Why does my 2004 mazda rx8 has no compression?

I took my car to my mechanic and he told me that my 2004 mazda rx8 has no compression, why?

Firstly, an average mechanic would not be able to get a proper compression reading from a rotary engine so your mechanic may be wrong. Rotary engines require special compression testing tools and different techniques than a normal piston engine. Only shops that specialize in rotary engines, or Mazda dealerships will be able to do this properly.

If you truly have no compression there’s a couple possibilities. The rotors have a couple sets of seals…on the side are a set of oil seals, and on the 3 apexes of the rotor are apex seals.

The apex seals sit in a spring-loaded slot and move in and out to maintain contact with the rotor housing. Severe carbon build-up can lock these seals so they can’t move and therefore can no longer seal.

The side seals can get damaged from severe carbon build-up in the intake or exhaust ports as some of them travel over the open port during the rotor rotation.

The common item above is carbon build-up. Have you been driving your motor gently? If so, that’s the main cause of carbon in a rotary engine. They need to be driven hard to burn off carbon deposits or issues like your can happen.

Proper oiling may be the cause. too. If the engine is “granny’d” in it’s driving habits there is less oil injected to protect these seals. Hitting high RPM frequently gives that extra little “squirt” of oil that helps protect the seals.

If you have lost any compression due to seal problems it requires a complete engine rebuild to fix, which can cost anywhere from $500 – $2000 depending on whether the rotors & housings are still Ok.

Rx8 Compression Test


Hot Start Cures:
1) once flooded put your accelerator pedal to the floor before you crank so that you get the maximum airflow through the engine to dry out the combustion chamber (just like a 2stroke). In future to stop the engine, run the engine up to 4000rpm then take your foot off the accelerator to shut off the petrol, and when the rpm comes down to 1500rpm turn off the ignition key. This turns off the fuel supply and dries out the engine for easy restart. Perform the latest ecu software update which also stops over fuelling when cold or hot.
2) drop by your local scrappy and install the biggest second hand (read £20) battery that will fit in your battery tray (Ford Transit Van battery etc)
3) Mazda have a bigger starter option (£350) that will spin a flooded engine at the required minimum 200rpm (just like a 2stroke)
4) Hot Start Cure: google “Mazda RX8 Ametech Engine Restorer” and just shake up and add a 400mls Ametech additive to the existing oil (under £30) and top up with Mazda mineral oil and drive normally. Hot start compression problem CURED within 300 miles or a week of normal driving. Lasts many years and adds £1000s to the value of the car. The tiny copper silver lead particles in the Ametech quickly fills in the rotational scratches in the double eliptical cylinder walls improving compression.

I had the same issue with my rx8, if you tend to not drive the car rough (redline every other day), use less than 93 octane fuel, don’t have the fuel system cleaned at regular intervals, or use synthetic oil then the most likely problem is as the other person said that you have carbon buildup and the apex seals are stuck, that was the issue with mine, Mazda extended the warranty for the engine core for this exact problem to (8yrs/100,000mi) they’ll put in an updated (teflon coated) refurbished engine under warranty at no expense to you. So pretty much you’ll get a “new” engine for free.

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why does my 2004 mazda rx8 has no compression?
i took my car to my mechanic and he told me that my 2004 mazda rx8 has no compression, why?

don’t even think about buying this car. it has a rotory engine and the engine must be replaced to fix the problem. You would be lucky to find someone who knows how to rebuild/replace a rotory engine and even if you did it will cost you way more than the car is worth. Do youself a favor and buy a mazda 3.

rx8 has no pistons!! It’s a rotary engine. I’m guessing the mechanic didn’t know what he was looking at since it was a rotary engine. You should go back and get your money back.

Not a very good mechanic if he didn`t tell you what was wrong. Normally that would be a ring/piston or valve problem in a normal engine. Being a rotary engine , then the seals are shot. What are the symtoms. Seems too soon for the seals to go. How many miles on the unit?

cnshinn is correct. Also, if you had zero compression, your car would not start.

join www.rx8club.com and www.rx7club.com and you’ll learn lots.

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