Compression test
 

Well did my first compression test motor has 71k.


dry
1-171
2-155
3-160
4-175

Wet
1-180
2-160
3-165
4-181


Haven't notice anything wrong with the car, just decide to do the test to see where I was at. Is this just normal wear? Should I be considering a head gasket replacement?

Thanks

Meh..youre kinda on the line of where you would want to investigate further and where you just kinda disregard it.

Youre down like 12% from cyl4 to cyl 2. Anything over 10% and you might want to look further into it.

Also Compression test doesnt tell you where the loss of compression is. For that you need a leak down test. Could be leaking at head gasket, valves, piston rings ect. No way to tell from just a compression test alone.

How many times did you crank the motor for each test? You want to make sure each cylinder was cranked over the same amount of times.

Freekn tappin

Just keep cranking until the needle stops rising. Cylinder 2 has a harder time coming up in mine but it comes to the same #s after a few more cranks.

Did another compression check today, kept cranking till the needle stop climbing.

Same damn results

175
155
161
176

Time for a leakdown test.

And remember that if the car drives fine ... in all honesty ... who cares. Why open it up unless there's something obviously wrong.

Just for something to compare to, I just did a compression test last week on my '07 with 61k.

It was: 161, 159, 150, 160.

Personally I'm not too worried... but it does look like cyl. 3 isn't sittin' as pretty as the rest.

Just did my buddy's 07 ms3 71k miles

170
170
155
175


Like you said lex I'm not going to worry about mine. I'll retest mine in a few months...

Well with that kind of mileage I could image how much carb on the valve and valve seat?
Might have valve seat problems of all the carb on it..

Did a test this weekend..

Cyl#1 160
Cyl#2 155
Cyl#3 143 Wet: 155
Cyl#4 170

Cab is smoking in traffic... FML

I think there's still a couple threads with "compression" in the title that you haven't copied this post into.

did another compression test after a year..... 2 and 3 went down slighty.
I still need to clean my intake vavles hopefully that will improve my numbers?

DRY
1-182
2-152
3-156
4-182

the minimum specification is 129.96psi, and maximum variance is 28.5psi

standard is 185.65psi

Time for a leak down test :-/

(5) If it is less than the minimum specification, or there is a cylinder with a compression value that differs from that of other cylinders by 196.1 kPa or more {2.D kgf/cm2, 28.5 psi}, add a small quantity of engine oil through the spark plug hole and perform Steps (1) to (3).
•If the pressure increases by adding the engine oil, the piston ring or the cylinder surface is worn, or they are damaged. Perform overhaul servicing.
•If the pressure does not increase, valve seizure, valve attachment failure, or pressure leakage from the cylinder head gasket might be occurring. Perform overhaul servicing.

how much more pressure should i expect with adding the oil? would only adding 5psi be consider piston rings or cylinder surface?

Thanks

5 psi could be gauge discrepancy.
If it jumps 15-30 psi, I'd say that's conclusive.

@Tokay444Finally got around and did a leakdown test today. 1 and 4 were good ,very slow leak. 3 and 4 was leaking very bad, I couldn't even find where it was leaking from. It almost seem like it was leaking from the hose going into the motor. But I did the same thing to 1 and 4, had zero issues with the hose.
I know I should be posting a % per cylinder but the crappy habor freight tool didn't seem to be working correctly. I'm going to try to rent a good leakdown tester and do this all over again

Forgot to mention I cleaned my vavles and also put in toyta seals. Did another compression test and it seem to help a bit.

8-1-13
180
155
165
185

By hose going in, do you mean at the trottle body?
Are you sure 2&3 were at tdc?

I'm talking about the hose that you use to attach to the cylinder to do the test. And yes both cylinders were at TDC. I did everything the same for all 4 cylinders. Cause at first I was thinking we had a leak on the tester hose. But when I did test again on the first cylinder it was good.

There's a couple of other threads you missed trolling.:puke:

Ok so i posted on a few threads, started a thread. Ive got something thats really ailing me right now. I just put in a reman'd block 5000 ago. Did a compression check from first 5 miles then 250 then 600 then 1500 then 3000 and now, they all were between 152 and 155 across all 4. Now my issue is im losing a bunch of oil. It doesnt seem to be burning it. It has a brand new corksport turbo on it with only 4500 miles...same amount as the new block. If the compression hasnt changed since the original compression test when the motor was first started, then i dont have any leaks in there, correct? Now im pushing a bunch of oil out of my blow valve. Im thinking its the pcv valve and stock pcv plate cause it cant handle the amount of boost from the CS turbo at 22 psi. Maybe im wrong. No oil on the turbo side of intercooler, and none on the TB elbow side except for in the blow off valve area, none in the end tank area. Getting really frustrated with this car. It was running so well. And it didnt start doing this with oil until my tuner upped the boost. Is it possible that blow off valve is just pulling it thru and shooting it out. I have drips under neath car ontop of tbe trans casing and all over my rad support. And the car itself is not leaking, ive sprayed the entire thing off with brake cleaner and i removed intake piping the only place it could be coming from on the side is the blow off valve. I dunno. Need help

I'm not the expert on these sort of things (don't you feel confident when people start like that), but that compression sounds low to me. This could be causing high crank case pressure and oil getting places.

Don't understand your comment about the blow off valve. Are you VTA and it's blowing out on your engine bay? There shouldn't be any oil there unless it's coming from the turbo... If you are BPV, then maybe it's coming from the PCV. I start by checking there and then maybe look into a catch can.

So, 2-3 years ago I had similar numbers and decided to build the motor.
I was somewhere around 180, 180, 155, 180. Cylinder 3 was low and it appears to be the common problem among these motor. I did a leak down test and had similar results, 3 was leaking pretty bad, and I'm pretty sure it was at the rings.
Anyway, I tore down the engine cylinder 3 looked ok , rings were ok.

The guy that did the work on the motor said that many of theese motors that he has done had oval cylinders instead of being perfectly round. I believe my 3 was oval. To bore the cylinder he used a torque plate, which makes sure that the cylinders will be perfectly round when mated with the head. (It is what I recall I am by no means an expert on this)


If I could go back in time, I would first keep track if I'm losing much oil and if not I would keep driving the car till failure. I have read about a guy with similar compression results that has been beating his car for years.

No its not low, for a remanufactured engine, not rebuilt. Everything will not have the tight tolerances of a brand new factory motor. The serviceable compression is 129. Amd anymore then a separation of 28 between any cylinder. And the compression has been 151,152,150,151 since the engine was installed 5000 miles ago, hasnt changed. The blow off valve, is a GFB dual port, set to 50/50. The oil is blow out the port to the atmosphere side. And its not in my valve breather line like i had thought. Its pulling oil through the little vacuum nipple on top of the BPV from the intake manifold.

Lemme also state that the car didnt burn a drop of oil since the beginning at 0 miles. It just started, so just its clear it started with that compression, no oil burning, still has the same compression, but now is pushing oil out the BPV. Leads me to believe the pcv valve has stuck and that the stock plate is not supporting the amount of crankcase pressure i have. Im going to do a leakdown test just make sure, but if that comes back as it should, then im going to install a dual vented Perm plate and catch can system. My mechanic is out till Monday, and its freezing here, so im gonna just drive my other car till then I dont want to cause any damage for some reason its something else. Ill keep everyone updated

So am having similar issue with my 08 speed3 have you been able to find out what is the reason your having oil coming out of the bov?

Stuck PCV usually.
The compression in his case is not low enough to blame excessive crankcase pressure.

Well i dont know what happened. But my compression starting in the cylinders closest to the fuel pump, its 110, 120, 120, 150. So the one hasnt changed one bit. But the others have dropped out of nowhere, only 4500 miles on the engine. Does anyone think it could be a head gasket? Im thinking either rings or head gasket. The warranty company is coming to check if I was racing it, which i was wasnt, i only just got done breaking it all but and have only just started in tweaking the base map. I use a reputable tuner also, Purple Drank tuning so its not that. I was on the maintenance on this like crazy. EVERY 500 miles or so I was giving it compression tests just to make sure there werent any issues. I axles on the front about 3 or 4 weeks ago and did a compression test then. Was fine, same as it was when i installed the motor, 150, 151, 152, 150. Then I dunno a week maybe not even, after that i started seeing this huge cloud of smoke after letting the car sitting after running and then spooling second gear up it would just BILLOW out. Then while driving itd be fine i thought it was just loading up, like it had a stuck pcv valve. Then 2 days after i saw that cloud i gave it another compression test and it had magically dropped from 30 psi on the inside cylinders and 40 on the one outside cylinder. So im in the process of figuring it out. Thoughts?

Well just an update, I'm on 150,120,120,110 compression test. I believe it's either rings or is it possible to be headgasket? Only reason I wonder is becoz it's like it progressively gets worse down the line like that side blew out. But anyways some ideas, or opinions would be great. I'm putting the stock intake pipe and hose back on so it doesn't look modded to much. Lol. I have question if I flash the car back to stock map will it idle ok with a 3.5 bar map sensor in it, I don't need it to drive around or boost, just idle. I'm gonna get this crap done so they send me another block. Before this one goes in I'm gonna order a plate and catch can to hopefully help prevent any compression issues in the future. Perm plate or damond Pllate...I like the perm plate personally.

Good news guys, company is sending a new long block. Awesome, now I'm gonna install nice pcv plate and catch can and FMIC to start off with, maybe just maybe keeping crankcase pressure in check and cylinder Temps at all times cooler will prevent this same problem in the future. Say a prayer for a fellow mazda modder

FMIC may be more of a hassle than the perceived benefit of cooler temps. My CPe TMIC cooled just as effectively as my current Cobb FMIC. If you truly want cooler temps, spray meth.

Looks like mine just shit the bed as just now as well... not happy
tested it only a few months ago with 180 compression across all 4 cylinders...
Took it for a drive just recently, noticed a puff of white smoke on WOT, took it out again last night and started getting misfiring, didnt feel right
Got home, tested at 150-180-180-180, gunky shit in cylinder 1. Bit of oil bumped it up to 200 indicating to me rings... 67k miles speed 6

That sucks dude. Low mileage too!

Yeah im pretty pissed off, I literally put the car up for sale a week ago and now this.. cant catch a break

im in the same boat was just about to sell to get something newer
and started getting turbo seal smoke at idle.

Did a compression test before I went and bought the CS turbo

Dry
cyl 1- 155
cyl 2- 156
cyl 3- 127
cyl 4- 136

wet
cyl 3- 210
cyl 4-194

So im 90% sure the rings are toasty, haven't don't the leak down test yet. Need to buy tool, but its like goddamn 9 years of excellence and right when I was ready to move on a Big FU and have to figure out what to do now

Obviously you already stated you have a problem, but yea being over 195 is crazy compression, coz even at their absolute best factory tolerance the highest they list is 195 I think, sorry if I'm wrong. And as far as that speed 6 with 67k miles, fix it and fucking keep it. That sounds like a beaut, I bought my 07, alil over 2 years ago with 116k miles on it. Drove it stock for about 10k, put a jbr powerpath stage 2 intake and an accessport with an e tune from strat, an not the off the shelf. At 136k it threw a rod at 65mph in 6th gear throwing the piston into the spark plug literally cutting off half the plug. Sat for about a month while i got a fresh build put in it, had that in for about 5k miles and ringlands let go starting burning oil like crazy, company sent me a fresh motor, dropped that in and alil over 10k on this new motor and compression holding strong. About to roll over 150k. Motor came in with 160 159 across all cylinders and its pretty much settled in around those numbers theyll all hit 160 if you crank it for 10 20 seconds, but they sit around 158, 157,159,157, which im happy with. Doesnt burn hardly any oil, about a qtr of a qt every 1500 miles. The first motor came in with 150 across all cylinders and dropped like a rock in a day to 150 135 127 115. My point is, they are becoming so hard to come by. Cherish these babies.

yeah that was with a shitty Comp tester Re did it with a reliable one and did
DRY
1- 195
2- 190
3- 160
4- 170

Wet
3- 175
4-185

Leak down Test- proved to be Rings and no other leaks
Did a bore scope and did not see any visible scoring so here to hoping the rings are just bad, no oval piston, and not out of spec and just need to hone it

So looks as I am rebuilding the motor

Hoping that I Don't have to drop the motor and bore it! Rather just be able to pop and drop the new internals.

Looking to do manley rods and pistons,arp head studs, cosmetics head gasket, CS Turbo

OEM head gasket.
Everything else that you've mentioned, as long as the ARP head studs are L19. Or better CA 625+..
Then add meth.

I would go with the OEM head bolts. The CS turbo isn't big enough to require upgraded studs. Even being pushed with meth. IMO of course.

+1 on the OEM head gasket though.

I swear I read a few times that pop-n-drop rebuilds haven't been that durable.

damn auto correct I meant Cometics Head Gasket. But either way Why OEM? and or are you just referring to size?

and Ill have to look into more the reliability of the pop and drops! My Dad is a custom Hot Rod builder, built more motors than i care to think about and was a big deal in the early to mid 90s, so he's helping me tear it apart and put it together. We shall see what needs to happen, hoping all clearances are there and just needs to be honed.

But i know thats a pipe dream

To do a compression test does the car have to be warm or can i do it on a cold start or doesnt matter?..

Forums are not for answering google questions.