Coolant flush ?

A little back story. 2004 4Runner 4.7. Replaced timing belt and water pump last summer. Everything been fine as son drove to college and back over the last 10 months. He got home Monday and I noticed it was a little low on coolant…I poured maybe 2 quarts into it so not too bad. For some reason when we bought it had orange coolant so when I replaced water pumped I used orange again. I used Zerex originally but when I topped off Tuesday I used Peak Orange OAT.

He was driving to Denver today and after about 30 miles he called me and the check engine light came on and then steam coming out of the overflow tank. I headed to him. When I look at the over flow tank it is gray in color and the radiator was obviously low on coolant. Not sure what happened I topped it off with some distilled water and a small amount of coolant hoping I could limp it home. I made it five miles and it started to get hot and then the steam showed up. Pulled over and had it towed home.

I’ve decided to replace radiator, thermostat, hoses and radiator cap. So I don’t really need to flush the radiator but I would like to flush the engine block and replace with the proper Toyota coolant.

Any body have an easy method for doing so? Also what about the heater core? Or any ideas on what could have went wrong. Truck has been so faithful so has me confused.

Sorry for the long winded post….

Thanks, Marty

 

I've drained/flushed UZFEs on both a 4Runner and an LX470 (V8s). Engine block is easy to drain despite being a minor PITA, as long as you have half-way decent socket set w/extensions.
Passenger side is a little more difficult than driver's side as it's mostly done by braille. I was surprised at the amount of coolant that came out, and will never not drain my blocks again when I change coolant.

Search for how-to's on the google, and be sure to get tubing to fit over the engine block drains to drain into empty water bottles. One or both engine block drains may be blocked by gunk/mineral deposits. When that happened to me, I simply poked it thru with a very skinny flathead screwdriver. Oh yeah...no pets present during this work, coolant is deadly to animals.

Probably not a bad idea to do a full flush with distilled water first. Ideally, do a few of them...distilled water by the gallon is cheap...fill...run engine...drain...repeat.
For sure use Toyota SLLC (pink) coolant. If not that, then Zerex (Asian), but honestly...coolant drain/flush is a long service interval item so I'd spend the extra for OEM SLLC.

I've replaced radiators in both the LX and a 2003 4Runner 2UZFE. The 4Runner was easy (I don't have much mechanical aptitude) and I did it solo, which I don't recommend as it's nice to have an extra set of eyes on things.

Finally, double check and top up radiator the next few mornings when it's cooled, in case and air burped out of the heater core(s).

 

Do you think I should flush thru Radiator as well even though I’ll be replacing it?

 

Good question and possibly above my pay grade. Hopefully others chime in here.

And actually, the very first thing I'd do it try to determine where exactly the problem(s) exist(s) first. Is the thermostat opening?

I'd probably flush thru the radiator first, with the drain at the bottom open or completely removed, just to get anything out of the radiator that could otherwise end up in the engine block. And then afterwards, when I mentioned flushing, I actually mean running the engine with the coolant system sealed, for at least a few minutes (thermostat has to open) so entire engine gets the distilled water circulating thru it for a few minutes and hopefully any impurities get water-born and come out easily when draining.

 

Appreciate the advice…..just wish I knew why it happened?

 

Check engine light should be scanned, see if it’s definitely related or something else. If nothing else it’s a clue.

 

When we got it home i drove to off trailer and engine light was gone…hopefully I can pulled a stored code maybe.

 

Maybe when the radiator got low an air bubble got sucked into the engine, you just topped it off but didn't burp the system and thats why it kept overheating?

If you don't want to drain the block, just do a couple fill/flushes with water first to cycle as much old stuff out as you can, then do an actual fill with the correct coolant.

 

Why orange coolant. Toyota is pink or red. Id make sure the correct coolant is in it.

 

There’s a good possibility that mixed coolants sludged up the cooling system resulting in overheating.

hopefully I’m wrong and it’s something simple like a stuck thermostat. Before replacing a bunch of parts, flush the cooling system.

 

There was orange in it when we bought it so I just stuck with that….should have switched to pink when I did the water pump.

 

I’m going to replace radiator for sure…..seems like where the cap goes might be a little oblonged…piece of mind also.

 

I wanna flush the whole system, but with replacing the radiator I feel like I need to flush it. What if I removed the thermostat and disconnected the upper and lower Radiator hoses and pushed fresh water thru the block. Would that work or not….I would then flush block with distilled water…then fill with pink antifreeze? thoughts?

 

There is a drain plug on the passenger side of the block. If you fill the block with water you won’t get it all out. Use that drain plug to get all the water out of the block. If you don’t get it all out your 50:50 mic is off. If the mix is off you will lose freeze protection

 

Did a block test today and it looks like NO gases in the coolant so the head gasket appears to be ok.

 

When I flushed my LX I used Thermocure https://www.crcindustries.com/crc-thermocure-cooling-system-rust-remover-flush-wt-32-oz/ . I probably didn't need to and I'm not big on additives, but some of the longtime guru purists on MUD recommended it. I followed the instructions on the bottle, then afterwards flushed the system six times, driving approx one hour each time I flushed it. At that time we we had an extra car so I it was easier to deal with. Each of those six run and flush/drain cycles was with distilled water...Made a point to thoroughly burp the engine each time as the LX has two heater cores and they are notorious for getting air bubbles in them. I pretty much was flushing it until the water was close to "clean" coming out, then did a final fill with SLLC and followed the FSM burping procedure multiple times the following few mornings.

 

Does the heater work? If you're not getting very hot air in the cabin then likely flow blockage or air bubble in the heater core.

 

I did notice that the heater was not blowing too hot of air which concerns me.

 

I did add a little water and coolant for to warm it up and it did burp a few times pretty good and the level dropped pretty good…as it was all over the floor

 

Read post #13 here... https://forum.ih8mud.com/threads/cooling-system-flush-burping-coolant-whats-your-process.1050470/

Actually the whole thread has good insights, but post #13 is solid and also includes the page from the FSM. You should also get one of those radiator overflow funnels mentioned in the thread, cheap on Amazon.

 

Thanks for the info….I bought one of those funnels looks like it can help a lot with mess. Lots of good info on there.

 

TL; DR yes, I that should work, too.

I won't admit it here, but once upon a time I went against the cardinal sin of introducing tap water via a hose under house water pressure, and did it backflushing my heater cores at the notorious heater T's on my LX. Also rigged up a shop vac to suck as much thru as possible...I was determined! Used a 5-gallon bucket for a catch except when I used the shop vac. I was surprised at some of the sediment-like debris that flushed out, including a few small bits of broken heater T. Didn't realize those had made its way into the system. The introduction of tap water was part of the reason I flushed again afterwards with so much distilled. The sun still rose the next day and the LX and its cooling system and front/rear heaters all work still flawlessly now, several years later.

 

Question…. I’m flushing the block as we speak. What if I can’t get the block drain plug on the passenger side out. It’s really tight and I definitely don’t want to snap it off?? The drivers side came loose and I’m getting good clean water out of it.
Thanks for all the help guys!!!

 

Firstly, you don't normally have to remove the entire plug/nut out to get that side of the engine block to drain, should drain when it's loose, unless its gunked up inside, and be sure you're loosening the right one, as IIRC its hard to get a visual on the correct nut/bolt/plug thing on passenger side. If you are getting the right one, I certainly wouldn't exceed beyond what you're comfortable with, as breaking a plug in that location would suck. Many/most of us don't even drain the blocks...I just started it a few yrs ago as a "best practices" kind of thing. You'll be fine only draining one side.

 

You will be fine with what you have gone through up until this point. The vast population will rarely drain the block beyond backflushing.

Check and verify PH after bleeding a few days after to get a good idea of your status.

 

PH? I just wanna get all the Orange antifreeze out.

 

Here's another good (I'm assuming) how-to video. Timmy usually does great work. I haven't watched this particular video but it is for the 2UZ...
https://timmythetoolman.com/video/e...d-cruiser-lx470-gx470-tundra-sequoia-4runner/

 

pH is to verify the coolant in there is in acceptable range and not diluted for example which could inform your future actions.

Even if you can't get it all out at once, nothing like some drain/fills to help dilute what's there into nothingness. (ideally)

 

Any updates, OP?

 

I’m actually working on getting the new radiator in as we speak.

Never could get the passenger side block drain plug to open but I’ll do some flushed with distilled water when it’s all back together