Livin9it2up1 Posted April 12, 2009 Share Posted April 12, 2009 This is my first Post on Hybrid so don't criticize me too much... Tonight i did a compression test on my "newly" Bought L28et, and it didn't exactly go how i wanted it too... Cylinder 2 and 6, 100psi, all the rest were between 145 and 155. I need to know where to start.. anybody else have a common problem and a solution to fix it?? i just don't want to tear down the motor to find out i just need to adjust the valves or something stupid like that. Quote Link to comment Share on other sites More sharing options...
1 fast z Posted April 12, 2009 Share Posted April 12, 2009 Could be valve lash. Could be flat lobes on the cam on those cyliners. Quote Link to comment Share on other sites More sharing options...
kolonelklink87 Posted April 12, 2009 Share Posted April 12, 2009 throw some oil down there? Quote Link to comment Share on other sites More sharing options...
spawpoet Posted April 12, 2009 Share Posted April 12, 2009 If you can do a leak-down test, you may be able to determine whether you are losing compression at your rings, or your valves. Also like the poster above mentioned you can throw some oil in the bad cylinders. If the compression rises significantly you need rings. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted April 12, 2009 Share Posted April 12, 2009 I would guess you're checking it because it is not running right. A car with a cylinder that isn't firing will have low compression on the non-firing cylinder........if it is getting fuel because the unburned fuel can wash down the rings causing a bad seal. The oil suggested above will get you around that and I hope you're checking compressison with the distributor or crank angle sensor unplugged and the throttle plate open as these will have an impact on your compression readings. If the car is not running on a cylinder or two, you can unplug the injector on that cylinder and run the engine for a small bit to get the proper amount of oil in the bore and rings and then do a compression test rather than put oil down the bores which could disguise a ring problem. Quote Link to comment Share on other sites More sharing options...
Challenger Posted April 12, 2009 Share Posted April 12, 2009 A car with a cylinder that isn't firing will have low compression on the non-firing cylinder........if it is getting fuel because the unburned fuel can wash down the rings causing a bad seal. When your testing compression your basically testing a non-firing cylinder so wouldnt all of them show the same low compression if its just fuel washing away the oil.... Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted April 13, 2009 Share Posted April 13, 2009 Simple talk here folks. He's talkingabout one or two cylinders that don't have the same compression as the others. THey probably fire, but individually removing a spark plug cable on either one of these will not affect idle RPM as much as the higher compression cylinders. To check to see if it is rings, you simply add some oil in the cylinder that is low and run the compression test again. If the compression rises to within 10% of the other cylinders you have a ring problem in that cylinder. If the compression does not increase then it is a valve problem. Yes you do want to have he throttle plate open fully when cranking, and preferably have ALL spark plugs out of their respective cylinders - why put more of a load on the battery and starter? Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted April 13, 2009 Share Posted April 13, 2009 When your testing compression your basically testing a non-firing cylinder so wouldnt all of them show the same low compression if its just fuel washing away the oil.... No..........because you're not running injectors while doing a compression test. If a the car has a miss because a cylinder isn't firing but the injector is still firing, it will wash fuel down on that cylinder and lower compression on that cylinder. So...........you condemn an engine that might only have a bad spark plug wire. Quote Link to comment Share on other sites More sharing options...
Challenger Posted April 13, 2009 Share Posted April 13, 2009 Oh, I guess Ive never heard of people testing without the injectors firing. Quote Link to comment Share on other sites More sharing options...
Livin9it2up1 Posted April 13, 2009 Author Share Posted April 13, 2009 (edited) I actual just got the engine and installed it on Friday of last week, i was told the compression was 135 -140 across, so i wanted to double check those #'s (i was expecting a rebuild soon.) When i did the test the fuel injection wasn't even hooked up yet and spark plugs were out only the starter was hooked up. so i wasn't washing any oil away or getting false readings. But Before i did the test i checked to make sure their was oil in the motor and it looked suprisingly clean but smelt of gas and was quite thin.. im going to finish wiring it in and do a leak down tomorrow and make a junk yard run to get a new speedo sensor so i can fill the tranny.. ill keep everyone updated. and thanks for the help everybody! Edited April 13, 2009 by Livin9it2up1 for got something Quote Link to comment Share on other sites More sharing options...
Livin9it2up1 Posted April 13, 2009 Author Share Posted April 13, 2009 Could be valve lash. Could be flat lobes on the cam on those cyliners. ahh i don't want to here that, i hope thats last case scenario.. Quote Link to comment Share on other sites More sharing options...
RUZN Posted April 13, 2009 Share Posted April 13, 2009 Valves arent bad to set up at all. two nuts start at front work your way back crank a it do the next. I can send the specific way to do it if you want. dosent take much time valve cover off easy liek 5 mins set TDC and go! TDC just turn crank by hand well socket on crank and a nice long breaker bar =-) what is it again like .035 or somethign guys? I'll look send me a PM if you need info Quote Link to comment Share on other sites More sharing options...
sweetleaf Posted April 13, 2009 Share Posted April 13, 2009 Run the engine for a bit and redo your test. You maybe surprised. Quote Link to comment Share on other sites More sharing options...
RUZN Posted April 13, 2009 Share Posted April 13, 2009 <-- (engine front) E II E I EE I E II E Put wrench on Crank pulley bolt. Turn till #1 cylinder valves closed. Cam lobes will be pointing up when closed. #1: Adjust only 1,3,7,8,9, and 11 using feeler guage measure the clearence between the cam lobe and the valve rocker. Valve clearance should be (hot) intake--(3,8,11) 0.010in or 0.25mm), exhaust --(1,7,9) 0.012 (0.30mm) If its not to spec loosen locking nut and turn pivot nut till the guage starts to move and its slightly crimped. By that I mean like not binded in so you cant get it out lol. #2: turn crankshaft again so #1 lobe points down. and adjust 2,4,5,6,10 and 12. As you did with first set of valves. #3: reinstall Cover and boom start her up! err then check your compression again... Quote Link to comment Share on other sites More sharing options...
Challenger Posted April 13, 2009 Share Posted April 13, 2009 Did you prime the oil pump? So...........you condemn an engine that might only have a bad spark plug wire. No spark plugs so it probably isnt the spark plug wire... Quote Link to comment Share on other sites More sharing options...
Livin9it2up1 Posted April 13, 2009 Author Share Posted April 13, 2009 <-- (engine front) E II E I EE I E II E Put wrench on Crank pulley bolt. Turn till #1 cylinder valves closed. Cam lobes will be pointing up when closed. #1: Adjust only 1,3,7,8,9, and 11 using feeler guage measure the clearence between the cam lobe and the valve rocker. Valve clearance should be (hot) intake--(3,8,11) 0.010in or 0.25mm), exhaust --(1,7,9) 0.012 (0.30mm) If its not to spec loosen locking nut and turn pivot nut till the guage starts to move and its slightly crimped. By that I mean like not binded in so you cant get it out lol. #2: turn crankshaft again so #1 lobe points down. and adjust 2,4,5,6,10 and 12. As you did with first set of valves. #3: reinstall Cover and boom start her up! err then check your compression again... Ill try that after the wet test today if i dont see results. thanks for the mini Tutorial! Did you prime the oil pump? Yeah i primed the oil pump Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted April 13, 2009 Share Posted April 13, 2009 Did you prime the oil pump? No spark plugs so it probably isnt the spark plug wire... LOL that information showed up after my posting........nice try though. Quote Link to comment Share on other sites More sharing options...
Livin9it2up1 Posted April 14, 2009 Author Share Posted April 14, 2009 (edited) Completed wet test today and the results as follow... compression test before wet test... after test. 100 ...................... 130 150...................... .170 160 ...................... 175 150 ...................... 175 115...................... .138 120...................... .140 i started with cylinder 6 so the last one is 1. So i believe the problem is the ring, or at least most of the problem... i guess im ripin the motor back out and doing a rebuild.... IF their is any lesson learned, don't go by what somebody say when you buy something, make sure for yourself.. at least i got a pretty good deal on my motor.. Now does anyone know where to find a cheap complete rebuild kit for a L28et?? Edited April 14, 2009 by Livin9it2up1 formating Quote Link to comment Share on other sites More sharing options...
Daeron Posted April 14, 2009 Share Posted April 14, 2009 have you checked the valve lash yet? if this is not a P90a head, then it has adjustable valves, and you could well be holding a valve cracked on those two cylinders. SOME P90A heads are hydraulic adjusters, some are solid, so you have to check visually which you have if it is a P90A... but i wouldn't condemn the engine without checking the valve clearances first, and probably a leakdown test to see where the air is escaping from. Quote Link to comment Share on other sites More sharing options...
Livin9it2up1 Posted April 14, 2009 Author Share Posted April 14, 2009 have you checked the valve lash yet? if this is not a P90a head, then it has adjustable valves, and you could well be holding a valve cracked on those two cylinders. SOME P90A heads are hydraulic adjusters, some are solid, so you have to check visually which you have if it is a P90A... but i wouldn't condemn the engine without checking the valve clearances first, and probably a leak down test to see where the air is escaping from. Mine is a non Hydraulic head, and i was gonna try to track down a leak down tester today, my auto store used to rent them but when i went their last night they didn't even sell them anymore.. Quote Link to comment Share on other sites More sharing options...
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