I own an 04 RX8 and it seems I have a bad engine. I bought the car in April and it's amazing but it's always had starting problems. I've changed everything, spark plugs, spark plug wires, starter, MAF sensor, Cat converter, O2 sensors, coil pack and it still won't crank like it should. I've taken it to a mechanic who checked my injectors and said they were fine. I also thought it might have a bad computer but he said the computer sent out normal pulses. So is it a bad engine? please help, i love the car too much to sell or trade. I am located near Raleigh, NC do you know of any rotary mechanics in the area?

 

Have you tried taking it to a dealer to get a compression test?


It's the only way to know for sure.

 

No I haven't. It'd be a hassle just to get it there though. It would also stutter when accelerating. It did turn off on me a couple times by itself. 6-speed.

 

Well, you have ruled out everything but compression.


And a compression test is needed to determine if it's compression. Not really another way around it.


If the hassle is from the dealer's end, then just tell them that you want a compression test. It's a service like anything else. You don't have to start with requesting a new engine or anything. Just ask for a compression test.

 

Right now a mechanic has it at his shop. However, I'll see if I can take it this week. What could be done if the engine has lost compression?

 

Rebuild or replace the engine.

Usually it's one or more of the following:
- 1 or more (of 6) Apex seals worn too far or broken/missing
- 1 or more (of 12) Side seals worn too far or broken/missing
- Side irons worn too far and the side seals can't seal
- Side seal springs deformed or warped pushing the side seal out of place
- Carbon caking has unseated 1 or more of either seal
- Housing worn too far

The only one you can attempt to fix without opening up the engine is the carbon buildup, and that chance of success is spotty at best (but far cheaper so won't hurt to try).

Opening up the engine always means a rebuild, since there are only 3 moving parts. There is nothing you can 'leave together' during disassembly.

 

What is an estimated price for a rebuild?

 

Just found out from the mechanic that it has 0 compression :/

 

The price of a rebuild can vary dramatically.

IF, and only IF, it's just the seals, then around $1,000-ish, depending on the price you get for all new seals, oil control rings, and water seals. However, usually low compression engines also need 1 or more other major parts replaced, housing, side iron, rotor, e-shaft.

None of them are cheap. Side irons can be lapped back to spec, housings can be re-chromed, etc... but it's very easy to have just a few of the parts drive you over the cost of a replacement engine. All brand new parts and you are looking at ~$6,000+ to rebuild. The housings alone are $2,000 retail through the dealer, though you can get new ones discounted down to about $1,100 or so through other sources, including Mazda's motorsports program.

Alternatively, a used engine still intact goes for between $700 and $2,000. A quality rebuilt engine through a vendor is in the range of about $3,000. A questionable quality Mazda reman is $2,900 to $4,000, depending on how much the dealer marks it up.


It's a very simple engine.

But none of the parts are easily produced, or produced in large volumes, so they get expensive.

These are the major pieces.


Plus oil control rings, coolant seals, side seals, corner seals, apex seals, and other gaskets, o-rings, etc...

 

Thanks for the information, do you know of any professional rotary mechanics in Raleigh-Durham area?

 

Not sure of any in NC. Might want to check with the southeast US guys (subforum)

 

My local mazda dealer you can get a reman for $2001. Plus like 150 for gasket set. Obviously that's parts only no labor