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ENGINE COMPRESSION LOW NEED OPINIONS.
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Old 07 Mar 2012, 04:02 AM   #1 (permalink)
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ENGINE COMPRESSION LOW NEED OPINIONS.

Hi guys what’s the stock engine compression on a 2007 hawkeye WRX has any one got any data how many psi should each cylinder be. I done a compression test and the numbers seem to be a bit low on all 4 pistons.
Piston 1. 117psi
Piston 3. 123psi
Piston 4. 120 psi
Piston 2. 123 psi
The engine seems like it’s running on 3 pistons number 1 piston doesn’t seem like it’s doing any thing took the coil connector of didn’t make no difference what so ever. Will hope fully do a wet compression test on it in the morning to see if the rings broken but if its just the valves sticking dosnt the compression still seem a bit low on the rest of the pistons? I know the figures don’t have to be the same but these figures look a bit to low if any one has any stock data to what the psi should be it will be a lot of help if it reads near enough the figures i have and its just the valves on piston number 1 might just do the valves but if there’s a big difference then it might be worth doing the rings and may be the bottom end as well. The cars only don 85000 on the clock.

All help is greatly appreciated in advance.



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Old 07 Mar 2012, 09:42 AM   #2 (permalink)
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Re: ENGINE COMPRESSION LOW NEED OPINIONS.

Afaik they should be more than 130 so your not that far away. The good thing is they're all close together. I'm sure someone else will be along soon to confirm the lower limit
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Old 07 Mar 2012, 09:53 AM   #3 (permalink)
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Re: ENGINE COMPRESSION LOW NEED OPINIONS.

balance across is more important than exact pressure, what level the exact pressure becoimes an issue im not 100% sure though
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Old 08 Mar 2012, 04:42 AM   #4 (permalink)
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Re: ENGINE COMPRESSION LOW NEED OPINIONS.

Hi guys thanks a million i really appreciate all the posts. I don a wet compression test and these are the figures i got.
Piston 1. 127psi
Piston 3. 135psi
Piston 4. 130 psi
Piston 2. 130 psi
All so got some info from the previous owner who bought it from the auction and handed it to bad hands to some corner garage and then just gave up. He said that they suspected the head gaskets no sniff test was don. The head gaskets were changed but still they couldn’t get it running right the chap was very upset and he had enough that when i got it I personally think they didn’t torque the heads down according to the data book as well.
Here is the funny part guys LOL. On HPI 1 owner and guess who the owner is ( x police car) that explains why the car is stalling and down at 85000 it wouldn’t surprise me if they were chasing some nut case in another Scooby and went bang and blow 1 of the piston rings.
While i was warming the engine up to do the compression test CEL started flickering so i plugged the code reader on it it came up with misfire on piston 1 and 3 when i pulled the plugs out number one wasn’t burning right i could smell the fuel fumes while i had it started as well. The CEL wasn’t on when i don the compression test the first time.
See what you guys think of the second figures on the compression test. I probably try getting some info of the dealers as well on the stock data compression . Will keep you posted thank once again keep the posts coming all help is appreciated. Will keep you posted of the outcome.



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Old 08 Mar 2012, 07:24 PM   #5 (permalink)
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Re: ENGINE COMPRESSION LOW NEED OPINIONS.

mmm, not sure if thats far enough apart to be a problem to be honest, doesn't look too bad.
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Old 08 Mar 2012, 09:37 PM   #6 (permalink)
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Re: ENGINE COMPRESSION LOW NEED OPINIONS.

Quote:
Originally Posted by ccsworks View Post
Hi guys thanks a million i really appreciate all the posts. I don a wet compression test and these are the figures i got.
Piston 1. 127psi
Piston 3. 135psi
Piston 4. 130 psi
Piston 2. 130 psi
All so got some info from the previous owner who bought it from the auction and handed it to bad hands to some corner garage and then just gave up. He said that they suspected the head gaskets no sniff test was don. The head gaskets were changed but still they couldn’t get it running right the chap was very upset and he had enough that when i got it I personally think they didn’t torque the heads down according to the data book as well.
Here is the funny part guys LOL. On HPI 1 owner and guess who the owner is ( x police car) that explains why the car is stalling and down at 85000 it wouldn’t surprise me if they were chasing some nut case in another Scooby and went bang and blow 1 of the piston rings.
While i was warming the engine up to do the compression test CEL started flickering so i plugged the code reader on it it came up with misfire on piston 1 and 3 when i pulled the plugs out number one wasn’t burning right i could smell the fuel fumes while i had it started as well. The CEL wasn’t on when i don the compression test the first time.
See what you guys think of the second figures on the compression test. I probably try getting some info of the dealers as well on the stock data compression . Will keep you posted thank once again keep the posts coming all help is appreciated. Will keep you posted of the outcome.



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shame to hear your problems when you say a wet test do you mean you squirted oil into the bores and they has been an improvement in compression pressure from that if so bore or piston wear is causing the loss in the compression pressure from your 1st post, heres my ej207 engine 2000 type ra classic version 6 at the time the engine had done only 60k miles when that test was done Compression Testing all even figures on mine thank god with a difference max 4-5psi on cy 1and 3 you might get a small difference but it shouldnt be like 20 psi in any one cyl either best get the proper compression figures from the dealers might be better to make a comparison then
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Old 08 Mar 2012, 09:47 PM   #7 (permalink)
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Re: ENGINE COMPRESSION LOW NEED OPINIONS.

Low compression on the first turnover and gradually building pressure while cranking over a good few times could be a problem with worn piston rings, a low compression reading on the first turnover and does not build up while cranking over for a good while might mean leaking valves or head gasket hope it helps
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Old 09 Mar 2012, 05:34 AM   #8 (permalink)
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Re: ENGINE COMPRESSION LOW NEED OPINIONS.

The compression builds up in about 5 to 6 turns of the crank. By wet test i meant about 3 squirts of oil to build up better compression.
If the stock figures are around 140psi and above like most impreza engines there shouldn’t be more than 10% difference between any of the cylinders even if we go by 140psi for instant the 10% difference shouldn’t fall to 126psi which is a difference of 14psi.
Like you says any lower then that some thinks wrong the highest figure we had on the wet test is 135psi if i work the maximum figure of 10% down leak on that its 121.5 very close to the first figures of the compression test apart from piston 1 hitting a difference of just under 19psi.
Which all so means every body’s opinions in the posts are excellent we all most getting to the problem before the engines out. I will keep this post going and will stick up some picture as well as soon as i start pulling the engine out and get to the bottom of the fault so others can see.
I will try the dealers for some data see how help full they are. I bought a data cd of the net as well will see how good it is hope fully should get it early next week. Will keep you guys posted as we go along.



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Old 09 Mar 2012, 11:57 PM   #9 (permalink)
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Re: ENGINE COMPRESSION LOW NEED OPINIONS.

Hi guys dealers were waste of time never mind the info they didn’t even put me through to the service department and am a garage what i wonder how they treat their customers guess will have to wait on the workshop CD to come.


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Old 14 Mar 2012, 03:18 AM   #10 (permalink)
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Re: ENGINE COMPRESSION LOW NEED OPINIONS.

Hi guys got the cd in today here is some info on the compression strait of the cd.

Hawkeye 2.5 wrx.

Compression (at 200 — 300 rpm):
Standard:
981 — 1,177 kPa (10 — 12 kgf/cm2, 142 —
171 psi)
Difference between cylinders
Less than 49 kPa (0.5 kgf/cm2, 7 psi)

Hawkeye sti.

Compression (at 200 — 300 rpm):
Standard:
981 — 1,177 kPa (10 — 12 kgf/cm2, 142 —
171 psi)
Limit:
882 kPa (9.0 kgf/cm2, 128 psi)
Difference between cylinders
Less than 49 kPa (0.5 kgf/cm2, 7 psi)

Hawkeye non turbo

Compression (350 rpm and fully open throttle):
Standard:
1,020 — 1,275 kPa (10.4 — 13.0 kgf/cm2,
148 — 185 psi)
Difference between cylinders:
49 kPa (0.5 kgf/cm2, 7 psi) or less

Been busy in the workshop didn’t get much time to spend on it my old leak down tester the percentage gauge was faulty. So got a new one today. Gona get busy this week pulling the engine out will hope fully put up some results of the issue and pictures.



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Old 29 Mar 2012, 02:15 AM   #11 (permalink)
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Re: ENGINE COMPRESSION LOW NEED OPINIONS.

Hi lads got a new down leak tester finally delivered last few days ago. Don the test
Number 1 cylinder lost of compression through outlet valves on TDC. Falling on moderate on the yellow
Number 3 cylinder the same outlet valves. On the yellow
Number 4 cylinder the same outlet valves. On the yellow
Number 2 cylinder is ok less then 10% which is normal on cold engine. On the green.
So had a little time today pulled the engine out and stuck it on the engine stand ready to strip down. here some pictures will put more up when i strip the heads of.



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Old 30 Mar 2012, 07:47 AM   #12 (permalink)
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Re: ENGINE COMPRESSION LOW NEED OPINIONS.

is it standard car?
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Old 30 Mar 2012, 10:07 PM   #13 (permalink)
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Re: ENGINE COMPRESSION LOW NEED OPINIONS.

Hi Tidgy as it’s an x police car they normally are remapped am not sure if it has been mapped back to standard settings I would have thought they normally do this when they get rid of them but as this one came in with engine problems am not sure.

When i don the leak down test cylinder 1 , 3 and 4 where leaking compression through the outlet valves each cylinder on TDC one by one you cold here the air coming out of the turbo as i had the down pipe of. Number 4 you could hear a very miner hissing from the dip stick it was showing 6 % loss on the gauge that’s normal on cold engine. I wouldn’t think anything is wrong with the piston rings.

I took the driver side cylinder head of today had a look valves looked like there where sitting on the valve seats properly so who ever had a go at putting the head gaskets in previously got the timing right first time round the valves dot look bent. The head gasket looks newly installed as well it got me a bit worried.

So I sprayed plenty of easy start and filled up the outlet valve channels where the outlet manifold goes to see if the easy start leaks out through the valve seats and after around 10 to 15 seconds later you can see the easy start leaking through the valve seats on the opposite side of the head where the valves face the pistons. The inlet valves seem ok just the out let valves were seeping through they weren’t badly dripping.

Would you recommend new valves?

Or regrind the same ones in with a bit of valve past and do the same ones?

Would regrinding the same ones make a big difference in the gap between the cam and the hydraulic lifters if I torque the cams down according to the book would the gap go to tight to where the valves won’t shut properly ? if so would it mean regrinding the cams as well. if that is the case i would put new valves in.


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Old 31 Mar 2012, 10:21 PM   #14 (permalink)
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Re: ENGINE COMPRESSION LOW NEED OPINIONS.

nopt realy best person to ask abotu mega tech stuff like that matey, but im a big fan of new over reused.
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Old 01 Apr 2012, 03:20 AM   #15 (permalink)
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Re: ENGINE COMPRESSION LOW NEED OPINIONS.

I was thinking the same thing new it is. Not really worth risking over a few extra pounds.
If there was adjustable types would have used the same ones wouldn't have matter. but don't want compression creeping out of them if there two tight on TDC the valve wont sit if there is no gap between the cam and the lifter. will keep the post going till its over.



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