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What are your tricks to clean out coolant reservoir sediment?

11 posts Started 23 Sep 2025 Last recovered post 29 Sep 2025 Wayback Machine snapshot 23 Jan 2026

#1

Since I am doing full cooling system refresh, also want to clean out the coolant reservoir too. 

I had this sitting for months with white vinager in it, it worked some, but not enuff. 

Waht are your tricks to clean out? 

[image: 20250923_170521-M.jpg]

thxz

#2

I think I have used CLR before with good results.  Something recently surprised me how well it worked, but I can't remember if it was Wheel Cleaner, Aluminum Boat Brightener or Bathroom Mildew Cleaner.  It was definitely something I usually having kicking around the shop utility sink.

#3

I'll probably get some CLR add a bunch of 1/4-20 nuts I already have and shake the shit out of it.....😛

#4
1 hour ago, mello dude

I'll probably get some CLR add a bunch of 1/4-20 nuts I already have and shake the shit out of it.....😛

Try without nutz first...  could etch/scratch the inside and make it more susceptible to staining (permanently).  

#5
20 hours ago, mello dude

Since I am doing full cooling system refresh, also want to clean out the coolant reservoir too. 

Regarding your full cooling system refresh I was wondering if you decided to do anything more than a water or water/vinegar cleaning flush of the cooling system? I'm in the middle of addressing the system myself and thought to ask what you used.

#6

Havent really thought about a system flush, my focus has been... thermostat, orings, hoses.... I'm sure you have seen the thread... 

Dunno if I will do a flush.......

#7

Did mine with Mould/Mildew bleach, didn't have any small enough hose end bungs, so I looped a piece of hose between upper & lower outlets so I could hang it up to soak & keep with all the crud submerged in bleach, came up better than expected.

Throw in a few stainless m4/m5 nut can't hurt to scuff the crud loose.

Central heating cleaner will shift it too, dunno if its aggressive to plastic tho?

#8

Was going to suggest CLR also. These tanks are still available new, $38.

#9

Saw the new ones too......

Did the CLR thing...add some in the bottom, let sit 10 minutes, shake rinse....repeat x3....

Almost got it all, but then I have some pea gravel...did the same again, add gravel, shake, dump, rinse x4...

Pretty much got it.....

#10

I used CLR with some (un-cooked) rice and shake shake shake... worked well enough for me. 

#11

Simple Green and just enough water to shake it all over. Never needed anything more. 

End of thread · 11 posts recovered Wayback Machine snapshot 23 Jan 2026