Tips on cleaning gunk out of cooling system? (1 Viewer)

[ikellymo]

I have a bunch of gunk in my cooling system. I’ve owned my 230k 2003 LX for several years but have no idea what the PO did. About 2 years ago I couldn't get any heat in the winter and had a well-rated indie shop in Berkeley, CA replace the the heater core and do the water pump/timing belt. The heater worked great immediately after, but I think the shop was a little light on the coolant flush for their own particular reasons. After, I paid a Lexus dealership to flush the coolant but they left it 1/2 gallon empty and I still saw a lot of "powder" in the coolant under the radiator cap. Solids settled out when I took a sample.

This winter, up in Portland, OR, the heater stopped blowing hot air and I had a 3rd shop confirm its a clogged heater core. Paid them $350 to do a really thorough reverse flush with no promises, and the inside air temp increased maybe 10deg, but still pretty cool.

So... I just reverse flushed my heater core myself with a hose and cleared out chunks of brown gunk. The flow rate immediately went from low to high but even after 30 minutes of flowing hose water I still saw chunks flowing out. I followed this Heater Core Flushing thread by @izzyandsue in 80 series forums, except I didn't really need the CLR. Just pulsing the hose pressure using a valve would clear out more chunks of gunk ... it literally looks like dense brown pond algae.

The heater blows really hot!!! ... for now. I think I have the heater core pretty clean but want to do a really thorough flush of the whole system because I can only imagine this gunk is everywhere.

I've read the following threads that give good instructions to find the 3 drain plugs:

1. Another Radiator Flush Question
2. Radiator Flush/Coolant Drain DIY @newbee mechanic thanks for the pics
3. Heater Core Flush

And I get the basic steps of capturing and recycling the poisonous liquid, use distilled water, use proper coolant (oh too much debate about this!!!), etc, but I'd like to be able to hose down the insides of the system and agitate with back-flow before I rinse with distilled water to really try to get all this gunk out. Has anyone done this before? Tips for getting it really clean? Can I run the engine while flowing the hose through it? Are there a lot of small cooling channels in the 2UZ-FE?

Here's a sample of the coolant from top of radiator as it sits before solids have settled out

Here are photos of some of the crap I drained out of the heater core after settling for a day.

Note that this is after

• ~$2500 water-pump, timing belt & alternator @ shop A
• ~$2500 heater core @ shop A
• ~$150 coolant flush @ shop B
• ~$350 coolant flush / heater core backflow @ shop C

I may end up waiting until it gets a bit warmer outside, but any advice would be hugely appreciated!

 

[JunkCrzr89]

I used thermocure and it turned the inside of my block from crusty brown to shiny silver. Smells like hell but works great and is compatible with Toyota coolant.

 

[ikellymo]

Great, I'm looking at Thermocure and Irontite ThoroFlush. I've had good luck with Evaporust products previously but wonder if the gunk I'm seeing is stop-leak or green+red and not rust :-/ Irontite ThoroFlush claims to dissolve all of that, but also looks pretty aggressive.

 

[TheForger]

I used thermocure and it turned the inside of my block from crusty brown to shiny silver. Smells like hell but works great and is compatible with Toyota coolant.

How many days did you let it circulate through your system before flushing it?

 

[JunkCrzr89]

Great, I'm looking at Thermocure and Irontite ThoroFlush. I've had good luck with Evaporust products previously but wonder if the gunk I'm seeing is stop-leak or green+red and not rust :-/ Irontite ThoroFlush claims to dissolve all of that, but also looks pretty aggressive.

In addition to rust inside the block, I had this nastiness in my coolant system when I first bought my 100. This is what happens when green and red are mixed.

I ran thermocure through the system for 300 miles and then flushed about 30 gallons of water through. It got rid of everything. I did do the flushes with the engine running.

 

[JunkCrzr89]

How many days did you let it circulate through your system before flushing it?

300 miles. I don’t remember how many days but probably a week or so.

 

[ikellymo]

In addition to rust inside the block, I had this nastiness in my coolant system when I first bought my 100. This is what happens when green and red are mixed.

View attachment 2525056

I ran thermocure through the system for 300 miles and then flushed about 30 gallons of water through. It got rid of everything. I did do the flushes with the engine running.

That looks a lot like my gunk - if not a bit softer. When you flushed water through, where'd your push water in and where'd you let it come out?

Did you notice particle suspension in the coolant?

 

[JunkCrzr89]

That looks a lot like my gunk - if not a bit softer. When you flushed water through, where'd your push water in and where'd you let it come out?

Did you notice particle suspension in the coolant?

I left the lower radiator hose connected, sent water through the radiator spout, and pulled the upper radiator hose, letting the engine do the work of pumping water through the system.

Yes, I had particle suspension in the coolant prior to my use of thermocure and the subsequent flushes. The previous owner (original owner) was averse to maintenance after the warranty ran out. I think the coolant had only been changed once in the 200k miles prior to me purchasing the Cruiser. The water pump had developed a leak at some point and PO just topped off the system with green Prestone $hit every couple of weeks for over a year before I bought it That's what caused the gunk (red was already in the system from when Toyota did the timing belt at 90k miles), but I guess the bright side is that he never ran the engine dry and always topped it off, so it never overheated or blew an HG (thankfully).

 

[LINUS]

Wow, I helped a buddy w/ a 60 he bought that had rusty color sludge for coolant as a starting point - his downhill gravel driveway was stained red for months when we did the ‘ol garden hose / Prestone cut/clamp adapter & just let it dump out the petcock & fill cap alternating.

Looks like the Thermocure stuff would have saved us ~2hrs & a 6’er waiting to get clean water as a final product (was Summer so we ran straight water for a few weeks).

One tip to tuck under the cap

 

[77mustard40]

Used Thermocure on my 80 a couple of months ago. Drained the old and flushed with hose, then drained block and all before refilling with Thermocure and distilled. Ran it a week, flushed again with hose and drained. Filled with distilled only, ran it up to temp with heaters on then drained again, repeated one more time for good measure. Filled with RED and distilled and its good to go. I got a lot of milky residue out of the system.

ORANGE is in my 100 and its looks ok, but I'm planning the same drill when I do my timing belt over the holidays.

 

[CorporalClegg]

Many of the products listed will do well, I'd suggest you remove the thermostat use two buckets and an electric pump. these are big systems and 20 gallons would be where I would start. And I would flush the rear heater core (if you have rear hvac) separately, dividing the system in more partitions would be even better. If you think you've got mixed mixed coolant sludge there are many products available if it's corrosion CLR or similar product is advised with this method by some manufacturers.

 

[ikellymo]

I left the lower radiator hose connected, sent water through the radiator spout, and pulled the upper radiator hose, letting the engine do the work of pumping water through the system.

Yes, I had particle suspension in the coolant prior to my use of thermocure and the subsequent flushes. The previous owner (original owner) was averse to maintenance after the warranty ran out. I think the coolant had only been changed once in the 200k miles prior to me purchasing the Cruiser. The water pump had developed a leak at some point and PO just topped off the system with green Prestone $hit every couple of weeks for over a year before I bought it That's what caused the gunk (red was already in the system from when Toyota did the timing belt at 90k miles), but I guess the bright side is that he never ran the engine dry and always topped it off, so it never overheated or blew an HG (thankfully).

Thanks for the details, I think you're helping me to piece together a mental "coolant system issue diagnostic chart" - which would be really cool to see actually. Man, learning to maintain this truck is the first time I ever learned to not mix coolants, and not to use tap water. It seems this should be much more common knowledge. How many people just top up their systems!

Used Thermocure on my 80 a couple of months ago. Drained the old and flushed with hose, then drained block and all before refilling with Thermocure and distilled. Ran it a week, flushed again with hose and drained. Filled with distilled only, ran it up to temp with heaters on then drained again, repeated one more time for good measure. Filled with RED and distilled and its good to go. I got a lot of milky residue out of the system.

2nd vote for thermocure, thanks!

Many of the products listed will do well, I'd suggest you remove the thermostat use two buckets and an electric pump. these are big systems and 20 gallons would be where I would start. And I would flush the rear heater core (if you have rear hvac) separately, dividing the system in more partitions would be even better. If you think you've got mixed mixed coolant sludge there are many products available if it's corrosion CLR or similar product is advised with this method by some manufacturers.

Thanks, I like the idea of flushing the individual parts of the system - maybe I'll do reverse flushes on each, then let a product circulate through the whole thing. I found the pressure from the hose to be quite effective at removing some of the gunk from my heater core, although I'm sure plenty would argue that the pressure can be harmful. There's also of course the balancing act of how to capture the most contaminated water and still get a thorough flush...

All the products claim that they remove rust or calcium, but few claim-to or discuss removing "other" sludge or deposits. So this is helpful if the red+green silicate precipitate sludge is also commonly dissolved. I ordered a bottle of Thermocure and will mix it into some of my collected sludge to test if it dissolves it.

 

[ikellymo]

Update: after I did the thermocure flush, the system worked for a bit then got clogged again within a month or so. Too much gunk remained in the bottoms of the engine.

I recently found a product sold by Cummins, manufactured by fleetguard called RESTORE. It’s a basic flush containing potassium chloride, and claims to remove silicate gel. It’s the ONLY product that I’ve seen claiming to remove silicates, not just rust or calcium deposits.

https://shop.cummins.com/SC/product/restore-cooling-system-cleaner-1-gal-cc2610/01t4N0000048oKBQAY

I bought it and ran the flush this weekend, and my heater now blows hawt!!! Looking forward to what happens through the winter…

 

[zgfiredude]

Thanks for circling back with the update. I'm getting ready for this as well as a Radiator replacement.

Would this be a good order of operations?
1. Drain the old and flush with hose.
2. Then drain the block block and all before refilling with Thermocure and distilled water. Run it for a week +/-.
3. Then flush again with hose and drain block. Fill with distilled only, run it up to temp with heaters on and then drain again. Repeat if deemed necessary.
4. Then replace radiator, hoses, thermostat, etc and fill with Red WS coolant.

 

[ikellymo]

Thanks for circling back with the update. I'm getting ready for this as well as a Radiator replacement.

Would this be a good order of operations?
1. Drain the old and flush with hose.
2. Then drain the block block and all before refilling with Thermocure and distilled water. Run it for a week +/-.
3. Then flush again with hose and drain block. Fill with distilled only, run it up to temp with heaters on and then drain again. Repeat if deemed necessary.
4. Then replace radiator, hoses, thermostat, etc and fill with Red WS coolant.

Did you do this already? What problem are you facing (rust, green/red mix sludge etc?)

 

[zgfiredude]

Doing it this weekend.....No "issues", cools fine but rad is starting to change color and want to replace prior to failure. It currently is on green antifreeze. I'm at 200k miles and have only had the rig for 2 months. I just want to do it right and do it well as preemptive.

Thx

 

[ikellymo]

Doing it this weekend.....No "issues", cools fine but rad is starting to change color and want to replace prior to failure. It currently is on green antifreeze. I'm at 200k miles and have only had the rig for 2 months. I just want to do it right and do it well as preemptive.

Thx

Your proposed procedure is inline with what I did. After the restore flush I ended up with 35gallons of fluid to take to the haz waste disposal. I had sealing 5ga buckets ready.

A good number of people on this forum would say to never let tap water touch the system so that it doesn’t get contaminated with minerals. Importance depends on your tap water.

I didn’t see that as an option so flushed with hose then rinsed that out with distilled.

Thermocure prolly makes sense if you don’t have sludge because it will tackle any rust deposits. And as I’m sure you know, never mix coolant chemistries because you can get sludge precipitates.

Good luck!

 

[zgfiredude]

@ikellymo thanks for circling back!

 

[kevgentile]

If someone's in a pinch and needs a good cleaning product, for many years we've had a lot of success using concentrated Shout detergent/cleaner.
Done quite a few Porsche 944's with a blown oil filter stand/heat exchanger that mixes oil and coolant, as well as after some headgasket failures. We fill the system with a fair amount and run to temp, drain and fill, run to temp, etc.