Poor Compression, Apex Seal Springs?
04-25-2005, 02:23 AM
#1
Senior Member
Thread Starter
Join Date: Aug 2003
Posts: 157
I rebuilt my engine for the 2nd time last fall and have been chasing down some hot starting, inconsistent idle, and low rpm hesitation problems ever since before the rebuild. Compression tested bad on the old engine, so I tore it down again. And this time compression is even on all 6 faces, but it is low(about 75psi w/ the engine hot and throttle wide open). This leads me to believe that my methods were right this time, but my materials were not. On this second rebuild, I reused everything except the side seals, one bearing, and the e-shaft. My e-shaft one one of the bearings got scratched somehow I guess by something that got into my oil system. I also replaced the side seals because they were not within the tolerances that Judge Ito posted on this message board. I reused all other hard seals because they only had 4k miles on them.
I believe that my apex seal springs are to blame for the poor compression. Shamefully, we managed to insert all of them upside down the first time. I didn't replace them because they looked okay. However, I now wonder if them not being inserted properly the first time made them lose some of their tension or damage them somehow.
My second guess is apex seals themselves. They looked and measured out perfectly fine before I installed them. However, I don't think that the seals went into the same slot they came out of, as there was some mix up as to which seals belonged to which rotor. If this was the case, is it possible that the apex seals were worn beyond the point where they would seat into another housing? They had 4,000 miles on them before the rebuild.
The side seals were spec'ed with great care this time, and all the seals floated smoothly in their slots. The compression is dead even on all 3 facings of both rotors, so this is why I believe the apex seals or springs are to blame. If you guys think that it is probably the springs, then I will tear the engine down again probably. However, if you guys think the apex seals will need to be replaced, then I will just drive it how it is until it dies or I graduate college(2 more years hopefully).
I've tried to be as detailed as possible without giving too much to read. Thanks for all your help as always.
I believe that my apex seal springs are to blame for the poor compression. Shamefully, we managed to insert all of them upside down the first time. I didn't replace them because they looked okay. However, I now wonder if them not being inserted properly the first time made them lose some of their tension or damage them somehow.
My second guess is apex seals themselves. They looked and measured out perfectly fine before I installed them. However, I don't think that the seals went into the same slot they came out of, as there was some mix up as to which seals belonged to which rotor. If this was the case, is it possible that the apex seals were worn beyond the point where they would seat into another housing? They had 4,000 miles on them before the rebuild.
The side seals were spec'ed with great care this time, and all the seals floated smoothly in their slots. The compression is dead even on all 3 facings of both rotors, so this is why I believe the apex seals or springs are to blame. If you guys think that it is probably the springs, then I will tear the engine down again probably. However, if you guys think the apex seals will need to be replaced, then I will just drive it how it is until it dies or I graduate college(2 more years hopefully).
I've tried to be as detailed as possible without giving too much to read. Thanks for all your help as always.
04-25-2005, 02:41 AM
#2
Senior Member
Join Date: Oct 2002
Location: Phoenix, AZ
Posts: 296
your lack of compression worries me... even with the low compression rotors your min compression per face should be over 90psi.
what your main focus should be is during the power stage why am i getting a weak compression. there are lots of good places to look.
1.Rotor running clearens.
2.lack of oil.... a good rule of thumb for every 800 rpms = 10psi of oil pressure
oil pump not in tolerance
did not properly clean oil cooler(sonic cleaning)
3.corner seals and side seal clearance
also give me more details about the problem of
rough idel
tell me more about your apex seals and springs. when you installed them did they make a "click" sound?
Are then New?
Aftermaket or O.E.M.
what your main focus should be is during the power stage why am i getting a weak compression. there are lots of good places to look.
1.Rotor running clearens.
2.lack of oil.... a good rule of thumb for every 800 rpms = 10psi of oil pressure
oil pump not in tolerance
did not properly clean oil cooler(sonic cleaning)
3.corner seals and side seal clearance
also give me more details about the problem of
rough idel
tell me more about your apex seals and springs. when you installed them did they make a "click" sound?
Are then New?
Aftermaket or O.E.M.
04-25-2005, 04:04 AM
#3
Senior Member
Thread Starter
Join Date: Aug 2003
Posts: 157
1. I am not sure what you mean here? Could you please explain.
2. Well my oil pressure seems okay. Idling at 850rpm I see about 30psi. It goes up from there. I don't remember for sure what it is at 7000rpm, but I believe it's around 90-100psi. I'll check tomorrow.
3. Well, I spent a few hours clearancing the seals this time around. One night we sat down and clearanced all the seals to Judge Ito's specs he posted on this message board. I made sure all the seals moved freely. I had to do a little massaging on one of the corner seal and apex seal grooves to get those seels to move freely, but I got it done. I took everything out that night and layed it out and marked everything and marked my rotors to make sure everything went back where it belonged. The next day when I assembled my motor I made sure everything went back together smoothly and double checked clearances between all the side seals and corner seals and made adjustments as necessary. I'm confident in that part of my build.
Well the engine idles great before it warms up. I have to give it a little gas to keep it going at first, which is normal for a car without the emissions equipment. However, after that point it idles at a steady 850 rpm. Once the engine warms up to operating temperature though, the idle fluctuates from stop to stop. One time the idle is at 1200rpm, then at the next stop it's 1000, then at the next it might be 1200 again, and at the next it might be 850, etc. It's almost always high though. It also doesn't sound or look as smooth as it does when cold though. However, it's not rough to the point that it shakes the car or anything like that.
I don't recall the apex seals making a click sound. I glued the corner piece to the main part of the seal and installed them in the rotors according to the manual. I had a hard time keeping the corner piece glued to the main seal during installation. However, I made sure that they all stayed attached and that all of the corner pieces were flush so that none of them got chewed up when I installed the next housing. They are Atkins Rotary 2-piece 2mm seals, and they have about 7,000 miles on them at this point. When I rebuilt the engine this time, they had 4,000 miles on them which was from the last rebuild.
2. Well my oil pressure seems okay. Idling at 850rpm I see about 30psi. It goes up from there. I don't remember for sure what it is at 7000rpm, but I believe it's around 90-100psi. I'll check tomorrow.
3. Well, I spent a few hours clearancing the seals this time around. One night we sat down and clearanced all the seals to Judge Ito's specs he posted on this message board. I made sure all the seals moved freely. I had to do a little massaging on one of the corner seal and apex seal grooves to get those seels to move freely, but I got it done. I took everything out that night and layed it out and marked everything and marked my rotors to make sure everything went back where it belonged. The next day when I assembled my motor I made sure everything went back together smoothly and double checked clearances between all the side seals and corner seals and made adjustments as necessary. I'm confident in that part of my build.
Well the engine idles great before it warms up. I have to give it a little gas to keep it going at first, which is normal for a car without the emissions equipment. However, after that point it idles at a steady 850 rpm. Once the engine warms up to operating temperature though, the idle fluctuates from stop to stop. One time the idle is at 1200rpm, then at the next stop it's 1000, then at the next it might be 1200 again, and at the next it might be 850, etc. It's almost always high though. It also doesn't sound or look as smooth as it does when cold though. However, it's not rough to the point that it shakes the car or anything like that.
I don't recall the apex seals making a click sound. I glued the corner piece to the main part of the seal and installed them in the rotors according to the manual. I had a hard time keeping the corner piece glued to the main seal during installation. However, I made sure that they all stayed attached and that all of the corner pieces were flush so that none of them got chewed up when I installed the next housing. They are Atkins Rotary 2-piece 2mm seals, and they have about 7,000 miles on them at this point. When I rebuilt the engine this time, they had 4,000 miles on them which was from the last rebuild.
04-25-2005, 05:41 PM
#4
Senior Member
Join Date: Oct 2002
Location: Phoenix, AZ
Posts: 296
1. rotor running clearnance is super important and it worries me that you don't know about it. it the amount of play(space) that the rotor has to move left/right in the engine. too loose(too much space) you will have problems with getting high enough compression to tight you will have problems getting enought oil to the rotors and side housing.
2. idel..... i think will be solved when you solve the compression problem. but in the mean time use a vaccum gauge and tell me what it says at idel.
3. that "click" when you install the apex springs is the springs setting into place. you might want to use a small flat blade screw driver and push the long apex seal down. when you push it in far enough then you will feel or hear a small click...... thise could also effect compression because the springs will not set right making an impropper seal.
2. idel..... i think will be solved when you solve the compression problem. but in the mean time use a vaccum gauge and tell me what it says at idel.
3. that "click" when you install the apex springs is the springs setting into place. you might want to use a small flat blade screw driver and push the long apex seal down. when you push it in far enough then you will feel or hear a small click...... thise could also effect compression because the springs will not set right making an impropper seal.
04-26-2005, 01:11 AM
#5
Senior Member
Thread Starter
Join Date: Aug 2003
Posts: 157
1. Okay, I understand what you're talking about now, but how would you adjust this. I checked E-shaft endplay when I assembled the engine, but I know that has more to do with bearing life than anything else. I measured my rotor housing and rotors with a micrometer to ensure that they were within spec. I think the only way you could have the problem you're speaking of is if you had a warped rotor housing, correct?
2. I'll see if I can find a vacuum gauge tomorrow. I know there was one around here somewhere, but I'll have to find it. I have an HKS boost gauge which I haven't got around to hooking up yet as well, so I might do that instead. Heh.
3) Well I really don't remember hearing a click, but I wasn't listening for one either. So maybe that coudl be my compression problem?
2. I'll see if I can find a vacuum gauge tomorrow. I know there was one around here somewhere, but I'll have to find it. I have an HKS boost gauge which I haven't got around to hooking up yet as well, so I might do that instead. Heh.
3) Well I really don't remember hearing a click, but I wasn't listening for one either. So maybe that coudl be my compression problem?
04-26-2005, 02:37 PM
#6
Senior Member
Join Date: Oct 2002
Location: Phoenix, AZ
Posts: 296
1.the AL housing can warp if you do not release the tension bolts in order. you might also be suffering from rotor housing shrinkage, and in that case you will have to buy new housings. INFO go here they talk about it a little. i can not stress how important rotor running clearens is. To change the clearens you might have to buy different end spacer. end spacer
2. at start up your engine runs very rich due to cold start up( you say your car runs fine around that time).... when you warm up your ecu will go back to its normal FUEL MAP which is not as rich. its still some what rich at idel give it that smoothness so if your having problems in the combution camber with the idel mixture. either you are not getting enough fuel(that "putt putt" type idel) to much air( if feel like it will dye any second) or not enough compression and since you said you have low compression i think that your idel problem will be solved when you solve the compression problem.
3. you need to know that they are 100% set .
2. at start up your engine runs very rich due to cold start up( you say your car runs fine around that time).... when you warm up your ecu will go back to its normal FUEL MAP which is not as rich. its still some what rich at idel give it that smoothness so if your having problems in the combution camber with the idel mixture. either you are not getting enough fuel(that "putt putt" type idel) to much air( if feel like it will dye any second) or not enough compression and since you said you have low compression i think that your idel problem will be solved when you solve the compression problem.
3. you need to know that they are 100% set .
04-26-2005, 04:17 PM
#7
Junior Member
Join Date: Aug 2004
Posts: 5
[quote name='ryosuke_fc' date='Apr 24 2005, 11:23 PM']I rebuilt my engine for the 2nd time last fall and have been chasing down some hot starting, inconsistent idle, and low rpm hesitation problems ever since before the rebuild. Compression tested bad on the old engine, so I tore it down again. And this time compression is even on all 6 faces, but it is low(about 75psi w/ the engine hot and throttle wide open). This leads me to believe that my methods were right this time, but my materials were not. On this second rebuild, I reused everything except the side seals, one bearing, and the e-shaft. My e-shaft one one of the bearings got scratched somehow I guess by something that got into my oil system. I also replaced the side seals because they were not within the tolerances that Judge Ito posted on this message board. I reused all other hard seals because they only had 4k miles on them.
I believe that my apex seal springs are to blame for the poor compression. Shamefully, we managed to insert all of them upside down the first time. I didn't replace them because they looked okay. However, I now wonder if them not being inserted properly the first time made them lose some of their tension or damage them somehow.
My second guess is apex seals themselves. They looked and measured out perfectly fine before I installed them. However, I don't think that the seals went into the same slot they came out of, as there was some mix up as to which seals belonged to which rotor. If this was the case, is it possible that the apex seals were worn beyond the point where they would seat into another housing? They had 4,000 miles on them before the rebuild.
The side seals were spec'ed with great care this time, and all the seals floated smoothly in their slots. The compression is dead even on all 3 facings of both rotors, so this is why I believe the apex seals or springs are to blame. If you guys think that it is probably the springs, then I will tear the engine down again probably. However, if you guys think the apex seals will need to be replaced, then I will just drive it how it is until it dies or I graduate college(2 more years hopefully).
I've tried to be as detailed as possible without giving too much to read. Thanks for all your help as always.
[/quote]
What apex seals are in there?
I've been having very similar problems with RA apex seals and springs. In other hand it may be a faulty CTS, or other sensor. Anyway it would be easier to check the sensors AND their signal at the ECU conectors. It may be as trivial as oxidised contacts somewhere.
I believe that my apex seal springs are to blame for the poor compression. Shamefully, we managed to insert all of them upside down the first time. I didn't replace them because they looked okay. However, I now wonder if them not being inserted properly the first time made them lose some of their tension or damage them somehow.
My second guess is apex seals themselves. They looked and measured out perfectly fine before I installed them. However, I don't think that the seals went into the same slot they came out of, as there was some mix up as to which seals belonged to which rotor. If this was the case, is it possible that the apex seals were worn beyond the point where they would seat into another housing? They had 4,000 miles on them before the rebuild.
The side seals were spec'ed with great care this time, and all the seals floated smoothly in their slots. The compression is dead even on all 3 facings of both rotors, so this is why I believe the apex seals or springs are to blame. If you guys think that it is probably the springs, then I will tear the engine down again probably. However, if you guys think the apex seals will need to be replaced, then I will just drive it how it is until it dies or I graduate college(2 more years hopefully).
I've tried to be as detailed as possible without giving too much to read. Thanks for all your help as always.
[snapback]704203[/snapback]
[/quote]
What apex seals are in there?
I've been having very similar problems with RA apex seals and springs. In other hand it may be a faulty CTS, or other sensor. Anyway it would be easier to check the sensors AND their signal at the ECU conectors. It may be as trivial as oxidised contacts somewhere.
04-26-2005, 04:29 PM
#8
Junior Member
Join Date: Aug 2004
Posts: 5
[quote name='ryosuke_fc' date='Apr 24 2005, 11:23 PM']I rebuilt my engine for the 2nd time last fall and have been chasing down some hot starting, inconsistent idle, and low rpm hesitation problems ever since before the rebuild. Compression tested bad on the old engine, so I tore it down again. And this time compression is even on all 6 faces, but it is low(about 75psi w/ the engine hot and throttle wide open). This leads me to believe that my methods were right this time, but my materials were not. On this second rebuild, I reused everything except the side seals, one bearing, and the e-shaft. My e-shaft one one of the bearings got scratched somehow I guess by something that got into my oil system. I also replaced the side seals because they were not within the tolerances that Judge Ito posted on this message board. I reused all other hard seals because they only had 4k miles on them.
I believe that my apex seal springs are to blame for the poor compression. Shamefully, we managed to insert all of them upside down the first time. I didn't replace them because they looked okay. However, I now wonder if them not being inserted properly the first time made them lose some of their tension or damage them somehow.
My second guess is apex seals themselves. They looked and measured out perfectly fine before I installed them. However, I don't think that the seals went into the same slot they came out of, as there was some mix up as to which seals belonged to which rotor. If this was the case, is it possible that the apex seals were worn beyond the point where they would seat into another housing? They had 4,000 miles on them before the rebuild.
The side seals were spec'ed with great care this time, and all the seals floated smoothly in their slots. The compression is dead even on all 3 facings of both rotors, so this is why I believe the apex seals or springs are to blame. If you guys think that it is probably the springs, then I will tear the engine down again probably. However, if you guys think the apex seals will need to be replaced, then I will just drive it how it is until it dies or I graduate college(2 more years hopefully).
I've tried to be as detailed as possible without giving too much to read. Thanks for all your help as always.
[/quote]
What apex seals are in there?
I've been having very similar problems with RA apex seals and springs. In other hand it may be a faulty CTS, or other sensor. Anyway it would be easier to check the sensors AND their signal at the ECU conectors. It may be as trivial as oxidised contacts somewhere.
I believe that my apex seal springs are to blame for the poor compression. Shamefully, we managed to insert all of them upside down the first time. I didn't replace them because they looked okay. However, I now wonder if them not being inserted properly the first time made them lose some of their tension or damage them somehow.
My second guess is apex seals themselves. They looked and measured out perfectly fine before I installed them. However, I don't think that the seals went into the same slot they came out of, as there was some mix up as to which seals belonged to which rotor. If this was the case, is it possible that the apex seals were worn beyond the point where they would seat into another housing? They had 4,000 miles on them before the rebuild.
The side seals were spec'ed with great care this time, and all the seals floated smoothly in their slots. The compression is dead even on all 3 facings of both rotors, so this is why I believe the apex seals or springs are to blame. If you guys think that it is probably the springs, then I will tear the engine down again probably. However, if you guys think the apex seals will need to be replaced, then I will just drive it how it is until it dies or I graduate college(2 more years hopefully).
I've tried to be as detailed as possible without giving too much to read. Thanks for all your help as always.
[snapback]704203[/snapback]
[/quote]
What apex seals are in there?
I've been having very similar problems with RA apex seals and springs. In other hand it may be a faulty CTS, or other sensor. Anyway it would be easier to check the sensors AND their signal at the ECU conectors. It may be as trivial as oxidised contacts somewhere.
04-28-2005, 04:35 AM
#9
Senior Member
Thread Starter
Join Date: Aug 2003
Posts: 157
Haven't been able to test vacuum at idle yet. Haven't been able to find my vacuum gauge. Today I noticed that the car seems to be strangely lacking power now. Hopefully I didn't blow anything. I haven't been too hard on it, so I don't think I should have. Tomorrow I'll try to find that damn gauge again.
I have Atkins Rotary Apex seals. Judge Ito told me that he uses them in all of his engines and they come out of the shop with 120psi compression, so I have confidence in the seals. That might be on new housings though and definately new seals I know.
CTS? Coolant temp sensor? The one in the back of the filler neck? Well, I checked all my ECU connectors with the ignition on and everything checked out except emissions equipment which was not connected. Didn't check it all at idle though I checked TPS, AFM, and O2 sensors while driving and they all acted normal. Maybe I should check the coolant temp sensor while driving...
I have Atkins Rotary Apex seals. Judge Ito told me that he uses them in all of his engines and they come out of the shop with 120psi compression, so I have confidence in the seals. That might be on new housings though and definately new seals I know.
CTS? Coolant temp sensor? The one in the back of the filler neck? Well, I checked all my ECU connectors with the ignition on and everything checked out except emissions equipment which was not connected. Didn't check it all at idle though I checked TPS, AFM, and O2 sensors while driving and they all acted normal. Maybe I should check the coolant temp sensor while driving...
05-01-2005, 08:47 PM
#10
Senior Member
Thread Starter
Join Date: Aug 2003
Posts: 157
I found my vacuum gauge. A buddy borrowed it a while back, and I got it back from him. I tested vacuum @ idle and am seeing 11 in. That definately coincides with my compression numbers I would say...
I'm still unsure if I want to tear the engine down though... I don't want to spend the money on a full rebuild right now.
I'm still unsure if I want to tear the engine down though... I don't want to spend the money on a full rebuild right now.