engine rebuild: how best to proceed

[floydvoid]

I have a chevy 2500 6.5 turbo manuel 93. I recently bought it used and have had trouble with excessive smoke.

After much research I have found that the passenger side front cylider has no compression in it and was told that it even has a slight vacuum.

I need to know how best to proceed from here. I have the time and the interest to rebuild this engine myself. I need some guidance as to where to start.

The mechanic told me that the problem with the cylider could be in the "top end" with the valves and rods.

Is it worth pulling off just the valve covers and trouble shooting this instead of pulling the engine and pulling everything apart and troubleshooting everything?


---Ryan

[bigeasy]

The rest of the motor is good ??
Just that cylinder?
Do a leak down test on that cylinder. Watch and listen for where the air excapes from.
Bubbles in radiator = cracked head or cylinder wall - blown head gasket
Air out exhaust = valves
Air out dipstick = piston hole or rings

If the rest of the motor is good i would just repair that cylinder.
Knowing whats wrong will tell you how deep you will need to dig to get at the problem.

[floydvoid]

Just that cylider has no compression
all the rest have good compression
all of the injectors checked out fine, I was told buy the shop that they wouold have to start pulling apart the engine to find out any more.

leak down test?
Not sure what that includes, what equipment is needed?

[bigeasy]

http://www.aa1car.com/library/leakdown.htm
http://www.geocities.com/dsmgrrrl/FAQs/leakdown.htm?200717
http://www.generac.com/publicPDFs/cylinderLeakDownHowTo.pdf
http://www.carcraft.com/techarticles/116_0406_cylinder_leakdown_tester/index.html

[floydvoid]

I pulled off my valve cover on the cylinder #2 side (cylinder in question) and found the second rocker arm in from the front of the car (#2 cylinder) off and the push rod off to the side of where it should be.

What is next?

Is this my intake valve? I assume it is...
What could have caused this to fall out of place?
Should I pull off the head and look at everything else?
Can I get another retainer and just pop everything back in place, or should the push rod get replaced?

I'm sure there are others that have been in this situation.

some of my other nylon retainers seem to not be set flat, they look like they are poping out, should they be replaced or is this normal?

Thanks

[Robyn]

The rockers are held in alignment with the little plastic buttons.

Remove the rocker shafts and replace all the buttons. (Ma General store)
The buttons are a weak link but not usually cronic.
They should all be replaced while your there just to head off a train wreck.

Replace the rocker shaft assemblies and tighten slowly just in case a valve hits a piston.

This can happen any time the rockers are removed. After you replace this stuff roll the engine through with a bar to make sure nothing hits.
Roll it at least 4 revs to make sure all valves clear the pistons and there is not any issues of binding.

Look the rockers and pushrods over to make sure they are in good order.
The copper colored end of the pushrods go UP to the rocker.

Roll the affected push rod on a flat surface, if it runs true its ok.
Just be sure the ball ends are not damaged and that the copper colored end is up to the rocker.

If the parts are undamaged just a set of new buttons will be all you will need to fix the issue.

These can be easily installed with a 1" piece of shaft and a hammer.
Place the rocker shaft assembly on a hard wood block, align the button barb in the hole and tap in until the head is flush with the shaft.
GOOD TO GO.

Robyn

[floydvoid]

The procedure for replacing the rocker shaft is still mysterious to me.

I've read about finding TDC and rotating in a certain direction or something? I'm not really even sure how to find TDC, do you have to pull the fan off for that?

the previous post didn't give much detail about how to avoid hitting the piston, what's the procedure?

thanks for the help

[Robyn]

The procedure is all well and good but most folks cant easily find TDC and do all the other.

Just tighten the bolts down slowly and allow the valves to open if they need to. If you encounter heavy resistance STOP. (Unless you are using BIG tools and not paying any attention you wont hurt anything)

Once the bolts are down snug let the thing sit about 20 minutes then roll the engine by hand (bar) to make sure there is nothing hitting.

Finish torquing the bolts on the rockers.

This is not a biggy as long as you are careful. If I have an engine apart and am replacing the heads I will make sure none of the pistons are at TDC when I bolt the heads on and then I can just zip things down.

Again if you go slowly and carefully you will have zero issues.
Use a short 3/8 ratchet to tighten the bolts and go back and forth a little at a time on them to get the shaft down and keeping it straight.

Good luck

Robyn

[floydvoid]

I'm waiting on the rocker arm retainers and have one rocker arm assmbly off.
I decided to figure out how to rotate the engine before going any further.

I tried pulling on a bolt on the balancer pully, but it didn't budge more than an inch. someone mentioned that I should put the belt on and ust the bolt on the alternator to rotate the engine. I did that and it moved another inch and the pully spins in on the belt.

should the engine be this hard to turn over?
How am I supposed to feel binding if the engine won't turn before I do anything?

thanks

[DmaxMaverick]

Glow plugs still in? Would turn a lot easier if you don't have to fight compression. Even so, it will be somewhat tighter than a gasser. Try a socket on the balancer bolt.

[Robyn]

Yup these engines are tough to turn over with the plugs in.

The center bolt on the ballancer with a good bar will giterdone though :)

Just be sure to rotate clockwise as you look at the engine so you dont unwind the ballancer bolt.

best

Robyn