Chevy 3.0 Rings

[reavesga]

Engine is running ok, but at idle there is some vibration. I checked my compression. #2 is 100 psi which is low. Oil in the cylinder brings it right up to 125 psi. #3 is low at 85 psi and oil has no impact. So the guess is valves. I learned how to do the compression check from the forums so here is the question. If I pull the head and or replace the head that should take care of #3. What do I need to do to replace the rings? Just pull the oil pan and then work the cylinder out? What size rings? Should I re machine the block and if so what do I tell the machine shop. Trying to keep the budget under control vs installing a reman engine. Honestly she fires right up and runs great from 1000 rpm on up, just at idle she is rough. I know both of these problems are not going to go away so based on 30-50 hours of use each season is it something to do now or do I have a few more seasons to go?

 

[Bt Doctur]

What do I need to do to replace the rings? Just pull the oil pan and then work the cylinder out? What size rings? Should I re machine the block and if so what do I tell the

The rings could be cracked or worn. you wont know untill you pull the piston and examine them. You wont know the condition of the main or rod bearings untill you take them apart also.Rings are sized to the pistons. If the bore is large beyond spec you need to install a larger piston with the correct size rings.You cant just do one cylinder, and you cant put .020 oversize rings on a std piston either

 

[Grub54891]

no sense trying to do a partial fix. Do it all, the cost differential isn't worth doing it twice. It's up to you to decide weather to run it or do it now.

 

[Silvertip]

The key as to what you CAN do and you SHOULD do is based on your statement about keeping a close eye on the budget. So here is my take on this from a practical standpoint as well as budgetary standpoint:
1) The engine must come out regardless what you eventually end up doing.
2) You pull the head, pull the pan, pull the pistons.
3) You either rent the proper snap gauge so you can determine the wear, out of round and taper of each cylinder. The option and probably best choice for you is to take the block (with crank) to an engine builder and have them do the inspection and provide you with the numbers. Armed with that information you can now make a decision as to whether you go with a total rebuild (boring, new oversize pistons and matching rings, machine the crank and new rod and main bearings, and of course a valve job, or if you can get away with a ring job. Just because a cylinder is down on compression doesn't mean a new set of rings can't be installed. Obviously whether you do that or not depends on what the inspection turns up. Worn cylinders with lots of taper and out of round will cause oil consumption early since the rings cannot compensate for that for very long. If even one cylinder is beyond re-ring spec, then an engine rebuild is your wise choice. If bores are all within reasonable tolerances, do a ring job and valve job along with a new set of bearings (provided the crank is ok) and go boating.