined in post #12. Very often system is not properly topped after some job like timing belt or coolant flush, etc..
 
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Did you top as outlined in post #12. Very often system is not properly topped after some job like timing belt or coolant flush, etc..
So you are saying just park the truck tilted up, and continue to fill at the radiator until I cant anymore? I havent tried that. Was thinking of renting a combustion leak test today.
 

2001LC

 
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So you are saying just park the truck tilted up, and continue to fill at the radiator until I cant anymore? I havent tried that. Was thinking of renting a combustion leak test today.
Front higher is best, as air bubbles raise to the high points. But some air get trapped. That's why it can take two or three cool down cycles to "burp" the air out.
 
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Front higher is best, as air bubbles raise to the high points. But some air get trapped. That's why it can take two or three cool down cycles to "burp" the air out.
Right. So I'll just make sure to park on an incline after driving it and keep the rad topped off.
 

2001LC

 
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Yes but remember to drive or get to operating temp with both heaters set to high heat. You can turn fan off once temp set. Get engine to 2K RPM for a few minutes minimum. Cabin heat should blow very hot when cooling system full and working as designed.

If after 3 cool down cycles it still keeps needed more, especial about the same amount more. Then yes you've a leak.

If head gasket, it can usually be seen from outside. It is possible to inspect every inch of gasket. It can be internal only, but not what we normally see. Number 1 cause of blown head gasket, is warped head from overheating. This is from running low on coolant 9 out of 10 times.
 
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Yes but remember to drive or get to operating temp with both heaters set to high heat. You can turn fan off once temp set. Get engine to 2K RPM for a few minutes minimum. Cabin heat should blow very hot when cooling system full and working as designed.

If after 3 cool down cycles it still keeps needed more, especial about the same amount more. Then yes you've a leak.

If head gasket, it can usually be seen from outside. It is possible to inspect every inch of gasket. It can be internal only, but not what we normally see. Number 1 cause of blown head gasket, is warped head from overheating. This is from running low on coolant 9 out of 10 times.
Ok so I'll tell you what I did. I let the truck get up to operating with the heaters on. At first it was kinda like warm air but after it got fully warmed up it was really hot so I guess thats good. I kept the RPMs up to around 2k like you said for quite a while. I checked under the hood and the res was at full, which before it was a little under full. Research tells me that this is normal, as when the systems gets hot coolant spills back into the res. Correct?

After that I turned it off. I checked this morning and the coolant level is back down to below half which I think is also normal, unless I have it backwards. I checked the radiator and coolant is at the bottom of the neck. I have to run an errand today. I will put a tad bit more coolant in the rad like you recommend, almost to overflowing. Run my errand and when I come back I will park it back on an incline (nose up), do the 2k RPM for a little bit and see where the level is. Then I'll turn it off and let it sit.

Currently there doesnt seem to be a need to add coolant right? If I start driving around and check the res level and its at low or below so I add coolant or not?
 

2001LC

 
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Yes coolant expand and contacts with temperature. The radiator will or should always be full. The reservoir however, will raise and fall with temperature, provide you have a good working radiator cap.

Keep in mind. Even after a full 8 hour cool down. OAT (Outside Air Temp) will either raise or lower level in reservoir. Example. on a 100 F OAT day reservoir should be near full line. Whereas if OAT -10 F reservoir will be near low line.

You do not need to run engine at 2K RPM after driving. Driving takes care of getting RPM's up for you. That is only needed to simulate driving. Engine turning faster turns water pump faster. This increase flow of coolant, which helps move air out of pockets.

If you look at reservoir, just after a drive where engine is at operating temp. It should have raised to near full line. If radiator full, but reservoir not going up in down with temperatures. Then chance 98% you've a bad radiator cap.
 
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Yes coolant expand and contacts with temperature. The radiator will or should always be full. The reservoir however, will raise and fall with temperature, provide you have a good working radiator cap.

Keep in mind. Even after a full 8 hour cool down. OAT (Outside Air Temp) will either raise or lower level in reservoir. Example. on a 100 F OAT day reservoir should be near full line. Whereas if OAT -10 F reservoir will be near low line.

You do not need to run engine at 2K RPM after driving. Driving takes care of getting RPM's up for you. That is only needed to simulate driving. Engine turning faster turns water pump faster. This increase flow of coolant, which helps move air out of pockets.

If you look at reservoir, just after a drive where engine is at operating temp. It should have raised to near full line. If radiator full, but reservoir not going up in down with temperatures. Then chance 98% you've a bad radiator cap.
Ah ok. I just replaced the rad cap with OEM so I know thats good. Actually the old one didnt look bad either. I'll report back after today's drive.
 
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Here are some pics I took tonight. 5 hours after letting it run, getting up it to temp and then revving it to 2k for a little while as I wasn't able to drive it. The coolant and the res was back up to Full.

I don't know if I need to add any coolant at this point but I know previous after a lot of driving I've need to add coolant.

20200323_201036.jpg


20200323_201057.jpg
 

Hugh Calgary

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I think you are having problems getting all the air out of the system. Here is the process I have used on 2 Land Cruisers and an FJ cruiser. Gets all the air out and avoids the frustration you are going through.
Before I drained the old coolant I drove the front wheels of the LC onto my ramps. The ramps are 10" high. After I drained the old coolant I used a Lisle 24680 Spill-Free Funnel to fill the radiator/engine with new coolant. This funnel attaches to the radiator in place of the radiator cap. I ran the engine until it got hot enough to open the thermostat. While the engine is warming up I make sure there is coolant in the funnel. Every minute or so I squeeze the upper radiator hose which usually makes an air bubble come out of the funnel. After I am sure the engine is hot enough to open the thermostat I turn off the engine and leave it until it is cold. I leave the funnel attached to the radiator and fill It half full of coolant.
 
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When engine is running at its optimal temp, the water on the white reservoir (not the the radiator -the rad cap should always be closed at all times when engine is running) goes UP a little. After using the vehicle, leave it for 8 hours or so to fully cool down, check the white coolant reservoir again you should notice the level will go back DOWN.
There’s two levels of coolant in the reservoir, hot - high / cold - high.
 
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94SRUNNER

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When engine is running at its optimal temp, the water on the white reservoir (not the the radiator -the rad cap should always be closed at all times when engine is running) goes down a little. After using the vehicle, leave it for 8 hours or so to fully cool down, check the white coolant reservoir again you should notice the level will go back up.
There’s two levels of coolant in the reservoir, hot - low / cold - high.
That is backwards...when the engine is up to operating temp the level in the reservoir goes up (as the system expands) and when the engine is cold the level in the reservoir goes down (as the system contracts).
 
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That is backwards...when the engine is up to operating temp the level in the reservoir goes up (as the system expands) and when the engine is cold the level in the reservoir goes down (as the system contracts).
I stand corrected. You’re right let me edit that. Thank you. Just noticed that now, have to focus on cooking supper first.
 

2001LC

 
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Here are some pics I took tonight. 5 hours after letting it run, getting up it to temp and then revving it to 2k for a little while as I wasn't able to drive it. The coolant and the res was back up to Full.

I don't know if I need to add any coolant at this point but I know previous after a lot of driving I've need to add coolant.

View attachment 2247184

View attachment 2247185
I like to see coolant into the neck of radiator, under the cap. I also like a minimum of 8 hours before taking cap off. It's import to not even loosen cap during cool down. So coolant should always be to neck now, after 8 (12 even better) hour cool down. If next time you check it is not, I'd top one more time. We want to see two times in a row, where coolant can not be added because it is so full. Both front and run heaters, should now be blowing very hot.

The reservoir should be at the same level each time now, if OAT is the same. Again lower if OAT lower, higher if OAT higher.

Make sure to hose off any spillage you see. Including front and back of radiator fins. Avoid getting your drive belt or pulleys wet, especially while engine off.

If you have access to tech stream, read your engine temp. You can also use IR temp gun. Shoot temp on back side of thermostat housing, just before water pump works well.
 
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So my radiator stays full but the level in the reservoir has been steadily going down. This is where is sits now fully warmed up. The most driving I did was about 35-40 mins through town.

20200326_133727.jpg
 

2001LC

 
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Copy from above: "The reservoir should be at the same level each time now, if OAT is the same. Again lower if OAT lower, higher if OAT higher. "

Note: OAT (outside air temp) when you check level of reservoir, after 8 hr cool down. If say it's 65F OAT, each morning when you check reservoir level. And level the same. You're good.

If on the other hand, it keeps dropping ever morning and you need to add. You've a leak.

But remember OAT effect level, not just engine temp.
 
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