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2011 Compression Test Results at 45K Miles

Old 04-10-2019, 02:21 PM
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2011 Compression Test Results at 45K Miles - Failure Is an Option

My engine warranty is up next month, so I took my 8 to the stealership to have it officially compression tested well in advance. It seems to have passed. Not beautiful, but passing. Very marginal, just like its owner. Congratulate me?

Props for the tech's grasp of grammar, capitalization, and punctuation.




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Old 04-10-2019, 02:44 PM
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7.3 @ 300 is 6.7 normalized, so failing? Sounds like the tech isn't quite grasping some other stuff :/
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Old 04-10-2019, 03:17 PM
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If it's a Mazda Compression tester, those numbers are normalized to 250rpms. Those numbers look pretty normal for a 45k miles engine.
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Old 04-10-2019, 04:01 PM
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You bring up the discussion I had with the service manager. It would be ~500 feet, but yeah. He said Mazda has 2 testers in use. One normalizes and the other does not. He says his rig does normalize, and these are the normalized numbers with the starter RPM included for my information, because I specifically asked for it. Obviously, a second opinion from another stealership is needed to be sure.

I'm hoping it is passing. I do not relish the idea of having to decide what to do with the car. It is long paid off and decently track prepared, which means passing compression equals easy decision to keep. If failing, I can get what probably amounts to a lousy job of replacing the engine for "free" or trade it on the 2019 MX-5 and be done with it, but with a car payment attached. And, there is always the risk I will miss the dumb grin it puts on my face.

.

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Old 04-10-2019, 04:51 PM
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Pretty sure the car payments would add up to more than a new non-crappy engine installed by non-crappy people?
The car only has 45k, it's practically new!
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Old 04-10-2019, 09:05 PM
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Well, that is certainly true. I do have the capability to install a reman myself in my horribly insufficient, terribly well air-conditioned, far too small four car garagemajal, however that brings up another key question. Which is better: an original S2 engine that barely fails compression testing and is pretty consistent on every rotor face, or a "new" reman from a reputable builder? I think I lean toward the known quantity of the original engine, which would severely limit resale opportunities in the future. I dunno. It's not an easy decision. Of course, in the best case, the car is worth at most $10K as it sits.

Also, have you driven the 2019 MX-5 Club? Damn, that car is fast compared to an 8! Handling is arguably better, too. So light and nimble...

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Old 04-10-2019, 11:12 PM
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Mazda remans, even the S2s, are nearly all brand new blocks coming from Japan with little to no reused parts. Usually just components like the oil pan, front cover, and some other minor components. Assembled by a technician that does it for a living, and they arent getting cranked out like crazy the way that they used to be. Id say a mazda reman might be a real good bet.
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Old 04-11-2019, 09:56 AM
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Good to see the numbers.

Assuming it starts from hot ok, and you're not feeling like it is overly down on power at the track, I would just keep on driving :-D
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Old 04-11-2019, 09:23 PM
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Originally Posted by Xero Ryuu View Post
Mazda remans, even the S2s, are nearly all brand new blocks coming from Japan with little to no reused parts. Usually just components like the oil pan, front cover, and some other minor components. Assembled by a technician that does it for a living, and they arent getting cranked out like crazy the way that they used to be. Id say a mazda reman might be a real good bet.
Especially if its free, which from the OP's comments it sounds like it still has some warranty left.
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Old 04-12-2019, 08:01 AM
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True. It could conceivably be "free" from the dealership, but then I have to trust the dealership monkeys to work on my car, which is asking a hell of a lot. How many dealership engine replacements end up being trouble-free I wonder? Also, I would have to find a way to make it fail its compression test and convince the dealer and potentially Mazda USA it actually failed.

Is it worth more now with a passing compression test result, or would it be worth more right after a warranty engine replacement? Thoughts on that question?

BTW, it shows no signs of low compression. Power feels about right. Never has any starting problems. Idles perfectly.

Maybe I should test the coolant for combustion gases and explore that avenue too...
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Old 04-12-2019, 08:19 AM
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I'm sure it's worth more with a fresh engine.

It sounds like the fear of dealer mechanics is playing into your rationale. Unless there are specific horror stories about that dealer (in which case find another?), they are still responsible for not having mix ups and get more training on the car than most other mechanics. They should know that the client can escalate to MNAO if it goes south.

There are obviously monkeys, but feel like the odds are on your side.

I'm kinda skeptical that their tester displays rpm but then also converts the numbers to Not that rpm. That sounds like really bad design, or user error.
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Old 04-12-2019, 09:48 AM
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Have you seen how awful my compression numbers are? For a very long time my 8 started up perfectly and showed zero signs of failing compression.. that is until my numbers dropped into the high 40's in psi when normalized.

It helped a lot that my starter cranks the engine at like 315-330rpm and i have a very healthy ignition and fuel system. They went a long way in getting all the life out of this engine and masking the symptoms as long as possible
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Old 04-12-2019, 02:51 PM
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Originally Posted by Steve Dallas View Post
How many dealership engine replacements end up being trouble-free I wonder? Is it worth more now with a passing compression test result, or would it be worth more right after a warranty engine replacement? Thoughts on that question?
I'm on my second engine. First engine failed at 65K, replaced under warranty in 2010. Car now has 140K - so something like 75K miles on the current engine. Had a compression test done a year ago and the scores were all in the high sevens and low 8's when normalized, so a solid engine. Haven't had any issues engine wise since the second motor was installed by my local dealer, and it was all free. Additionally, I would definitely think the car is worth more to a potential buyer knowing that the engine has recently been replaced.
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Old 04-12-2019, 08:01 PM
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Two most pressing questions needing answers: 1. Is it actually failing? 2. Can I make it fail before the end of next month?

The plan is to take it to the track for 8 hours of drive time the first weekend in May. I may do it without premix. Then, I'll take it to another Mazda dealer across town to see what their results are--without premix this time.

And yes, I absolutely hate having someone else work on my car. I have done 95% of all work on this car myself so far. I trust no one.

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Old 04-12-2019, 08:22 PM
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Originally Posted by Steve Dallas View Post
True. It could conceivably be "free" from the dealership, but then I have to trust the dealership monkeys to work on my car, which is asking a hell of a lot. How many dealership engine replacements end up being trouble-free I wonder? Also, I would have to find a way to make it fail its compression test and convince the dealer and potentially Mazda USA it actually failed.

Is it worth more now with a passing compression test result, or would it be worth more right after a warranty engine replacement? Thoughts on that question?

BTW, it shows no signs of low compression. Power feels about right. Never has any starting problems. Idles perfectly.

Maybe I should test the coolant for combustion gases and explore that avenue too...
Dealer-installed remans come with a warranty, though, so I don't see why you should worry. It's short, but if something is really messed up during the installation, then it wouldn't take long for the issue to surface anyway.

And I know Miata is the answer and all, but... maybe try something else out? If you don't want to be strapped by car payment then go explore the used market.
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Old 04-13-2019, 01:16 AM
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If youre set on a miata:

Get a reman installed in the 8, keep all the paperwork and documentation
Drive a couple of thousand miles to break in the engine.
Sell private party to a buyer that you provide all proof of a fresh reman to in order to put your 8 at the top of the market

Use profit as a larger down on a Miata


End result: you get a miata and someone gets a 8 with a fresh motor with properly documented history
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Old 04-13-2019, 01:20 PM
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I donít understand what the problem is. Lol. If you like the car and want to enjoy it at the track, go for it.

Seems like a healthy engine to me with those numbers. Itís only got 45k for crying out loud.

Now if youíre feeling like itís time for something new in your life (plus car payment) then thatís a different story.

That engine passed the test. For all you know, that engine can still be enjoyed for another 50,000 miles easy before NEEDING a rebuild.
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Old 04-19-2019, 06:52 PM
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Originally Posted by Xero Ryuu View Post
If youre set on a miata:

Get a reman installed in the 8, keep all the paperwork and documentation
Drive a couple of thousand miles to break in the engine.
Sell private party to a buyer that you provide all proof of a fresh reman to in order to put your 8 at the top of the market

Use profit as a larger down on a Miata


End result: you get a miata and someone gets a 8 with a fresh motor with properly documented history
Yeah, this is likely the best way forward, assuming I can get it to fail a compression test to Mazda USA's satisfaction. As it sits, with a barely passing engine, it is worth probably $10-12K, which is just-keep-it money, and it is depreciating more every day.

Originally Posted by Fijibluefg2 View Post
I don’t understand what the problem is. Lol. If you like the car and want to enjoy it at the track, go for it.

Seems like a healthy engine to me with those numbers. It’s only got 45k for crying out loud.

Now if you’re feeling like it’s time for something new in your life (plus car payment) then that’s a different story.

That engine passed the test. For all you know, that engine can still be enjoyed for another 50,000 miles easy before NEEDING a rebuild.
I won't know if the engine is truly healthy until I have a second opinion. The plan is still to take it to the track for at least 6 more hours and have it re-tested at a different dealership--one that I know for a fact has done many engine replacements.

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Old 05-09-2019, 04:03 PM
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New set of results, still with no clear outcome. Different dealership after a 3 day Italian tune-up and a fresh tank of gas without premix.

Normalized to sea level and 250 RPM:

R1
6.8, 7.1, 7.2

R2
6.9, 6.6, 6.6

The service manager insisted the failure point for warranty replacement according to Mazda is 6.3. I seem to remember it being 6.8 and need to verify it with Mazda NA.

If it is failing, I will go ahead with the reman under warranty. If passing, it is barely passing, which rather sucks for all options but trade-in, although who knows how long it will continue to seemingly run fine? I could get several more years of enjoyment out of it and weigh my options again when it finally gives up.

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Old 05-09-2019, 04:19 PM
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The minimum is 6.9 kgf/cm≤ normalized, your SA should double check the service manual.



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Old 05-09-2019, 04:38 PM
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Minimum by Mazda is 6.9, your motor failed. If the dealer is giving you trouble with the warranty, give MNAO a call and typically that helps. You can also tell them you are unhappy with the service the dealership is providing (assuming you feel like that is the case) and request that the repair is done at the Mazda Dealer/Service Center of your choosing once approved for a warranty claim for remanufactured engine, they may honor that request.

Edit: Also, There is a maximum allowance of 1.5 between the highest and lowest number of the 3 values on a rotor, and a maximum allowance of 1.0 between the highest and lowest respective numbers between the front and rear rotor.

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Old 05-09-2019, 04:43 PM
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Youíre at a cross road...

if you like the car, keep it. Engine is perfectly fine to me. Iíve had a daily RX-8 below 5.0 bar and ran fine, although down on power and didnít wanna hot start.

Had another @ 6.0 bar that ran perfectly without any issues.

I think yours is still enjoyable for many years to come.
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Old 05-09-2019, 04:59 PM
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Old 05-10-2019, 08:24 AM
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Originally Posted by UnknownJinX View Post
The minimum is 6.9 kgf/cm≤ normalized, your SA should double check the service manual.

Yeah, I found that in my FSM yesterday evening. The engine is failing on 2 of the 3 metrics. It is definitely on its way out, according to the specs.

Being that I just lost my job, a warranty reman is my only option short of continuing to drive it as-is, which makes no economic sense. Now to find a dealer I can more or less trust in the DFW area and start the battle...

For posterity, here is how the engine was used and maintained:

USAGE
Occasional daily driver and weekend tourer
Track toy once per month for ~4 years

MAINTENANCE
Regular JASO FD premix since 5K miles at 1/2 Oz per gallon street, 1 Oz per gallon track
Oil changes every 3K miles, weight varied from 20 to 40, conventional and synthetic
No cat or high flow race cat since 10K miles
BHR coils since 10K miles
Spark plugs changed every 10K miles


I wonder where it would be without the track hours? Better or worse or the same? Hmmm...

.

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Old 05-10-2019, 11:05 AM
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I think it could have had more wear with tracking, but IDK, really.

My car had 43k miles when I bought it, and it had higher numbers(or I wouldn't have bought it). It was first owned by a neurologist, so I assume that the car isn't driven too hard. The second owner said he drove it in the summer as a spirited driver, but I don't he has done any tracking. I am the third owner.

Too many factors to consider here.
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