Does my radiator need to be totally full?

[hadji_85]

I'm changing my rad fluid, I want to get the coolant out of the engine so that i can clean it up.

(1)Could i fill the rad half way turn on the LC until it gets hot enough to take the fluid from the rad and then (2) drain out the fluid in the rad (the fluid in the rad should be the fluid that was in the engine).

 

[corsair23]

Read the FSM re: how to do a full flush of the system. If you don't have a FSM then I'd suggest getting one or take the vehicle in and have someone flush the system for you. Usually not that expensive to do and should only take 1-2 hours. If you like/want to do it yourself then get a FSM or at least a Haynes.

As to your question...I'd fill the radiator full with water after the first drain then run the cruiser with the heater on for awhile. Drain and repeat until all you get is the clear water. Then do a 50/50 ratio or whatever is appropriate for your climate.

GL

 

[hadji_85]

Read the FSM re: how to do a full flush of the system.

GL

My FSM says
1. drain the coolant from the rad and engine drain plug
2. slowly fill the system with coolant
3. reinstall the rad cap
4. warm up engine, check for leaks
5. recheck coolant level

Is there perhaps another section you were talking about that goes more in depth on how to fully clean the coolant out of the system?

 

[GXO]

search

 

[RavenTai]

search

and see the FAQ

 

[Romer]

My FSM says
1. drain the coolant from the rad and engine drain plug
2. slowly fill the system with coolant
3. reinstall the rad cap
4. warm up engine, check for leaks
5. recheck coolant level

Is there perhaps another section you were talking about that goes more in depth on how to fully clean the coolant out of the system?

After step 1, refill with water and rad flush stuff you buy at the parst store. Read the instructions on the bottle. After that cycle. Drain and run water through again.

Step 3 should be mixture of coolent and water. Most prefer to buy there water by the gallon so the normal tap water minerals won't be in the fluid.

 

[Proven]

In some cars you need to turn on the heat setting to drain the heater cores also. Not sure if you need to do this in a cruiser, but I have had to do this before when draining to get it all out. You just move the temp to full heat.

 

[Grench]

1. Drain while -warm-.
2. Let cool 15 minutes.
3. Fill with tap water
4. Warm it up.
5. Drain.
6. Repeat steps 2-5 four more times. If it isn't coming out so that you can see a 1/2" washer through a foot of the drain water in a 3 gallon bucket, then do it again.
7. Repeat steps 2-5 two times using distilled water instead of tap water.
8. Fill with 1/2 distilled and 1/2 Toyota red coolant or equivalent.

Search & use the FAQ. There are some VERY good write ups. Some more extreme than others.

 

[Beowulf]

My FSM says
1. drain the coolant from the rad and engine drain plug

Be aware that there is a drain valve (petcock) on the radiator and there is a brass plug on the side of the engine block to drain the coolant from the engine.

-B-

 

[hadji_85]

why do you need to drain from the engine also? why not just keep draining from the radiator? Seems like there should be coolant in the engine when it starts up.

 

[Grench]

When I did mine, I disconnected the top hose on the vehicle left side of the radiator (DS on US models). If you cut the bottom out of a distilled water jug it will angle into that hose and you can put 2 gallons directly into the block when you're filling.

The engine has a good 2 gallons+ of dirty crap filled sludgy water in it. You aren't going to get it to travel uphill to the radiator to pull it out. That is why there is a drain plug there. Read the FAQ & writeups on this as there is an order to removing the petcock, block plug and radiator cap that makes it easier and lessens your likelihood of getting burnt by the stuff coming right out of the block into your face.

 

[Beowulf]

I'm changing my rad fluid, I want to get the coolant out of the engine so that i can clean it up.

why do you need to drain from the engine also?

You want to drain from the engine so you can get the coolant out of the engine. That was the statement you made in your first post. I guess I'm being dense here but this seems intuitively obvious to me. The brass plug is a lot easier to remove than the petcock on the radiator. 12mm socket on a 2' extension through the DS wheel well. You don't need to remove the tyre. Tighten gently when you put it back in. (spec is probably in the FAQ but it's something like 18-20 ft/lbs.)

-B-

 

[sseaman]

what do you all do with the massive amount of old coolant/ water with old coolant, i cannot find anybody that will take it.

 

[Beowulf]

This is a good question and I believe we have covered this a long time ago and there were mixed opinions on what to do with it. Add to this that there are mixed local regs on what to do with the old coolant.

I have a "friend" :wink: :wink: that flushes it down the toilet.

The rationale is that ethelyne glycol decomposes when exposed to sunlight (or so my friend discovered when he was researching how to dispose of it.) Also, this friend's mechanic drains coolant directly to the sewage system.

-B-

 

[informationjunky]

Most auto stores will take it.

 

[ozarkmud]

I've looked in the '96 FSM and I don't see any answer to how full the radiator should actually be. Inch from the top or two, or flush with the neck, etc. This is a really good question. Can't see it in the FAQ, either.

Could someone show me where I can find this out?

Thanks!

Edit:

Did more digging on this. It seems like one could run the level lower in the radiator and not even need an expansion tank: Deleting Coolant Overflow Bottle - https://forum.ih8mud.com/threads/deleting-coolant-overflow-bottle.1030643/

If it never overheated excessively, it should never dump coolant. But if it did, it'd be on the ground, and that isn't good.

There are radiator caps that are vent only, and some that allow fluid to return. If it allows fluid to return, I'm not sure if that might cause an issue.

A lot of older vehicles didn't have expansion tanks. In that case, I think the lower level makes sense. Otherwise, it sounds like you could fill it mostly full.

I'm not sure how much cooling effectiveness percentage you'd lose running a radiator with less fluid and no tank, vs completely full.

 

[jonheld]

With a cold non running engine, radiator should be filled to the top of the filler neck. Overflow bottle should be filled to the full line.
This allows the radiator cap to function correctly. Otherwise you'll be compressing air as the engine comes up to temp.
The system self bleeds up to a point, but you should always start with a full radiator.

 

[mudgudgeon]

I've looked in the '96 FSM and I don't see any answer to how full the radiator should actually be. Inch from the top or two, or flush with the neck, etc. This is a really good question. Can't see it in the FAQ, either.

Could someone show me where I can find this out?

Thanks!

Edit:

Did more digging on this. It seems like one could run the level lower in the radiator and not even need an expansion tank: Deleting Coolant Overflow Bottle - https://forum.ih8mud.com/threads/deleting-coolant-overflow-bottle.1030643/

If it never overheated excessively, it should never dump coolant. But if it did, it'd be on the ground, and that isn't good.

There are radiator caps that are vent only, and some that allow fluid to return. If it allows fluid to return, I'm not sure if that might cause an issue.

A lot of older vehicles didn't have expansion tanks. In that case, I think the lower level makes sense. Otherwise, it sounds like you could fill it mostly full.

I'm not sure how much cooling effectiveness percentage you'd lose running a radiator with less fluid and no tank, vs completely full.

Yes you can run without expansion bottle with a non-pressurised system.

Part of what your radiator cap does is allows an increase in pressure within the cooling system. This raises the boiling point of coolant significantly. Gives you a greater safety margin in terms of critical coolant temperature.

Running the system as designed by Toyota, the radiator will be full to overflow hose level at the cap.

 

[sunrk]

I recently had issues with this on my 80 and replaced the radiator cap (a factory one supplied with the brand new factory radiator I fitted in 2017). The radiator should be full of fluid. Remember a radiator is not actually a radiator but a convector. It doesn't 'radiate' heat to reduce temperature of the coolant (but sort of does if there is no airflow through it) hence why it's important for the fan and fan clutch to work well.

 

[ozarkmud]

Thanks for the information! I refilled it about up to the neck, so should be good to go.

I'm curious, if one were to leave the level lower than the top, what would happen as the system compressed the air? Would it cool less effectively?

I know being under pressure raises the boiling point quite a bit. It does seem like you don't *have* to have a expansion tank to run a pressurized system, but there'd have to be an air gap under some conditions.