Rebuild or Buy New Engine
 

I have a 1985 Freightliner Day cab with a 350 big cam Cummings engine, mileage unknown, but will soon have to make a decision on to:

1. Rebuild
2. Buy a Used Engine
3. Buy a Rebuilt Engine

I haul logs for a living, longest radius I go one way is 150 miles, and avg 1500 to 2000 miles a week. The reason I am asking this question is the 350 seems to be losing some of its get up and go.

I know it has quite a few miles on it, but am unsure as to what would be my best route.

Short answer - it depends. Have your mechanic look it over from top to bottom, and he should be able to tell you what the best route is.

I think having someone to check it out is a good idea. If it needs to TLC and you plan on keeping the truck, you may want to either rebuild the engine you currently have or buy a new one. Personally, I don't like the idea of buying a used engine. You never know what you are getting. You can do an oil analysis, inspection and dyno. That should give you the information you need to make a decision.

Re: Rebuild or Buy New Engine
 

If your engine does need a rebuild, it would probably be better to buy a reman/rebuilt unit. The downtime would definitely be less than waiting on a rebuild.

You will probably be down about 5 days or so if you do a rebuild, depending on availability of parts and scheduling. If you buy a remanufactured engine you could probably get turned around in 2-3 days.

Re: Rebuild or Buy New Engine
 

1. How much money do you want to spend?
2. How long are you going to keep the truck?
3. Would the engine rebuild be worth more than the truck and does the 21 year old truck have enough life left in it?

I've been in this situation before as have other guys that I know. You may be better off buying another tractor, keeping this one and fixing it later. I have regretted getting rid of every tractor that I got rid of. Should just keep them, make repairs, and keep them close to home. Good luck with your decision.

Whether you decide to rebuild it or buy a re-man, I would consider moving up to a 400 BC. If you rebuild it, there are not many parts differences between a 350 and a 400. The pistons have a different compression ratio but, you would be changing them anyway and they should be the same price. The injectors, fuel pump calibration, and the timing key on the cam is different. That should be all you need to change, and hauling logs you could probably us the power increase.

Heck, he could probably order some of those nifty parts from Pittsburg Power and build a 700hp engine. 8)

Approximately how much should it cost to do the rebuild. Taking it from a 350 to a 400. I cannot afford to do this just yet, but would like to get an idea on how much I need to set aside for this including labor, and for the week I would be down.

I am not expecting an exact for sure figure, but an estimate.

This forum is so great to learn from. I really appreciate the advice and info from everyone.

Has anyone ever, or know anyone who has rebuilt a 350 big cam to a 400, and if so were you pleased with the results.

I have never had a Cummins rebuilt, but I had a Detroit 60 rebuilt inframe for $7300 and I had a 425 Cat that I was shopping around and couldnt find anyone to do it for less than $11000. I sold that truck to the junk man. I would say the Cummins would be closer to the $7300 but probably not cheaper, parts for the Detroit usually are less expensive.

Probably around $10,000 would be a good estimate. I would use Cummins brand parts instead of after-market, for the pistons and liners especially.

I know a guy who rebuilt a Cummins 500 about a year or two ago and I believe he paid about $8,400. But it depends on what you do. I would count on $10,000. If you are going to rebuild the engine, I would replace everything, such as the turbo.

What about a reconditioned engine? We have one of them in one of our trucks and it's better than a new engine.

A reconditioned engine would probably have you down for a shorter time period than doing an in-frame.

Re: Rebuild or Buy New Engine
 

I owned a 350 BC 2 for 18 years and inframed it once and had to put a cam in it earlier this year. I've since sold the truck, But it was running very good.

What I would advise is to have someone who knows this engine check it out. You may just need the engine tuned up, Or you might have a bad injector, fuel pump, etc.

If you've lost power suddenly it might be something simple.

If you're due for an oil change get it analyzed if you can. If you change it yourself look at it close and smell it for diesel contamination or signs of coolant.
Always watch it at the dip stick too, by feel and smell for diesel contamination. Or say, it used to use a gallon of oil a week and all of a sudden it's not. It may be diesel getting into the oil from a bad injector or ?