I am doing an SR swap for someone and today I did a compression test to get an idea of the condition of the enigne. I put some oil down in the cylenders and turned it over by hand for a few mins. I then hooked up a jumper battery and used an ignition switch bypass switch to engadge the starter.Here are the resaults#1- 30 psi
#2- 150 psi
#3- 120 psi
#4- 120 psi
Now I took and put shop air into the #1 sparkplug hole and with the 1 cyl at TDC air was coming out the intake pretty strong. That leaves two possablities broken/burnt valves or maybe just carbon buildup around the seats. Also when the engine is cranking there is a loud tapping noise from the front timming chain cover. I hope the importer will help him out if there is anything internal needed.
SR compression resaults.....
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Imissmyturbo
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Imissmyturbo
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Just so you know, this probably isn't a problem. I've done a few installs, always check the compresison. Usually there's one, or even two, cyls that are low. The reason is that these motors sit for often long periods without running. The valves that are open tend to stick open (hence the hissing into the intake manifold).
What I do is make sure the oil pan is good, change the oil and filter. Hook up a mechanical gauge if you have one. Pull all the plugs and squirt 4 or 5 pumps of oil from an oil can into each cyl. put the plugs back in. Hook up a battery and crank it over for 30 seconds (not too long or you'll burn out the starter). Note turning it over by hand won't get the oil flying around, what you need to do is ge the oil to the valve stems and seats.
Now pull the plugs again and check the compression. I've had ones that were reading zero now read 120 just after doing this. Sometimes you need to repeat the process on the bad cyls.
Oh.. why change the oil and hook up the gauge? That's problem number 2 the loud tapping from the timing chain... this is because the oil pressure isn't up, and the timing chain tensioner isn't being pumped up. Repeat the 30 second cranking (with the plugs out) until you see pressure on the gauge... when you have pressure you should no longer have loud tapping.
Note... let the starter cool down for at least 5 minutes between 30 second cranking sessions.
Once you have oil pressure you should be able to see oil dripping from the spray bar onto the cam lobe when looking through the oil filler hole.
Redarding the compression... you probably won't see 150 across the board, but you should be able to get the bad cyls up to 120 or so. Once the motor has been run up to temp and cooled a couple of times then you should see even compression across the board.
-Martin.
What I do is make sure the oil pan is good, change the oil and filter. Hook up a mechanical gauge if you have one. Pull all the plugs and squirt 4 or 5 pumps of oil from an oil can into each cyl. put the plugs back in. Hook up a battery and crank it over for 30 seconds (not too long or you'll burn out the starter). Note turning it over by hand won't get the oil flying around, what you need to do is ge the oil to the valve stems and seats.
Now pull the plugs again and check the compression. I've had ones that were reading zero now read 120 just after doing this. Sometimes you need to repeat the process on the bad cyls.
Oh.. why change the oil and hook up the gauge? That's problem number 2 the loud tapping from the timing chain... this is because the oil pressure isn't up, and the timing chain tensioner isn't being pumped up. Repeat the 30 second cranking (with the plugs out) until you see pressure on the gauge... when you have pressure you should no longer have loud tapping.
Note... let the starter cool down for at least 5 minutes between 30 second cranking sessions.
Once you have oil pressure you should be able to see oil dripping from the spray bar onto the cam lobe when looking through the oil filler hole.
Redarding the compression... you probably won't see 150 across the board, but you should be able to get the bad cyls up to 120 or so. Once the motor has been run up to temp and cooled a couple of times then you should see even compression across the board.
-Martin.
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compression
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I disagree with the last post. If you hear a tapping over the noise over the noise of starter during cranking, then it is probably a bent valve, especially with numbers that low.The timing chain tensioner is spring loaded and should be working properly.If numbers dont improve by using the prevoius posts advice, I would pull the valve cover and do a thorough inspection.Not all the motors that come over here were driven by a japanese grandma to the grocery store once a week. Mine came over and had a blown turbo and head gasket, not too mention an OS Giken twin disc racing clutch that was thoroughly used.I was planning to rebuild it anyway, so no big deal.good luck.
I can't dissagree with you... many of these motors have been beaten on pretty hard in Japan :-)
Out of a personal sampling of 7 or 8 only one had a bad head gasket, only one didn't have uneven compression readings on first try.
So what I'm saying is don't jump all over your engine supplier yet, by all means let him know that you have uneven compression results, tell him you'll try a few things... as there's a good chance there's nothing wrong with this motor. And while your engine supplier will probably exchange the motor it's a lot of hassles, probably shipping expenses involved to. Also there's a good chance that any replacement you get will have uneven compression too.
-Martin.
Out of a personal sampling of 7 or 8 only one had a bad head gasket, only one didn't have uneven compression readings on first try.
So what I'm saying is don't jump all over your engine supplier yet, by all means let him know that you have uneven compression results, tell him you'll try a few things... as there's a good chance there's nothing wrong with this motor. And while your engine supplier will probably exchange the motor it's a lot of hassles, probably shipping expenses involved to. Also there's a good chance that any replacement you get will have uneven compression too.
-Martin.