Home |
Search |
Today's Posts |
|
Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
Reply |
|
LinkBack | Thread Tools | Display Modes |
#81
Posted to rec.crafts.metalworking
|
|||
|
|||
compression gauge puzzler
On Mar 20, 10:25*pm, jon_banquer wrote:
On Mar 20, 7:14*pm, Ed Huntress wrote: On Wed, 20 Mar 2013 18:53:49 -0700 (PDT), jon_banquer wrote: On Mar 20, 6:49 pm, Ed Huntress wrote: On Wed, 20 Mar 2013 18:35:00 -0700 (PDT), jon_banquer wrote: On Mar 20, 6:24 pm, jon_banquer wrote: On Mar 20, 6:04 pm, Ed Huntress wrote: On Wed, 20 Mar 2013 19:59:49 -0400, wrote: On Wed, 20 Mar 2013 11:49:22 -0400, Ed Huntress wrote: On Wed, 20 Mar 2013 08:42:16 -0700, "PrecisionmachinisT" wrote: "Ken Grunke" wrote in message .... I am assuming there has to be a separate check valve INLINE between the plug adapter and the gauge below the release valve. That is what I am missing. It may be a fitting I had, but absent-mindedly misplaced. Could be a spring and or check ball is missng or gunked up at the spark plug fitting end... --FWIW blowing into the end with your mouth probably won't produce enough hose expansion to actuate a ball type check valve. Sorry for jumping into the middle without having read the thread, but there are two kinds of compression testers: the regular kind, which have a button to activate the check-release valve; and leak-down testers, which have no such valve. I have both. They look almost the same. Perhaps, if Ken's tester doesn't have a check valve, he has a leakdown tester. If so, it will have a spark-plug-thread terminal end. Regular testers *may* have such a thread. Mine just has a tapered rubber plug. A leakdown tester should have 2 guages and WILL have a connector for compressed air. Mine has one gauge. It's around 45 years old. And as I noted in an addition to the post above, it has a Schrader valve for pumping up the cylinder. What's the second gauge for? With mine, you just attach it, make sure both valves are closed, and pump it up. Test dry, then test wet (with about an ounce of oil in the cylinder; more for a V-engine). Is there something else that I've missed? -- Ed Huntress One gauge tells you your air input pressure, the other your cylinder pressure. It's about doing a comparison. You're always going to have a percentage of leak and you want about the same percentage of leak for every cylinder. Watch this. It's a well done video: http://www.youtube.com/watch?v=QNf0IOIvIcY That's interesting, and I'm sure it's faster to use than the old ones. From what he demonstrated, though, I see no way to identify ring versus valve problems. I guess you could run the test wet as well with that rig, but it's a different animal. You could pump mine up with a bicycle pump, if you had to, but I always had a little compressor handy. -- Ed Huntress Consider that you are going to have to take the engine apart if you have "dead holes" anyway so the need for exact specifics doesn't really matter that much. All you're really looking to see is if you have "dead holes" and generally what the problem might be. I'm sure it's a practical solution or they wouldn't go to that complication. And in a commercial shop, time is money, and the old way of running those tests could take a whole Saturday morning. If it was a Bristol or a Jag engine, it was worth the play time. Otherwise, not. God save me from ever having to do a hot valve-lash job on a six-cylinder Triumph again... -- Ed Huntress Many commercial auto repair shops don't even know what a leak down test is and all they know and do are compression tests. Well, if you want, you should go to the dealers and large-chain stores because of the better go-between that the auto mechanics have with the factory, rather than going to the mom and pops (cheaper though). |
#82
Posted to rec.crafts.metalworking
|
|||
|
|||
compression gauge puzzler
On Mar 23, 9:53*am, Transition Zone wrote:
On Mar 20, 10:25*pm, jon_banquer wrote: On Mar 20, 7:14*pm, Ed Huntress wrote: On Wed, 20 Mar 2013 18:53:49 -0700 (PDT), jon_banquer wrote: On Mar 20, 6:49 pm, Ed Huntress wrote: On Wed, 20 Mar 2013 18:35:00 -0700 (PDT), jon_banquer wrote: On Mar 20, 6:24 pm, jon_banquer wrote: On Mar 20, 6:04 pm, Ed Huntress wrote: On Wed, 20 Mar 2013 19:59:49 -0400, wrote: On Wed, 20 Mar 2013 11:49:22 -0400, Ed Huntress wrote: On Wed, 20 Mar 2013 08:42:16 -0700, "PrecisionmachinisT" wrote: "Ken Grunke" wrote in message .... I am assuming there has to be a separate check valve INLINE between the plug adapter and the gauge below the release valve. That is what I am missing. It may be a fitting I had, but absent-mindedly misplaced. Could be a spring and or check ball is missng or gunked up at the spark plug fitting end... --FWIW blowing into the end with your mouth probably won't produce enough hose expansion to actuate a ball type check valve. Sorry for jumping into the middle without having read the thread, but there are two kinds of compression testers: the regular kind, which have a button to activate the check-release valve; and leak-down testers, which have no such valve. I have both. They look almost the same. Perhaps, if Ken's tester doesn't have a check valve, he has a leakdown tester. If so, it will have a spark-plug-thread terminal end. Regular testers *may* have such a thread. Mine just has a tapered rubber plug. A leakdown tester should have 2 guages and WILL have a connector for compressed air. Mine has one gauge. It's around 45 years old. And as I noted in an addition to the post above, it has a Schrader valve for pumping up the cylinder. What's the second gauge for? With mine, you just attach it, make sure both valves are closed, and pump it up. Test dry, then test wet (with about an ounce of oil in the cylinder; more for a V-engine). Is there something else that I've missed? -- Ed Huntress One gauge tells you your air input pressure, the other your cylinder pressure. It's about doing a comparison. You're always going to have a percentage of leak and you want about the same percentage of leak for every cylinder. Watch this. It's a well done video: http://www.youtube.com/watch?v=QNf0IOIvIcY That's interesting, and I'm sure it's faster to use than the old ones. From what he demonstrated, though, I see no way to identify ring versus valve problems. I guess you could run the test wet as well with that rig, but it's a different animal. You could pump mine up with a bicycle pump, if you had to, but I always had a little compressor handy. -- Ed Huntress Consider that you are going to have to take the engine apart if you have "dead holes" anyway so the need for exact specifics doesn't really matter that much. All you're really looking to see is if you have "dead holes" and generally what the problem might be. I'm sure it's a practical solution or they wouldn't go to that complication. And in a commercial shop, time is money, and the old way of running those tests could take a whole Saturday morning. If it was a Bristol or a Jag engine, it was worth the play time. Otherwise, not.. God save me from ever having to do a hot valve-lash job on a six-cylinder Triumph again... -- Ed Huntress * *Many commercial auto repair shops don't even know what a leak down *test is and all they know and do are compression tests. Well, if you want, you should go to the dealers and large-chain stores because of the better go-between that the auto mechanics have with the factory, rather than going to the mom and pops (cheaper though). I prefer to work on my own vehicles and the last place I would ever go is a large-chain store such as Pep Boys. If I can't work on a certain kind of vehicle, or I don't want to invest the time and money into the equipment that it would take to work on a certain type of vehicle, I simply don't buy it. This is the same reason lots of people prefer to drive older vehicles. Some even insist on a vehicle having a carburetor rather than fuel injection. I don't go that far. This kind of reasoning has nothing to do with what I can or can't afford or what others can or can't afford and this kind of logic escapes flamers like KiddingNoOne who loves to brag about his Chevy Volt, which is a vehicle I wouldn't touch with a ten foot pole. |
#83
Posted to rec.crafts.metalworking
|
|||
|
|||
compression gauge puzzler
On Mar 23, 9:47*am, Transition Zone wrote:
On Mar 21, 4:31*pm, jon_banquer wrote: On Mar 21, 12:31*pm, Ed Huntress wrote: On Thu, 21 Mar 2013 14:42:38 -0400, wrote: On Thu, 21 Mar 2013 08:09:51 -0400, Ed Huntress wrote: On Thu, 21 Mar 2013 02:19:21 -0400, "Steve W." wrote: Ed Huntress wrote: On Wed, 20 Mar 2013 18:45:39 -0700 (PDT), jon_banquer wrote: On Mar 20, 6:38 pm, Ed Huntress wrote: On Wed, 20 Mar 2013 18:24:12 -0700 (PDT), jon_banquer wrote: On Mar 20, 6:04 pm, Ed Huntress wrote: On Wed, 20 Mar 2013 19:59:49 -0400, wrote: On Wed, 20 Mar 2013 11:49:22 -0400, Ed Huntress wrote: On Wed, 20 Mar 2013 08:42:16 -0700, "PrecisionmachinisT" wrote: "Ken Grunke" wrote in message .... I am assuming there has to be a separate check valve INLINE between the plug adapter and the gauge below the release valve. That is what I am missing. It may be a fitting I had, but absent-mindedly misplaced. Could be a spring and or check ball is missng or gunked up at the spark plug fitting end... --FWIW blowing into the end with your mouth probably won't produce enough hose expansion to actuate a ball type check valve. Sorry for jumping into the middle without having read the thread, but there are two kinds of compression testers: the regular kind, which have a button to activate the check-release valve; and leak-down testers, which have no such valve. I have both. They look almost the same. Perhaps, if Ken's tester doesn't have a check valve, he has a leakdown tester. If so, it will have a spark-plug-thread terminal end. Regular testers *may* have such a thread. Mine just has a tapered rubber plug. A leakdown tester should have 2 guages and WILL have a connector for compressed air. Mine has one gauge. It's around 45 years old. And as I noted in an addition to the post above, it has a Schrader valve for pumping up the cylinder. What's the second gauge for? With mine, you just attach it, make sure both valves are closed, and pump it up. Test dry, then test wet (with about an ounce of oil in the cylinder; more for a V-engine). Is there something else that I've missed? -- Ed Huntress One gauge tells you your air input pressure, the other your cylinder pressure. I don't understand that. All you care about is the air you get into the cylinder, right? I used to do a lot of leakdown tests, and I think I remember how they were done. All I did was pump the cylinder up to some pressure and time how long it takes to drop to some lower pressure. Do the test dry, then wet, in each cylinder. If it falls faster when dry, it's rings. If it's the same time when wet, it's valves. Am I missing something? It's a percentage test with two gauges. If you have cylinder(s) with major discrepancies you find out where the air is leaking to. If you hear air in the exhaust pipe it's a bad exhaust valve. If you hear air in the intake it's a bad intake valve. If you hear air in the crankcase (check where oil dipstick is) it's bad piston rings. OK, I can see where that's a lot faster, and it actually combines the equivalent of a regular compression test (sort of) and an old-fashioned leak-down test. With the older equipment, you only would do a leak-down test if all cylinders looked good in the regular test but you had some reason to believe one or more cylinders still had a problem. You could do both tests dry and then wet to try to isolate the problem a bit; pressure loss with a wet cylinder meant a valve or head-gasket problem, so you had to pull the head in either case. The only thing I see wrong with the newer device is that it only checks the rings at TDC, while a conventional compression test will show a cylinder is off from any problem along the whole stroke -- like a scored cylinder that isn't scored along the full length of the stroke (an engine that's been over-revved a lot, or which has a cracked lower ring). Also, a valve that's out of adjustment, or which has a sticky lifter, but which is still fully closed at TDC on the compression stroke, will not show you the valve problem. Anyway, it's not something I'm likely to do again. I just thought, mistakenly, that the OP might have been looking at an old-style leak-down tester. It appears that it was just a missing Schrader valve stem in a conventional compression tester. That's what we save old bicycle inner-tubes for -- spare Schrader stems, and gasket material. Actually you can use a leak-down tester through the entire stroke IF you have the proper tools to rotate the crank. So you have to back off the rocker arms or remove the camshaft? No, you can test it MOST of the way down on the power stroke and *Most of the way up on the compression stroke. Leakage at the bottom of the stroke doesn't amount to much as there is never any useable pressure down there Ok, I can see that. It would solve a lot for me if I actually tried one out. -- Ed Huntress * The downfall of Usenet is that it's not the resource it once was for *learning. Oh it still is, it just still comes along with the typical trash and junk (to be thorough). Many of the better posters have left and are now on web based forums. In the case of CADCAM many of the better posters have never been on Usenet and are now on LinkedIn. My CADCAM Technology Leaders group on LinkedIn hit 550 members yesterday and I expect it to have 1000 members by the end of 2013. |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Another RCD puzzler | UK diy | |||
vacuum cleaner puzzler. | Home Repair | |||
Can I stick two 4 gauge and one 6 gauge wire into a 3/4" conduit | Home Repair | |||
Engine compression rating = cilinder lb compression | Home Repair | |||
PUZZLER??? | UK diy |