Elless400

I just replaced my fan bracket, radiator and thermostat in my 96 LS400

Everything's reconnected properly, thermostat's the right direction (breather at the top as well).

Well, I can't fill up with coolant from the inlet housing hole. It fills the housing then acts plugged. I was very careful throughout this process.

Is there some trick to this?

Elless400

I just checked, and the coolant level dropped in the housing a bit, down to the thermostat spring, so it is going somewhere, very slowly.

I bought the Denso radiator from Amazon and the OEM thermostat from Lexuspartsnow.

Is an airlock of this magnitude possible with these engines?

It had seemed to stop draining from all places earlier in the day before I cleaned up for the night, then, the next morning, the bag I'd covered the upper radiator hose pipe with had filled with coolant, magically.

Also, a decent little amount of coolant came out when I removed the original thermostat. This was AFTER I had drained the coolant via the valve at the bottom of the radiator.

What is going on here?

Banshee365

Did you remove the overflow bottle cap when you drained the coolant the first time? Since it seems you didn't have any overheating issues prior to your repair you probably don't have any blockages. Cooling system blockages are really rare anyway. You may just not be used to how the cooling system fills. When the block and heads fill the inlet will stop taking coolant. Then it will start forcing coolant into the overflow bottle if you fill it to the tippy top and let it go down. You can see the small hole that goes to the bottle.

Elless400

Before the drain I loosened the overflow cap to allow air to come in, but didn't remove it completely because I like things covered to keep out foreign materials.

I also took off the inlet plug and capped the hole loosely with a rigid bag (same idea regarding foreign materials). The bag could not and did not get sucked in.

I did everything without lifting the vehicle at any point. It just occurred to me that this could be an issue. I hope it is because that's an easy fix. Too late to mess with it tonight though.

ankurdave

It sounds like you only drained coolant from the radiator and not the engine block?

I did this recently when cleaning the throttle body since I was feeling too lazy to lift the car to access the engine block drains. I encountered some similar problems: coolant still came out of the throttle body coolant hoses during disassembly, and the inlet housing wouldn't take much coolant after reassembly.

I figured it was because draining the radiator was ineffective at draining the engine block due to the thermostat being closed. I just topped up the reservoir, started the engine, and kept refilling it as necessary. Eventually the system took all the coolant I had drained from the radiator.

Elless400

. That's correct. So, you're supposed to drain from the block as well, every time?

oldskewel

iTrader: (1)

Yes, if your goal is to drain all the old fluid.

But if you just wanted to drain enough to do the work you needed - e.g., radiator and water pump change, you can leave the old fluid in the block.

So if your old fluid was pretty new, leaving the block drains untouched is not a problem.

There should be coolant filling instructions printed on the coolant reservoir.

I find that filling coolant with the car either on an incline with the front up, or with the front jacked up, or both, will make things easier. Make sure the heater is set to full hot so the heater valve opens. Fill at the reservoir, let the car run, with a funnel in the reservoir opening. At some point when things warm up enough, the thermostat will open and the reservoir level will start dropping. Keep it topped up. Then you'll get bubbles coming out. To encourage the bubbles to make it to the reservoir, you can rev the engine or squeeze the upper radiator hose.

Here's where I go off-script usually, but it works for me: I don't actually use the bleed screw (mine used to leak slightly, and now that I've got the screw and a new washer in there with no leak, I'd rather leave it untouched if I can). I do what I said above, then the next few times I drive it, I check the level afterwards (or before), and add more if needed (once it is safe to remove the cap). There will be bubbles in the system and they will eventually work themselves all the way to the reservoir, as long as the system is pretty much full.

Banshee365

Agree with the above.

To answer your question, the 1UZ isn't very sensitive to air pockets. Just fill it, drive it, and refill until the level stop going down. You may hear some gurgling in the dash with higher rpm while it's working the air out.

Elless400

Thanks everyone! I'm extremely wary of running the car with very little coolant, while filling slowly from the inlet plug. There's basically nothing in the radiator, and probably not that much in the engine. Hopefully nothing gets ruined during this scary process.

Why wouldn't at least the bottom of the radiator fill, I wonder? Basically the engine just seems nearly stopped up. It seems that at least the bottom of the radiator would fill without first running the engine.

I'll have to play with it when I get home.

ankurdave

When I drained the radiator I only got about a gallon of coolant out, leaving almost 2 gallons still in the engine block.

It is kind of curious. The filler bolt opens onto the engine side of the thermostat, so you wouldn't expect it to fill the radiator directly via the lower radiator hose. But it's slightly above the upper radiator hose, so coolant should trickle into the radiator that way. It didn't seem to do that for me either.

Elless400

Thanks for the heads-up, ankurdave.

Out of curiosity, I'll see how much came out of mine when I get home. Then I'll partially pre-fill the empty radiator through the top hose out of paranoia and top-off everything else before running the engine.

8055y

Hey man, Jumping in on this thread a little late.

I just put in a new radiator and hoses on my 95. Here are the main points to double check:

1) To drain the entire block you'd need to open the drain plug on the bottom of the radiator (passenger side) while the reservoir cap is open/off. At stock height you shouldn't need to lift the car to get a coolant catch under there.

2) once you've installed all your new parts make sure the reservoir cap is open and use the fill point above the thermostat to re-fill the coolant into the car. These cars are well engineered so you'll see the reservoir filling up simultaneously. Once the fill point stops allowing you to add more fluid, make sure no bubbles are coming up and then close it.

3) Now, I'm not sure if this is Lexus procedure, but what I did is start the car and let it get up to operating temp. The thermostat should open up at about 130 degrees F (thats what my temp meter reads)
This will cycle the coolant through the system and help remove any other air pockets. Close the cap on the reservoir.

Please note that Lexus hoses (OEM) are not super crazy hard (my old Audi hoses where not very flexible at all, but my new Lexus hoses have some give/flex) , so you should be able to feel that the coolant is running through the hoses by squeezing them.

For the first shake down drive keep an eye on your temp gauge. Make sure your fans are turning on. I added a digital temp gauge just so I could better monitor my motor since I do a lot of long distance drives. So far, even in the desert on a 95 degree day going up hill with the AC on it hasn't gone over 182.

Elless400

Conclusion,

Yes, the engine was full of coolant.
​​​​No my radiator wouldn't fill via the inlet housing.

​​​​​​I carefully pre-filled the radiator through the top radiator hose and it took 75 percent of a gallon before it would have been too full to put the hose back without a small mess.

When I ran it up to temp with the heater on, the level in the reservoir stayed pretty much the same. I didn't have to top up at all. No leaks, temp was perfect, so I took it out for a freeway romp.

Uneventful. All is well. Once home, I checked the reservoir and no change. Full. I'll see how much coolant it needs in the morning, but I won't extend this thread for the sake of that report.

So, thanks again to everyone and I wish you all the best.