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How does the car drive so well having failed a compression test??

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Old 09-02-2015, 12:02 AM
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How does the car drive so well having failed a compression test??



First post. Was considering purchasing a specific 8 but it failed the compression test at my local Mazda dealer. Had the master rotary tech do the test.

My question is (given the numbers in the attached picture), how should this car be behaving? I drove it and started it a few times (hot and cold). It started every time and seemed to have normal power. No indication of power loss around town or on the freeway.. Got it above 60 mph too so it didn't go into limp mode or anything. Idles with the faintest of roughness around 900rpm

121k on original engine and and originally purchased and serviced religiously from day ONE at the same local dealership (I have the service history paperwork from mile 10 to now).

Has (sohn?) oil mod and is being fed 2stroke. Also coolant hose delete to throttle body. (Sorry I don't know the tech terms for the mods I tried to list but you 8 buffs should know what I mean).

The guy that owns it is a super nice guy and seems intelligent on rotary care and I believe he has done everything he can to take care of it.

Numbers don't lie, and the compression test fail was a HUGE bummer today but other than that and needing new tires/alignment, the car is in pretty nice overall condition.

I will not discuss price because I know their bottom line (and its up there imo) but it is ultimately their car and if they want a certain amount for it, that is their thing. Before the compression fail, I was prepared to go for it


How much would you value an 05 wwp gt with 121k with all of the info I've given?

I am very drawn to rx8's they are so unique. I don't know what it is about rx8's that makes me want to basically buy one with an essentially blown engine ... But it seems to drive fine.

Can anyone shed some wisdom for me?

Thanks so much, guys!
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Old 09-03-2015, 05:00 PM
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Don't pay over $3000 for any 2005 RX8 in decent shape with a failing engine, even if it still runs. At max $3000 you can then better afford to replace the engine. Some folks here say they have gotten them for even less with a blown engine. RX8s can run for a time with failing engines, but you are spinning the dice that you won't get stuck on the road somewhere driving one with these compression numbers. If you think the test was done improperly and you think the motor is fine, your only choice would be to get another compression test done from another rotary-compression tester.

Bottom line is, if you have never owned a rotary car before, you will not really be able to tell yourself how it should feel or perform. You don't want to overspend a lot for a car that you will have to pour many thousands into for a replacement engine after purchase.

I personally would look for another RX8 with an engine with good compression numbers.

First Read the new and potential owners thread below.

https://www.rx8club.com/new-member-f...t-here-202454/


Below is the RX8 clubs maintenance schedule. It is important that your check the maintenance records before you buy any RX8.

RX8 Club’s recommended maintenance schedule, more comprehensive and proactive than Mazda’s schedule.

30,000 miles:
- Replace Ignition coils
- Replace Plug wires
- Replace Spark plugs
- Clean MAF (mass air flow sensor)
- Clean ESS (e-shaft sensor)
- Reset ESS profile
- Clean power steering connections
- Clean battery terminals and clamps
- Replace transmission fluid
- Replace coolant (Mazda FL-22 is highly recommended)
- Replace air filter
- Replace brake fluid (fluid in the brake lines AND the clutch line)
~$300 USD in parts if you shop smartly.


every 60,000:
...all 30,000, plus...
- Clean all chassis electrical grounding points
- Replace accessory belts
- Clean OMP lines
- Replace rear differential fluid
- Replace thermostat
- Clean / Straighten AC condenser fins
- Clean / Straighten oil cooler fins
- Inspect catalytic converter
- Clean / Inspect intake valving
- Consider / inspect all points in 90,000+ as well, many items fail early
~$130 USD in parts if you shop smartly.

90,000:
...all 30,000, plus any 60,000 not yet done, plus...
- Replace coolant bottle
- Replace radiator hoses
- Replace radiator
- Replace front O2 sensor
- Replace motor mounts
- Inspect clutch pedal assembly for flex / weld breaks
~$900 USD in parts if you shop smartly.
At 100k, anything original in the cooling system is really suspect and failure prone. It represents the biggest threat to your engine.
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Old 09-03-2015, 10:44 PM
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Thank you for referring me to the club's maintenance schedule recommendations. I see it recommended in several threads and plan to do my best to keep this car in good running order.

Ended up, probably against my better judgement, purchasing the car.

With the engine having so many miles on it to begin with I figure, when it goes, it had a good run and we will just start again.. It seems, no matter how well someone takes care of these cars, the inevitable happens at some point. I'm just glad that I am in a place in my life right now that I can afford (even though it would suck) to keep the car alive rather than someone else buying it and treating it like **** and junking it.

This may sound stupid but I like to buy "forever cars". When I purchase a car I plan to keep it. OF COURSE I will not keep every car I buy and I'm going to make mistakes along the way (perhaps with this car. Who knows!) but I like to buy cars that excite me.

I'm not a mechanic or a gear head but I still consider myself a car guy in a sense and I'm excited to see where this car takes me. ...

You may see a post from me tomorrow or next week or next month or in the spring or in a year saying: "Welp! It finally happened!" But I will not be sour about it. I will just do my best to educate myself (with a great deal of help from this forum. Been lurking off (mostly off) and on for a couple years). My interest in this car goes back to 2004 and a little before but I've only recently made peace with the stigma of this engine. Every time I've driven one throughout the years I've smiled and I finally get to smile whenever I want (as long as the car starts! Lol)

I don't mean to sound care free with the seriousness of the impending doom because I do not want to be dumping thousands of dollars into this car in a day or a week or a month but I plan on owning this 8 (just as if I were to have a seemingly healthier rx8) long enough that I will be a part of the end of this motor's life no matter when it happens so I have made a sort of peace in my mind with it. ...I know. I'm crazy

As with so many people I've talked to about this car, the thought on owning this car seems to be universal. It kind of is what it is...

Bottom line, I plan on enjoying the hell out of this car while I am the owner...unless of course it kicks me in the nuts over and over again. Then this pretty little bitch is going on the curb next to the free couch and box of firewood on the corner and I'm cutting my losses.

Wish me luck, everyone!

Justin-
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Old 09-04-2015, 08:12 AM
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We get it and we are with you. I have owned seven rotary Mazdas and they all touched my soul. Hey as long as you are prepared to replace that engine someday, then just enjoy it and work on any other maintenance areas that are important for an RX8 that age. We are all here to help you get the most out of the car. Cheers !!
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Old 09-04-2015, 10:27 AM
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Hey, thanks!
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Old 09-04-2015, 11:58 AM
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How does the car drive so well having failed a compression test??

We've all been there congrats on your purchase. Take good care of that baby and post up some pics!
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Old 09-04-2015, 02:01 PM
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Pics coming soon.. I can get an exterior pic up in a minute but I have an interior detail scheduled for the end of this month and I need to replace the center vent cover because the sliders are broken so I have a replacement on order.

Keep your eyes out for a "full" unvailing around the end of the month. I might wait until I have full access to create new threads outside of the new members forum. Hopefully the car starts by then

Justin

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Old 09-04-2015, 02:49 PM
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I'm going to do some paint touch ups after the detail so the scrapes are a bit less noticeable.

And LOOK! I've already started a fund from the change the previous owner left in the car! I'm practically half way there!

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Old 09-05-2015, 06:38 PM
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Don't mean to hijack but we're kinda on the subject of it.

Can a bad clutch, bad ignition coils or the combination of the two cause an RX8 to fail a compression test?

I failed a compression test, yet my clutch and coils were needing to be replaced so I went ahead and did it and now it's driving like a beast. Would it be worth it to get another test or would those issues not even factor in to the compression test?
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Old 09-06-2015, 12:43 AM
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Originally Posted by Dave Davidson View Post
Don't mean to hijack but we're kinda on the subject of it.

Can a bad clutch, bad ignition coils or the combination of the two cause an RX8 to fail a compression test?

I failed a compression test, yet my clutch and coils were needing to be replaced so I went ahead and did it and now it's driving like a beast. Would it be worth it to get another test or would those issues not even factor in to the compression test?
Totally unrelated to compression. Another test would just be money pissed away ... It'll still fail.
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Old 09-06-2015, 12:50 AM
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Originally Posted by gwailo View Post


First post. Was considering purchasing a specific 8 but it failed the compression test at my local Mazda dealer. Had the master rotary tech do the test.

My question is (given the numbers in the attached picture), how should this car be behaving? I drove it and started it a few times (hot and cold). It started every time and seemed to have normal power. No indication of power loss around town or on the freeway.. Got it above 60 mph too so it didn't go into limp mode or anything. Idles with the faintest of roughness around 900rpm

121k on original engine and and originally purchased and serviced religiously from day ONE at the same local dealership (I have the service history paperwork from mile 10 to now).

Has (sohn?) oil mod and is being fed 2stroke. Also coolant hose delete to throttle body. (Sorry I don't know the tech terms for the mods I tried to list but you 8 buffs should know what I mean).

The guy that owns it is a super nice guy and seems intelligent on rotary care and I believe he has done everything he can to take care of it.

Numbers don't lie, and the compression test fail was a HUGE bummer today but other than that and needing new tires/alignment, the car is in pretty nice overall condition.

I will not discuss price because I know their bottom line (and its up there imo) but it is ultimately their car and if they want a certain amount for it, that is their thing. Before the compression fail, I was prepared to go for it


How much would you value an 05 wwp gt with 121k with all of the info I've given?

I am very drawn to rx8's they are so unique. I don't know what it is about rx8's that makes me want to basically buy one with an essentially blown engine ... But it seems to drive fine.

Can anyone shed some wisdom for me?

Thanks so much, guys!
That's the way it is with our Renesis engines. Many times they can run STRONG right up till the moment of catastrophic failure. If it fails the compression test it IS gonna fail; its just a matter of time. It could be a year or more till it fails or it could be tomorrow. If'n you have low compression the sooner you have it rebuilt the better. It generally costs significantly less to rebuild a seemingly good running engine than one that's failed completely.
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Old 09-06-2015, 11:31 AM
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Originally Posted by Colon Terminus View Post
Totally unrelated to compression. Another test would just be money pissed away ... It'll still fail.
That's sadly what I figured, thank you very much for answering my question.
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Old 09-06-2015, 07:56 PM
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Tried posting a photo a couple days ago, but it's waiting on moderator approval. I assume that's because I'm still a new member.

In addition to the vent cover, I'm looking into getting a new shift boot as well. The boot has aged with the car and has a few wear holes. Also, didn't notice when looking at the car initially but the rubber on parking brake handle is broken on the bottom (only visible when the parking brake is pulled up). Looked for parking brake diy's but didn't come across any yet. Would the parking brake be difficult to replace?

I really want everything to be in as good of shape as possible. The vent and shift boot (found diy's for both) seem easy. How about the parking brake?

Thanks guys!

Justin
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Old 09-10-2015, 06:37 PM
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can any year rotary go in the 04 RX-8?
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Old 09-10-2015, 06:41 PM
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Originally Posted by #1Hoochie View Post
can any year rotary go in the 04 RX-8?

Practically speaking? No. With a ton of money and fab skills? Sure.
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Old 09-10-2015, 06:51 PM
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Originally Posted by #1Hoochie View Post
can any year rotary go in the 04 RX-8?
Any year 04-08 MT Renesis can go into an 04 MT. Don't know anything about the AT cars.
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Old 09-10-2015, 07:10 PM
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I have been driving my 8 for 2 years and 40,000kms with compression numbers less than you have . It doesn't start too well hot or cold and doesn't have much NA power but mine is boosted so I don't care .
The key to keeping it starting every time is starter speed and ignition health .

It would be worth trying the decarb procedure on yours to bring it back a little.
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Old 09-13-2015, 09:19 AM
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It doesn't take much compression to keep an engine running and making power but you will definitely lose power if the compression drops that much.
The problem with dropping compression is that it's not you are now having a low compression engine like a lawnmower, the air thats leaking through the caps will cause other issues as well.
Personally, I would drive it till it dies and then do whatever you want.
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Old 09-14-2015, 12:00 PM
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Last night I successfully replaced my broken center vent above the radio (directional sliders were broken, so could not direct air) thanks to eBay and these two videos:



Obviously I did not take my entire dash apart like in the 2nd video

Today, I will be re securing the passenger front fog light (thanks to some help from rx8club). I discovered it was almost completely loose while giving the 8 its first bath. It appears to be holding on by only the top screw! Yikes! Hahaaha

Later this week will be a new (well...used but not broken) parking brake handle and a new (yes, this one will actually be new) leather shift boot to replace the current one that has wear holes in it.

Have a great day, everyone!

Justin-
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Old 09-14-2015, 03:20 PM
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Well.. The fog was not loose from the mount. All 3 screws were tightly in place. The housing was completely cracked from ear to ear..

Super Glued it as a quick fix. If it holds it holds (I suspect it won't). Probably source an oem replacement on eBay sometime down the road, as it's an easy enough D.I.Y. to replace. Might remove the reflectors in both of them too the next time I have to get under there. Thoughts on that?
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Old 02-23-2016, 02:09 AM
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Sorry to dredge up an old thread but there is a black plastic epoxy made by Permatex that works very well for those type of repairs and it is easily located at most parts stores.
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Old 02-23-2016, 09:45 AM
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New to RX8

Hi everyone,I bought my RX8 a week ago,I have been admiring this car for quite some time,about 5 years.I did a lot of research on its design and performance and its problems.I can honestly say its the best car to drive and worth the wait.I picked up a 2007 model, the 190hp version.I took the car for a test drive and I got all the service records from the main dealer.There are a few things I have to fix on the car but just minor,paint chips on the rims,the front parking light bulb,the air fins on the side I want to take off or respray,the central locking from the key fob isn't working so I have some detective work to do,signal is going through to the PJB so will have to check lock activation.I will post pictures when I get time.Great to have a site like this!
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Old 02-23-2016, 11:59 AM
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When you do get the car, create your own thread in the new members forum and how us pics and more details.
And while you're there, make sure you read all of the new owner sticky threads and read the announcements!
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Old 03-03-2016, 12:31 AM
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Originally Posted by gwailo View Post

I'm a few hundred thousand pennies away from my next rebuild. :D
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Old 03-03-2016, 11:42 AM
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For a starter??
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