We should also keep in mind that the engine, heads, and other components may, in some cases, not be original to the vehicle year model and vin. This is why you can not simply guess at what you're working on by simply checking the year model and vin in every situation. A visual and/or physical (i.e. measurement, etc) verification is sometimes, if not always, necessary.

 

I don't believe you. Show me your documentation. In any case the vehicle is a 1997.

You have this correct, but this fact was already established way back in this same thread and there actually is a photo of the screw in stud in the post just before yours.

Please tell me how bent valves or pushrods causes zero compression in cylinders #2 and #5, but loosening the rockers restores compression?

Please tell me how this causes zero compression in cylinders #2 and #5, but normal compression is observed in the rest.

 

5 cents worth:

I suppose the spider is off the engine and the valve covers as well.

I think FMB42 still has a point.

- As the rockers are off also pull the pushrods and check them for out of round
- Carefully check the rockers themselves (evtl. remove one from a "good" cylinder to have a reference.

Carefully investigate the problem. The question is WHY is it doing this.
Having 4 cylinders doing a correct job offers something to check against. Clearances etc.
If the lifter valley is open I would also pull the lifters in question. Again make sure position and orientation are marked and check them carefully.

Once the lifter is out you can actually look at the camshaft lobes in question. Again pulling one of the good ones gives you something to compare against.
For the lifters:
To remove most probably the 1997 has a plastic bar with the 6 guides held in place by 2 bolts. I have never tried to pull a lifter with rods still in place but I think you can lift the retainer high enough for a single lifter to be pulled. If that is not viable either leave it or you have to pull all rockers and all studs.

Now we are talking some serious mechanics work on the innards of an engine. It is imperative to work in a safe (for you as well as for the engine) way. Have your tools orderly, take a lot of pictures. Have some rags and some solvent ready to clean the parts that you remove right away. Have some tape and a pencil ready to mark them.

Get e.g. a drawer organizer from a kitchen store or IKEA. The various compartments are handy to store the stuff that comes off that engine and can be marked with tape and the pencil.
Grab some nail varnish from GF or friend or sister. It is solvent based and sticks well to steel. I usually mark locations with it.

Work slowly and deliberately and observe every single part that comes off. I'll give you an example:

The lifters have been running for 250'000 miles in one direction and have gotten used to its counterpart the camshaft even if being roller lifters. So it is important to put them back where they belong in their respective bore. But not only into the correct location but also in the orientation they came out of the bore. This is where nail-colors come in handy.

Once a lifter is out observe it closely. The hydraulic lifters usually have a small oil bore in the mid section. Should be on one side only - so this is a nice thing to observe and note as now you can write it up on a piece of paper and you have the orientation double marked should the varnish not stick or you will wipe it away once you put it back together.

I'm in the midst of a loooong engine build on a 1994 4.3l V6. Waiting for the custom pistons for the build. I normally work in a place where we restore old Italian cars. So I know my way around 12 cylinder V engines as well as some V8's I've had my fingers on. One of which is a 1964 Studebaker where I will pull the valvetrain within the next 10 days.

I have to go to my small work-room and will take a couple pics for you to get the idea.

Good work!

Cheers


Just found the link again. Could be useful as a general reference.

http://www.kohlerpower.com/onlinecatalog/pdf/tp6103.pdf

 

Lesmyer

Do you have a thread on your S10 race truck? Would be nice to exchange a bit on what you have done vs. what I'm doing to my 4.3.

Cheers Mark

 

I apologize if I've upset people in here. But, like Mark above says, we are 5 pages into this without knowing why this engine is doing what it's doing. This tells me that there could be more going on here than just a valve train problem. Probably not, but the possibility is still there...

Meanwhile, I would again recheck that the rocker that the R. studs, pivots, nuts, and push rods are undamaged, clean, lubed, and assembled correctly (also make sure that the push rods aren't plugged up, if you haven't done so already).

If all is OK with the above, then I think you might want to consider replacing the valve lifters of the offending cylinders. It could be that the internals of these lifters are stuck at full height/length and, as such, are keeping the valves from seating properly when the rocker nuts are torqued properly. This sometimes happens with high mile lifters after the rocker nuts are removed or loosened. This would, of course, explain why you have a loss of comp in #2 and #5 cylinders when the R. nuts are torqued down, yet compressing returns when you loosen the nuts up.

 

1989 S10 first gen short box w/383. Runs [email protected] with open headers. [email protected] through the mufflers

 

very cool

 

Ya, those are some strong numbers.

 

Thanks guys! I put another video up (more interesting vantage point), but I put it in the "Lounge". Mods: Sorry about the completely off topic post. I couldn't help myself.

....... and back to the real topic of this post.

 

That truck is bad *** !...OK I have taken out the studs for those faulty cylinders, except one, because its stripped. I dont know what I'm supposed to be looking for as far as damaged. What do damaged studs look like ?
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