Engine Rebuild Help!

[wilkyflex]

1992 D-250 is missing on one cylinder and has alot of blowby. I was losing 1/2 gallon of oil every 50 miles or so. With this information, is there anything I should check before I pull the engine and start to rebuild it?

[wilkyflex]

If I do start a rebuild, some other questions I have are:
How do I determine if I should use standard or over-sized pistons?
How do I choose a rebuild kit that is good quality parts? I see different ones on ebay and I have no idea about their quality. Doing this big of a job, I don't want to be cheap on parts.
What other tips, tricks, secrets, recommendations can you provide?

Thanks everybody for your help!!!
Dean

[ellis93]

You won't know what piston rings you need until you down the engine. If it's an unmolested cummins (stock) and there is little to no groove at the top of the cylinder,or scored wall,then standard size rings will be what's needed. Chances are if you've an excessive amount of blowby then you could have a head issue. I had bad valve stem seals once that would fill the cylinders full of oil and made the engine smoke like a train. It also had huge amounts of blowby. I installed new seals and the issues where resolved.

If your worried about part qlty then go back to cummins,they worked for a long time before

Regardless of parts needed,I'd completely disassemble the engine and inspect before ordering anything.