Subarutex Posted October 18, 2005 Share Posted October 18, 2005 Ok geniuses, help me out on this one. Left bank is at 60psi compression, right bank is at 100. Regardless both are low, however will the engine yeild lower compression with the 260 duration Delta cams? If that is the case, it could be that I just still ahve the cam timing fubar'd. If that isn't the case, seems logical that A: the head gaskets aren't sealing, or B: I have multiple leaking valves. Block is rebuilt, remachined, rebearinged, repistoned, reringed, everything. New oil pump. Heads are reconditioned as well. 260 duration Delta Cams. Copper HG's @ 75 ft/lbs. Quote Link to comment Share on other sites More sharing options...
hooziewhatsit Posted October 18, 2005 Share Posted October 18, 2005 warning: *thinking outloud* I would think that since the compression on both sides are the same, it would be a timing belt issue. Unless all the valve seals where equally worn (unlikely?) I don't think the compression would be the _same_. Same with the HGs. Besides, the cam timing is a lot easier to re-check then HGs or valves. Quote Link to comment Share on other sites More sharing options...
Subarutex Posted October 18, 2005 Author Share Posted October 18, 2005 Just talked to a guy at Delta Cam. He said to expect a loss of at most 15psi of compression from the cams. Which, should be 160 or thereabouts... so minus 15 should be 145 or so would be acceptable. If the cam timing is so far off to yeild this bad of compression... how does the car still run??? Quote Link to comment Share on other sites More sharing options...
northguy Posted October 18, 2005 Share Posted October 18, 2005 If the timing is off just a bit, with one of the valves open a very minor amount during detonation (say the exhaust valve) wouldn't compression be pronounced and different - say 60 as opposed to 100 - ? Just a thought. Quote Link to comment Share on other sites More sharing options...
NoahDL88 Posted October 18, 2005 Share Posted October 18, 2005 Stoopid question, you are doing the compression test with the throttle open yeah? as far as one bank being good and the other not, it would seem that one cam is either off a tooth, or it was ground wrong. i'd try sticking in some stock cams and see if that clears it up Quote Link to comment Share on other sites More sharing options...
Subarutex Posted October 18, 2005 Author Share Posted October 18, 2005 Open throttle for compression test? really? I didn't... Quote Link to comment Share on other sites More sharing options...
JWX Posted October 18, 2005 Share Posted October 18, 2005 I hope thats sarcasim, especially with your "forum title" but ya I'd check leak down. maybe put some dye in it to see where its going. oh make sure the engine is turning fast enough. I just got to thinking, did you ever break this engine in? Quote Link to comment Share on other sites More sharing options...
DrKrazy Posted October 18, 2005 Share Posted October 18, 2005 I just got to thinking, did you ever break this engine in? Kinda what I was thinking, not broken in properly and wasted a cam? Seen it happen before. Quote Link to comment Share on other sites More sharing options...
JWX Posted October 18, 2005 Share Posted October 18, 2005 well I was thinking if he never got it broken in, and he was running rich, he might not have good sealing of the rings. Quote Link to comment Share on other sites More sharing options...
Subarutex Posted October 18, 2005 Author Share Posted October 18, 2005 What would define breaking in properly guys? I'd like to hear all your theories, cause everyone has a different one. Whose do you trust? Brian the subaru Guru? A 15+ yr certified subaru technician? A 10+ yr certified subaru technician? A guy thats been building high power big blocks since before my mom was born? I've personally heard 4 or 5 different ways of breaking in one of these engines. When I originally got the block (from a certified subaru mechanic), I was told to just drive it, that was it. No break in procedure. After those rings failed (due presumably to high boost, as 2 pistons were cracked after only 150 miles) I had the 2 pistons replaced and new rings put in the engine. The hone was touched up, and this certified subaru mechanic told me prime the engine, then start it and hold about 2500 for 10-15 minutes. I did that. Since then I've driven maybe 50 miles on it, mainly in loops around my block. I keep changing the cam timing, and disty timing trying to find the correct spot. I also don't understand how I could "waste a cam". These cams aren't brand new, and were installed and ran well on my previous motor. Also... I don't know how anything i've posted has been sarcastic? I'm honestly looking for opinions on whether or not a RUNNING car can have cam timing off soo bad to yeild these compression numbers. Or how can I have a RUNNING car when half my engine is running at 60psi... Most engines need atlease 90psi compression to run at all. I'm geniunly surprised by hearing about opening the throttle when checking compression. Are you supposed to do it? or not? I've never done it that way, am I just that retarded for not knowing how to do it? Quote Link to comment Share on other sites More sharing options...
idosubaru Posted October 18, 2005 Share Posted October 18, 2005 it's a good idea to leave the throttle open and all the spark plugs removed when compression testing. not necessary, but not a bad thing either. having the throttle open allows the engine easier access to air supply (not the old 80's band) and removing all the plugs frees the engine up to turn easier. if it's both cylinders then i would look for something that affects both like the cam or t-belts. particularly since yo'ure getting the same compression ratio in both...it therefore the cause must be somethign that affects both equally....like belts or cam. i don't know but random thoughts: i'd be checking the timing belt as well. i'd check the belt, the tensioner, the cam sprocket and make sure nothing is out of whack. make sure the cam sprocket is seated where it's supposed to be, can't imagine it would be off but doesn't take long to check on the passengers side either. pull a valve cover and turn the motor over by hand and see if everything appears to be opening and closing properly. with the plug hole open you can see the top of the piston and make sure both valves are closing at the right times...maybe compare to the other side and see if things look the same. Quote Link to comment Share on other sites More sharing options...
DrKrazy Posted October 18, 2005 Share Posted October 18, 2005 The hone was touched up, and this certified subaru mechanic told me prime the engine, then start it and hold about 2500 for 10-15 minutes. I did that. I also don't understand how I could "waste a cam". These cams aren't brand new, and were installed and ran well on my previous motor. That's always how I've been told to break in engines also. Well, 1500-2500 rpms for 10-15 mins depending on the engine. Didn't realize the cams were used, should've read better...I have only seen brand new cams that were not lubed correctly and then the engine just started up and wailed on flatten out cam with a few hundred miles. Watched a buddy of mine do that twice when rebuilding an engine in a cavalier..he just wouldn't listen to me when I told him not to wail on the engine for awhile. Would just turn it on for the first time and wrap it up to 5k right away..he learned his lesson eventually. Each time it was a flat cam. Quote Link to comment Share on other sites More sharing options...
Subarutex Posted October 18, 2005 Author Share Posted October 18, 2005 it's a good idea to leave the throttle open and all the spark plugs removed when compression testing. not necessary, but not a bad thing either. having the throttle open allows the engine easier access to air supply (not the old 80's band) and removing all the plugs frees the engine up to turn easier. if it's both cylinders then i would look for something that affects both like the cam or t-belts. particularly since yo'ure getting the same compression ratio in both...it therefore the cause must be somethign that affects both equally....like belts or cam. i don't know but random thoughts: i'd be checking the timing belt as well. i'd check the belt, the tensioner, the cam sprocket and make sure nothing is out of whack. make sure the cam sprocket is seated where it's supposed to be, can't imagine it would be off but doesn't take long to check on the passengers side either. pull a valve cover and turn the motor over by hand and see if everything appears to be opening and closing properly. with the plug hole open you can see the top of the piston and make sure both valves are closing at the right times...maybe compare to the other side and see if things look the same. Thanks Gary. I knew to take all the sparkplugs out, never heard about the throttle though, i'll add that to my things to do. Very good idea about taking the valve cover off and checking things out, hadn't thought about that. I was just going to play around with moving the cam a tooth this way or a tooth that way on the belt. Any neat method to check if a piston is at TDC? I spose just a good penlight shining down in there would do decent... Dr. Krazy... The only flat cam i've seen was one that came out of my friends chevy 350 after about 250,000 miles, it was baaad. Quote Link to comment Share on other sites More sharing options...
Do It Sidewayz Posted October 18, 2005 Share Posted October 18, 2005 Any neat method to check if a piston is at TDC? I spose just a good penlight shining down in there would do decent... Just stick your thumb over the spark plug hole and turn the engine over slowly with a wrench. you will be able to feel it. when it's at TDC Quote Link to comment Share on other sites More sharing options...
suberdave Posted October 19, 2005 Share Posted October 19, 2005 another thing to do other than opening the TB is to pull the fuel pump fuse. with the fuel spraying every time the ign is turned on. the fuel can wash down the cyl's and cause a low comp ratio. this could be likely if the first 2 cys's are the ones at 100psi and the last 2 are at 60psi. pull all plugs. hold the TB open pull the Fuel/IGN fuse that will give you your best ratio. thought i would give you my $0.02. Quote Link to comment Share on other sites More sharing options...
WJM Posted October 19, 2005 Share Posted October 19, 2005 that or look at the flywheel....atleast, for #1. you need to send the car to me and all will be fixed. Seriously, WOT for compression checks and plugs out...testing RPM is stated to be ~350 RPM. My RX ran perfectly fine with one side at 60 psi and the other at ~140. Ran butter smooth. That side had some kinda of head crack/head gasket...never found out what it was, i just replaced the HG ad entire head as I was autoxing that same morning. ProSolo+no sleep in last 48 hours=not so good end results. I know its alot of work...but I would put stock cams back in it and see what that does. I know you dont want to hear this...but...I used copper's only once. They leaked like crazy. Car ran fine...but leaked bad...leaked compression, coolant, oil...you name it. I wont use CUHGs again until I get some ARP studs. I dont think you can put enough TQ on the CUHGs with the stock bolts. Since the compression is the same on each cyl. per side...it looks to be an air delivery issue. Again, try stock cams. Quote Link to comment Share on other sites More sharing options...
Subarutex Posted October 19, 2005 Author Share Posted October 19, 2005 I've grown to hate the CUHG's too. I'm actually just trying to rule out the cams as the cause, because the motor is already weeping a bit of oil out of the HG joints. So if it is for sure not the cams, i'll pull the motor and put stock HG's in it. Quote Link to comment Share on other sites More sharing options...
jeffast Posted October 19, 2005 Share Posted October 19, 2005 what he ment was generally when one bank losses compression in these cars it is a broken timing belt Quote Link to comment Share on other sites More sharing options...
WJM Posted October 19, 2005 Share Posted October 19, 2005 I've grown to hate the CUHG's too. I'm actually just trying to rule out the cams as the cause, because the motor is already weeping a bit of oil out of the HG joints. So if it is for sure not the cams, i'll pull the motor and put stock HG's in it. *ding ding ding* Thats what my 89 RX did... Quote Link to comment Share on other sites More sharing options...
JWX Posted October 19, 2005 Share Posted October 19, 2005 I just asked if it was broke in, I don't care who you listen to/how you do it. I'm starting to wonder if its not the CUHGs. but i'd hate for you to take it apart agian to do teh head gaskets. Quote Link to comment Share on other sites More sharing options...
Subarutex Posted October 19, 2005 Author Share Posted October 19, 2005 I just asked if it was broke in, I don't care who you listen to/how you do it. I'm starting to wonder if its not the CUHGs. but i'd hate for you to take it apart agian to do teh head gaskets. I'd hate to take it all apart and do the HG's and then have them not be the problem... Thats why i am trying rule out everything else first. Quote Link to comment Share on other sites More sharing options...
Cougar Posted October 19, 2005 Share Posted October 19, 2005 I would doubt very much that the gaskets are the problem. To me, having those readings that you got is very encouraging. If it was the gaskets then it would seem that the readings would be random since the leaks would vary in each cylinder. Since the pressures are exactly the same on each side I would guess that the higher side is maybe a tooth off and the lower side is two teeth off on the cams. You might try moving the lower side first a couple of teeth one way or the other if you can't figure out which way to go then see what the pressure is. This may then be a guide for doing the other side. Quote Link to comment Share on other sites More sharing options...
JWX Posted October 19, 2005 Share Posted October 19, 2005 well how well does it run? kinda rough? think the problem could be the safc? maybe its messing with the signal from a sensor? I really don't think its the cams, but it could be. Quote Link to comment Share on other sites More sharing options...
Subarutex Posted October 19, 2005 Author Share Posted October 19, 2005 It will idle after a little bit of coaxing. Pig rich at idle though, to the point of blowing gas out the back. Off boost it runs OK. Not great. Boost hits anytime below 3500rpm and the motor is choked off and wants to die, doesn't want to rev. If boost hits after 4000rpm it pulls ok. But i'm only pushing 5psi, so its hardly a pull at all... Quote Link to comment Share on other sites More sharing options...
WJM Posted October 19, 2005 Share Posted October 19, 2005 Hm. MAF? TPS? Quote Link to comment Share on other sites More sharing options...
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