Low Compression
 

Hi all. Just got a 2006 RX8 and I took it to a Mazda dealership and they told me that it had low compression. I've been driving it 100 miles a day for the last 3 weeks and it doesn't give me any problems at all. What is the low compression doing or not doing to the vehicle? Is it gonna break down on me soon? Is this fixable? I've searched the forum, but this is all greek to me. It's stuff on top of stuff on top of stuff. Thanks all!

It means you need a new engine. Sorry to say it like that.
The good news is it's 2006 and if it's under 100,000 miles it must still be under warranty, Mazda should replace it. Educate yourself on this forum about what are good things to do at the same time, like changing the ignition coils (which are not covered by the engine warranty).

In a nutshell, your engine is worn out below spec and it's not producing the power it once did. With that comes reduced reliability. You will begin to experience difficulty starting the car when it's warm, for example. Eventually it won't start or hold idle. How soon or how late depends entirely on how far gone it is. Did the dealership happen to give you the actual compression values?

Also, since you're new to rotaries, suggest that you read up on adding the oil and other important items in this thread: https://www.rx8club.com/rx-8-discuss...t-here-202454/

Oh no!!!!! It's like 120,000 miles so I'm SOL on that one. I have to find the results on the test. I think they tech said something like one of the rotors or something to that effect went out. I was thinking brakes, but I think he meant engine? The lower power is exactly what I noticed cause I was for sure these cars were at least a little quicker than what I'm driving. I'll for sure read up on the thread today. Thanks a million my man.

It's 8 yr/100,000miles right? or was it 10 yr/100,000...

If I could only roll back the miles lol.

8 year /100,000 miles.

Yep, the rotor the tech was talking about was likely an engine rotor.
The compression values you're looking for look something like this:

Rotor 1: #.#, #.#, #.# @250rpm
Rotor 2: #.#, #.#, #.# @250rpm

Rotor 1: 6.1, 6.0, 6.1 @237rpm
Rotor 2: 5.7, 6.0, 5.9 @ (didn't specify)

I'm at 130,000K miles

thats bad men.. well do you have 4k? yes? noup? if u think yes then then buy another engine if not sell or trade u car right away! good luck

Anybody got any suggestions about rebuilding the motor? I've read it, but I have no idea exactly what it means. Can I do that with this one?

You can but find someone to do it right. Also depends on what all you need for the rebuild sometimes its cheaper to just buy a new one.

With my luck I'll have to buy a new one lol.

Don't skimp on the rebuild if you're going to do it. Your risk doing it again very soon if someone cuts corners. Mazmart is one place to go, RotaryResurrection is another (both are active on this forum). Buying a used good condition engine is another option, but be super careful, get its compression verified before buying.

Mazda itself will sell you a rebuilt engine (don't let them tell you it's new.. it's not), but sometimes their rebuilds are wonky.

Thanks for the insight. I'll check with both. In your honest opinion, would $4K be a fair selling price being that the compression is low?

Sounds a bit low, but I'm not in the US, don't have a good gauge of the market. After all you say it drives well so far.

I would sell it really just to get rid of it. It's not giving me problems per say, but it seems like it's going to give me major ones eventually. I'd have to sell one of my other cars to come up with the money to get the RX8 "fixed". I don't know if I want to do that now.

Rotary Resurrection is probably the cheapest reliable rebuilder (though shop around). The rebuild cost however, will depend on how many of your engine's parts are reusable. Right now, with it running "ok", is the time to get the work done. Continuing to drive it will almost certainly result is a major failure that wrecks the internals, driving up the cost of repair considerably.

What's your highway mpg, by the way?

i bought a car like yours over the summer, it needed an engine, but still ran ok. he was asking $4500, and i was the only interested party.

so i would have the car detailed*, ask $5k and be prepared to take $4k. actually if you were closer, and i didn't have 5 cars already, i'd buy it.



*the last car i bought looked clean in the pictures, but i've spent a more time scraping the old owner off the interior than anything else, yuck! i think the PO was a dog that spilled soda...

Thanks for the feedback guys. I don't know if I can afford to fix it so I might just have to sell it.