So I had a compression check done on the car I am interested in purchasing this weekend. I am not too familiar with these numbers. Going to post them here to make sure they are ok. The inspection says All Areas of the car are in good condition and it say A/C is INOP ( I assume it means In operable but I knew this going in)

Rotor # 1 69.7 82.07 85.08
Rotor # 2 81.05 96.8 90.0

Thanks for any feedback; I am also going to do a search to read up

 

not good. does the car start and run?

 

What? yes it starts has a new engine with 3K on the engine Mazda said the #'s where good. Got a compression test done for piece of mind

 

those numbers dont seem toooo bad :/

 

U guys serious? What are good numbers then?

shop manual says 690 kPa {7.0 kgf/cm2, 100 psi} minimum @ 250 RPM. Differential limit of chambers is 150 kPa {1.5 kgf/cm2, 21 psi} @ 250 RPM.

 

You just answered your own question.

 

.

 

Yeah, that engine is on borrowed time...was it a cold test or after the engine had warmed up? check out this thread for what are good numbers:
https://www.rx7club.com/showthread.p...ht=compression

 

i agree that that first number on rotor 1 looks like a chipped apex seal, especially being so out of line with the others. even if the numbers are within specs, they should be within 10 percent of each other at the most.

 

Just a note Mazda did the compression test and it is a New Reman engine with around 3-4K on the engine. Not sure if it is cold or warm test

 

Dude! it seems like your motor has 80K miles on it with hthose numbers. I hope you bought it with a warranty.

 

I have not bought the car yet. Was debating its purchase. Owner says its a new reman engine with 3-4K on it

 

i just read the for sale thread on this car. looks like a sweet car, but really, those compression numbers are not worth $18k. if he wants knock $2500 off the price, then it might be worth it. i'm basing this on the 93 silver on red in the for sale section that had the same compression numbers you posted.
andy

 

yes that is the car. Thanks for double checking. Wonder why the compressions don't seem right. Maybe Mazda Dealer doesn't know what they are doing or did something wrong. I called a rotory specialst and they said the numbers where ok with exception to the 69 was bit concern but not anything big as long as you push normal boast

 

Those numbers are a bit low. they should be 85-125 ish.

Any lower and some thing is up.

 

When i had my series4 engine re-built they where all over 100.

 

What effects the compresion and what relation or parts does it have a effect on damaging?

 

Well apex seals are a big one, I’ve seen one’s with real badly worn rotor housing end plates have low compression after rebuilds.

But thats all i can real think of right now.

 

Not a rebuild but a Reman new Mazda Engine. The guy has receipts for $4400

I Emailed another rotory specialist here locally for advice and recommendations

thanks

 

you should look else where or tell the guy to blow his motor up and get a new reman

 

Called the Mazda dealership Tech and he said it was good as long as its below 5 or (50)

Probably buying this weekend, pending if all other items I see on the car are in the condition state by seller. Flight already booked, wish me luck

 

Maybe you should look into getting a second compression test. It's possible that mazda screwed up, but not likely. Remember 100psi is minimum, most would say you could get by with 90 mimimum. Sure the car would probably run another 1-2 years, but you wouldn't be able to drive it like you want to. Like others mentioned you should see if you could get the guy to knock off a couple grand.

 

How much cash does the guy want for it?
[edit] btw after reading this whole thread. Move on, dont go with this one.

 

I am starting to think the numbers I posted are confusing people but maybe they did mess up. Mazda said the engines fine so I might run with this one. Obviously going to test drive it first

 

If thats PSI then I really wouldnt suggest it. I have a 93 Black Touring with 55 original. It has over 100 on both rotors.