Low Coolant, Gunk on Radiator Cap - Next Steps Before Panic?

Looking for opinions on next steps here. Pictures below are what I found after draining coolant and popping the cap off. Maybe a quart or so came out of the radiator drain (dead cold - a bunch still in the block maybe?). Coolant reservoir has some “tub rings” in it but no coolant.



Was running fine and not overheating; but I've put about 2,000 miles on it since I bought it in June. Maintained its entire life at a single Firestone location in the Denver area, one owner, gave me all the records; coolant done on schedule at 100k and 150k, now at 199k - well maintained but not exceptionally/OCD grade. No mention anywhere about overheating, low coolant, or sealants - but, wouldn't be hard to "forget" those records, especially if it was an emergent issue and didn't come up in routine maintenance. PO seemed like a very good, up front guy..then again; was also an attorney, so there is that. Either way, it’s my problem now. Had a Blackstone test done when I got it home and oil-wise, it was clean. Coolant is murky; but not chocolate milk. No visible leaks anywhere.

So, I was originally going in to tear it down to refresh everything, new radiator, seals, the whole shebang and thought pulling that rear crossover to replace the seals would be a lot easier with the transmission out (getting ready to do the clutch while waiting on my front end parts to arrive). Looking for some input as my strategy may need to change here. My current thinking as far as options:

1. Crack open the block drains and hopefully get a lot more coolant; refill with distilled water and flush it out with a bottle of IronTite ThoroFlush I’ve got kicking around from my last (much older, iron block) project. Then buy whatever tools needed to vacuum/pressure check things for further diagnosis.
2. Stop everything and get the vaccum/pressure check tools.
3. Stop everything, and send a coolant sample out to see what’s going on there.
4. Combination of 2 & 3.
5. See if TacomaWorld has seen this before, and already knows my head gaskets are done for and just plan for that job too while the Black Friday dealer sale is on (silver lining).
6. Set it on fire and drive it off a cliff?

Thanks in advance…

 

Shy bladder?

Scares me to touch these things but with all the suspension out the access is pretty good so I cracked the block drains. Still a bit concerned about the lack of coolant in the radiator - got way more out of my Subaru 2.5's radiator when I did it a couple weeks ago, but feeling a bit better. Vial sample is from the very last drops of the block drain, realized everything else went in an oil pan so if I want to test that wouldn't be any good! Doesn't look as bad as what came out of the radiator; may have just been some settled crap at the petcock.

 

Looks like they were using some kind of "universal" coolant and probably tap water (thus the deposits), definitely not Toyota Pink and distilled water.

It holds about 2 gallons total.

 

A radiator only drain gets about 3/4 to 4/5 of a gallon.

Only a quart came out? That sounds low for sure.

 

I'm going to leave it drained and redirect my attention back to the transmission side of things while I wait for the Bezos Stork to drop off a vacuum filler with a gauge. Blackstone's coolant test really isn't going to be that helpful, seems it pretty much just tells you concentration and if it's time to change or not so I can strike that one off the list.

I planned to start with this side of things for this very reason, until things came up and I couldn't get to it right away - then the end of year sales started so I rolled the dice and fired the parts cannon on a huge amount of stuff (and I almost always lose gambles), so I've got some paranoia revolving around that..bear with me..

 

Vacuum fillers are nice.
But the 4.0 takes coolant nicely.
It doesn't air lock too bad at all....

I'd maybe considered going with a pressurizer.
Then monitor the pressure for leakdown.

But it's all good.
Fill'er up. Drive it, keep an eye on it.

Never worry until you have to.
I'd worry if it "goes low' again.

Who know what the PO did, or didn't do?

 

Just a word of caution, using a vacuum fill tool on debilitated cooling systems can cause other things to start leaking. Ask me how I know lol.

The 4.0L cooling system self bleeds pretty easily with just using a spill free funnel.

 

Heater core?

 

Yea, aged radiators, hoses, and other plastic connections as well.

Don't get me wrong I love the vacuum fill tool but I avoid using it on older systems and/or if the condition of cooling system components is in doubt.

 

Good points, I was going to use the vacuum as a "leak finder" but it makes far more sense to use pressure as that's what it sees in service. I was able to cancel that vacuum filler and I'll look for a pressure tester, might be easier to find locally.

Regarding the spill free kit - is that really worth it over a steady hand and normal funnel if the 4.0 isn't prone to airlock? I've seen them referenced a lot; but I also saw people rave over the Motive oil filler funnel on the 3G, and I bought the kit - the filter stuff was nice, but that funnel was a terrible design and really didn't gain anything over a standard one, no clue what the fuss was about unless people hadn't owned a funnel at all before..

 

Spill free is 100% worth it.
It's all I use now.

 

Yea I use mine all the time at the shop, the other advantage is you can keep some coolant at the bottom of the funnel and run the engine to allow the rest of the air to escape instead of trying to keep the radiator topped off and likely spilling some when the bubbles come up.

I use the vacuum fill tool alot too on newer stuff that is harder or sometimes impossible to bleed.

 

Thanks for the input. I was going to skip the no-spill, but antifreeze is right up there with brake fluid for me on the spectrum of "fluids I hate dealing with," but maybe I'll not mind coolant service so much if I have the right stuff to make it less of a mess (also: I can use my dog's safety as an excuse to enable my tool buying addiction - anything for the children!!).

I did go ahead and spring for a pressure tester as well, I initially didn't think it would actually tell me much since if it's still had enough coolant to be fine over several thousand miles it might not be something I can see in a day or two. But, air will leak faster than coolant, so maybe not! My radiator also showed up with a hole in the box from the inlet poking out, but otherwise looks totally unscathed somehow, so just to be sure, I can use it to bench test that before installation as well.

 

I'd toss a new radiator cap on too, that one looks original.

 

I wouldn't use a vacuum to fill your coolant. Those are short cuts used in some shops to try and make the job go faster not do it better. They can do more harm than good. Get the funnel that attaches to your radiator and run your engine until the fan comes on. That will burb you coolant system of air. It takes a while though. It's difficult for a shop to make any money doing it the correct way but for a home mechanic it's much better way to do it.


As some else has already stated you can't get all the coolant/water out. For my own cars I drain and fill it. Drive it one day and do it again to get out as much as I can. I do the same for transmission flush. Drain and fill once. Drive it one day. Drain it again.

 

Yep, it's getting radiator, cap, hoses, bypass hoses, crossover seals, thermostat, fan clutch, pump - whole shebang. All Toyota; no excuses.

 

Spent some time cycling distilled water through today. Must have had an air pocket, couldn't get any heat out of it and the lines weren't very warm; but I pulled the hoses and blew some air through both ways and then dumped water as well with no apparent back pressure through either the core or the lines to the engine. Wound up just looping them at the core area, my last jugs of water finally got them heated up at least (is there any sort of valve on this system that was maybe stuck?).

I was watching pH though after the second round and it was weird; the water I drained was alkaline, 8.5+. I then checked the water going in (store bough steam distilled), which checked in around 5. 2-3 more cycles and I expected it to come down but it just hovered at ~8.5. I then adjusted the "fresh" water down, eventually as low as 3.5-4; same results. I got the same numbers with a color changing dye and a digital meter, wondering if something was off.

Every drain though, I was getting some of this brownish-reddish particulate in the bucket out of both the block drains and radiator. Does this look like anything recognizable?

 

I don’t recall anything like that coming out of mine?
But then again, I drained mine in to a pan. Dumped it in a gallon jug and never payed anymore attention to it.

I check mine for the freeze point.
Other than that, I don’t check anything else.

I just change it every 5 years.

 

Just spitballing here and I’m very much an idiot, so take this with a grain of salt.

Maybe the silicates breaking down and dropping out of the coolant?
Was one of the major failure points for the 6.0 powerstroke.

 

Yeah I'm more just curious if I'm seeing signs of something previously added to patch up a problem, or if that's just normal "stuff" in high mileage cars. I'm doing a TON of work in addition to this so I'd hate to get bitten in the ass 6 months from now when I was already 40% of the way to XYZ and have another vehicle to drive and a garage (may be my only car in the next 6-7 months if I go back to school & apartment life).

Going to leave the cooling system intact for now until the pressure test stuff shows next week.