97 Rocker Valve Adjustment
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Posts: 4,340
From: North Central Indiana
I'd perform a leak test before and after. But again, I think you have one or more internally stuck lifters on each of the offending cylinders. I, of course, could be wrong tho. However, replacing the studs and nuts isn't that expensive or time consuming... So, yes, I'd go ahead and do a leak down test with both the old and new rockers. If the before and after leak down results are the same (i.e. no comp with the nuts torqued, and comp is restored with them loosened), then I'd go down the path of stuck lifters. At that point you could either go through the trouble and expense of replacing the lifters (be sure that you use the 'non-adjustable type), or you could try some of the 'unconventional' and possibly risky methods of freeing them up while they're still installed. We can talk about that later tho. Also be sure to follow the leak down test procedure exactly as per the instructions with the battery disconnected (you will need a compressor for this btw).
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Joined: Nov 2007
Posts: 2,185
From: Zurich
I think he's still down to figure exactly what went wrong with that rocker arm.
The rounded corners would indicate that a previous owner has worked on them already. Have they put everything back correctly?
My question would be: "What does the full assembly on these blazers look like?".
I mean from bottom up
- lifter (hydraulic roller i suppose - is it working correctly or is something wrong there?)
- pushrod (ball tips on both sides i guess - straight? - correct length?)
- rocker arm (pressed sheetmetal or does it have a roller?)
- what is in the rocker arm (most they have a special spacer (rounded) washer then the nut
- stud (that we have seen - how does it compare to a "good" one and what is OEM specs?)
How does the whole valvetrain of the defect cylinders differ with one of the "good" cylinders?
The rounded corners would indicate that a previous owner has worked on them already. Have they put everything back correctly?
My question would be: "What does the full assembly on these blazers look like?".
I mean from bottom up
- lifter (hydraulic roller i suppose - is it working correctly or is something wrong there?)
- pushrod (ball tips on both sides i guess - straight? - correct length?)
- rocker arm (pressed sheetmetal or does it have a roller?)
- what is in the rocker arm (most they have a special spacer (rounded) washer then the nut
- stud (that we have seen - how does it compare to a "good" one and what is OEM specs?)
How does the whole valvetrain of the defect cylinders differ with one of the "good" cylinders?
New Member
Joined: May 2017
Posts: 67
Please research and carefully study the following terms: 1. Hydraulic valve lifters and how they operate. 2. Hydraulic valve lifter that is stuck and/or hydro-locked at a fully extended position and the problem this creates (i.e. LOSS OF COMPRESSION). Note: searching the net on #2 in regard to 4.3 liter V6 GM engines is also highly recommended. If you have any questions and/or don't understand the above terms, then please ask and we'll try to explain it for you.
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Starting Member
Joined: Mar 2017
Posts: 220
From: Tulsa, OK
i bought these (pic) bolt grip sockets to pull the rounded off stud. So a leak down test isn't needed ? If so, I'll need a air compressor, how much psi output should the compressor have ?
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Joined: Oct 2014
Posts: 4,340
From: North Central Indiana
In review..... You did not have compression on #2, #5 with the rockers tightened. You did have compression on #2, #5 with the rockers backed off a couple of turns. So it was concluded that something was holding a valve open on each cylinder. Because you over-tightened at least one rocker enough to break it off, I'm assuming that the nuts on the affected cylinders were turned down past their normal stop. This would damage both the nut and the rocker stud. Because it would require an air compressor (crude leak down) to determine exactly which stud/nut was holding things open, I suggested replacing all four studs/nuts on the affected two cylinders and see if the compression is there with the rockers tightened. If you now have compression, you are done with that particular problem and putting air in the cylinders with a compressor will do nothing more for you.
Others have suggested that lifters sticking in an outward position holding the valve open can cause the same problem, and it could do that if this was the case. But I will tell you that in all the years I have worked on cars, I have never ever seen a lifter stick that way. If a lifter fails, usually it collapses and gives too much clearance for any number of reasons. But if you want to mess with them, be my guest.
As others have suggested, it would be a good idea to roll the 4 pushrods for #2 and #5 on the bench to make sure they are not bent for some reason - and that is easily done.
So my suggestion is to go ahead and replace the four studs and rocker nuts on #2 amd #5. Make sure there is compression on those cylinders, and then try to start it. If it doesn't start, then we will need to check to make sure distributor is in correctly.
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Joined: Oct 2014
Posts: 4,340
From: North Central Indiana
Original problem was intake gaskets/coolant leak. Then distributor was damaged. Then screwdriver tip was broken off in cylinder trying to find #1 and head was pulled to retriever broken screwdriver tip. Then rockers were tightened excessively trying to adjust them, breaking off one stud. As I understand it, it has been no-start since near the beginning of this sequence.
The rounder corners on the stud in question happened when current owner tried to remove it. As I understand it, this is the only one he had problems getting out.
At this point it is unknown if this engine will last any time at all, but it should at least start without spending much on it. Fuel pressure doesn't seem to be an issue and he has spark at the coil and the injectors are being driven by the PCM.
I am betting he will still have a no-start after restoring compression on #2 and #5 - but I also think the distributor will simply be in wrong and I can easily walk him though correcting that.
Last edited by LesMyer; Jun 19, 2017 at 08:38 AM.
Thread Starter
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Starting Member
Joined: Mar 2017
Posts: 220
From: Tulsa, OK
Looks like the tools should do the trick!
In review..... You did not have compression on #2, #5 with the rockers tightened. You did have compression on #2, #5 with the rockers backed off a couple of turns. So it was concluded that something was holding a valve open on each cylinder. Because you over-tightened at least one rocker enough to break it off, I'm assuming that the nuts on the affected cylinders were turned down past their normal stop. This would damage both the nut and the rocker stud. Because it would require an air compressor (crude leak down) to determine exactly which stud/nut was holding things open, I suggested replacing all four studs/nuts on the affected two cylinders and see if the compression is there with the rockers tightened. If you now have compression, you are done with that particular problem and putting air in the cylinders with a compressor will do nothing more for you.
Others have suggested that lifters sticking in an outward position holding the valve open can cause the same problem, and it could do that if this was the case. But I will tell you that in all the years I have worked on cars, I have never ever seen a lifter stick that way. If a lifter fails, usually it collapses and gives too much clearance for any number of reasons. But if you want to mess with them, be my guest.
As others have suggested, it would be a good idea to roll the 4 pushrods for #2 and #5 on the bench to make sure they are not bent for some reason - and that is easily done.
So my suggestion is to go ahead and replace the four studs and rocker nuts on #2 amd #5. Make sure there is compression on those cylinders, and then try to start it. If it doesn't start, then we will need to check to make sure distributor is in correctly.
In review..... You did not have compression on #2, #5 with the rockers tightened. You did have compression on #2, #5 with the rockers backed off a couple of turns. So it was concluded that something was holding a valve open on each cylinder. Because you over-tightened at least one rocker enough to break it off, I'm assuming that the nuts on the affected cylinders were turned down past their normal stop. This would damage both the nut and the rocker stud. Because it would require an air compressor (crude leak down) to determine exactly which stud/nut was holding things open, I suggested replacing all four studs/nuts on the affected two cylinders and see if the compression is there with the rockers tightened. If you now have compression, you are done with that particular problem and putting air in the cylinders with a compressor will do nothing more for you.
Others have suggested that lifters sticking in an outward position holding the valve open can cause the same problem, and it could do that if this was the case. But I will tell you that in all the years I have worked on cars, I have never ever seen a lifter stick that way. If a lifter fails, usually it collapses and gives too much clearance for any number of reasons. But if you want to mess with them, be my guest.
As others have suggested, it would be a good idea to roll the 4 pushrods for #2 and #5 on the bench to make sure they are not bent for some reason - and that is easily done.
So my suggestion is to go ahead and replace the four studs and rocker nuts on #2 amd #5. Make sure there is compression on those cylinders, and then try to start it. If it doesn't start, then we will need to check to make sure distributor is in correctly.
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Joined: Oct 2014
Posts: 4,340
From: North Central Indiana
Can you please take a closeup photo of the rocker stud (top and side) so I can see what we are working with.
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Joined: Nov 2007
Posts: 2,185
From: Zurich
Lesmyer excellent problem solving strategy.
Maybe TTRD can get a hold on some friend with a good toolset.
It seems that we can all work with nearly a garage at our hands.
I've assembled tools over 30 years and got nearly everything needed on my cars.
A picture would be nice of all the valvetrain parts of one cylinder laid out.
I've not yet seen a 1997 valvetrain.
Maybe TTRD can get a hold on some friend with a good toolset.
It seems that we can all work with nearly a garage at our hands.
I've assembled tools over 30 years and got nearly everything needed on my cars.
A picture would be nice of all the valvetrain parts of one cylinder laid out.
I've not yet seen a 1997 valvetrain.