Hello
Please share your thoughts . Yes I am a newbi ! I bought a 84 RX8 a week ago .
I am very good with my hands and enjoy working on stuff ! I have extensive tools !I am 64 retired ...
My question I used a compression tester yesterday to do a compression test on my 8 and I took the shrader valve out . I only got about 10 lbs PSI steady over all three lobes of the rotor .Both rotors test the same I removed all 4 plugs to do the test . I would think it would not run at alll with compression that low ??? But it runs damn good . Compression guage has been in tool chest for about 15 years ,
Can you read the plugs how they look like a convential engine ? One trailing plug looked oil fouled ?
She was hard to start ...but I think part of that was me not knowing starting and shut down preceedures .
I think she needs a complete tune up !!

 

You did the test wrong. I can spot at least two problems with how you did the test.

If you fully understand that using an analog compression tester is only going to get you a rough guess at best, I'll point out which problems you had. I'm wary of just pointing them out and you redo it and rule the engine dead when it might not be, or good when it might not be. An analog compression tester really can't properly do what you need it to do.

I highly recommend taking it to a Mazda dealer and get it properly tested with a rotary compression tester.


Yes, you can 'read' the plugs.

Ignition health is critical, in a perfect world trying to maintain peak condition, the RX-8 needs it's coils replaced every 20,000 miles or upgraded to BHR's, and plugs need to be changed every 10,000 miles...or even earlier. We have a hugely filthy combustion environment.

There is no "startup procedure" or "shutdown procedure". It's like any other car when starting and any other car when shutting off. Any special tricks you feel you have to do, or may have to do, all mean that you have neglected maintenance somewhere. Maintain the car properly and you can start it up and shut it down like any other car.


It sounds like you really need to take the time to read through the new owner's thread here: https://www.rx8club.com/new-member-f...t-here-202454/

 

I second RI's recommendation to go to a dealer or rotary specialist for a proper compression test.

Just to keep you from going batty wondering about the 10 psi, by taking out all the plugs the compression was let out through the plug hole that you did not put your gauge into. Compression tests on a rotary are done with one plug per rotor left in, and the tester screwed into the other. Just like any other twin plug engine. It's my understanding that seasoned rotary mechanics can make some sense of readings using a conventional compression gauge with the shrader valve out, but at best it's incomplete and approximate.

If you believe in what owner's manuals say, the one shutdown procedure is to not turn it off until it's up to operating temperature.

If you don't know the maintenance history of your 8, then it would be good to replace plugs, coils and wires now. Also change the oil and filter, and whatever other fluids you believe have a finite lifetime.

Welcome to the rotary world.

Ken

 

Guys thank you for your reply . I have been reading RX8 stuff here .
Ken thank you as you answered a question I wanted to know . Only one plug out at a time !
I traded my 2004 Trailblazer to a young guy with a new born , He just did not have the money to maintain it . If I would have know what I know now I would have had a compression test done before trading . Oh well live and learn .
I love the challange of learning new tech . !!! I am a hands on guy !
Reason for wanting a compression test ... is to see if engine was in condition to do a complete turn up . The infomation I have is that yes it is worth doing a complete tune up !!!

Thanks again Guys
Such a thrill to red line it in 2nd gear !!!!! Grin

 

Certainly an 04 RX8 can use a complete tune up, with new coils, plugs, wires and fluids. But FIRST get that proper compression test done before spending more on tune up items. You need to know the TRUE health of your engine before going forward. If you have a failing engine you will need every penny for that rebuild or reman. Your gut feeling after this improper compression test is not really valid with a used rotary engine, you need the set of six numbers, three faces per rotor.

 

I am going to redo the compression test this morning . I got the info from this video I have the exact same compression gauge as seen in this video .
Ill let you know what I find out ...

 

This will NOT give the definitive six numbers you need to know the true health of each rotor on each of the three faces, and don't forget it all depends on your cranking rpms and you altitude (above or below sealevel) A proper rotary tester will give a readout and printout of the six numbers and cranking speed.

You may be saving some money to do it yourself here, but you won't get the full info you need

 

Guys I redid the compression test this morning . Got 80plus lbs on all lobes . uniform across the board .Removed the trailing plug on each rotor to so the test . I did find rear rotor wires were crossed up . I took her out for a test spin and Holy Moley she runs good !!!!! Nice smooth idle !!
Yeah I know it is not the Stealer high tech test . But for my use I got what I want . I dont mind spending the money to do a complete tune up and fix the other bugs ...Now !!!
Issues ...leak some where in radiator ? Water level light on on dash
Previous owner changed out radiator .. ... and when condenser was remover AC needs to be recharged ..
Also cant regulate temp cool to warm , it only blows hot .. I had to order a r 12 adapter to R134 for my vacuum pump ... It should be here tomorrow ..
I changed oil today ... It was dirty , and from my reading CLEAN oil is important .
I check air pressure in all tires they were low ... aired up to 34 lbs all around ..
I also cleaned the MAF valve ..it was clean ..

 

More often than not that's a bad sensor in the coolant bottle. The float tends to absorb coolant and get heavy. Keep an eye on the coolant level for a while before doing anything precipitous. There are a couple of long threads on this. Proper fix is to replace the coolant bottle. Workaround is to unplug the sensor, and visually check the level whenever you're under the hood. Easy if you've got the translucent bottle.

Alternative to unplugging is to leave it on, and make up an interesting story if a passenger asks what the light is. It can look like a Greek temple, a Rolls Royce radiator, or a merry-go-round.

Ken

 

Thanks Ken !
I do have a fluid leak , I think it is a busted hose . Have to remove battery box and air box to examine hoses ... Its on the left hand side .
\
Go Harvick

 

Old people: Spending money on things they don't need while saving on something useful to maybe solve problems that them might have sometimes.

 

Young people: destroying nice cars because they have no clue what they are doing or how to drive. "I know how to drive I've watched every fast and furious 100 times and play need for speed all the time."

 

Big smile !!!