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.
Originally posted by vaughnc
----- Original Message -----
From: "RX-7 Rotary Car Nut" <email@example.com>
Sent: Saturday, March 13, 2004 12:46 AM
Subject: Rust Clogged Radiators - Flush with CLR??
OK I've got 2 cars now that have rust clogging the fins causing temperature spikes in warm weather. Both have 150-175K body miles, both show 20-30 degree temperature differences between the upper & lower coolant passages.
Both cars drain clean, have new thermostats, and new fan clutches, and good working water pumps.
A friend recommended filling the radiator with CLR for 3 days as it disolves rust. Of course I'd drain the coolant first and block off the upper & lower coolant passages.
Any thoughts on this? I'd like to avoid paying a radiator shop for roding the radiators, acid cleaning, etc... This sucks antifreeze rusts your radiator internally. You'd think there'd be a coolant filter or something
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