The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 47-55.1 Battery charging issues

dsraven · 05-06-2021, 03:54 PM

as a mechanic I have had jobs that came from another shop and they have done this or that and the problem still has not been resolved. sometimes tunnel vision can happen and we overlook something sorta obvious. usually I tell my customer that I have my own way of doing things and don't rely on the previous shop's results. I have worked with enough guys over the years to know that we all do things differently and can come up with different results with different people doing the same test on the same vehicle. with that said, it may be a good idea to start from scratch and do all the normal tune up checks and do them like you have never seen the truck before so you won't have any preconceived opinions and you will every test properly. I understand this is time consuming but in the end it may save you time and money on parts. start with a compression test. dry then wet. have a spare battery kicking around so you can have somewhat the same cranking speed. a 12v battery will not harm a 6v starter as long as you don't spend a long time cranking and let it cool off if it heats up. just ensure you do the same thing for all cylinders for each test. compression tests should be done on a warm engine but if you can't get it to start I guess that is out the window.

-mark and remove all the spark plug wires from the plugs, then remove the spark plugs and lay them on the bench in order so you can reference the soot/burn pattern, gap etc if required.
-disable the coil by removing the power wire from the coil or grounding the high tension lead well. if grounding the high tension lead ensure it can't come undone from it's ground and cause a spark as there is fuel closeby plus you don't wanna be the recipient of a random ground to person if things go awry
- tie the throttle and choke wide open
-ensure the wheels are blocked fore and aft and then place the transmission in neutral or park if automatic trans
-hook up a remote starter switch if there is an electrical starter solenoid type "start", figure out how to operate the starter linkage from under the hood for the old fashioned "step on the starter" style or have a friend assist with either scenario from inside the cab. this is usually the best method but sometimes (98% of the time) we work alone
-have a note pad ready with columns for cylinder numbers and corresponding columns for dry and wet tests for each. I usually have a long page so I can also track valve lash etc for each cylinder
-connect your compression tester and perform a dry compression test making sure to document your results right after each test is done so you don't get mixed up. crank the engine so each cylinder gets 5 tries to get to it's max number on the gauge. there is some controversy about how many cranks to give but if you give each cylinder 5 tries that should be sufficient. some will crank it until a max number is achieved whether that happens in 5 or 8 or whatever. just do the same for each cylinder. move on to the next cylinder and do the same until every cylinder is charted. should you have any cylinders that seem to be higher or lower than the rest redo the test on those cylinders and chart the results. should you have cylinders that seem to take considerably more cranking to get a max result then note that in the chart.
-when done do a wet test. that means you will squirt engine oil into each cylinder prior to each test. a hand operated oil can works best for this and you will want to test it out first soo you know how much oil is going in. then ensure to give each test the same amount of oil. squirt the oil in, install the compression tester, wait a second or 2 so the oil has a chance to make it's way around the piston and then do the test. again, do the same for each cylinder so time the "second or 2". chart the results right away and then remove the tester. place a rag over the spark plug hole and crank the engine so you can capture any oil that may spray out of the hole when you crank the engine for the next cylinder test. move on to the next cylinder, do the same, and so on until the wet test is complete for every cylinder
-now you can compare the results. the dry test should come up with all cylinders being somewhere in the correct pressure range, about 130 psi I think but don't quote me, and they should all be within 10% of each other or somewhere within about 10 psi since 10% of 130 is about 13. if you have a low cylinder that usually indicates worn or broken rings or a valve that isn't sealing well for some reason (possibly valve train wear, camshaft timing, bent pushrod, bad rocker arm etc) or something else that is allowing the pressure to bleed out. sometimes a bad head gasket or a hole in a piston. a higher than normal reading could indicate high carbon build up in the cylinder or possibly an exhaust valve that isn't operating properly so the air that is allowed to come into the cylinder has no way to get out. a cylinder that is "using oil", as indicated by a glance at the spark plug for that cylinder, may give false higher readings because it has excess oil in the cylinder that is helping to seal the rings. a bad valve seal or worn valve guides can also contribute to this extra oiling as well as plugged or insufficient crankcase venting
-next compare the results to the spark plugs. if you have a low cylinder check the plug to see how that cylinder was firing. the same goes for a high reading.
-if you come up with problems you can do a cylinder leak down test. sometimes i will simply air up a cylinder, held at top dead center on the compression stroke, so I can quickly tell if there is leakage through a valve. air up the cylinder using compressed air from the shop line through the spark plug hole (I have had to break an old spark plug and thread or weld in a pipe fitting to allow a valve and an airline fitting since I may not have that particular spark plug threaded adapter. do whatcha gotta do sometimes) and be aware that if the engine is not mechanically held at TDC then it may want to turn over when the air is added. then listen through the exhaust pipe and the carb for the sound of air leaking into that system. that sound would indicate leakage through that valve. air coming out of the adjacent cylinder's spark plug hole would indicate a blown head gasket or some other problem between these cylinders. air coming through the oil filler or crankcase venting system would indicate worn rings or a hole in a piston. bubbles in the rad would indicate a cracked cylinder, cracked cylinder head or head gasket issue. below there are a few links for some basic tests. the guys page also has many more tests and descriptions that you can peruse on your own time.
-next move on to doing the valve train check and lash check/adjustment. I always recommend charting this prior to and then again after any adjustments are made. you can compare results to those compression pressures and also the spark plug condition. check each rocker for wear where it contacts the valve stem and also where it pivots. while you are there check the pushrods for wear and being straight. check the area for signs of improper oiling etc. a rocker with a worn out contact area against the valve stem will be next to impossible to adjust properly and if the rocker is worn out on the pivot point then it also becomes hard to get a lasting adjustment. use your own discretion in these areas as it can be like opening a can of worms and sliding down the slope of "while i am here I might as well do the ...". soon an in-frame rebuild has been done. part of the valve train check also includes how much lash there is in the timing components. one way to quickly check this is to turn the engine one direction for 1/2 a turn at least and line up the timing mark pointer. this is so the gear train will be loaded one way and you will have a reference mark for how many degrees the crank turns in the next step. then remove the distributor cap and mark a position on the distributor housing that is inline with the rotor. sometimes a piece of tape works well for this. bridge the gap with tape stuck to both parts and then cut the tape in the gap or place tape on both parts and mark each with a line so you can tell if the rotor turns. next turn the engine slowly the opposite way that you did before while watching the distributor rotor. when the rotor is seen to move stop and check how many degrees the crank moved before the rotor, which is attached to the camshaft, moved. I understand there is also lash in the gears between the distributor and the camshaft but this is just to get a rough idea of the gear lash without removing a timing cover. when doing your valve lash adjustments the engine should also be cranked over a few turns while you check for all the rockers moving the same amount. a rocker that doesn't move the same as the rest would indicate a worn cam lobe. a valve that is protruding more than the rest would indicate a valve that has worn into the valve seat. also check for broken valve springs while you are there and the condition of the umbrella valve seals seen by peering through the coils of the springs. they should be complete and soft rubber.
-next check the ignition system for problems starting at the power source and moving through the system. sometimes there is a poor connection on the back of the ign switch that causes a voltage drop. sometimes it is a poor connection on the ballast resistor or the coil or the wire that goes through the distributor housing to the points. check the rotor, cap, wires, plugs for cracks, carbon tracing etc.
-next check the fuel system. do a pump pressure and output flow test. document the results. then check/replace the filter(s) and check the fuel cap vent and seal against the filler, check the tank outlet line for bends or kinks and follow the lines right up to the carb ensuring all is good with no tight restrictive bends, kinks or soft spots n the rubber components. pull the lid off the carb and check the float level and what is in the bottom of the bowl. check to ensure the accelerator squirter nozzle is aimed at the edge of the throttle butterfly valve and that the squirter is working properly. check for full throttle at the carb when the pedal is all the way down. full choke activation when the cable is pulled.
-next check for vacuum leaks. a smoker machine can be built easily with items normally found at home. you could google it. basically smoke is forced into the intake manifold at the carb end and the exhaust pipe is plugged. you check for smoke coming from any intake fittings, gaskets etc.
-check the exhaust heat riser for proper operation
-check the exhaust for tight bends or reasons for obstruction. the system can be checked for pressure build up while running by welding an o2 sensor bung into the pipe and using a vacuum/pressure gauge but, again, that takes time and money and an engine that runs. since there is no catalytic converter the only reason for restriction would be obvious pipe problems or a muffler problem. shake the muffler and listen for loose things rattling around inside.
-next check the battery. have it load tested after a full charge and some time to sit after. then check the starter draw or remove the starter and have it checked by a shop that has no history with the starter. since you say it heats up quickly there may be issues internally. just because it was rebuilt doesn't mean it was done correctly. there is no huge stockpile of used cores at the rebuild shops for the old stuff so it may be that there were some marginal parts that were re-used and, yes, it works but it may not be optimal. a hot starter usually means it has used a lot of amperage. possibly an internal reason for that if there is no external heat source like a bad connection or a tight, hard to turn engine.

here is a link to compression testing
https://dannysengineportal.com/compr...n-it-tell-you/

here is a link to leak down testing
https://dannysengineportal.com/how-t...hout-a-tester/

here is a link on how to do a vacuum test
https://dannysengineportal.com/vacuu...han-you-think/

fuel-air-compression-spark. all at the right time-BOOM. it runs.

hope something in there helped somebody. lol.
gotta go. I got a life off the computer apparently.

05-06-2021, 03:54 PM	#38
dsraven Registered User Join Date: Nov 2010 Location: calgary alberta Posts: 7,832	Re: Battery charging issues as a mechanic I have had jobs that came from another shop and they have done this or that and the problem still has not been resolved. sometimes tunnel vision can happen and we overlook something sorta obvious. usually I tell my customer that I have my own way of doing things and don't rely on the previous shop's results. I have worked with enough guys over the years to know that we all do things differently and can come up with different results with different people doing the same test on the same vehicle. with that said, it may be a good idea to start from scratch and do all the normal tune up checks and do them like you have never seen the truck before so you won't have any preconceived opinions and you will every test properly. I understand this is time consuming but in the end it may save you time and money on parts. start with a compression test. dry then wet. have a spare battery kicking around so you can have somewhat the same cranking speed. a 12v battery will not harm a 6v starter as long as you don't spend a long time cranking and let it cool off if it heats up. just ensure you do the same thing for all cylinders for each test. compression tests should be done on a warm engine but if you can't get it to start I guess that is out the window. -mark and remove all the spark plug wires from the plugs, then remove the spark plugs and lay them on the bench in order so you can reference the soot/burn pattern, gap etc if required. -disable the coil by removing the power wire from the coil or grounding the high tension lead well. if grounding the high tension lead ensure it can't come undone from it's ground and cause a spark as there is fuel closeby plus you don't wanna be the recipient of a random ground to person if things go awry - tie the throttle and choke wide open -ensure the wheels are blocked fore and aft and then place the transmission in neutral or park if automatic trans -hook up a remote starter switch if there is an electrical starter solenoid type "start", figure out how to operate the starter linkage from under the hood for the old fashioned "step on the starter" style or have a friend assist with either scenario from inside the cab. this is usually the best method but sometimes (98% of the time) we work alone -have a note pad ready with columns for cylinder numbers and corresponding columns for dry and wet tests for each. I usually have a long page so I can also track valve lash etc for each cylinder -connect your compression tester and perform a dry compression test making sure to document your results right after each test is done so you don't get mixed up. crank the engine so each cylinder gets 5 tries to get to it's max number on the gauge. there is some controversy about how many cranks to give but if you give each cylinder 5 tries that should be sufficient. some will crank it until a max number is achieved whether that happens in 5 or 8 or whatever. just do the same for each cylinder. move on to the next cylinder and do the same until every cylinder is charted. should you have any cylinders that seem to be higher or lower than the rest redo the test on those cylinders and chart the results. should you have cylinders that seem to take considerably more cranking to get a max result then note that in the chart. -when done do a wet test. that means you will squirt engine oil into each cylinder prior to each test. a hand operated oil can works best for this and you will want to test it out first soo you know how much oil is going in. then ensure to give each test the same amount of oil. squirt the oil in, install the compression tester, wait a second or 2 so the oil has a chance to make it's way around the piston and then do the test. again, do the same for each cylinder so time the "second or 2". chart the results right away and then remove the tester. place a rag over the spark plug hole and crank the engine so you can capture any oil that may spray out of the hole when you crank the engine for the next cylinder test. move on to the next cylinder, do the same, and so on until the wet test is complete for every cylinder -now you can compare the results. the dry test should come up with all cylinders being somewhere in the correct pressure range, about 130 psi I think but don't quote me, and they should all be within 10% of each other or somewhere within about 10 psi since 10% of 130 is about 13. if you have a low cylinder that usually indicates worn or broken rings or a valve that isn't sealing well for some reason (possibly valve train wear, camshaft timing, bent pushrod, bad rocker arm etc) or something else that is allowing the pressure to bleed out. sometimes a bad head gasket or a hole in a piston. a higher than normal reading could indicate high carbon build up in the cylinder or possibly an exhaust valve that isn't operating properly so the air that is allowed to come into the cylinder has no way to get out. a cylinder that is "using oil", as indicated by a glance at the spark plug for that cylinder, may give false higher readings because it has excess oil in the cylinder that is helping to seal the rings. a bad valve seal or worn valve guides can also contribute to this extra oiling as well as plugged or insufficient crankcase venting -next compare the results to the spark plugs. if you have a low cylinder check the plug to see how that cylinder was firing. the same goes for a high reading. -if you come up with problems you can do a cylinder leak down test. sometimes i will simply air up a cylinder, held at top dead center on the compression stroke, so I can quickly tell if there is leakage through a valve. air up the cylinder using compressed air from the shop line through the spark plug hole (I have had to break an old spark plug and thread or weld in a pipe fitting to allow a valve and an airline fitting since I may not have that particular spark plug threaded adapter. do whatcha gotta do sometimes) and be aware that if the engine is not mechanically held at TDC then it may want to turn over when the air is added. then listen through the exhaust pipe and the carb for the sound of air leaking into that system. that sound would indicate leakage through that valve. air coming out of the adjacent cylinder's spark plug hole would indicate a blown head gasket or some other problem between these cylinders. air coming through the oil filler or crankcase venting system would indicate worn rings or a hole in a piston. bubbles in the rad would indicate a cracked cylinder, cracked cylinder head or head gasket issue. below there are a few links for some basic tests. the guys page also has many more tests and descriptions that you can peruse on your own time. -next move on to doing the valve train check and lash check/adjustment. I always recommend charting this prior to and then again after any adjustments are made. you can compare results to those compression pressures and also the spark plug condition. check each rocker for wear where it contacts the valve stem and also where it pivots. while you are there check the pushrods for wear and being straight. check the area for signs of improper oiling etc. a rocker with a worn out contact area against the valve stem will be next to impossible to adjust properly and if the rocker is worn out on the pivot point then it also becomes hard to get a lasting adjustment. use your own discretion in these areas as it can be like opening a can of worms and sliding down the slope of "while i am here I might as well do the ...". soon an in-frame rebuild has been done. part of the valve train check also includes how much lash there is in the timing components. one way to quickly check this is to turn the engine one direction for 1/2 a turn at least and line up the timing mark pointer. this is so the gear train will be loaded one way and you will have a reference mark for how many degrees the crank turns in the next step. then remove the distributor cap and mark a position on the distributor housing that is inline with the rotor. sometimes a piece of tape works well for this. bridge the gap with tape stuck to both parts and then cut the tape in the gap or place tape on both parts and mark each with a line so you can tell if the rotor turns. next turn the engine slowly the opposite way that you did before while watching the distributor rotor. when the rotor is seen to move stop and check how many degrees the crank moved before the rotor, which is attached to the camshaft, moved. I understand there is also lash in the gears between the distributor and the camshaft but this is just to get a rough idea of the gear lash without removing a timing cover. when doing your valve lash adjustments the engine should also be cranked over a few turns while you check for all the rockers moving the same amount. a rocker that doesn't move the same as the rest would indicate a worn cam lobe. a valve that is protruding more than the rest would indicate a valve that has worn into the valve seat. also check for broken valve springs while you are there and the condition of the umbrella valve seals seen by peering through the coils of the springs. they should be complete and soft rubber. -next check the ignition system for problems starting at the power source and moving through the system. sometimes there is a poor connection on the back of the ign switch that causes a voltage drop. sometimes it is a poor connection on the ballast resistor or the coil or the wire that goes through the distributor housing to the points. check the rotor, cap, wires, plugs for cracks, carbon tracing etc. -next check the fuel system. do a pump pressure and output flow test. document the results. then check/replace the filter(s) and check the fuel cap vent and seal against the filler, check the tank outlet line for bends or kinks and follow the lines right up to the carb ensuring all is good with no tight restrictive bends, kinks or soft spots n the rubber components. pull the lid off the carb and check the float level and what is in the bottom of the bowl. check to ensure the accelerator squirter nozzle is aimed at the edge of the throttle butterfly valve and that the squirter is working properly. check for full throttle at the carb when the pedal is all the way down. full choke activation when the cable is pulled. -next check for vacuum leaks. a smoker machine can be built easily with items normally found at home. you could google it. basically smoke is forced into the intake manifold at the carb end and the exhaust pipe is plugged. you check for smoke coming from any intake fittings, gaskets etc. -check the exhaust heat riser for proper operation -check the exhaust for tight bends or reasons for obstruction. the system can be checked for pressure build up while running by welding an o2 sensor bung into the pipe and using a vacuum/pressure gauge but, again, that takes time and money and an engine that runs. since there is no catalytic converter the only reason for restriction would be obvious pipe problems or a muffler problem. shake the muffler and listen for loose things rattling around inside. -next check the battery. have it load tested after a full charge and some time to sit after. then check the starter draw or remove the starter and have it checked by a shop that has no history with the starter. since you say it heats up quickly there may be issues internally. just because it was rebuilt doesn't mean it was done correctly. there is no huge stockpile of used cores at the rebuild shops for the old stuff so it may be that there were some marginal parts that were re-used and, yes, it works but it may not be optimal. a hot starter usually means it has used a lot of amperage. possibly an internal reason for that if there is no external heat source like a bad connection or a tight, hard to turn engine. here is a link to compression testing https://dannysengineportal.com/compr...n-it-tell-you/ here is a link to leak down testing https://dannysengineportal.com/how-t...hout-a-tester/ here is a link on how to do a vacuum test https://dannysengineportal.com/vacuu...han-you-think/ fuel-air-compression-spark. all at the right time-BOOM. it runs. hope something in there helped somebody. lol. gotta go. I got a life off the computer apparently.