Results of not flushing your coolant......
Joined: Oct 2003
Posts: 11,576
Likes: 27
From: Morristown, TN (east of Knoxville)
For the poster asking why teh FD coolant seals go so quickly, it is not the seals....these are the identical seals used in all the 86+ engines that lasted 200-300k sometimes. The issue is the environment they are in...the REW engine creates more heat and pressure than the older less powerful engines. There is inadequate oil cooling, coolant cooling, and intercooling all packed into the smaller FD enginebay, with no hood venting, making 55-70hp more (in stock form, and how many stock FD's do you see?) than the previous most powerful rotary.
Also, Rich, you may want to clarify that those in more southern/hotter areas should use less coolant and more water, and simply flush it more often. Coolant does not cool as well as water, and in such sensitive engines the wrong mix can actually lead to running too warm across the board. In fact one of the rx-8 guys recently had his car at the dealership for 2 weeks troubleshooting a running-hot issue that was eventually fixed by running more water and less coolant. The dealership had just done an engine swap for him and refilled the system with the mazda premix supplied coolant (50/50).
OF course those further north will want to run a higher mix of antifreeze for the wintertime...meanwhile here, it never drops below about 25*F on the coldest winter nights. Hell, we haven't seen more than 1/2" of snow since about 2002.
Also, Rich, you may want to clarify that those in more southern/hotter areas should use less coolant and more water, and simply flush it more often. Coolant does not cool as well as water, and in such sensitive engines the wrong mix can actually lead to running too warm across the board. In fact one of the rx-8 guys recently had his car at the dealership for 2 weeks troubleshooting a running-hot issue that was eventually fixed by running more water and less coolant. The dealership had just done an engine swap for him and refilled the system with the mazda premix supplied coolant (50/50).
OF course those further north will want to run a higher mix of antifreeze for the wintertime...meanwhile here, it never drops below about 25*F on the coldest winter nights. Hell, we haven't seen more than 1/2" of snow since about 2002.
Well if anything, this is a good excuse to spend a bunch on money on dual oil coolers/v mount set up w/ Al rad/possibly a FEED hood/FMIC.
-Ben
-Ben
Last edited by apexFD; Sep 10, 2007 at 11:29 AM.
Also, people needs to understand, "DON'T use Tap water"!
regular water that comes out of your faucets have way too much minerals and junk in it. Use distilled water! Has anyone seen an rotary that ran just in tab water and small amount of coolant?? Yikes!
regular water that comes out of your faucets have way too much minerals and junk in it. Use distilled water! Has anyone seen an rotary that ran just in tab water and small amount of coolant?? Yikes!
Why coolant seals fail
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/why-o-rings-fail-my-theory-626093/
I've tended to do two test, one for electrolysis with a voltmeter, the other with coolant test strips for ph and glycol percentage to dictate when to change fluid.
Though often enough if I opt to have work done on my car, like two months ago, coolant often gets replaced, with tap water, I'll post my test results.
I've tended to do two test, one for electrolysis with a voltmeter, the other with coolant test strips for ph and glycol percentage to dictate when to change fluid.
Though often enough if I opt to have work done on my car, like two months ago, coolant often gets replaced, with tap water, I'll post my test results.
Last edited by danny hahn; Sep 11, 2007 at 01:21 PM.
I flushed mine every 2 years and used distilled/filtered water. My 94 lasted 108k untill I blew the engine from over boosting. The only coolant issues I ever had were leaky radiator hoses (which caused me to nearly over heat 3 times) and a bad AST cap (which caused coolant to bubble out of the reservoir). I've always said that improper coolant service is the number one cause of coolant seal failure.
It's an R-1
So, Heat management has never really been a problem; ever. Dyno results w/stock twins resulted in 300RWHP.
So, failure on my part to routinely change my coolant resulted in engine death.
This thread may offer you some comfort and guidance

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/4-stages-coolant-seal-failure-691205/
I just hope I got smart about using distilled water and changing my coolant at less than two-year intervals soon enough to head off any coolant seal problems in my FD.
Posted coolant test results in this thread:
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/why-o-rings-fail-my-theory-626093/page3/
Synopsis:
Had my coolant changed while having some work done at the shop a month ago and 1200-1500 miles. They forgot to use distilled water. Alright no big deal since I hadn't used it in the past, and I am interested in the test readings as an indicator to change coolant.
Tested the coolant, about 33% glycol and a pH close to 8 at 14C. Voltmeter readings 0.3V no accessories 0.25V with accessories.
Comparing the previous figures, note the drop in volts from 2.9v to 0.3v. Much closer to the recommended 0.1V.
The only signs of aluminum decay was on the radiator in and out under the pipe clamp 2 and a half years ago. no further external signs of electrolysis.
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/why-o-rings-fail-my-theory-626093/page3/
Synopsis:
Had my coolant changed while having some work done at the shop a month ago and 1200-1500 miles. They forgot to use distilled water. Alright no big deal since I hadn't used it in the past, and I am interested in the test readings as an indicator to change coolant.
Tested the coolant, about 33% glycol and a pH close to 8 at 14C. Voltmeter readings 0.3V no accessories 0.25V with accessories.
Comparing the previous figures, note the drop in volts from 2.9v to 0.3v. Much closer to the recommended 0.1V.
The only signs of aluminum decay was on the radiator in and out under the pipe clamp 2 and a half years ago. no further external signs of electrolysis.
Thread Starter
Joined: Mar 2001
Posts: 30,804
Likes: 646
From: FL-->NJ/NYC again!
That may be part of it. However, your seals are (were) 15 years old, and that may be very close to the limit of coolant seal life expectancy.
This thread may offer you some comfort and guidance
https://www.rx7club.com/showthread.php?t=691205
This thread may offer you some comfort and guidance

https://www.rx7club.com/showthread.php?t=691205
actually, they were out of a reman that was ~5 years old. It never had the coolant changed.
That may be part of it. However, your seals are (were) 15 years old, and that may be very close to the limit of coolant seal life expectancy.
This thread may offer you some comfort and guidance
https://www.rx7club.com/showthread.php?t=691205
This thread may offer you some comfort and guidance

https://www.rx7club.com/showthread.php?t=691205
Think of your engines coolant system as being an automotive variant of a typical marine environment. All the same rules apply. Failure on the operator's part to locate sacraficial metal, i.e. zinc, for example, or some such substitute will result in destruction of ALL metal parts, in the order of their respective atomic numbers as they are placed on the periodic table, and directly attack your prop. This is because cavitation resulting from the spinning action of a prop, or in this case, a water pump impeller, gives rise to carbolic acid. Hence the need to change the coolants chemistry to, in part, prevent this.
Anyone who's worked around marine craft knows what I mean. Replacing chunks of lead or zinc mounted by the screws is far cheaper then replacing the prop(s)
every season.
Thread Starter
Joined: Mar 2001
Posts: 30,804
Likes: 646
From: FL-->NJ/NYC again!
As a follow up, there was even damage to the wp and wp housing! the pump blades were pretty badly pitted, and you can see the way the wp housing was disintegrating from the attached pic.
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