Bad compression in Cyl 2 & 3....

[danny_speed3]

So my worst nightmare just came true last night.

I just bought a 08 mazdaspeed3 from friends of friends last Saturday. Seemed to be in really good condition with 86k miles and they gave me a bunch of parts with it.
The car ran and shifted great, no smoking anywhere, dry as a bone underneath.

Decided to replace the spark plugs just to be safe and did a compression check since it was open.

I didn't have time to do a wet test because it got dark.

182
152
150
180

With two cylinders that close to eachother and that close in psi, I'm wondering if I have a cracked head gasket.

I don't have the gear to do a leakdown test. I'm just wondering what my next steps should be. And if anyone here has gone that route, how much would it cost to just take it to a shop and have them rebuild it?




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[Jeff23spl]

take it easy, you definitively have some wear but you are far from an engine that will stop working...It could be dirty valves or even injector seals, this is why i would do a leak down in that case...I ran 1 year with 1 at somewhere between 125-140psi...

rebuilding an engine without wrenching on it yourself...can go from 5 to 10k or even more depending on what you do along with it.

[danny_speed3]

Originally Posted by Jeff23spl take it easy, you definitively have some wear but you are far from an engine that will stop working...It could be dirty valves or even injector seals, this is why i would do a leak down in that case...I ran 1 year with 1 at somewhere between 125-140psi... rebuilding an engine without wrenching on it yourself...can go from 5 to 10k or even more depending on what you do along with it.

The only reason I believe it's a head gasket is because of how similar the low psi cylinders are. But I could be wrong and I wouldn't be too upset if I was.

I have a friend that might have leakdown stuff from his 2010 speed3. Do you think if I tried a wet compression it would help narrow down the possibilities?


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[MSMS3]

Originally Posted by danny_speed3 The only reason I believe it's a head gasket is because of how similar the low psi cylinders are. But I could be wrong and I wouldn't be too upset if I was. I have a friend that might have leakdown stuff from his 2010 speed3. Do you think if I tried a wet compression it would help narrow down the possibilities? Sent from my iPhone using Tapatalk

Yes. The low cylinders are still within the minimum spec, which I think is 130 psi.

A wet test and a leak down test might help narrow things down. If you are not smoking or consuming oil, it might be the head gasket, but I would expect water in your oil, milky looking. Might be injector seals leaking compression. That would be an easier fix.

[Bingo]

So I did a compression test on my car a little over two years (20k miles) ago.
1: 140
2: 150
3: 110
4: 160
I burn about a quart every 1k miles, and I’m slightly modded and tuned to 20 psi on the K04. Leak down test had air coming from the oil cap confirming my suspicion that the rings have seen better days.
I’ve autocrossed my car multiple times since then without issues, and still have plenty of fun on on ramps. I still drive it like it should be.
This being said, I’m prepared for any catastrophic damage since it’s not my only car, and I do plan on rebuilding it when I’m done rebuilding another car.

Point is, low compression really is not the end of the world. As others have stated though, a leak down test will narrow down the cause, I highly doubt it’s the head gasket.

[Jeff23spl]

Agree with Bingo, if it didn't overheat and you are still on stock engine, head gasket is not likely the problem. there is a tendency to have #2 or #3 to let go first...i agree with peoples that believe it came from the intake design. middle runners tend to get a lil more air flow than the other 2 but all 4 get the same fuel and timing...They would make them run hotter and leaner and being the first to knock if knock occur...

[danny_speed3]

Originally Posted by Jeff23spl Agree with Bingo, if it didn't overheat and you are still on stock engine, head gasket is not likely the problem. there is a tendency to have #2 or #3 to let go first...i agree with peoples that believe it came from the intake design. middle runners tend to get a lil more air flow than the other 2 but all 4 get the same fuel and timing...They would make them run hotter and leaner and being the first to knock if knock occur...

I believe there might be some knock. I get readings from 5.95-21 while just cruising around town.

I haven't really done anymore a wot bc of current issues but when I did I think I only hit maybe 3.2 max, not sure though.


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[Jeff23spl]

under cruising conditions reading knock mean nothing as a brand new one will read some also....It is only under boost that it matter.
When mine was low compression i beated the shit out of it all the time and even made a dyno with friends where everyone was expecting my engine to blow up but because of the nature of the problem, it was just smoking a bit and i still made more than many others...

[danny_speed3]

Well, just got the call from my mechanic.

All four cylinders are under 125psi, and cylinder 2 has no compression at all.

He recommended an upper rebuild, so he's still crunching the numbers and I haven't gotten a price yet but it's not looking good. I probably can't afford that let alone convince my wife.

I know this thread was dead anyway but I'm pretty upset friends of friends sold me this car and told me it was in such great shape and I just had to tell someone.

Take care of your cars people, there's only so many speeds left.


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[Spectrix]

Originally Posted by danny_speed3 182 152 150 180

-------------------------------------------------------

Originally Posted by danny_speed3 Well, just got the call from my mechanic. All four cylinders are under 125psi, and cylinder 2 has no compression at all.

I like your first set of numbers better. You sure the car is driving fine with zero compression on #2 ?

[danny_speed3]

Yea lol me too.

Not sure if I messed up the test or what but he got very different numbers.


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[MSMS3]

Originally Posted by danny_speed3 Yea lol me too. Not sure if I messed up the test or what but he got very different numbers. Sent from my iPhone using Tapatalk

Either you are not driving fine or you need a different mechanic. I really think you need a different mechanic. Here’s why:

I could see you making a mistake on cylinder 2 compression if you said it was zero psi, but how can you get a 152 psi reading and it actually be zero? Your compression gauge wouldn’t even move if there is no compression. You can’t “mess up the test” by getting a higher number than actual.

[danny_speed3]

Originally Posted by MSMS3 Either you are not driving fine or you need a different mechanic. I really think you need a different mechanic. Here’s why: I could see you making a mistake on cylinder 2 compression if you said it was zero psi, but how can you get a 152 psi reading and it actually be zero? Your compression gauge wouldn’t even move if there is no compression. You can’t “mess up the test” by getting a higher number than actual.

I might have to take it to a different guy, or do another compression test when I get it back. I told him I only wanted a quote for right now.

Looking for a different mechanic would be awkward, he's been a family friend for my whole life and he's one of the most honest guys I know. It's hard to believe he might be trying to pull a fast one on me...


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[Jeff23spl]

with 100psi the engine would run on 4 but with 0, it wouldn't run well so if it keep running, the last test was bad...you can just test it again...