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Old 09-30-2020, 05:20 PM   #1
oreganobag
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Default 2005 STI - Low Compression On All Cylinders

Looking at a one owner (It has a second owner, but he basically inherited it and has had it garaged for the year he had it), adult owned 2005 WRX STI that is completely stock at around 90k miles. The car is in excellent mechanical condition, no rust, according to the PPI I had done, but a compression test showed low psi in all cylinders. The test was done at high altitude, about 1 mile, so normally they see the engines at about 120 psi, where here it was 85 - 90. There were no misfires or codes or CELs.

"Found cylinder 1 at 85 psi, cylinder 2 at 90 psi, cylinder 3 at 87 psi, cylinder 4 at 87 psi. Specification minimum 142 psi. (Test performed while engine warm, throttle open, at cranking speed). Verified compression readings with 2nd gauge(with same readings)."

The current owner noted the car had lower viscosity synthetic oil than what was recommended, and this might cause the lower PSI, as well as carbon build-up from being garaged for several months. He's going to change the oil back to stock and take it on a drive with the highest quality gas he can get to try and kickstart that back to normal. Also, the timing belt does need to be replaced as that hasn***8217;t been done yet, but I assume the shop would check if the belt wasn***8217;t aligned.

Other minor issues are squeeky rear suspension, a light leak on the rear struts and a tiny leak on the oil pan (which I don't care about and are easy enough to fix) and the rack boots seeping (don't know too much about this).

The price on the car is good and I don't mind spending a couple thousand to get it running perfect, but what am I really looking at for repair costs to fix the low compression if it is ringlands? I plan on keeping the car pretty much stock except a safe tune, OAS, Killer B Oil Pickup (and probably the oil pan now that this one has a tiny leak), and some more aggressive suspension.
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Last edited by oreganobag; 09-30-2020 at 06:38 PM.
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Old 09-30-2020, 05:49 PM   #2
Max Capacity
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General rule is all compression #'s should be with in 10%.

If you buy this, I would keep some money saved and plan on a new OEM ej257 sometime next year. That's $1800. plus gasket set $230. Have the heads rebuilt. That should give you a good car from many years.

Along with a a 3" catted down pipe and Cobb AP, you'll have a fun reliable car. For even better performance get it custom tuned.

Most of us run 5w-40 oil year round in these engines.
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Old 10-01-2020, 09:08 AM   #3
BlackFighter
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Was the test done on a cold eng or a warm eng? As long as they are all close with each other i wouldn't worry too much about it. There is no way all 4 ringlands broke and the car running fine. I would send a oil sample to blackstone and have it looked over by a subi shop. Dont over think this.

Last edited by BlackFighter; 10-01-2020 at 11:26 AM.
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Old 10-01-2020, 09:36 AM   #4
blurred
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Quote:
Originally Posted by oreganobag View Post
Looking at a one owner (It has a second owner, but he basically inherited it and has had it garaged for the year he had it), adult owned 2005 WRX STI that is completely stock at around 90k miles. The car is in excellent mechanical condition, no rust, according to the PPI I had done, but a compression test showed low psi in all cylinders. The test was done at high altitude, about 1 mile, so normally they see the engines at about 120 psi, where here it was 85 - 90. There were no misfires or codes or CELs.

"Found cylinder 1 at 85 psi, cylinder 2 at 90 psi, cylinder 3 at 87 psi, cylinder 4 at 87 psi. Specification minimum 142 psi. (Test performed while engine warm, throttle open, at cranking speed). Verified compression readings with 2nd gauge(with same readings)."

The current owner noted the car had lower viscosity synthetic oil than what was recommended, and this might cause the lower PSI, as well as carbon build-up from being garaged for several months. He's going to change the oil back to stock and take it on a drive with the highest quality gas he can get to try and kickstart that back to normal. Also, the timing belt does need to be replaced as that hasnít been done yet, but I assume the shop would check if the belt wasnít aligned.

Other minor issues are squeeky rear suspension, a light leak on the rear struts and a tiny leak on the oil pan (which I don't care about and are easy enough to fix) and the rack boots seeping (don't know too much about this).

The price on the car is good and I don't mind spending a couple thousand to get it running perfect, but what am I really looking at for repair costs to fix the low compression if it is ringlands? I plan on keeping the car pretty much stock except a safe tune, OAS, Killer B Oil Pickup (and probably the oil pan now that this one has a tiny leak), and some more aggressive suspension.
It's a 2005.

The engine is worn and you should prepare for a rebuild at any point in the future (could last a long time).
All of the suspension, steering, transmission, and interior components are at/or nearing end of their best life and will require replacing or serious maintenance.

It's an old car and will need at least 10k spent on it over the couple of years unless all of these parts have been replaced recently by the current owner.

I had a 2006 that I recently sold with 165,000 miles on it and other than original engine (which was also around 126-129psi on all 4 cylinders compression) however I had replaced basically everything in the car between 2013-2015 and it was ready for another 10 years of virtual care-free service.
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Old 10-01-2020, 10:05 AM   #5
BlackFighter
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Who cares on the year, it all depends on how many miles are on the eng, how it was driven, and stored. If the other 2 owners didn't beat the piss out of it and had it in a garage in a dry climate it should still be fine. Maybe some hoses need changing like PVC, and deff change out all of the fluids. 90k miles is not that much if it was taken care of on a full stock car. There are people with over 140k miles on stock eng. I believe Unabomber is on stock eng with over 100k miles on it and running strong.

I would also change out the timing belt with water pump, the oil pick up ASAP, maybe avcs solenoid just in case, replace spark plugs, clean/replace injectors, replace the fuel pump sock, maybe replace the pump itself since you are already there and like said before send out a oil sample to Blackstone. When you own a high performance car at high miles you should always anticipated on things braking so yes deff keep some cash available on those days but i wouldn't lose sleep over it. Who did the comp test?

When it comes to suspension and drivetrain that's a whole diff story. 04-05 STi were known for the struts prematurely failing and leaking, so if you hear a clunk in the rear, you might want to replace your struts, top hats, maybe clutch if slipping with syncros. Upgrade brake lines wouldn't hurt too.

Last edited by BlackFighter; 10-01-2020 at 11:27 AM.
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Old 10-01-2020, 10:20 AM   #6
Jedi03
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they should do "wet" and "dry" compression test...basically add a few drops of oil into the cylinders to see if the rings are gone or not...could be rings sticking, could be alot of different things, but plan for the worst and if you make the decision enjoy it like its meant to be!
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Old 10-01-2020, 10:22 AM   #7
rtv900
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This is going to sound absolutely CRAZY and I hesitate to even ask it, but:

does the engine have ANY operating issues AT ALL??????????
or are you just not seeing the number on a piece of paper you thought you should see?

I'm guessing you are buying the car to drive right? So if it runs fine why even consider a new engine?
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Old 10-01-2020, 10:24 AM   #8
oreganobag
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Quote:
Originally Posted by BlackFighter View Post
Was the test done on a cold eng or a worm eng? As long as they are all close with each other i wouldn't worry too much about it. There is no way all 4 ringlands broke and the car running fine. I would send a oil sample to blackstone and have it looked over by a subi shop. Dont over think this.
They said it was warm when tested. They've tested other STI's at about 120 PSI due to the elevation. The owner of the car, when he picked it up, said the shop was really busy and doesn't think they got the car warm enough. The car looks spotless and completely stock, so I think the guy that owned it before the current owner inherited it really took good care of it. The current owner doesn't really drive it, doesn't even live in the state that it's garaged in, and is an older gentleman that's been working with me on getting everything I need to make a decision on the car.
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Old 10-01-2020, 02:44 PM   #9
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Originally Posted by BlackFighter View Post
There are people with over 140k miles on stock eng. I believe Unabomber is on stock eng with over 100k miles on it and running strong.
Yes, Mine was over 165k miles on stock engine with bigger turbo.

My point is that older cars need replacement of parts more frequently and most 05 sti will not be "low mileage" anymore. It seems that the current owner doesnt take care of it having the wrong oil, wrong gas, suspension issues not taken care of etc thats the only reason i suggest being ready for more money to be spent than hoping its all good as it sits.
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Old 10-01-2020, 11:40 PM   #10
Andy342
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85 psi is pretty worn out.

My car read about 80 to 85 psi on all cylinders and actually ran pretty well. It was starting to knock so I ended up replacing the engine.

2010 STI, 181k miles, also tested at about 5000 feet. I don't think the elevation really makes much difference. Also I doubt oil viscosity or 'carbon from sitting ' would affect anything either.

Your rings and cylinders can be worn without having broken ring lands.

Budget for a new engine and if it makes sense, get the car.
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Old 10-02-2020, 08:20 AM   #11
benflynn
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Always suspect the actual # given on comp gauges. When we set up a stand up jet ski for as much cranking psi the fuel will hold, we have to do the math instead of trust the comp gauge. I lean more towards are they close to the same more than the actual number given, cause the gauges are very often incorrect.
If you just mill away Checking with the gauge, usually it will seize

262k here taking a bigger turbo beating daily, but I have a built shoRt block on stand by
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Old 10-02-2020, 07:01 PM   #12
scoobyfast
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Why not try a leak down test? Might help with determining any piston/ring issues.
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Old 10-04-2020, 12:39 AM   #13
BuiltWRXFL
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If the car runs normal and doesn't smoke like an 18 year old with a medical card obtained from an online physician then I'd guess the test was wrong. 4 cylinders with compression in those numbers should run poorly.

Take it to a another shop tell them what happened see if they get different results.

You can also get lower compression readings from a poor battery sometimes, but all 4 just sounds off to me.
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Old 10-05-2020, 09:30 AM   #14
rtv900
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Quote:
Originally Posted by Andy342 View Post
2010 STI, 181k miles, also tested at about 5000 feet. I don't think the elevation really makes much difference.
elevation absolutely makes a difference

that has the same affect as throttling an engine at sea level
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