does this sound like low compression
 

hello all, so my car has 172,000 miles on it. it must
have been rebuilt once already, well at least i and a few other rotorheads think by the way the engine looked and the condition of everything when i first bought it 2 years ago. anyways, so its getting harder and harder to start. at first i thought it was the starter so i swaped in another one and it still did it. next my buddy told me about something he read in a book about mazdas and such about similar problem and it was called worn rotor seals i think. and my car makes more smoke on start up than it used to and i mean pretty good clouds of black smoke. I get really horrible gas milage like 13mpg in a NA. but ya let me know what you think or if youve had a similar experience. I am trying to get this figured out because i am tring to sell my car. so i can let the person know. thanks matt22

do a compression check on it

i am looking into getting that done i jsut got to find a
place i dont think my local mazda dealership touches
rx7's lol.

you can use a piston engine compression tester to get a rough idea too

ya, just go buy a $20 compression tester, you'll use it so many times it'll be well worth it...keeping tabs on what the engine compression's doing over the course of months, years will ease your mind when something goes wrong...how's your idle, BTW?

my idle is ok, it now back down the the 700 -900 range, some days its higher though. So i jsut need to go buy a regular compression tester. thanks matt22

Yep. Buy one at autozone for 20-25 bucks. I don't know what you would look for compression wise. I think 8-10:1 is good?

Do it on each rotor of course.

Good luck

well, on the NA I believe mazda states that you want at LEAST 6:1 and anything below that is crap. however, you probably should rather see between around 8 or 9 as row-tar-eeeh said.

I bought a tester at advance autoparts, then returned it the next day and got my money back. The mazda dealer wanter $120 to do a test, and I did it for free :-)

If I was going to be down in Eugene Matt, I would bring my compression gage and we could test it. My NA had 90 on it before I rebuilt it, and it got 27mpg freeway and about 18 driving hard. It was very easy to start and didn't smoke at start-up or any time. The rebuilt street port I now have gets about the same freeway mpg, and about 22 mixed city / hwy with around 15 driving it VERY hard. :) I love weight reduction.

shoot well i guess i will jsut go get one then. might use
it for my other car(s) as well. might be good to keep a
log of of biweekly compression tests. lates matt22.