no compression
01-14-2010, 10:06 PM
#1
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no compression
I did a compression test on sunday and as I guessed no compression on one cylinder ( the rear) which is coincidentally the cylinder I have previously heard a large bang from and two or three times after that slightly quiter bang/explosions from. So seeing I had no compression (literally 0-10 pounds) I added some oil to the cylinder figuring if it was the rings it would go up, and up it went, almost all the way to 20 lbs. so I surmised it must be a head gasket (later thought possibly valve also). So I got a head gasket and pulled the head today only to see no signs of a blown head gasket or a bent or stuck valve. what I did notice was a ton of carbon build up ( like between a 16th and 8th) on the piston an valves and some marring and scratches on the inside of the head where it looks like the cam chain rode against it a little. Did I have a partial cct failure and the timing was off afterward? Any ideas or thoughts would be accepted, good and enlightening ones sought and appreciated.
01-15-2010, 08:25 AM
#4
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I would guess the noise you heard was the cam chain jumping after a CCT failure... and of course, with the cams improperly timed you would not have been able to build compression. Excessive carbon on the valves will keep them open enough to lose compression as well, but you should of been able to build some at the very least.
01-15-2010, 08:52 AM
#6
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+2
It sounds like the cams jumped time, causing the valves to be open during part of the compression stroke.
Make sure you haven't bent any valves, reassemble and you will probably be ok - with new CCTs of course.
It sounds like the cams jumped time, causing the valves to be open during part of the compression stroke.
Make sure you haven't bent any valves, reassemble and you will probably be ok - with new CCTs of course.
01-15-2010, 10:41 AM
#7
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I wonder if the carbon build up is due to the timing slip, I hope the valves are ok. This might be stupid but would a bent valve be evident to visual inspection? They looked ok, other than being covered in carbon.
01-15-2010, 10:57 AM
#8
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Spray some contact/brake cleaner on the valve heads in the combustion chamber. Look for how fast it seeps between the valve seats and valve faces. This will give some indication of how well the valves are seated. A bent valve will probably not seat well.
There would likely be evidence of contact between the valve and piston, if it touched.
The carbon buildup is normal. A combination of impurities in the gas and burned oil. Adding Techron or something like it will clean it out pretty well.
*edit* I see VTRsurfer already suggested this. I like contact cleaner's low viscosity. Since you aren't removing the valves, just do the seep check.
There would likely be evidence of contact between the valve and piston, if it touched.
The carbon buildup is normal. A combination of impurities in the gas and burned oil. Adding Techron or something like it will clean it out pretty well.
*edit* I see VTRsurfer already suggested this. I like contact cleaner's low viscosity. Since you aren't removing the valves, just do the seep check.
Last edited by RCVTR; 01-15-2010 at 10:59 AM.
01-15-2010, 01:30 PM
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Spray some contact/brake cleaner on the valve heads in the combustion chamber. Look for how fast it seeps between the valve seats and valve faces. This will give some indication of how well the valves are seated. A bent valve will probably not seat well.
There would likely be evidence of contact between the valve and piston, if it touched.
The carbon buildup is normal. A combination of impurities in the gas and burned oil. Adding Techron or something like it will clean it out pretty well.
*edit* I see VTRsurfer already suggested this. I like contact cleaner's low viscosity. Since you aren't removing the valves, just do the seep check.
There would likely be evidence of contact between the valve and piston, if it touched.
The carbon buildup is normal. A combination of impurities in the gas and burned oil. Adding Techron or something like it will clean it out pretty well.
*edit* I see VTRsurfer already suggested this. I like contact cleaner's low viscosity. Since you aren't removing the valves, just do the seep check.
01-15-2010, 01:50 PM
#10
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01-15-2010, 02:27 PM
#11
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I usually use highgrade (Iknow it's unnecessary, so is a motorcycle) and the bike sees 9000 often enough off stops. Not all that exciting on one good cylinder. I only mentioned the deposits as they seemed excessive.
01-15-2010, 02:53 PM
#12
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Octane number is only an indication of how much pressure the fuel can withstand before autoignition occurs. It is not a measure of fuel quality.
Some of the premium fuels like Chevron and Shell contain additives to prevent deposits in the engine. I use them almost excusively. But maybe I'm just caught up in the hype. I don't know how well they actually work.
Some of the premium fuels like Chevron and Shell contain additives to prevent deposits in the engine. I use them almost excusively. But maybe I'm just caught up in the hype. I don't know how well they actually work.
01-15-2010, 03:40 PM
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01-15-2010, 10:11 PM
#14
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The first time I did the leak test one of the intake valves leaked. I attached the cam and lifted the valve, cleaned around it and then it sealed. I did a little cleaning, put in a new head gasket (the old one didn't show any signs of being blown) put the head back on and timed it (guessed at compression vs exhaust stroke by how hard it was to turn with the other plug in, make sure to turn cc wise if doing this). I checked the compression and it was about 120 with a slightly drained battery and really cold. So I guess everything is better but I'd love to know what was wrong. A few questions I'm left with
1. What"s the proper torque for the two silver 10 mm bolts on the chain side? I half sapped one off in there but it didn't come apart, I'll have to take a pic it maybe be the luckiest I've ever been
2. after the popping noise I opened up the oil fill and smoke came out, If it was a valve or a head gasket then how did the smoke get there. If it was not then how did pulling and cleaning and resealing the head help?
3. when timing I noticed that the exhaust timing mark would never line dead up with the top of the head, a one tooth switch put it lower than it had been high so I left it high, after the chain was tight it was still a tiny bit high. has anyone else noticed this? is this correct and ok?
1. What"s the proper torque for the two silver 10 mm bolts on the chain side? I half sapped one off in there but it didn't come apart, I'll have to take a pic it maybe be the luckiest I've ever been
2. after the popping noise I opened up the oil fill and smoke came out, If it was a valve or a head gasket then how did the smoke get there. If it was not then how did pulling and cleaning and resealing the head help?
3. when timing I noticed that the exhaust timing mark would never line dead up with the top of the head, a one tooth switch put it lower than it had been high so I left it high, after the chain was tight it was still a tiny bit high. has anyone else noticed this? is this correct and ok?
Last edited by spladle160; 01-15-2010 at 10:23 PM. Reason: forgetfulness
01-16-2010, 05:01 AM
#15
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The first time I did the leak test one of the intake valves leaked. I attached the cam and lifted the valve, cleaned around it and then it sealed. I did a little cleaning, put in a new head gasket (the old one didn't show any signs of being blown) put the head back on and timed it (guessed at compression vs exhaust stroke by how hard it was to turn with the other plug in, make sure to turn cc wise if doing this). I checked the compression and it was about 120 with a slightly drained battery and really cold. So I guess everything is better but I'd love to know what was wrong. A few questions I'm left with
1. What"s the proper torque for the two silver 10 mm bolts on the chain side? I half sapped one off in there but it didn't come apart, I'll have to take a pic it maybe be the luckiest I've ever been
2. after the popping noise I opened up the oil fill and smoke came out, If it was a valve or a head gasket then how did the smoke get there. If it was not then how did pulling and cleaning and resealing the head help?
3. when timing I noticed that the exhaust timing mark would never line dead up with the top of the head, a one tooth switch put it lower than it had been high so I left it high, after the chain was tight it was still a tiny bit high. has anyone else noticed this? is this correct and ok?
1. What"s the proper torque for the two silver 10 mm bolts on the chain side? I half sapped one off in there but it didn't come apart, I'll have to take a pic it maybe be the luckiest I've ever been
2. after the popping noise I opened up the oil fill and smoke came out, If it was a valve or a head gasket then how did the smoke get there. If it was not then how did pulling and cleaning and resealing the head help?
3. when timing I noticed that the exhaust timing mark would never line dead up with the top of the head, a one tooth switch put it lower than it had been high so I left it high, after the chain was tight it was still a tiny bit high. has anyone else noticed this? is this correct and ok?
01-18-2010, 04:01 PM
#18
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I have just seen that you have stretched a cam sprocket bolt, you need to replace it, torque is 7 lb/ft if my memory still holds true.
The bolt will have a thin stretched section and could break loose or snap, could destroy your engine.
The bolt will have a thin stretched section and could break loose or snap, could destroy your engine.
01-18-2010, 05:02 PM
#19
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It's not worn rings or the compression would have gone up when I put oil in the cylinder and would not have been helped by a new head gaskets and cleaning the valves. And yes I will most definitely have to replace that bolt it was being held together by a single thread. Thanks for finding that torque value, I'm planning on putting some loctite on those bolts I'm paranoid about anything coming loose in there.
01-18-2010, 07:35 PM
#22
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I wanted to get these to adjust the valve timing. Will need to make an adapter to fit a degree wheel to the crank and a dial to measure the valve opening.
The problem is that there is nothing to compensate for the timing chain stretch unless you have an infinitely adjustable cam sprocket or a gear drive.
http://www.orientexpress.com/Honda/S...1997-2005.html
The problem is that there is nothing to compensate for the timing chain stretch unless you have an infinitely adjustable cam sprocket or a gear drive.
http://www.orientexpress.com/Honda/S...1997-2005.html
01-19-2010, 01:10 AM
#23
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I did a compression test on sunday and as I guessed no compression on one cylinder ( the rear) which is coincidentally the cylinder I have previously heard a large bang from and two or three times after that slightly quiter bang/explosions from. So seeing I had no compression (literally 0-10 pounds) I added some oil to the cylinder figuring if it was the rings it would go up, and up it went, almost all the way to 20 lbs. so I surmised it must be a head gasket (later thought possibly valve also). So I got a head gasket and pulled the head today only to see no signs of a blown head gasket or a bent or stuck valve. what I did notice was a ton of carbon build up ( like between a 16th and 8th) on the piston an valves and some marring and scratches on the inside of the head where it looks like the cam chain rode against it a little. Did I have a partial cct failure and the timing was off afterward? Any ideas or thoughts would be accepted, good and enlightening ones sought and appreciated.
01-19-2010, 01:16 AM
#24
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just food for thought here,if there was excess carbon on the crown of the piston then you would have higher compression which would cause the head gasket to go,also if there are signs of carbon then the valves were likely to have gotten some on there seats which over time will lead to 1 or more sticking open and eventually you would loose all compression,this whole set of circumstances would arise from oil getting into the combustion chamber,weather thats from a valve seal/s or piston rings would have to be determined by the oil test which should not have raised compression if it were the valve seals but would if piston rings were at fault
01-20-2010, 03:56 PM
#25
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The carbon on the valves and sticking open is the conclusion I have come to as upon a leak test one valve did leak. If it were the rings than when I added a few cc's of oil the compression would have risen and a blown head gasket would probably have been at least somewhat apparent upon visual inspection.
01-25-2010, 10:36 PM
#26
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So I stayed up late tonight and put it back together since I got my APEs today.
1. The APEs are h@## to get adjusted where your not paranoid there wrong.
2. before I put the head cover back on the rear I turned it over by hand for a while and noticed a tiny metalic tink whenever the exhaust valve got to about 3/4 open. Could it have been the spring seating or.. I just don't know, and I'm not sure I want to.
3. I got it all together and, drum roll... nothing. tried to fill the carbs, nothing. sucked on the sync port in the vacuum hose, nothing. Turned the petcock valve to on, oh yeah that worked
4. So to prove to myself I needed to go to bed I noticed It ran ok but sounded really strange, the crank and timing caps were still off. The final straw that's driven me back in the house I seriously thought that the pressure bursts from the crank cap were exhaust and was worried about how it got there.
Can't really complain about my tired stupidity to much though. It's running
1. The APEs are h@## to get adjusted where your not paranoid there wrong.
2. before I put the head cover back on the rear I turned it over by hand for a while and noticed a tiny metalic tink whenever the exhaust valve got to about 3/4 open. Could it have been the spring seating or.. I just don't know, and I'm not sure I want to.
3. I got it all together and, drum roll... nothing. tried to fill the carbs, nothing. sucked on the sync port in the vacuum hose, nothing. Turned the petcock valve to on, oh yeah that worked
4. So to prove to myself I needed to go to bed I noticed It ran ok but sounded really strange, the crank and timing caps were still off. The final straw that's driven me back in the house I seriously thought that the pressure bursts from the crank cap were exhaust and was worried about how it got there.
Can't really complain about my tired stupidity to much though. It's running
01-26-2010, 04:12 PM
#28
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Um so how important are the dowel pins between the head and motor? I kinda found one on the floor but am hesitant to pull everything apart to replace it since I can't see it's function after the head is installed
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