97 Rocker Valve Adjustment
#31
06-07-2017, 03:23 AM
Join Date: Mar 2017
Location: Tulsa, OK
Posts: 220
If you have no compression on #2 and #5 with rockers torqued to 20 psi, but compression returns when you loosen the rocker nuts - then the stop surface on the studs and nuts are damaged and they need replaced. The nuts are turning down past where they should stop when torqueing and this is holding a valve open. Make sure you replace the rocker nuts too
You shouldn't notice any miss on a cylinder if compression is above around 60 psi. I once had an old V8 that was so worn out that it had 60-80 psi on all cylinders. It ran fine with no misses and didn't even use much oil, but was very difficult to start in cold weather and had little power. Came from beating it up and down those white rock gravel roads they have in Iowa with no air cleaner or muffler for a year or so. Thought I had a hot rod!! This car ultimately ended up being my first successful engine rebuild. I won't even comment on my first try when I was 14 - that was already a lost cause when I started.
Good luck. Don't forget there can be other things preventing from starting, but without compression on all cylinders there is no reason to even try to start it. If it doesn't start after these repairs, let us know and we can go through checking the distributor and it's installation. The rest you pretty much have already covered.
Keep in mind that it will be very hard to start after squirting oil in the cylinders (requiring extrended cranking), and then it will smoke like crazy and run poorly for a little when it does start. Probably you will want to crank it over for maybe 30 seconds with all the spark plugs out to get as much oil out as possible before putting them back in.
You shouldn't notice any miss on a cylinder if compression is above around 60 psi. I once had an old V8 that was so worn out that it had 60-80 psi on all cylinders. It ran fine with no misses and didn't even use much oil, but was very difficult to start in cold weather and had little power. Came from beating it up and down those white rock gravel roads they have in Iowa with no air cleaner or muffler for a year or so. Thought I had a hot rod!! This car ultimately ended up being my first successful engine rebuild. I won't even comment on my first try when I was 14 - that was already a lost cause when I started.
Good luck. Don't forget there can be other things preventing from starting, but without compression on all cylinders there is no reason to even try to start it. If it doesn't start after these repairs, let us know and we can go through checking the distributor and it's installation. The rest you pretty much have already covered.
Keep in mind that it will be very hard to start after squirting oil in the cylinders (requiring extrended cranking), and then it will smoke like crazy and run poorly for a little when it does start. Probably you will want to crank it over for maybe 30 seconds with all the spark plugs out to get as much oil out as possible before putting them back in.
OK I had to return my compression tester to get money for a tool set (Stanley 226-Piece + 70-Piece Bonus Mechanic Set) to remove the rocker studs. What should I look for when I take them out ? And I cant afford "new" studs and nuts, but I live less than a mile from a salvage yard, can I pull studs and nuts from a salvage yard from engine with low mileage ? And if so what should I be looking for to avoid buying ? And can I pull the studs from any 96-2002 4.3 with the screw type studs or I need to find a specific vehicle ?
Last edited by Tynan Tha Real Dill; 06-07-2017 at 04:17 AM.
#32
06-07-2017, 07:42 AM
Thats awesome, your first engine rebuild was at 14 ? Yea this Blazer has 245,000 miles on it. I realize I'll need to replace it soon, but I need to at least last until I can work some time to get the money up.
OK I had to return my compression tester to get money for a tool set (Stanley 226-Piece + 70-Piece Bonus Mechanic Set) to remove the rocker studs. What should I look for when I take them out ? And I cant afford "new" studs and nuts, but I live less than a mile from a salvage yard, can I pull studs and nuts from a salvage yard from engine with low mileage ? And if so what should I be looking for to avoid buying ? And can I pull the studs from any 96-2002 4.3 with the screw type studs or I need to find a specific vehicle ?
OK I had to return my compression tester to get money for a tool set (Stanley 226-Piece + 70-Piece Bonus Mechanic Set) to remove the rocker studs. What should I look for when I take them out ? And I cant afford "new" studs and nuts, but I live less than a mile from a salvage yard, can I pull studs and nuts from a salvage yard from engine with low mileage ? And if so what should I be looking for to avoid buying ? And can I pull the studs from any 96-2002 4.3 with the screw type studs or I need to find a specific vehicle ?
Yeah, first attempt was at age 14, but it never ran again. This should be good for a laugh. Tore it down because of a couple of spun rod bearings after driving my car around the farm for a couple years without changing the oil. Finally so much dirt that oil filter couldn't pass sufficient oil. Yes, my Grandfather sold me a car against my mother's wishes when I was 12 (for $21) and I virtually lived in that car with big dreams of doing stuff with it, etc. Consulted with my great uncle who told me I would need to smooth up that crank with emery cloth. So I went at the rough crank with emery cloth for quite some time, and bought new bearings and rings from JC Whitney. Bolted everything together and it was locked up tight. Discovered that if I loosened the rod bolts a little on the cylinders that had spun bearings, it would turn. So I bought some shim stock and made shims to fit between the rod and cap to spacer them out. Didn't bother to hone the cylinders. Re-used the head gasket. Put the engine back in and filled it up with straight water, which went directly into the cylinders and hydro-locked it. Ended up burning up the starter trying to get it to turn again. It sat for a year with water in the cylinders and then I pulled the head and discovered all the rust.....
.
Last edited by LesMyer; 06-07-2017 at 08:01 AM.
#34
06-08-2017, 06:48 AM
Join Date: Mar 2017
Location: Tulsa, OK
Posts: 220
You should be able to get the studs and nuts from any 1996 up 4.3 Blazer or Jimmy or S10 pickup. Should be plenty of them in the junkyard. Mileage really shouldn't matter. They don't wear.
Yeah, first attempt was at age 14, but it never ran again. This should be good for a laugh. Tore it down because of a couple of spun rod bearings after driving my car around the farm for a couple years without changing the oil. Finally so much dirt that oil filter couldn't pass sufficient oil. Yes, my Grandfather sold me a car against my mother's wishes when I was 12 (for $21) and I virtually lived in that car with big dreams of doing stuff with it, etc. Consulted with my great uncle who told me I would need to smooth up that crank with emery cloth. So I went at the rough crank with emery cloth for quite some time, and bought new bearings and rings from JC Whitney. Bolted everything together and it was locked up tight. Discovered that if I loosened the rod bolts a little on the cylinders that had spun bearings, it would turn. So I bought some shim stock and made shims to fit between the rod and cap to spacer them out. Didn't bother to hone the cylinders. Re-used the head gasket. Put the engine back in and filled it up with straight water, which went directly into the cylinders and hydro-locked it. Ended up burning up the starter trying to get it to turn again. It sat for a year with water in the cylinders and then I pulled the head and discovered all the rust.....
.
Yeah, first attempt was at age 14, but it never ran again. This should be good for a laugh. Tore it down because of a couple of spun rod bearings after driving my car around the farm for a couple years without changing the oil. Finally so much dirt that oil filter couldn't pass sufficient oil. Yes, my Grandfather sold me a car against my mother's wishes when I was 12 (for $21) and I virtually lived in that car with big dreams of doing stuff with it, etc. Consulted with my great uncle who told me I would need to smooth up that crank with emery cloth. So I went at the rough crank with emery cloth for quite some time, and bought new bearings and rings from JC Whitney. Bolted everything together and it was locked up tight. Discovered that if I loosened the rod bolts a little on the cylinders that had spun bearings, it would turn. So I bought some shim stock and made shims to fit between the rod and cap to spacer them out. Didn't bother to hone the cylinders. Re-used the head gasket. Put the engine back in and filled it up with straight water, which went directly into the cylinders and hydro-locked it. Ended up burning up the starter trying to get it to turn again. It sat for a year with water in the cylinders and then I pulled the head and discovered all the rust.....
.
#35
06-08-2017, 06:50 AM
Join Date: Mar 2017
Location: Tulsa, OK
Posts: 220
its OK I understood lol my new tool set arrives today, so I'll be pulling those studs today and I'll take pics when I report.
#36
06-08-2017, 07:14 AM
Actually he sold the car to me (he really gave it to me - it was worth a lot more) when I was 12. I drove it for a couple of years and tried to fix it when I was 14. Vehicle went to the junkyard when I was 16.
My Grandpa was not a "fun" guy (very serious type with little sense of humor and old-fashioned) but he never ever treated me like a little kid. If I thought I could do something he would let me try it (like driving or building stuff or putting shingles on buildings, or working with farm equipment) and he would take the time to show me how to do things. Drove my Mom crazy because he never would ask her before exposing her baby to danger starting when I was about 8 years old! And I was certainly game for doing new stuff. Eventually she figured out that he really didn't care what she thought and that I wasn't going to be happy sitting inside the house playing with toys. My Grandpa really had a big positive impact in who I eventually became. I think he was a pretty special man.
Good luck on your repairs
Last edited by LesMyer; 06-08-2017 at 07:54 AM.
#37
06-08-2017, 02:38 PM
First make sure that none of the int. and exh. cam lobes on the offending cylinders aren't excessively worn (just compare them with the known good cyls by eye).
Second, these engine are known to have 2 very different valve lash adjustment procedures depending on the rocker arm and stud designs (regardless of the VIN #). One type simply requires that you torque the rocker nuts down to 20 ft.lbs, while the other requires that you take each cyl. to TDC (both valves closed) and then tighten the rocker nuts until there is zero lash (slight drag on the push rods while turning/twisting them by hand), followed by tightening the nuts a further 3/4 of turn. You'll need to search this forum, and/or the net, in order to determine exactly which rocker and rocker stud type you have.
Btw, this issue of different valve lash adjusting procedures has stumped many mechanics...
Second, these engine are known to have 2 very different valve lash adjustment procedures depending on the rocker arm and stud designs (regardless of the VIN #). One type simply requires that you torque the rocker nuts down to 20 ft.lbs, while the other requires that you take each cyl. to TDC (both valves closed) and then tighten the rocker nuts until there is zero lash (slight drag on the push rods while turning/twisting them by hand), followed by tightening the nuts a further 3/4 of turn. You'll need to search this forum, and/or the net, in order to determine exactly which rocker and rocker stud type you have.
Btw, this issue of different valve lash adjusting procedures has stumped many mechanics...
#38
06-08-2017, 04:12 PM
First make sure that none of the int. and exh. cam lobes on the offending cylinders aren't excessively worn (just compare them with the known good cyls by eye).
Second, these engine are known to have 2 very different valve lash adjustment procedures depending on the rocker arm and stud designs (regardless of the VIN #). One type simply requires that you torque the rocker nuts down to 20 ft.lbs, while the other requires that you take each cyl. to TDC (both valves closed) and then tighten the rocker nuts until there is zero lash (slight drag on the push rods while turning/twisting them by hand), followed by tightening the nuts a further 3/4 of turn. You'll need to search this forum, and/or the net, in order to determine exactly which rocker and rocker stud type you have.
Btw, this issue of different valve lash adjusting procedures has stumped many mechanics...
Second, these engine are known to have 2 very different valve lash adjustment procedures depending on the rocker arm and stud designs (regardless of the VIN #). One type simply requires that you torque the rocker nuts down to 20 ft.lbs, while the other requires that you take each cyl. to TDC (both valves closed) and then tighten the rocker nuts until there is zero lash (slight drag on the push rods while turning/twisting them by hand), followed by tightening the nuts a further 3/4 of turn. You'll need to search this forum, and/or the net, in order to determine exactly which rocker and rocker stud type you have.
Btw, this issue of different valve lash adjusting procedures has stumped many mechanics...
Last edited by LesMyer; 06-08-2017 at 04:16 PM.
#39
06-09-2017, 06:15 AM
Join Date: Mar 2017
Location: Tulsa, OK
Posts: 220
First make sure that none of the int. and exh. cam lobes on the offending cylinders aren't excessively worn (just compare them with the known good cyls by eye).
Second, these engine are known to have 2 very different valve lash adjustment procedures depending on the rocker arm and stud designs (regardless of the VIN #). One type simply requires that you torque the rocker nuts down to 20 ft.lbs, while the other requires that you take each cyl. to TDC (both valves closed) and then tighten the rocker nuts until there is zero lash (slight drag on the push rods while turning/twisting them by hand), followed by tightening the nuts a further 3/4 of turn. You'll need to search this forum, and/or the net, in order to determine exactly which rocker and rocker stud type you have.
Btw, this issue of different valve lash adjusting procedures has stumped many mechanics...
Second, these engine are known to have 2 very different valve lash adjustment procedures depending on the rocker arm and stud designs (regardless of the VIN #). One type simply requires that you torque the rocker nuts down to 20 ft.lbs, while the other requires that you take each cyl. to TDC (both valves closed) and then tighten the rocker nuts until there is zero lash (slight drag on the push rods while turning/twisting them by hand), followed by tightening the nuts a further 3/4 of turn. You'll need to search this forum, and/or the net, in order to determine exactly which rocker and rocker stud type you have.
Btw, this issue of different valve lash adjusting procedures has stumped many mechanics...
Last edited by Tynan Tha Real Dill; 06-09-2017 at 06:21 AM.
#40
06-12-2017, 05:08 PM
Again, not all '96 W vin 4.3 engines have screw in studs (regardless of what some of the various service manuals state). The vast majority are screw in, but a small number went out in '96 with a W vin while having pressed in studs.
If there is a 'hex' on the stud were it bottoms into the head, then they are screw in. If not, they are pressed in.
Unfortunately, bent valves could also be the problem. However, this often results in bent push rods as well. A 'spin' test of the rods while they're installed will usually show if they're badly bent (otherwise, you can, of course, remove them and roll them on a flat surface). Meanwhile, a leak down test might good idea at this point (if you haven't done so already).
Also consider that the cam may have jumped timing due to worn sprockets and/or a worn cam chain.
If there is a 'hex' on the stud were it bottoms into the head, then they are screw in. If not, they are pressed in.
Unfortunately, bent valves could also be the problem. However, this often results in bent push rods as well. A 'spin' test of the rods while they're installed will usually show if they're badly bent (otherwise, you can, of course, remove them and roll them on a flat surface). Meanwhile, a leak down test might good idea at this point (if you haven't done so already).
Also consider that the cam may have jumped timing due to worn sprockets and/or a worn cam chain.