I recently had a compression test done at my local Mazda dealership. It runs OK but the test results were not so good. 564 kPa rotor 1 and 531 kPa rotor 2. They said 830 kPa was standard and 680 kPa was minimum. Can anything be done outside of tearing it apart and rebuilding it to improve this? It's an '85 with 118,000 ks Cheers, Dave

 

keep on running it.
it's about 80ish psi.
look for yourself:
http://www.vici.com/ref/cht_pres.php
I would wait longer.seriously 118 km ..that is nothing..

 

Agreed! If your that worried, but a table spoon of transmission oil into your gas, it always brings the compression up lool

 

?..what?..so it can smoke?
NO Atf in the gas..please.
they are doing away with Drive-Ins so they do not need any Mosquito Machines!

 

I'd get another compression test done, who knows if that one was done properly. If the battery wasn't in perfect shape or they didn't have the throttle held open those compression numbers would have been effected. Get a simple regular compression tester, pull the valve core out of the hose, and try it yourself.

 

It doesnt smoke... Unless you decide to pour in more than just a table spoon or even a cap full. I've tried it many times on those engines that sit for 4-5 years and I see no issues But then hey, all rx7's tend to behave differently.... I wonder if there all just robots in disguise

 

There is one problem with ATF. It tends to be a little harsh on rubber seals unless those seals have been designed to be used in an environment with ATF. Small amounts probably wont hurt anything but larger amounts or direct concentrated contact could potentially harm the seals within the engine. As part of deflooding i would never suggest it.

 

Don't use ATF at all. And definitely don't mix it with fuel..that's not very smart.

Get another compression test or do it yourself. And no there's no other way to bring compression up. There's a reason its down and can only be remedied by fixing the problem. And that means tearing apart the engine.

And if the engine still runs and doesn't flood then don't worry about it just keep driving it until it blows up.

 

Although Kamloops isn't at a terrifically high altitude, even altitude affects compression numbers - it certainly does here in Calgary, ~3500' above sealevel. I never see the factory numbers around here.

 

Don't fret compression numbers.

If the car starts easily, makes good power, and gets reasonable fuel economy (reasonable for a rotary) then compression is fine regardless of the numbers.

 

How warm was the engine when tested? cold tests will be lower
That compression is fine as long as it starts well, has power and RX7'ish economy - keep driving it.

Some folks would recommend various gas additives such as Marvel Mystery oil or ATF.
Just driving it hard (legally) once in a while will help it too.

 

I agree it's possibe the comp. may not have been done properly...but more likely the seals aren't moving freely. If the car is stored I'd open it up in the winter, spend a gasket kit on it and reuse most seals...more likely just carbon build up. You can try adding some Seafoam in the mean time. Edit: I say this because i'd rather not wait till a seal breaks and takes out some housings but not all will agree.

BTW, the spoonfull of ATF goes through the spark plug hole (lower) into the chamber directly and it's a very well documented trick and does no damage for the small time it is there. Just don't leave it there for long and start the engine right after putting the spark plug back. An oil squiter can makes it easier btw.

 

Thanks to all for the replies. I've had good luck with seafoam, I'll give it a try. I had a sale fall through on the results of the compression test so after the seafoam/ atf I might try another with my own tester. It runs fine, i think so I'm not too worried. Cheers, Dave

 

Tried the seafoam trick. 1/3 each in the tank, crankcase, and down the carb. We'll see what happens. One cool thing, I accidently left the air cleaner off when I took it for a drive- what a great sound it makes when the revs go up, cool! I'll drive it a little more and try another compression test. Cheers, Dave

 

Ya.Ok..leave the air cleaner off...
suck in Dust,dirt,debris,etc into the internals...and you are wondering if the compression test was OK?
I know it sounds cool but please put the thing back on!!..how old are you?..12?
you want me to come over there and put a card in your bicycle spokes too?
I will ya know..I live in a freakin trailer park,and I know about "engine alterations"...after all My HOUSE has wheels!.LOL!

 

As long as you're on a good clean road, honestly you don't get a whole lot of dust in the engine bay. I just run steel mesh screen on the velocity stacks on my Rx-4. I couldn't get a filter setup to flow enough air for it. The engine was very restricted by the air cleaner setup I had on it before.

 

^^this from a guy that makes engine noises and has windshield wipers inside the car!...Buggy!..my N/A waterpump housing??