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I hesitate to askI have recently developed a severe hesitation problem. Cyl 1 shows compression of 120. Other 3 have 150. If I squirt oil into 1, it also shows 150. There has been no change in compression or vacuum (18), but the hesitation and
I have recently developed a severe hesitation problem. Cyl 1 shows
compression of 120. Other 3 have 150. If I squirt oil into 1, it also shows 150. There has been no change in compression or vacuum (18) since before the problem, but the hesitation and missing started suddenly as I was driving last week. Prior to this, I ran smoothly at all speeds up to 85 mph., although the engine had been a little weak, I consume very little oil, except at sustained very high speeds, Now the engine idles nicely, but hesitates under load under any driving conditions. I removed the #1 spark plug wire and grounded it to the block. Car runs much smoother now on 3 cylinders at all speeds than it had been on 4 with one missing.. Questions: Will running the car like this on a short term basis damage the engine? Could raw gas ignite in the exhaust system and damage it? (I can't shut off gas supply because this is a carb engine, not EFI.) Is there any way to tell if problem is rings rather than valves without pulling the cylinder head? Thanks, Tom |
Re: I hesitate to askI have recently developed a severe hesitation problem. Cyl 1 shows compression of 120. Other 3 have 150. If I squirt oil into 1, it also shows 150. There has been no change in compression or vacuum (18), but the hesitation a
"tom" <tom@adelphia.net> wrote in message
news:fvn061l0vqme8bcfk090oqkvvja426t5sa@4ax.com... >I have recently developed a severe hesitation problem. Cyl 1 shows > compression of 120. Other 3 have 150. If I squirt oil into 1, it > also shows 150. There has been no change in compression or vacuum > (18) since before the problem, but the hesitation and missing started > suddenly as I was > driving last week. Prior to this, I ran smoothly at all speeds up to > 85 mph., although the engine had been a little weak, I consume very > little oil, except at sustained very high speeds, > > Now the engine idles nicely, but hesitates under load under any > driving conditions. I removed the #1 spark plug wire and grounded it > to the block. Car runs much smoother now on 3 cylinders at all speeds > than it had been on 4 with one missing.. > > > Questions: > Will running the car like this on a short term basis damage the > engine? > Could raw gas ignite in the exhaust system and damage it? (I can't > shut off gas supply because this is a carb engine, not EFI.) > Is there any way to tell if problem is rings rather than valves > without pulling the cylinder head? > > Thanks, > > Tom > 1) Don't run it with the ignition dead on one cylinder. Find and fix the problem. Running with 25% unburned fuel entering the exhaust will toast the exhaust system very quickly and will worsen the ring wear in the dead cylinder as the gasoline washes the oil away. (I wonder if that is why the compression is low in the first place... inadequate oil to seal the rings.) 2) The compression problem is almost certainly with the rings. Your oil test is used to tell the difference: the oil temporarily seals the rings better, and in your case that restored compression. The valves have to seal well to do that, so your valves are good enough. Now, that isn't a good sign, but that probably has little to do with the hesitation. What you describe isn't what I'd call hesitation as much as it is really ratty running, so I'll address that first, then move on to classic hesitation. Bad running under load makes me think of poor ignition. If you've recently done a tune-up, I think you got a bad part. I once got a distributor cap that lasted one hour, then one cylinder died completely. But if it's been a while, now is the time. The distributor cap, plug and wire are all big time suspects for this symptom. The two things to look at for actual hesitation suddenly appearing are the carburetor and the ignition timing - especially the advance. If the hesitation occurs even when you floor the accelerator while travelling 30-40 mph, I'd bet on the carburetor. With the engine off, pull the air cleaner off the carb and look down the throat at the throttle butterfly in the primary barrel. It will be easiest if the engine is warm so the choke is open. Open the throttle by hand and watch for a solid stream of gasoline in the throat. If that is weak or missing, you have found the cause - a bad accelerator pump. It's a very common failure. The cure is a carburetor rebuild, or exchange if you are especially wealthy. If that looks okay, put it back together and start the engine. Remove all vacuum hoses from the distributor and plug them. Connect a timing light and operate the throttle by hand, slowly and rapidly. You should see the timing advance smoothly as you open it slowly, and rapidly advance matching the engine speed as you open it rapidly. If either of these are not true, you have problems with the mechanical advance in the distributor. A replacement from the wrecking yard is one approach to that. The other is to disassemble the distributor and clean and lube the advance weights and the plate they ride on. If there are pits in the plate where the weights are at idle or at full advance, sand them out with fine emery paper. The distributor work is about the same skill level as the carb rebuild... medium. Don't forget to reconnect the hoses! So... what model and year is this? Mike |
Re: I hesitate to askI have recently developed a severe hesitation problem. Cyl 1 shows compression of 120. Other 3 have 150. If I squirt oil into 1, it also shows 150. There has been no change in compression or vacuum (18), but the hesitation a
"tom" <tom@adelphia.net> wrote in message
news:fvn061l0vqme8bcfk090oqkvvja426t5sa@4ax.com... >I have recently developed a severe hesitation problem. Cyl 1 shows > compression of 120. Other 3 have 150. If I squirt oil into 1, it > also shows 150. There has been no change in compression or vacuum > (18) since before the problem, but the hesitation and missing started > suddenly as I was > driving last week. Prior to this, I ran smoothly at all speeds up to > 85 mph., although the engine had been a little weak, I consume very > little oil, except at sustained very high speeds, > > Now the engine idles nicely, but hesitates under load under any > driving conditions. I removed the #1 spark plug wire and grounded it > to the block. Car runs much smoother now on 3 cylinders at all speeds > than it had been on 4 with one missing.. > > > Questions: > Will running the car like this on a short term basis damage the > engine? > Could raw gas ignite in the exhaust system and damage it? (I can't > shut off gas supply because this is a carb engine, not EFI.) > Is there any way to tell if problem is rings rather than valves > without pulling the cylinder head? > > Thanks, > > Tom > 1) Don't run it with the ignition dead on one cylinder. Find and fix the problem. Running with 25% unburned fuel entering the exhaust will toast the exhaust system very quickly and will worsen the ring wear in the dead cylinder as the gasoline washes the oil away. (I wonder if that is why the compression is low in the first place... inadequate oil to seal the rings.) 2) The compression problem is almost certainly with the rings. Your oil test is used to tell the difference: the oil temporarily seals the rings better, and in your case that restored compression. The valves have to seal well to do that, so your valves are good enough. Now, that isn't a good sign, but that probably has little to do with the hesitation. What you describe isn't what I'd call hesitation as much as it is really ratty running, so I'll address that first, then move on to classic hesitation. Bad running under load makes me think of poor ignition. If you've recently done a tune-up, I think you got a bad part. I once got a distributor cap that lasted one hour, then one cylinder died completely. But if it's been a while, now is the time. The distributor cap, plug and wire are all big time suspects for this symptom. The two things to look at for actual hesitation suddenly appearing are the carburetor and the ignition timing - especially the advance. If the hesitation occurs even when you floor the accelerator while travelling 30-40 mph, I'd bet on the carburetor. With the engine off, pull the air cleaner off the carb and look down the throat at the throttle butterfly in the primary barrel. It will be easiest if the engine is warm so the choke is open. Open the throttle by hand and watch for a solid stream of gasoline in the throat. If that is weak or missing, you have found the cause - a bad accelerator pump. It's a very common failure. The cure is a carburetor rebuild, or exchange if you are especially wealthy. If that looks okay, put it back together and start the engine. Remove all vacuum hoses from the distributor and plug them. Connect a timing light and operate the throttle by hand, slowly and rapidly. You should see the timing advance smoothly as you open it slowly, and rapidly advance matching the engine speed as you open it rapidly. If either of these are not true, you have problems with the mechanical advance in the distributor. A replacement from the wrecking yard is one approach to that. The other is to disassemble the distributor and clean and lube the advance weights and the plate they ride on. If there are pits in the plate where the weights are at idle or at full advance, sand them out with fine emery paper. The distributor work is about the same skill level as the carb rebuild... medium. Don't forget to reconnect the hoses! So... what model and year is this? Mike |
Re: I hesitate to askI have recently developed a severe hesitation problem. Cyl 1 shows compression of 120. Other 3 have 150. If I squirt oil into 1, it also shows 150. There has been no change in compression or vacuum (18), but the hesitation a
It's my guess that you have a very serious problem--probably bad rings in
at least one of the cylinders. In most cases, if the rings in one cylinder are bad--the rest of them will need to be replaced very soon. In other words, a mechanic or yourself will have to replace all of the rings. In some cases, it's cheaper to buy a rebuilt engine. Prior to selling rebuilt engines--all of the rings are replaced regardless of the condition of the old rings. If other people respond, there advice may be better then my advice since I am NOT a certified mechanic--just a back yard mechanic that in the past has done only minor work on various types of automobiles. I should note--in case you don't know--replaced rings involves taking the engine apart. In article <Q9CdncJMF7Tk9v3fRVn-qA@sedona.net>, "Michael Pardee" <michaeltnull@cybertrails.com> wrote: > "tom" <tom@adelphia.net> wrote in message > news:fvn061l0vqme8bcfk090oqkvvja426t5sa@4ax.com... > >I have recently developed a severe hesitation problem. Cyl 1 shows > > compression of 120. Other 3 have 150. If I squirt oil into 1, it > > also shows 150. There has been no change in compression or vacuum > > (18) since before the problem, but the hesitation and missing started > > suddenly as I was > > driving last week. Prior to this, I ran smoothly at all speeds up to > > 85 mph., although the engine had been a little weak, I consume very > > little oil, except at sustained very high speeds, > > > > Now the engine idles nicely, but hesitates under load under any > > driving conditions. I removed the #1 spark plug wire and grounded it > > to the block. Car runs much smoother now on 3 cylinders at all speeds > > than it had been on 4 with one missing.. > > > > > > Questions: > > Will running the car like this on a short term basis damage the > > engine? > > Could raw gas ignite in the exhaust system and damage it? (I can't > > shut off gas supply because this is a carb engine, not EFI.) > > Is there any way to tell if problem is rings rather than valves > > without pulling the cylinder head? > > > > Thanks, > > > > Tom > > > 1) Don't run it with the ignition dead on one cylinder. Find and fix the > problem. Running with 25% unburned fuel entering the exhaust will toast the > exhaust system very quickly and will worsen the ring wear in the dead > cylinder as the gasoline washes the oil away. (I wonder if that is why the > compression is low in the first place... inadequate oil to seal the rings.) > 2) The compression problem is almost certainly with the rings. Your oil test > is used to tell the difference: the oil temporarily seals the rings better, > and in your case that restored compression. The valves have to seal well to > do that, so your valves are good enough. > > Now, that isn't a good sign, but that probably has little to do with the > hesitation. What you describe isn't what I'd call hesitation as much as it > is really ratty running, so I'll address that first, then move on to classic > hesitation. > > Bad running under load makes me think of poor ignition. If you've recently > done a tune-up, I think you got a bad part. I once got a distributor cap > that lasted one hour, then one cylinder died completely. But if it's been a > while, now is the time. The distributor cap, plug and wire are all big time > suspects for this symptom. > > The two things to look at for actual hesitation suddenly appearing are the > carburetor and the ignition timing - especially the advance. If the > hesitation occurs even when you floor the accelerator while travelling 30-40 > mph, I'd bet on the carburetor. > > With the engine off, pull the air cleaner off the carb and look down the > throat at the throttle butterfly in the primary barrel. It will be easiest > if the engine is warm so the choke is open. Open the throttle by hand and > watch for a solid stream of gasoline in the throat. If that is weak or > missing, you have found the cause - a bad accelerator pump. It's a very > common failure. The cure is a carburetor rebuild, or exchange if you are > especially wealthy. > > If that looks okay, put it back together and start the engine. Remove all > vacuum hoses from the distributor and plug them. Connect a timing light and > operate the throttle by hand, slowly and rapidly. You should see the timing > advance smoothly as you open it slowly, and rapidly advance matching the > engine speed as you open it rapidly. If either of these are not true, you > have problems with the mechanical advance in the distributor. A replacement > from the wrecking yard is one approach to that. The other is to disassemble > the distributor and clean and lube the advance weights and the plate they > ride on. If there are pits in the plate where the weights are at idle or at > full advance, sand them out with fine emery paper. The distributor work is > about the same skill level as the carb rebuild... medium. Don't forget to > reconnect the hoses! > > So... what model and year is this? > > Mike -- NEWSGROUP SUBSCRIBERS MOTTO We respect those subscribers that ask for advice or provide advice. We do NOT respect the subscribers that enjoy criticizing people. |
Re: I hesitate to askI have recently developed a severe hesitation problem. Cyl 1 shows compression of 120. Other 3 have 150. If I squirt oil into 1, it also shows 150. There has been no change in compression or vacuum (18), but the hesitation a
It's my guess that you have a very serious problem--probably bad rings in
at least one of the cylinders. In most cases, if the rings in one cylinder are bad--the rest of them will need to be replaced very soon. In other words, a mechanic or yourself will have to replace all of the rings. In some cases, it's cheaper to buy a rebuilt engine. Prior to selling rebuilt engines--all of the rings are replaced regardless of the condition of the old rings. If other people respond, there advice may be better then my advice since I am NOT a certified mechanic--just a back yard mechanic that in the past has done only minor work on various types of automobiles. I should note--in case you don't know--replaced rings involves taking the engine apart. In article <Q9CdncJMF7Tk9v3fRVn-qA@sedona.net>, "Michael Pardee" <michaeltnull@cybertrails.com> wrote: > "tom" <tom@adelphia.net> wrote in message > news:fvn061l0vqme8bcfk090oqkvvja426t5sa@4ax.com... > >I have recently developed a severe hesitation problem. Cyl 1 shows > > compression of 120. Other 3 have 150. If I squirt oil into 1, it > > also shows 150. There has been no change in compression or vacuum > > (18) since before the problem, but the hesitation and missing started > > suddenly as I was > > driving last week. Prior to this, I ran smoothly at all speeds up to > > 85 mph., although the engine had been a little weak, I consume very > > little oil, except at sustained very high speeds, > > > > Now the engine idles nicely, but hesitates under load under any > > driving conditions. I removed the #1 spark plug wire and grounded it > > to the block. Car runs much smoother now on 3 cylinders at all speeds > > than it had been on 4 with one missing.. > > > > > > Questions: > > Will running the car like this on a short term basis damage the > > engine? > > Could raw gas ignite in the exhaust system and damage it? (I can't > > shut off gas supply because this is a carb engine, not EFI.) > > Is there any way to tell if problem is rings rather than valves > > without pulling the cylinder head? > > > > Thanks, > > > > Tom > > > 1) Don't run it with the ignition dead on one cylinder. Find and fix the > problem. Running with 25% unburned fuel entering the exhaust will toast the > exhaust system very quickly and will worsen the ring wear in the dead > cylinder as the gasoline washes the oil away. (I wonder if that is why the > compression is low in the first place... inadequate oil to seal the rings.) > 2) The compression problem is almost certainly with the rings. Your oil test > is used to tell the difference: the oil temporarily seals the rings better, > and in your case that restored compression. The valves have to seal well to > do that, so your valves are good enough. > > Now, that isn't a good sign, but that probably has little to do with the > hesitation. What you describe isn't what I'd call hesitation as much as it > is really ratty running, so I'll address that first, then move on to classic > hesitation. > > Bad running under load makes me think of poor ignition. If you've recently > done a tune-up, I think you got a bad part. I once got a distributor cap > that lasted one hour, then one cylinder died completely. But if it's been a > while, now is the time. The distributor cap, plug and wire are all big time > suspects for this symptom. > > The two things to look at for actual hesitation suddenly appearing are the > carburetor and the ignition timing - especially the advance. If the > hesitation occurs even when you floor the accelerator while travelling 30-40 > mph, I'd bet on the carburetor. > > With the engine off, pull the air cleaner off the carb and look down the > throat at the throttle butterfly in the primary barrel. It will be easiest > if the engine is warm so the choke is open. Open the throttle by hand and > watch for a solid stream of gasoline in the throat. If that is weak or > missing, you have found the cause - a bad accelerator pump. It's a very > common failure. The cure is a carburetor rebuild, or exchange if you are > especially wealthy. > > If that looks okay, put it back together and start the engine. Remove all > vacuum hoses from the distributor and plug them. Connect a timing light and > operate the throttle by hand, slowly and rapidly. You should see the timing > advance smoothly as you open it slowly, and rapidly advance matching the > engine speed as you open it rapidly. If either of these are not true, you > have problems with the mechanical advance in the distributor. A replacement > from the wrecking yard is one approach to that. The other is to disassemble > the distributor and clean and lube the advance weights and the plate they > ride on. If there are pits in the plate where the weights are at idle or at > full advance, sand them out with fine emery paper. The distributor work is > about the same skill level as the carb rebuild... medium. Don't forget to > reconnect the hoses! > > So... what model and year is this? > > Mike -- NEWSGROUP SUBSCRIBERS MOTTO We respect those subscribers that ask for advice or provide advice. We do NOT respect the subscribers that enjoy criticizing people. |
Re: I hesitate to askI have recently developed a severe hesitation problem. Cyl 1 shows compression of 120. Other 3 have 150. If I squirt oil into 1, it also shows 150. There has been no change in compression or vacuum (18), but the hesitation a
"Jason" <jason@nospam.com> wrote in message
news:jason-1504052128070001@pm4-broad-2.snlo.dialup.fix.net... > It's my guess that you have a very serious problem--probably bad rings in > at least one of the cylinders. In most cases, if the rings in one cylinder > are bad--the rest of them will need to be replaced very soon. In other > words, a mechanic or yourself will have to replace all of the rings. In > some cases, it's cheaper to buy a rebuilt engine. Prior to selling rebuilt > engines--all of the rings are replaced regardless of the condition of the > old rings. If other people respond, there advice may be better then my > advice since I am NOT a certified mechanic--just a back yard mechanic that > in the past has done only minor work on various types of automobiles. I > should note--in case you don't know--replaced rings involves taking the > engine apart. > > The reason I'm not focusing on the low reading is that 15% low shouldn't be noticable to the driver. I've driven a 67 Chevy that had 2 of its 6 cylinders below 50 psi, and it wasn't the biggest problem that clunker had! The cylinder being dead is the real problem, and it's possible the compression will be normal enough once the cylinder starts burning the gasoline instead of bathing in it. Of course, if the compression is bad enough the cylinder won't fire at all, but that is usually when the compression gets lower than the tire pressure! Mike |
Re: I hesitate to askI have recently developed a severe hesitation problem. Cyl 1 shows compression of 120. Other 3 have 150. If I squirt oil into 1, it also shows 150. There has been no change in compression or vacuum (18), but the hesitation a
"Jason" <jason@nospam.com> wrote in message
news:jason-1504052128070001@pm4-broad-2.snlo.dialup.fix.net... > It's my guess that you have a very serious problem--probably bad rings in > at least one of the cylinders. In most cases, if the rings in one cylinder > are bad--the rest of them will need to be replaced very soon. In other > words, a mechanic or yourself will have to replace all of the rings. In > some cases, it's cheaper to buy a rebuilt engine. Prior to selling rebuilt > engines--all of the rings are replaced regardless of the condition of the > old rings. If other people respond, there advice may be better then my > advice since I am NOT a certified mechanic--just a back yard mechanic that > in the past has done only minor work on various types of automobiles. I > should note--in case you don't know--replaced rings involves taking the > engine apart. > > The reason I'm not focusing on the low reading is that 15% low shouldn't be noticable to the driver. I've driven a 67 Chevy that had 2 of its 6 cylinders below 50 psi, and it wasn't the biggest problem that clunker had! The cylinder being dead is the real problem, and it's possible the compression will be normal enough once the cylinder starts burning the gasoline instead of bathing in it. Of course, if the compression is bad enough the cylinder won't fire at all, but that is usually when the compression gets lower than the tire pressure! Mike |
Re: I hesitate to askI have recently developed a <SNIP> LONGESTSUBJECT LINE IN HISTORY
tom wrote:
> I have recently developed a severe hesitation problem. Cyl 1 shows > compression of 120. Other 3 have 150. If I squirt oil into 1, it > also shows 150. There has been no change in compression or vacuum > (18) since before the problem, but the hesitation and missing started > suddenly as I was > driving last week. Prior to this, I ran smoothly at all speeds up to > 85 mph., although the engine had been a little weak, I consume very > little oil, except at sustained very high speeds, > > Now the engine idles nicely, but hesitates under load under any > driving conditions. I removed the #1 spark plug wire and grounded it > to the block. Car runs much smoother now on 3 cylinders at all speeds > than it had been on 4 with one missing.. > > > Questions: > Will running the car like this on a short term basis damage the > engine? > Could raw gas ignite in the exhaust system and damage it? (I can't > shut off gas supply because this is a carb engine, not EFI.) > Is there any way to tell if problem is rings rather than valves > without pulling the cylinder head? > > Thanks, > > Tom ------------------------------ Look inside your distributor cap for red dust. If you find it , do a google(groups) search for 'red dust'. I think your timing belt has jumped a tooth. Did you ever tell us what kind of car it is, or the mileage ? ? ? 'Curly' |
Re: I hesitate to askI have recently developed a <SNIP> LONGESTSUBJECT LINE IN HISTORY
tom wrote:
> I have recently developed a severe hesitation problem. Cyl 1 shows > compression of 120. Other 3 have 150. If I squirt oil into 1, it > also shows 150. There has been no change in compression or vacuum > (18) since before the problem, but the hesitation and missing started > suddenly as I was > driving last week. Prior to this, I ran smoothly at all speeds up to > 85 mph., although the engine had been a little weak, I consume very > little oil, except at sustained very high speeds, > > Now the engine idles nicely, but hesitates under load under any > driving conditions. I removed the #1 spark plug wire and grounded it > to the block. Car runs much smoother now on 3 cylinders at all speeds > than it had been on 4 with one missing.. > > > Questions: > Will running the car like this on a short term basis damage the > engine? > Could raw gas ignite in the exhaust system and damage it? (I can't > shut off gas supply because this is a carb engine, not EFI.) > Is there any way to tell if problem is rings rather than valves > without pulling the cylinder head? > > Thanks, > > Tom ------------------------------ Look inside your distributor cap for red dust. If you find it , do a google(groups) search for 'red dust'. I think your timing belt has jumped a tooth. Did you ever tell us what kind of car it is, or the mileage ? ? ? 'Curly' |
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