I got a leakdown/compression test. Help me read the numbers please

[chris_photo]

I have an 07 STI with 59.5k miles on it. It started getting major power srges and hesitation. I brough it in to the dealer and they recommended plugs. I went for it and they also did a compression and leakdown test. Well it didnt fix the problem so they did a factory reflash and it fixed it. My car seems as slow as a Civic now.

I've got no mods other than an open source map from gabedude from a couple years ago.

Here are the results.

(I know the cyclinders seem out of order but this is what they put on my service order. Not sure if they screwed up the order or not.)

1. 145 PSI 10%
3. 140 PSI 15%
2. 135 PSI 22%
4. 140 PSI 14%

So is my engine gonna blow?

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[stikevgl]

BOOM!!!! <----- that was you engine

[chris_photo]

Seriously. What do you think of the numbers?

[DigitalPunk]

they look good to me

[badmammajamma]

Think of compression numbers as a shot group on a target in a pistol range if they are close together you are good...YOU are good.

[bcblues]

Looks fine to me.

[Granite]

Originally Posted by stikevgl

BOOM!!!! <----- that was you engine

these are the kind of guys who shouldnt be on forums

[knightriders]

im not super familiar with subie boxer motors but his cylinders a leaking a lot of air.

OP i think everyone is just looking at compression numbers which do look fine. but the leak down (which is less known about and maybe no one knows what theyre looking at) are very high for me. those percentages are how much air is leaking out through the valves when the cylinder is at TDC. anything over 10% is way too much in my motor, and i cant imagine its any different in a boxer.

it looks like you have valves bent on 3 maybe all 4 cylinders, which would also explain your symptoms.

[misterau]

Compression is good. U do not want more than 10% difference from the highest # to the lowest#

[WaXed]

Originally Posted by knightriders

im not super familiar with subie boxer motors but his cylinders a leaking a lot of air.

OP i think everyone is just looking at compression numbers which do look fine. but the leak down (which is less known about and maybe no one knows what theyre looking at) are very high for me. those percentages are how much air is leaking out through the valves when the cylinder is at TDC. anything over 10% is way too much in my motor, and i cant imagine its any different in a boxer.

it looks like you have valves bent on 3 maybe all 4 cylinders, which would also explain your symptoms.

Can you explain this better?
if the valves are bent and not sealing then all the rpessure is lost
it is just the time it takes to lose the pressure which changes depending on the amount of leakage
a percentage to me doesn't explain much
is there a calcuation formula?

[Turn in Concepts]

The compression is fine as mentioned, but I don't like the leakdown numbers. Did they tell you were the leakage was coming from? Intake, exhaust crank case?

Tony

[2gnt2wrx]

Originally Posted by knightriders

those percentages are how much air is leaking out through the valves when the cylinder is at TDC. anything over 10% is way too much in my motor, and i cant imagine its any different in a boxer. it looks like you have valves bent on 3 maybe all 4 cylinders, which would also explain your symptoms.

You shouldn't make posts like this, Just because one cylinder has a higher percentage loss doesn't mean it can only be a bent valve. It could also be leaking by the rings into the crankcase or a valve not seating all the way.

[DCales]

07's are known to have bad factory tune issues. Also the compression results are within range, typically 10% between the highest and lowest reading is good. Leakdown results are wacked. Im thinking that the tech did not have the pistons at TDC when he took the readings. At 22% in cylinder #3 i highly doubt the compression would be as high as it shows. Its possible that a valve may have not been fully seated allowing the leakdown to happen.

Have you considered having it dyno tuned by any chance? Maybe an access port alone would improve the situation. I know that you said you have an open source tune but its possible that something is going on that would be found during a tuning session.

[Vmaxlvr]

Ok subscribed, i have an 08 and pretty much same engine. This **** is scaring the hell out of me.

[chris_photo]

Thanks for the replies.
My mechanic friend (he mostly works on Hondas though) thought the numbers on the leakdown test was high too.

The service dept didn't explain much about the test results. All they were willing to tell me was everything was within spec. I did to speak to the mechanic and he did say one cylinder was "kinda so-so" but also within spec considering the mileage.

I am concerned because my car was at the shop for over 24 hours which leads me to believe that they were stumped with my initial problem.

I brought in the car because of a major hesitation issue that came out of nowhere. When I first dropped it off, the main tech took my car for a test drive with me and he knew immediately there was a problem. He looked around my engine bay and noticed that I was low on coolant. He hooked up his laptop and couldn't find any error codes, no cel. He said that replacing spark plugs might fix it because it's recommended at 60k.

So I leave it overnight. I call the next day and they just finished doing the spark plugs and were gonna take for a test drive. I asked about a leakdown/compression test and they said it wasn't necessary yet.

I call later that day and they're still working on my car and they finally performed a leakdown test. They didnt give me the results yet but they were trying to sell me a battery? Saying that was one of the failed tests. I said BS. I'll replace my own battery, fix my car please.

Finally, the day after that they say my car is fixed and come pick it up.

Basically, they replaced the plugs and reflashed my ecu with a factory map. It's slow but the hesitation is gone. Car is smooth but with the power of a Civic. I plan on doing a dyno ecu tune this time around.

My goal is to make sure this car lasts me another 3-5 years without an engine rebuild. It's my daily driver and I commute 60+ miles a day. If I'm gonna drive that much, I might as well have fun, right? :-)

So do you think the dealership is avoiding warranty work? Should I shop my car around to other Subaru dealerships for warranty work?

[the suicidal eggroll]

Originally Posted by DCales

07's are known to have bad factory tune issues. Also the compression results are within range, typically 10% between the highest and lowest reading is good. Leakdown results are wacked. Im thinking that the tech did not have the pistons at TDC when he took the readings. At 22% in cylinder #3 i highly doubt the compression would be as high as it shows. Its possible that a valve may have not been fully seated allowing the leakdown to happen.

True, they might have accidently done the leakdown on #3 at the wrong TDC (in between exhaust and intake strokes, instead of at the top of the compression stroke). If that's the case, either the intake or exhaust valves could have been slightly open, resulting in high leakdown numbers.

[aaronmsadler]

Originally Posted by chris_photo

I have an 07 STI with 59.5k miles on it. It started getting major power srges and hesitation. I brough it in to the dealer and they recommended plugs. I went for it and they also did a compression and leakdown test. Well it didnt fix the problem so they did a factory reflash and it fixed it. My car seems as slow as a Civic now.

I've got no mods other than an open source map from gabedude from a couple years ago.

Here are the results.

(I know the cyclinders seem out of order but this is what they put on my service order. Not sure if they screwed up the order or not.)

1. 145 PSI 10%
3. 140 PSI 15%
2. 135 PSI 22%
4. 140 PSI 14%

So is my engine gonna blow?

You dont have it anymore. I doubt the map gabedude gave you was the problem if it ran fine for 2yrs. It probably feels slow cause you are back on a stock map.

[chris_photo]

Originally Posted by aaronmsadler

You dont have it anymore. I doubt the map gabedude gave you was the problem if it ran fine for 2yrs. It probably feels slow cause you are back on a stock map.

Yup, I am aware of that. I know the custom map is gone.

I'm gonna log the facctory reflash and see how bad it is.
I will probably load the old map I had or get a dyno tune. Havent decided yet.

[some dude]

Update?