urdrwho Posted August 22, 2013 Share Posted August 22, 2013 A few weeks ago I did a compression test on cyl 4. It was a cold engine and I have no idea what masochist would / could try to do this on a warm engine. Plus I've never been a fan of removing spark plugs on a hot alum head. Anyhow the psi was 78 and within 10 minutes there was no leak down. Until the engine has run for about 2 minutes, this car has some nasty piston slap. I wonder what the results would be on a warmed engine. The test was a dry test. Not sure what to think??????? Maybe I'm not thinking well after yesterdays attack on to head by some European Hornets. Got a bit too close to their nest and they gave me a nasty hurt'in head. Those are big creatures. Link to comment Share on other sites More sharing options...
pleaidestar Posted August 22, 2013 Share Posted August 22, 2013 I sir am that type of masochist, that's really the only way to get an accurate number, especially if you have bad rings or scored cyls..I was always told that under 80 is a bad cylinder 110-120 is the best you could hope for on a high mileage motor. I'm no auto mechanic but I play one on tv. Link to comment Share on other sites More sharing options...
SBT Posted August 22, 2013 Share Posted August 22, 2013 You should try it on a 4th Gen Legacy... have to undo the motor mounts and lift the engine to clear the side rails. But as Pleaid mentioned, don't check it on a cold engine. Engine needs to be at operating temp to make sure rings are fully expanded against the cylinder wal. - Pro amore Dei et patriam et populum - Link to comment Share on other sites More sharing options...
urdrwho Posted August 22, 2013 Author Share Posted August 22, 2013 Well so be it. I'll need to do it on a warm engine. I suspect that on a warm engine I will be hitting higher numbers. Just a bit more room by the chassis / plug hole on the 2.5 would have been nice. I sir am that type of masochist, that's really the only way to get an accurate number, especially if you have bad rings or scored cyls..I was always told that under 80 is a bad cylinder 110-120 is the best you could hope for on a high mileage motor. I'm no auto mechanic but I play one on tv. Link to comment Share on other sites More sharing options...
Tr00b Posted August 22, 2013 Share Posted August 22, 2013 Cyl 4 on my pos is low too. I saw a mechanic use a box end wrench as a supporter kina to get the compression tester threaded in. Helps keep the hose straight in the hole acts like a 2 PC driveshaft. He had no problems getting to cyl 4. Link to comment Share on other sites More sharing options...
pleaidestar Posted August 22, 2013 Share Posted August 22, 2013 Well so be it. I'll need to do it on a warm engine. I suspect that on a warm engine I will be hitting higher numbers. Just a bit more room by the chassis / plug hole on the 2.5 would have been nice. You will hit a better number, keep in mind they will all be different but if they are all within ten you should be good to go so long as they are above 100-120. Link to comment Share on other sites More sharing options...
johnegg Posted August 22, 2013 Share Posted August 22, 2013 is this a 96 - 99 DOHC ej25? they are the worst of the H4. not as bad as the H6 though. for the H6 working from under neath is said to help. did you look at it from the bottom? but the SOHC engines are not so bad. the plug tubes are angled up making it a little easier. but on the DOHC the tubes are absolutely horizontal. a real bear. i would do a couple of others, cold. even cold if they all fall in the same range you will know that #4 is not out of the ordinary. and #1, & #2 are easier to reach. it would also be nice to know if any one else has compared cold numbers to warm numbers. and if so how much increase did they see? is the timing right? Link to comment Share on other sites More sharing options...
urdrwho Posted August 22, 2013 Author Share Posted August 22, 2013 Not sure of the year because it is a transplant (I didn't do the job). I took it to the dealer and they couldn't tell me the year. Doing the #4 is not fun but not too bad with the windscreen washer reservoir removed. The 95 with the 2.2 is a lot easier. The horizontal makes it interesting when you go searching for the plug hole. is this a 96 - 99 DOHC ej25? they are the worst of the H4. not as bad as the H6 though. for the H6 working from under neath is said to help. did you look at it from the bottom? but the SOHC engines are not so bad. the plug tubes are angled up making it a little easier. but on the DOHC the tubes are absolutely horizontal. a real bear. i would do a couple of others, cold. even cold if they all fall in the same range you will know that #4 is not out of the ordinary. and #1, & #2 are easier to reach. it would also be nice to know if any one else has compared cold numbers to warm numbers. and if so how much increase did they see? is the timing right? Link to comment Share on other sites More sharing options...
johnegg Posted August 22, 2013 Share Posted August 22, 2013 so it is DOHC? Link to comment Share on other sites More sharing options...
urdrwho Posted August 23, 2013 Author Share Posted August 23, 2013 Looking at the sides of the timing cover (from the front view) yes it is DOHC. so it is DOHC? Link to comment Share on other sites More sharing options...
pleaidestar Posted August 23, 2013 Share Posted August 23, 2013 So there is four cams on the motor? Irrelevant anyway just that you will most likely have to loosen the mounts and lift it about four inches past the frame rails to comfortably thread the compression tester in there..johnegg is absolutely right that you can do the test cold and more or less get the compression numbers, but they will vary more than if the rings are expanded. Link to comment Share on other sites More sharing options...
urdrwho Posted August 23, 2013 Author Share Posted August 23, 2013 It was not too difficult to get my flexible hose compression gauge into the #4 hole. On a hot engine it would not be as nice but if I put my mechanic gloves on it would be possible without burning off my skin. Wonder if there are any stats from people that did the compression check on a cold engine? So there is four cams on the motor? Irrelevant anyway just that you will most likely have to loosen the mounts and lift it about four inches past the frame rails to comfortably thread the compression tester in there..johnegg is absolutely right that you can do the test cold and more or less get the compression numbers, but they will vary more than if the rings are expanded. Link to comment Share on other sites More sharing options...
pleaidestar Posted August 23, 2013 Share Posted August 23, 2013 I'm sure there is, an fsm will probably tell you the specs out of the factory, you can probably poke around in the n/a forum to get some answers..but I would think all would be different because of wear and tear. Link to comment Share on other sites More sharing options...
SBT Posted August 23, 2013 Share Posted August 23, 2013 Knowing which year would be helpful, but the FSMs that I have access to, it doesn't seem to matter. DOHC Compression Specs from the FSMs - cranking at maximum 350 RPMs 1996 CR: 9.5. Compression - Standard: 176 psi - Limit: 137 psi 1997 CR: 9.5. Compression - Standard: 176 psi - Limit: 137 psi 1998 CR: 9.5. Compression - Standard: 176 psi - Limit: 137 psi 1999 CR: 9.5. Compression - Standard: 176 psi - Limit: 137 psi - Pro amore Dei et patriam et populum - Link to comment Share on other sites More sharing options...
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