hey guys, i have an 04 MT and the extended warranty expires this year (2004 + 8 = 2012 right?) anyway, do you think i should bring my 8 into the dealer to do a compression check on her? there has been nothing out of the ordinary wrong with it, this would be kind of like a precaution i guess. Do you think this is a good idea? how much would it cost for them to do a compression test? if the test shows any abnormalities will they replace my engine no questions asked?

Note: i plan on doing a zex nitrous install soon so i would like to get this out of the way ( for obvious warrenty violating reasons) thanks!

 

lol zex nitrous...
better go check the compression before the warranty runs out or maybe it already did and you missed it.

 

Well the nitrous is ordered , not yet installed. And I'm within the warranty, I only have 74k miles, but is it just a waste of my money if I havent had any problems? I think I actually have a compression gauge at home (plugs into spark plug right?)

 

well just because it's an 04 doesn't mean your warranty is expired, it is from the purchase date. like mine is an 05 that was made in late 04, but not bought until may of 06. so even though mine is an 05 my warranty is good until may of 14.

 

Okay so ill bring her into mazda today, what should my wallet expect for a compression test? Do i just bring it in and ask them to test both rotors or is there something specific I should tell them?

 

I did a compression test and it was around $80 CAD.

Then they charged me $20 extra cause my car was too low :D

 

Most dealers require appointments, so might want to call them first. I've only ever found 1 in 15 years of my driving life that takes walk-ins.

That being said, call Mazda North America Operations even before that. Give them your VIN and find out exactly when the warranty expires. It expires based on the original date of sale. And that could have been 2003 for 2004 models, or even 2005. For example, my 2005 was first sold in September of 2006, giving me 1yr and 9 months "extra" according to your "math" of 2004 + 8 = 2012.

You might already be out of it...

I've been charged $0, $80, $95, and $165 for my 4 compression tests, though not in that order. The $0 was the free one under warranty when they diagnosed the engine compression loss and got it covered.

 

That's a good idea after the warranty expires...lol

 

Okay so I just picked the car up from Mazda after paying the 180$ they wanted for the compression test ... The results :
Cylinder #1 RPM:297 ; 8.1 7.7 7.8
Cylinder #2 RPM:298 ; 7.8 7.5 7.8
The report goes on to say "readings are borderline pass/fail, contacted Mazda tech line, recommend lack of power/decarbon and retest"

So im taking it back on Thursday for the to do the decarbon underwarranty so I at least don't have to pay that . But I had thought any readings over 7 are okay, I think I dont have a good understanding of this. The tech told me if the readings don't get better after the decarbon I may be able to get a new engine under warranty so that's kinds cool. Can someone explain to me what "normal" readings should be? Thanks !

 

The "normal" compression is based on the RPM speed. You have a REALLY good starter to be cranking over at 297rpm.

Normalization chart:


So it looks like your 7.5 is only ~ .6 above the failing mark at that crank speed. Those numbers would be great if you had a crank speed of 250rpm...

 

The acceptable range of compression @ 250 RPM as follows:

KPA:
830 standard
680 minimum
150 diff / chamber
100 diff / rotors

Kg F / cm^2:
8.5 standard
6.9 minimum
1.5 diff / chamber
1 diff / rotors

PSI:
120 standard
98.6 minimum
21.8 diff / chamber
14.5 diff / rotors

Remember values need to be normalized for 250 rpm.

 

I still have the old stock crappy starter though, why would I have such a high rpm?
I

 

Because you probably have a really good battery attached to it, and the starter itself is in great shape.

BC.

 

so some good new .. mazda did the zoom zoom cleaner and retried the compression test... got a call from the service manager and they placed an order for a new engine for my rx! it was soooo painless im almost surprised. so ill be picking up my loaner car tomorrow...

 

Going to have mine tested soon. Great info everyone.