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Series II Compression Test Results & Discussion

Old 01-21-2016, 06:21 PM
  #51  
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Originally Posted by Jastreb View Post

[RANT]
I honestly regret getting the warranty engine replacement. The original engine had compression that was getting low, and below spec on one rotor, but at least it could go up a hill at 70mph in 5th gear without detonation. I wanted a strong engine as a starting point for performance mods - instead I have basically ruined my ownership experience for the last 6 months. Should have left well enough alone, and saved money for a proper custom re-build (time & money I have spent trying to troubleshoot the re-man). Now I am down to my last option - take it back to the dealer and hope they can either find and fix the cause, or get me another re-man (which would be the 3rd re-man to go into the car).
[/RANT]
This is why being paranoid is a bad thing when it comes to rotarys. I've had engines with 85 psi last 50+ thousand miles and NEVER fail to not start hot or cold. It's better to trust the original S2 engine that's built in Japan than the remans. I don't know who Mazda is using for remans these days but, Williams tech rebuilt the engines back when I was a Mazda parts manager back in 2007-2008. Those rebuilds were basically junk. All these compression numbers you guys keep paying for and throwing around is a waste of your time. Why???? Because y'all want a free engine?? Buy a compression check gauge, remove the shradder valve and do your own. Sometime it's just better to leave well enough alone because you can't control all the other issues that can and will come up as soon as the dealer starts pulling your engine. Today's Mazda mechanics don't have a clue how these engines run and most have never even rebuilt one. My advise, at 75k miles and higher, if it cranks up and runs all day everyday and is reliable, leave it the hell alone. The apex seals in these things are very short and light for high rpm reving. As they get shorter they loose there spring tension so the compression will lower over time. Plus these side seals wear down faster because of the side exhaust. These engines aren't like the 3mm sealed engines of the 1st gen Rx7. Those engines would easily last 200+ thousand miles because they were lower reving and the seals were damn near bullet proof. This coming from a 20b guy who did his own engine swap.

Last edited by T-von; 01-21-2016 at 06:37 PM.
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Old 01-21-2016, 07:45 PM
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My 25k mile S2 failed compression test and had engine replaced under warranty.
Unfortunately no compression numbers or troubleshooting on the failed engine.
Crossing my fingers on the reman. There's a lot of sealant ooozing externally...
They did a good job though, mechanically. Everything is tight, no drips, tech was very thorough.

Car is under warranty till Oct 2017. Sept 2017 it goes for compression test. If good, fine. If fails, the (next) reman engine will be yanked right out and sent to a reputable builder.
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Old 07-19-2017, 10:54 AM
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2009 R3 - 61,000 miles

The car cranks up quick every time, no hot start issues or issues of any kind really except that there is a slight stumble at idle occasionally, barely big enough for the tach needle to register, but I can hear/feel it.

I purchased the car for a discount from a non-mazda dealership on the basis that compression was below spec (according to their local mechanic's comp test):

R1: 102.7 - 100.4 - 99.8 --Normalized for 250 rpm @0ft-- R1: 97.5 - 95.3 - 94.6
R2: 108.9 - 108.6 - 105.5 --Normalized for 250 rpm @0ft-- R2: 103.4 - 103.1- 100.2
@303 rpm and 900ft elevation

Of course I already called Mazda North America to confirm the extended engine warranty was still in place prior to purchase ;-). I figured I'd drive hard for a couple days with no premix, then take it in for a Mazda comp test.

(results are converted from Kpa)
R1: - 121.8 - 117.5 -117.5 --Normalized for 250 rpm -- R1: 104.8- 101.1- 101.1
R2: 121.8- 120.3- 120.3 --Normalized for 250 rpm -- R2: 104.8- 103.5- 103.5
@332 rpm and 0 ft elevation

The tech wrote a narrative on the service report about how the high cranking rpm of the starter was producing inflated compression results and that when normalized for 250 rpm were borderline. However he privately confided that mazda will not accept normalized results for warranty purposes and suggested that I either replace the battery with a weak one,or install and S1 starter so the results will be more accurate.

My concern is that with that hit & miss quality of remans and the fact that my "Italian tune up" seemed to actually raise compression instead of lowering it, am I better off trying to save this engine, via a decarbon procedure or continuing down the reman path? Keep in mind the warranty is up at the end of the month.

Thanks

Last edited by sharingan 19; 07-19-2017 at 10:58 AM.
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Old 07-20-2017, 07:23 AM
  #54  
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It is your call here. But yes you need to get a compression test result that Mazda will accept. Try to contact MNAO to be sure what you were told is accurate. Often dealerships get it wrong. MNAO will ultimately make the final decision on approving any warranty engine replacement, not your local dealer.

Don't let that warranty period expire without proper test results. I got a reman approved by Mazda in 2016 with my (borderline failing numbers) test results, with just one week left on my warranty period (8years was up). My reman has been very strong and I have taken additional steps to help keep it running for a long time.

Another fellow RX8club member and friend of mine in Arizona, with his 8year warranty time almost up, had a dealer give him the runaround about his compression test numbers until the warranty ran out, and then he was out of luck for any Mazda reman. The dealer just really didn't want to bother doing the work, even though Mazda pays for it. Don't let a local dealer rob you of thousands of dollars of work that you are entitled too.

Just my advice. Don't delay, it could personally cost you thousands of dollars if you have to pay for an engine replacement yourself. If you intend to keep this car, don't miss out here.


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Last edited by gwilliams6; 07-20-2017 at 02:37 PM.
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Old 02-26-2018, 05:13 PM
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Got a 2011 R3 last August, love the car but I've been worried about the compression.

Test last Aug, @18500 miles. Hot, somewhat humid day

Rotor 1:
800
770
780
@250
Rotor 2:
790
790
790
@250

Today @24500, cold rainy weather
Rotor 1:
730
740
700
@250

Rotor 2:
730
740
740
@250

First thing I did after I got it was swap in new plugs. Just swapped in new coils a few weeks ago. I've had the occasional hot/hard start, maybe twice in the last few months. Any cause for concern? Can weather result in such a massive change in numbers?
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Old 06-18-2018, 11:06 PM
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Recently got a 2011 GT

Had it tested yesterday:
R1 8.6, 7.2, 8.6
R2 8.6, 8.5, 8.6

With the one facing so off it's 'borderline'. Talking like ~1PSI here to be considered failing by difference in faces.

42k original engine. Worth risking the reman lottery or just deal with some side seal weakness?

Drives great, no problems so far
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Old 06-19-2018, 09:52 AM
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it could be some carbon deposit stickiness of the side seal. maybe a decarb procedure will loosen it and restore that little bit of compression loss
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Old 07-14-2018, 01:53 PM
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Originally Posted by alphawolff View Post
Recently got a 2011 GT

Had it tested yesterday:
R1 8.6, 7.2, 8.6
R2 8.6, 8.5, 8.6

With the one facing so off it's 'borderline'. Talking like ~1PSI here to be considered failing by difference in faces.

42k original engine. Worth risking the reman lottery or just deal with some side seal weakness?

Drives great, no problems so far
Would Mazda replace under warranty?
I thought it needed 690 and down on a face.
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Old 07-14-2018, 04:47 PM
  #59  
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Originally Posted by Herksr3 View Post
Would Mazda replace under warranty?
I thought it needed 690 and down on a face.
Like he mentioned, there is a limit on how much compression can differ between faces and rotors, so if all the other faces are mid 8s while one face has a flat 7, that's still a fail.
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Old 07-16-2018, 01:15 AM
  #60  
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This is from the Service Manual:

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