When did they start making 78" buses? And which buses are CHEAP to operate?

[Brad_SwiftFur]

Originally Posted by RomaniGypsy

Is there, somewhere, a detailed step by step set of instructions for rebuilding one of these engines? I've never rebuilt an engine. The most engine work I've ever done is a tune-up and a carburetor cleaning.



What could an 8.3 or 466 rebuild cost at a shop?



What is a "spun" bearing? (I was reading that rebuild shops often won't accept as a "core return" an engine that had a spun bearing. Hell, I don't even know what a main bearing is. If it's on the bottom end of the engine, my guess would be that it's the bearing where the piston meets the crankshaft. How close am I to being correct?)

1. Yes, I'm sure there is. I've never looked.

2. Probably in the 6000-8000 range. Much of it is labor.

3. The crankshaft has "Rod bearings" (the rods that connect the piston to the crank), and the "Main bearings" (the ones between the crank and the block). Christopher has it right about a "spun" bearing. Basically the bearings have small tabs that are intended to keep them in place. If the engine is run dry, overheated, or just plain all the way to its limits, the bearings can spin in the block. If they wear to the point of being half their original thickness, you can also end up with a "stacked" bearing, which is exactly what is sounds like (the 2 worn halves stacked on top of each other.)

pengyou:

The Cummins 6BT 5.9 engine is not sleeved. Just like the T444/7.3, 6.9, IH 9.0L, and many others, it must come out for a trip to the machine shop. Engines that have to come out, it might make sense to buy a "crate engine" which usually come with warranties. Someone still has to do the labor, however.

[Rusty]

Originally Posted by pengyou

...

I, also, am not related to either Warren Buffet or Bill Gates, but I was thinking that if I get something that looks aesthetically good...


When you talk about engines you talk about wet sleeves? What does that mean? AFAIK, the 6bt has sleeves that can be pounded out of the block without having to machine the block (unless there has been some damage to it).

Funny you should mention Uncle Warren, I was just on the phone with him and he gave me some more stock tips.

Just to confuse issues...Cummins 5.9L 6BT - Engine In-frame Rebuild Kit | eBay

[pengyou]

Originally Posted by Rusty

Funny you should mention Uncle Warren, I was just on the phone with him and he gave me some more stock tips.

Just to confuse issues...Cummins 5.9L 6BT - Engine In-frame Rebuild Kit | eBay

Yes, ads like the ebay one are the source of my confusion.

[Twigg]

Most of the difficult work on any engine rebuild is in the cylinder head. If you can't do that yourself but can get the head off, take it to a shop and then you are just paying for the work they do on the bare unit. You can measure the head distortion with basic tools. A thick piece of plate glass and a set of feeler gauges will get you close enough IF you cleaned off the mating face properly. In the shop they will use a surface table, and feeler gauges, but only because they have one (a surface table is a heavy piece of cast iron (or maybe granite) that has been ground very flat) Specialist shops may use fancy depth gauges or even a laser scanner to achieve the same result, more accurately.

The rest is fairly straightforward if the crank bearings are okay.

If the rebuild can be done "in-frame" it means that once you drain the oil and remove the sump, the crankshaft with the pistons attached must come out from the bottom (It will be heavy, lower it on a transmission jack and make a note of what cap goes where, and which way round).

You don't need much in the way of special tools. For example, a ring insertion tool can be made from a baked bean can and some worm-drive clips. Anyone can use plasti-gauge to measure cap-bearing clearances.

The problem you will have is that even the best service manual will not teach you how to use the tools. If you don't have basic mechanical knowledge and competence you stand a good chance of making it very much worse.

Re-assemble a crankshaft wrong and you won't necessarily be able to tell when you start the engine. You will be able to tell when it does several thousand dollars of damage to the crank and block.

Diesel engines are fairly simple beasts, but they are big and very heavy, and not for beginners unless you can get a knowledgeable friend to steer you through the process.

It's simple stuff, but not necessarily easy ... those are very different concepts.

Automatic transmissions, on the other hand, are not for the faint-hearted and with 40 years experience wrenching on engines of many kinds, I'd pay a specialist for that. Torque converters, which is a scary term, are relatively easy if you can get the transmission out.