SLOWLY open coolant overflow tank with car running..make sure to use nice thick towel while releasing the coolant system pressure..once the pressure is released take the cap off and look if you have air bubbles coming up to the surface from the bottom of the tank.. if you have air bubbles coming up you have bad coolant seal in one of the rotor housings.

Good idea. I will try this when the car is back running again. :D

Yes, it is a good coolant test for coolant leaking inside Rotor Housing(s), compression blow back, usually it is only a very small fine string of bubbles...bigger the bubble string the worse the leak.

You must do it on a Hot Engine, BUT, be VERY VERY CAREFUL slowly releasing Pressure Cap and have some spare coolant or distilled water/water for a top up.

As said by Nad, use a thick large towel over the cap and keep your head/face well away from outlet, be prepared for a gushing of Hot Coolant.

Or just start the car with the cap off and let it warm up fully.

Its most likely just oil and that plug most likely is not firing.

Did you check to see if you are getting good spark, do you have the BHR kit?

? Really...you should think about that one again mate..

It has to be hot, engine off, remove cap, then start up...then look.

Letting it warm up with cap off will just spew out coolant.

Really ;) it will only spew coolant if it pressurizes and you remove the lid....

Naturally, you are missing my point..

Normally, if you remove a cap on a cold/semi warm motor and start up car to get it hot with cap removed, will just overflow as coolant/system is trying to pressurize.

Having said that, I have not tried it with cap off in an (my) RX-8 (no need to yet), but every other car I have renewed coolant in normally does so from cold/warm with cap off.

Or doing a major re-fill top off after a large leak, and yes air pockets are also an issue or severe compression blow back.

guys i am curious about this whole Sohn OMP adapter thing, should i get it for my rx8, i have a 2005 with about 50,000km, i dont use any pre-mix in my gas and use it on a daily basis, what should i do to add some life to my engine?

24,000 Miles...forget Sohn, go with a Pre-mix.

I have done it a bunch of times. Sometimes a small bit dribbles over but not much. But then again my car didn't take long to warm up either. We will see how differently it behaves with a new motor and the turbo system.

thanks will do that, what ratio should i use .5 ounce to 1 gallon?

:lol: You take advice just like that?

OK..
To test for Compression or Water leak into Rotor Housing (that was the question) engine must be hot, and t/stat open.

Yep, give it a go, seeing yours is an S1, that amount of Pre-mix is good.

I would not bother with Sohn adapter, it is not going to really rectify lack of middle Apex Seal lube. Only Pre-mix can really do that.

Frankly, the OEM MOP set up is rubbish in S1, and that will draw criticism, but it is, it is unreliably, blocked Nozzles, fragile Nozzle supply lines, that set up should never have been used... you never know if a Nozzle is blocked or not with OEM, Sohn may show you when it is too late...Pre-Mix is the best for S1...8 Oz.

Yup there was a little oil/gas on the thread when I pulled the plugs out...on every one of them. I didn't get any engine code though, and although the mpg is a bit low, it wasn't that bad. (maybe around 18 on avg)

I was taking out the whole stock ignition system from the previous owner and putting in the BHR kit. I can already see the increase in mpg in the first fuel up, I don't really trust my butt dyno..since I don't drive it everyday.

Yeah I just let it idle until the thermostat opens and then the level in the reservoir will drop and you will start to see small bubbles rise up. This was one of the methods I used to determine my engine was toast.

As for the SOHN, well it was disappointing that I developed a coolant leak because I really wanted to see this engine go at least 75,000 before I had to tear it apart. I wanted to see what a higher mileage engine looked like with a SOHN and higher oil pressure from the start. But I still believe injecting clean 2 stroke is far better than injecting "dirty" engine oil. Plus, it allows me to run Mobil1 0W-40 without worry and it appears by examining my bearings, that the Mobil1 worked pretty well.

no I don't I did some other research as well as I know a few RX8 owner locally who are premixing as well

Okay good. I'm not trying to insinuate ASH8 doesn't know his stuff, because he does. But I would just hate for someone to just take advice without properly researching because there is a lot of wrong information thrown around on this board and other places as well. We all have opinions on different things and a lot of the hot topics are still being debated because there are no clear cut answers one way or another. Heck I have even found that talking to different builders will have you head spinning.

garages actually have a "sniffer" that can tell if that is actually combustion gases in the coolant bubbles. With that--it leaves no doubt.
Bubbles in a fully warmed engines coolant--is never a good thing though.

he should listen to your "I think ..." theories instead?


this thread must be powered by Everfail batteries ...

:lol: This thread rocks. I realize it does not offer anything conclusive in terms of why the engines fail prematurely but I think we can all agree that there is no one reason and until someone does actual long term scientific testing there will never be a real answer. The same goes as to whether premix or the SOHN actually helps extend engine life. But I do think that the changes made on the Series II motor tell us a lot.

The thread is Possible Engine Failure Theory..:)

Coolant Entry is one failure and poor Compressions is another, you can have both (unusual) or one...;)

Rotary engine coolant leak (into Rotor Housings was a very common issue, up until 1985 when Mazda appears to have mastered their OE Orange Coolant Seal, as it has not changed in close to 30 years, before that many Coolant Seal changes, it is now the exact same Seal for FC and FD RX-7 and both Series of RX-8...exact same part number.

The common and easy test for Coolant Entry IS what I have stated, usually a very fine single (or dual) string of bubbles the size of a pin head...you must have a HOT engine.

If you get large bubble blow back then 9 times out of 10 it is pouring water out of the exhaust, and is really struggling to even start...if you can get it to.

Failure due to Compressions is another fact, not theory..:)

I am not going to repeat what has already been said a thousand times, if you look back in history and what has been done to current RX-8, the answer in staring you in the face in regard to Apex Seals...

Side Seals...well the factory has not changed seal tolerances or gaps only the SS Spring...as we know IF a SS goes (breaks) it does so much damage then conclusions to theories is difficult.

Sometimes a solution to an issues one thinks they have 'resolved', results in revealing a problem in another area or a RPM or heat range or emissions or economy...or....

But what does Mazda know!!..more guys in the US have made way more than the 200,000 Renesis Engines and they have WAY more experience than MMC .

Slow clap....sorry mate :)...only joking....it is a good thread.

There is one theory that I can't recall being discussed and that is the OWNER and their maintenance..car use !... ..a real possibility ;)

Sorry for the late response I have been extremely busy with school lately and havent been on the forums much.... No I am hearing the high pitched noise from my OMP Vacuum line that is attached to the intake tube. I believe I posted a video of it a few pages back or so..... The sound you are hearing through your consol could just be whining from the transmission. I can hear mine start to whine a bit at certain rpms and at cruising speeds in town (50-60km/h in 3rd gear usually is where I hear it the loudest).

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