I just got a 94 B6 that i want to put in my Suburban. The engin is all torn down but he price was right. it came with new pistons and some bearings. I looked at every single part and didn't notice any cracks damage or excessive wear. I am not sure if it's 100% complete but all the costly parts are there. Seems like somebody wanted to rebuild it then just gave up.

Is there anything particular i should be looking for in terms of advisable repairs? Should i magnaflux it before i take it to the shop? What parts do i need to take to the machine shop? How do i find a good shop? How do i examine the injection pump? How hard is it to rebuild the pump if necessary?

I will appreciate any tips on rebuilding the engine. Basically I want to do by myself as much as possible meaning if the tool to get the job done is not a lot more than getting it done by somebody else i'll do it.

Thank you.

 

Well, first of all, where are you located? Somebody here might know a good machine shop if you tell us where you're located. And you should also ask around. When you see a Dodge/Cummins truck stopped at a gas station, ask the driver if he knows of any good shops in your area. Ask at the local NAPA store who's doing good work.

Whenever I've rebuilt an engine I always take the block, crank, rods, pistons and cam in to the machine shop and let them inspect everything, and bore, hone, turn... whatever they suggest is what I have done. Then get a good valve job on the head.

 

Good point. I'm in Justice IL

 

Wow, Chicago outskirts. Would be willing to bet qualified shops up there would be way too high, and I wouldn't trust the fly by nighters.

First things first, how many engine builds have you done? Diesels aren't really first timer friendly. The next thing to do is get a Cummins repair manual, hit me up with a PM for a good source.

 

I messed with my 50cc two stroker when i was a youth and that's all my engine work experience. Although I'v done some work around the truck since i got it a couple of months ago, like oil changing, replacing transmission oil lines, installing AC delete pulley and the last two took me less time than what a dealer shop wanted to charge me for. Even though i didn't know what the heck i was doing in the beginning, didn't have decent tools and had to crawl in puddles underneath the truck.

I feel rather confident, cause i'm not in a hurry and know how to follow instructions.

Right now i'm completing my tools. I bought a used snap-on torque wrench, a set of combination wrenches 4.5 through 16 and 7/16 trough 1". I'm trying to hunt down a decent used engine stand and hoist.

I haven't really looked for a machine shop yet but after i find one and get there the parts Robert Rausch mentioned i will work on the valves as he suggested.

By the way the engine came with two heads. One supposed to be allowing better power output but the seller did't know which one it was. How can i find that out?

 

Hmm, unless you have a ported head, which would be obvious, I am not aware of any one head in the 12 valve series making more power than another.

Do the heads look the same?

 

As far as I know the 12v only had 2 heads available. The one for the 89'-91.5' trucks that had 9mm injector tips, and the later heads that came with 7mm tips. The 7mm, or 91.5'+ heads are the ones you want. Which should be what you have.

As for the engine, why did the guy tear it down to start with? The new pistons, what kind and overbore are they? The crank I'm betting is fine, so just have the shop polish it and check the clearances. The block will need to be bored if the pistons are bigger than stock. If they are stock I recommend having the block honed to get some good cross hatch to seat the rings better. Have them check the head and block surfaces. Mine was only .0015 out on the block and the head was .003. Well within what is acceptable, but I went ahead and had them both decked .010" and installed the .020" thicker marine gasket.

All the bearings you will need is rod bearings, mains, and the one cam bearing. Its best to have a shop install the cam bearing.

When looking for a shop just be blunt and ask them if they have ever worked on a B series cummins. If they say yes ask them how many cam bearings you need. If they immediatly say 1, go with that shop. I called several shops around houston getting answers from 4-7. I finaly found a shop the guy knew it was one, and that was my clue he knew cummins. When I showed up to drop everything off, he drives and old 91' First Gen. LOL