Hey guys, I got a rotary compression tester off a member on here to borrow for a few days and hooked it up today.

I got some wide readings, and plugged them into this java program I found on here, and they didn't look real good.

Anyone else care to calculate these readings and tell me what they think?

Car was not cold, but not hot. I think it probably sat for 30 minutes after being driving by the time I got around to checking the compression.

Car wasn't cranking fast enough so I hooked another battery up which explains the wide rpm difference.

Rear rotor
78 80 80 psi
215 rpm

72 75 74 psi
193 rpm

Front rotor
82 81 80 psi
208 rpm

73 75 74 psi
184 rpm

Thanks guys, - Logan.

 

Yup... those are all under the minimum allowed tolerance.
Look into a new engine from the dealer before the warranty expires (if it hasn't already).
You have 8yr/100K mile warranty on the motor (provided you kept a good maintenance record).

 

Can I ask where you looked to verify the results? I just had a compression
test done at my local Mazda dealer with the following results. Dealer said
rotor 1 was just below spec but I shouldn't worry. He suggested I replace the
plugs, coils, and wires due to the harder start when warm (takes about 2-3 sec of cranking). They would be happy to do it for ~$650 but I plan to do it
myself. P.S. The compression check was $156.

Rotor 1 Rotor 2
---------- -----------
1) 6.8 96.72 7.4 105.25
2) 6.8 96.72 7.7 109.52
3) 7.2 102.41 7.6 108.10

RPM 294 303
DIFF 5.69 PSI 4.27 PSI

Rotor to Rotor Diff 12.8 PSI

 

mljhn yours appears to be within tolerance.

 

I have problems identifyin the graph.
It may be pretty low at 300rpms though.

 

Did you have the throttle at WOT during this test? The cranking RPMs are still too low and you'll need to have the battery load-tested and will want to make sure you have the "updated" starter before drawing any further conclusions.

 

I am willing to bet your engine has 6-12 months left on it, if that.

 

Dying.

Soon you will see it in the 5.x zone.

 

Well I have been searching and reading so I am a little concerned by the 6.8
readings, especially at 294 rpm. I'll give the plugs, coils, and wires a try and
even try cleaning the engine with the DIY/TSR. It's an '04 with 53k miles.
Bought it used a couple weeks ago, my first one, so I'm not even sure if there was a
problem Mazda would replace the engine since I don't have any of the
previous owners oil change records apart from a few listed in the carfax.

 

Hey nycgps, u know any good spots in NY to get a compression test done ?

 

Man, you guys are depressing me...

 

in NYC? There is a place but its not open for business yet ... its called NYCGPS

seriously, I ordered the official tester but its a long wait, I probably get it next month tho.

Other than that, you can go Wayne Mazda to do the test, but its gonna be 100 bux (I charge 20)

 

I called up my local mazda dealer and requested an engine compression test today. He asked me what was wrong with the car, I said poor gas economy, and that theres some white residue on the dipstick. lol didn't really know what to say, I just wanted to know what kind of condition my engine was in before warranty ended. but anyways, so began the engine compression test($100). about 30mins later the dealer calls me to tell me that my starter is very slow and won't get an accurate reading for the test, (starter was moving at 130rpm). He tells me he can replace it for 380, but unconvinced I told him to do a diagnostics first (additional 100). The cause was a with my remote start and the clutch bypass, for some reason it made cranking slower. He ended up not charging me for diags, and proceeded with the compression tests. and heres the result:

300RPM

chamber1:
900kpa
910kpa
900kpa

chamber2:
890kpa
900kpa
910kpa

I'm the 2nd owner with almost 60k miles with original engine. I'm not sure what the specs are but i think these numbers are decent. Eh at least i know my old engine is still good. As long as the mazda techs says its good i'm fine with the engine. What you guys think? most of the compression threads /posts i see are in psi or running at 200rpm, these numbers ok?

 

wow, **** outa here, those "numbers" are so made up and 300 rpm is just rare.

 

Should I go back and verify these numbers? You thing this is bogus? like i said I haven't seen others with similar test results.. Not sure if this is a good or bad thing, but my engine running strong.

 

well I mean you could be "lucky" to have a proper clearance engine.

but thats just rare.

no point going back there. I mean if they were lying, u think they will tell u the truth now ?

if the test was real, then u will just get the same results.

just let ur car be at this time.

 

Yea i'm just glad to hear my engine is not dying or on borderline. I'll keep up with the regular maintenance and decide what i want to do with this car.

 

Those numbers are pretty standard. No such a big deal.

 

One little trick you can do is attach a big battery charger of 200Amps or so to your battery and you'll instantly get higher rpm. This will not skew your data. About $130 from Harbor Frieght and great to have around the garage. A jumper box is pretty worthless for this to BOOST cranking power. Your looking to BOOST amperage.

 

Hi Guys,

What do you think of these compression values? The 322 RPMs are real or that what the computer printed, I was present at the test (new starter, new & powerful battery, I guess), it was not done on Mazda but by a guy of my local forum that the rotary compression tester that goes to a computer. The car is a 2007 with 25.000 miles that never had a decarb (not my car). The test was done at 2165 feets (Madrid).

RPMS: 322
Front: 791/811/818kpa
Rear: 783/798/794kpa

 

I was talking about 300 rpm.

its just rare the stock starter even updated one can spin this fast. Unless his battery & starter are new

and both rotor's numbers are too close to each other, which is just "another" rare. especially when the engine has gone thru lots of miles.

but like I said he could be "lucky". Thats all I can say.

 

Lmao..i think I'll pass on Wayne Mazda. Make sure you put me on your waiting list! Haha. My car is an 04 with 125,XXX miles. Mazda put in a new engine back in 2005....curious to see what my compression test results would be.

 

Yea i upgraded my starter with an 2007, and upgraded to a 1000amp optima red top battery. I've seafoam, and used BK44 carb cleaner i think thats what it called, on my engine around the 55k mark. I like to take care of my car