If there's no sign of it anywhere, how do you KNOW that you have a coolant leak? Keep in mind the coolant level will naturally decrease as time goes on.

 

I am aware that it will decrease over time but I had to fill it when i was in DC for Hot Import Nights because the light had come on...its only been like 3 weeks and i checked it again just to make sure it was doin alright and the level was really low again. The other reason im led to believe that there is a leak somewhere is because when i pull into my garage at night after work and i turn the car off. i can walk inside for like 2 min. Turn around and come back to the garage and you can definitely smell burnt coolant. Its very apparent. Is it possible that it may only be leaking when im on it hard? Thats when the weird sound starts and is most apparent. When i have it to the floor. If i dont put it to the floor (Almost full throttle) the car accelerates pretty much as it would any other time. The sound is still there but ever so slightly. Very odd.

 

If you are not seeing any external coolant leaks on garage floor, I would then be having my cooling system pressure tested, IF it is losing pressure without any external drips it is your motor...ie, engine rebuild..sorry.

You could (very rare) have a leak inside under the dash around your heater/tap/core.

You can do a test yourself IF you feel confident to remove the radiator cap when the engine is hot (be careful for blowout of Hot coolant), once removed you or someone else rev your engine to around 3000 RPM and hold it there for about 30 seconds or more, IF you see tiny bubbles (pin head size) appearing out of the top of the radiator neck, then this is a guarantee you need an engine rebuild. You have rotor housing seals that are leaking coolant into rotor chamber(s).
Compression blowing back into engine cooling system, similar to a blown head gasket in a 4 banger.

 

Sorry to say this also, as I have also posted this before, 90% of marbles in the can is a high carbon build up on rotors and or worn out spark plugs....I go with carbon build up...the ONLY way to really fix this is again ...is engine rebuild...FULL STOP.
Every rotary ever made has this issue...FULL STOP...its not a flaw, it get worse for owners who nurse/nanny their cars, not enough open throttle running, sitting under 4000RPM all the time your are guaranteed to have carbon build up (marbles).
It definitely helps if you run a pre-mix of 1000:1 at the start on the engine life.

 

I will defintely try removing the radiator cap to see if i can see any bubbles. I assume that these bubbles will be apparent. Ill let you know what comes of this. Thank you.

 

Remember be careful of hot coolant.
Your engine MUST be a normal temperature (hot).
You have to maintain the revs at 3000-3800 RPM for more than 30sec WHILE you are looking for blow-back bubbles.
And as I said the bubbles appear out the radiator neck like a "tracer line" and are VERY small, because usually any internal leak is very small.
The worse the leak the larger the bubbles,but, once a rotary gets to "large" bubble it is drinking Coolant.
Have some top up coolant handy when finished.
Is your car still under warranty?

 

ASH, I can say that for certain my car or the one I test drove at the dealer (with 30 miles!) is not making this sound due to carbon buildup. Rotary ping marbles is a different sound from my marbles; much sharper sounding.

 

A new 8 should not have any "marbles"

There are "some" standard procedures a good Mazda dealer "should" do..
As a general rule if you are not using a higher octane fuel you can have issues more in a slight drop in performance, you should not get the old "pinging" sounds that "banger " (4,6 cylinder) motors can have....stick with high octane.
If you have poor high end performance with a slight hesitation or breakdown at higher RPM, It could then be a number of things.

Electrical... have you the latest Mazda coil packs?, what is the condition of your Spark Plugs, even weather conditions can cause some problems if you do a lot of short distance driving in colder climates a "hotter" range plug can help.
Plug Leads?

You say you have a much "sharper" sound, is it obviously at higher RPM.
Have you experimented in changing fuels?...even brand...
do you run a pre-mix, i think some members may have a too high ratio that MAYBE fowling (oiling) up their plugs.
If you don't give pre-mix a try at about 800-1000:1 Ratio....1 mil per litre Fuel.

 

ASH, my problem is not ping. The car at the dealership was not pinging and various rotary mechanics that have ridden in my car agree it's not ping. Rotary ping sounds like marbles while my sound can more accurately be described as sand. It is a flow issue through the heater core; very obvious when you consider you can hear it very faintly sometimes at lower rpms when the engine is stone cold. I do premix; these days at 2 oz. per 12 gallons of fuel just as a safety measure. The car started doing this right after break in when I started to redline it regularly and at that time the plugs were 1,000 miles old.

 

When did the marbles end up in the rotors? It's in the heater core in the cabin. All the sound comes from the passenger side near the footwell; where the heater core is. Well, atleast that's the situation in my case. It only starts to be apparent when I have it on WOT.

 

Mine is the same as LionZoo and 8rotor8, it sounds like sand in a whirlwind vacuum and seems to be behind the glove box or the passenger foot well. I wished Mazda would issue a TSB on it already. I’d like to be able to hear the engine above 6k RPM.

 

You should hear how loud it gets when I rev to 9800k. I just start turning up the radio. But I think LionZoo told me that Mazda in Burlingame came up with a valve that took care of the problem.

 

According to Phantom Menace, yes they have a part. It's one of those you have to complain to get it issues though.

 

i think i figured this out. could the problem be that the rotors are out of balance, or that they unbalance under hard acceleration, or that there's not enough oil getting to them? on mazda's 4A website while reading about the difference between the 13b and the renesis, i found this:

"Rotors are dynamically balanced according to the mass of oil entering them to reduce vibration during hard acceleration. And counterrotating fixed gears for the front and rear rotors achieve smoother rotation and lower gear noise, allowing greater enjoyment of the carefully-tuned engine note and its pleasingly sporty sound."
http://4a.mazda.com/product/rx8/driving01.html

 

If you are hearing noises from the engine, that is not the marbles. The marbles comes from behind the glovebox.

It has nothing to do with the engine.

 

I have the rattling problem. When I accelerate on the highway and have the driver's window open, the rattling sounds like it is coming from underneath the car. If I have all the windows closed, it does sound like it is coming from the other side of the glovebox. The problem definitely occurs more frequently when I have other passengers in the car so there appears to be a correlation with load. The rattling is getting worse, the service department at my dealer has yet to reproduce it, although I did provide a recording of the sound to them. I am nearing 100K km. on the car so reaching the end of the engine warranty. I would really like to know the name of the valve referred to in this thread. I have no visible loss of coolant level and have not topped it up for some time. Based upon my symptoms, would there be any other likely causes? Any help from those who have experienced a similar problem and resolved it would be really appreciated. I love this car but the rattling is driving me crazy.

 

That isn't the marbles.

 

I finally got around to listening to the WAV file on page two.
That is the sound of the auxiliary port hardware rattling inside the manifold.

 

I think most people that are experiencing the sound in question have it like the WAV on page 2.

Its high RPM.

The "sleeves" of the aux ports are floppy by design (take out the manifold and it becomes apparent).
If the clearance to the end housing is even the slightest bit loose, when those ports rotate under command of the APV motor, they will wiggle from the aerodynamic force of the intake charge.
That would easily account for the faint aluminum on steel type sound that is heard.

 

**** Im glad im not the only one.!!!!!!!!!!!!!!!

 

Fixed my "MIAC-Detonation" and it was easy ....look...

https://www.rx8club.com/rx-8-discussion-3/no-more-detonation-%2Amiac%2A-121249/

 

I recently brought my car in for the "sand" in a blender noise, behind the glove box, only happens above 6k rpms. Its an '05 pearl touring. I bought it used w/ 8k miles on it and now has 13k. They still have it, but they can't recreate it.... I find that very hard to believe. Is this one of those situations you drive the guy around yourself so that you know he's hearing it? Whats the proper procedure if they just act oblivious to it?

 

Say you want to ride with the tech when he's diagnosing your car. If you let them drive it by themselves, they'll never find the problem. I figure they have the stereo turned up so much that it's impossible to hear anything else.

 

Finally got around to taping the noise. Video is poor its from a camera instead of a camcorder but its easier to transfer and does the job.

YouTube Link

Can't hear it great but its better than nothing.

 

damn it, I think my car started doing this today.
05 MT, 33,000 Miles