LB7 repower - pre planning & questions

[Mark Rinker]

With two LB7s now totalling nearly 350K miles, its probably time that I purchase a 'ready spare' engine, turbo, Allison, transfer case, etc. for the unfortunate (yet unavoidable) day that I have a major drivetrain repair to deal with.

Question: What is the most cost effective approach to repowering a broken, high-mile LB7 powered truck under the following circumstances? Is an LB7 spare advisable, or are there any advantages to using componants from an LLY or LBZ drivetrain? This will affect what spare I buy.

My thought is to buy a complete drivetrain like this,

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&ih=002&sspagename=STRK%3AMEWA%3AIT&viewitem=&item=120065703983&rd=1,1

selling the extra parts I don't need to defray initial costs, such as computers, harnesses, intercoolers, etc.

1) 'Bottom end' problem - crank, bearings, rods, etc. (Longblock/heads swap from LB7 or LLY donor, reusing all LB7 accessories, wiring harness, computer, turbo, non-EGR LB7 exhaust manifolds, etc.)

2) 'Heads' problem - cracked head, head gaskets, losing coolant, pressurizing coolant system, overheating, etc. (At these miles, probably swap entire motor similar to above.)

3) Turbo failure. (How interchangeable are LB7, LLY, LBZ turbos?)

4) Transmission failure. (How model year interchangeable are Allison 1000s, TCMs, etc.)

5) Transfer case failure. (How model year interchangeable are tcases.) I won't own floor shift models anymore due to higher rebuild costs and scarcity of donor used cases/parts.

[AndyL]

I'd say your early, each one will likely last 300K.

Injector/Turbo/Tranny problems are still MUCH easier to replace individually. I would bet the core "innards" will last longer than 300K with proper care.

[Mark Rinker]

I hope you are right! The reality is that these trucks are pulling heavy loads and working hard every day. Some say that it may shorten their lifespans, others say it may lengthen it...but I think its fair to say that I am going to see componant failure along the way, either way.

Having a 'spare' tranny, tcase, turbo, etc...allows for a planned replacement by a mechanic (labor only at the time) and not a panic trip to the dealership for an expensive part AND labor. I have found that most dealerships are not stocking DMax componants and you can wait days for Tcases, waterpumps, etc.

With my recent luck, I am trying a reverse karma zen thing. "If I have the parts on the shelf, ready to go...maybe they won't break!!!" If and when they do, I'll be ready.

[AndyL]

Nothing like being prepared, I'm with ya! But perhaps waiting would net you a LBZ spare once finally required?

Or:

I still think your replacement should be a C4500 CAT 7.2!!!

[Mark Rinker]

Now you are with me...but...IF I were to snag an affordable LBZ drivetrain complete, how useable would the componants be on my two LB7s?

i.e. The transfer case will swap in, no problem. The turbo? Nope. Waterpump? Not sure...

What I'd do is tear the whole unit down to the componants I want, shelve them, and sell the rest. I envision a bare longblock, turbo, waterpump, IP, tcase, transmission - all prepped and ready to go. All the rest would get resold a la carte to defray the costs of the other componants.

I think the easy answer is to find a low mile LB7 drivetrain and I know everything will work!

[AndyL]

Surly you wouldn't bolt a 300K mileage water pump onto your standby engine?

How about the CAT?

Have there been any reports of anyone "wearing out" their Duramax?