Surprisingly this hasn't been discussed anywhere on rx7club.com that I can find.

Most people say just replace, upgrade, or rod-out your radiator when you begin seeing coolant spikes and big temperature differences between the upper & lower radiator pipes. I want a "fix what you got" solution to remove the rust particles clogging my radiator fins that no coolant system flush will fix.

So here's my current conversation on this from the fc3s e-mail list. I'm planning to do what Felix recommends below pretty soon. My only concern is the rust remover touching plastic parts of the radiator. So I'll check into that next.

BTW - Everyone should install a REAL aftermarket temperature gauge so you can catch this stuff before you break a coolant seal.

Message: 9
Date: Sat, 13 Mar 2004 02:05:04 -0500
From: Felix Miata <**********>
Subject: Re: Rust Clogged Radiators - Flush with CLR??

No filter needed when you replace the coolant before it wears out, normally well before 3 years of age.

The problem with radiator shops is finding one to actually do what needs doing and/or not waste your time convincing you the only appropriate course of action is to buy a new core. There aren't any like that around here any more.

Last time mine needed cleaning I started with CLR (after removing my radiator from the car) on recommedation of my local A/C shop. I wasn't satisfied that 28oz of the $4.99 stuff was high enough concentration, so after running that a while I went to Home Depot and found an equivalent product sold by the gallon and used 3/4 of that.

I don't remember the name, but the receipt says 021709370478 RSTSTNRMVR
$9.98. Running cooler than ever now.

-- Felix Miata

 

Hey thats sounds like a pretty good idea, but does clr eat away at the rubber?

Last thing I would is to flush my ratiator with that, little bit gets stuck some where and it eats away at my coolent seals.


And if it doesn't eat away at rubber, could you run it with a bit of water threw your engine for about 10 min to get what ever rust in the engine out?

 

DO NOT FLUSH YOUR COOLANT SYSTEM with this stuff. This is for your radiator only which should be removed from the car.

Ideally you'd soak it in a "kiddy pool" full of the yet unknown "Home Depot heavy duty liquid rust remover." I think the walmart CLR stuff might be too weak too.

You'd remove the rubber sealing radiator cap & detach the rubber coolant hoses when removing it from the car.

 

Sounds like pretty decent idea, but arent parts of our radiator plastic? Does it harm plastic?

 

OK I think I'll try this stuff first. It comes in a plastic bottle & I called them to confirm it's safe on plastics. They say it's stronger than CLR for rust & can be dumped down the drain

http://www.ironout.com/products/rust..._iron_out.html

 

Check the ingredients list for acids.
Some of these cleaners will eat aluminum.

Test it on a piece of aluminum foil.
That will tell you how long you can leave it before rinsing.

I have used the purple degreaser to flush my cooling system, but I rinse it immediately.

 

OK according to their help line:

1) The products good for 24 hour s only, so you'll need to re-soak it 3 times for 3 days.
2) It shouldn't pit or dissolve aluminum, but it may discolor it
3) No harmful effects on plastic

Good tip on testing with aluminum foil. I'm heading over to the The Container Store tonight to find the right-sized bin so I won't need 15 galons to fill up a kiddy pool

 

You don't need to soak the entire radiator in the stuff, just the inside where the rust is. Remove the radiator and lie it flat on the ground with the connections pointing upwards. Pour in the stuff until if reaches the top of the connections. You might want to tip it slightly as it fills to remove air, then lie it down as the lower connection overflows.

 

what about coca-cola ?

 

that would remove the rust but leave sticky crap all over the inside, so no dice on the one, but good idea...

 

i wouldnt do it just for the simple fact that other (probably better) cleaners would work fine and are cheap, but what if you washed it out quickly enough? i'm really not too worried about it. it was a half joke half serious post. i may buy a 20oz (591mL) coke and dab it on a rag to clean a bit of rust flakes off a turbo. its brand new, but the exhaust side has a tad bit of rust.

 

Don't want to leave the radiator cap on and I doubt my home-made plugs will keep the liquid in. So I figure just buy a near-sized container, use home-made plugs & fill the radiator up to remove any air, fill container up enough to cover the radiator, dunk the radiator, remove home-made plugs.

I'll give it a try though and see if my plugs can keep the stuff in so I won't waste product.

 

You don't need to plug anything. The hose connections are pointing upwards, so they're the high point. The radiator cap has to be on obviously. Why wouldn't you want it on?

Filling an entire container is just wasting many times more cleaner than is necessary.

 

I know I could pull the hoses & radiator out of the engine bay & krimp the hoses, but I'd have to remove the low coolant sensor on the bottom of the radiator (hole) so the sensor won't be damaged. I don't want any rubber exposed to this stuff, so no radiator cap or hoses will be attached.

I was thinking of balling up some aluminum foil to shove in the radiator holes, but it would be hard to get a good tight fit on some of the holes.

You right, I don't want to waste product by filling a 55gal washpan, so I'll come up with something like wrapping the radiator in plastic for a watertight seal so the water won't spill into the washpan.

BTW - this stuff powder, so I'll start with the recommended strenghth of 1cup|1gal

 

You could put replace the level sensor (top of radiator) and temp switch (bottom of radiator) with bolts and replace the radiator cap with a cheap filler cap. No hoses need to be attached and nothing needs to be crimped. Easy.

 

yeay that sounds good, I could probably find a 1/8" or similar fitting to plug up the sensor holes. Luckily I just bought a thread pitch ruler so I can figure out what size & pitch the bolt shaft is without dragging them down to the hardware store.

Ideally the radiator should be right side up so the crud will fall down & drain out of the lower radiator hole. So I'll probably still use home-made plugs for the upper & lower radiator holes.

I'm trying to track down the "mystery product" Felix Wankle keeps talking about for rust removal. All I know is his receaipt from Home Depot says 021709370478 RSTSTNRMVR - $9.98 He said it worked wonders, so I'd prefer to use that instead of the stuff above.

 

OK here's the stuff Felix recommended. I'll call their helpline tomorrow & verify it's safe on plastics & exposure time and if recoats are needed.

Note Zep Doesn't list it on their website, so it may be discontinued. This is liquid, not powder so you'll need 4 gallons x $9.98/ea.

HDRUST32 Zep Calcium, Lime & Rust Stain Remover - 1 Gal $9.98

 

OK the Zep guys say this stuff's not safe on aluminum.

They also verified the 021709370478 RSTSTNRMVR product that Felix Miata mentioned isn't one of their products. So I'm going with the iron out.

 

I don't suppose you've tried that Iron Out stuff yet, vaughn, and if so how'd it go? I saw that stuff sitting there at home depot today and considered it. I didn't realize it was a solid that you mix yourself.