More Lives for a CAT 3126

[guest]

What can you do to a CAT 3126 250hp in an FL80 with 470,000 miles that is currently running fine to make it run that way longer? It's mated to an Eaton 6 speed. This engine has not been run with synthetic oil, nor have oil additives been used. Recent oil analysis shows no coolant, shavings, etc. Mileage is good (about 10 mpg) and power is good. I know there are mixed opinions about the 3126 and I am not asking whether anyone likes or dislikes the engine. What I am asking is what specific preventive maintenance items would you do to the motor at that mileage to make it more reliable? Assume that the filters and fluids are replaced on schedule and CAT filters are used. Switchout of rubber lines with steel braid has been done and valve adjustment has been done on schedule. No leaks anywhere on the engine. It has fresh hoses, belt and alternator and one injector has been replaced.

Would you replace the rest of the injectors?

New head, pistons, rings?

New main bearings and rod bearings?

What else would you do to the engine, if anything (don't say replace it with a Cummins)?

Would you look for a new engine if you could get one for under $10k?

How much would you invest in a rebuild?

Assuming you can't you do an in-frame rebuild on it, why can't you?

Other than the parts mentioned above, what is there in the engine to break in a high mileage engine that might make sense to replace now rather than waiting for it to break? I just hate the idea of something like an injector tip breaking off and causing a chain reaction that messes up the whole motor.

Would you switch to sythetic oil?

Is there any fuel additive that could realistically give me more service from the engine?

Would you lower any of the maintenance intervals (I am changing oil at 10k right now)?

When people talk about rebuilding this engine, they talk about a long block rebuild, but why wouldn't I use the block from this engine if it's running fine and I can take the downtime?

I don't want to get rid of the truck, it's too clean and I simply would not get what it's worth (to me) anyway. Even if I put $15,000 into replacing the engine, I would still be happy with the truck and my investment in it. I would just rather spend a little money now that more money later since I know that this engine is nearing a mileage level where lots of people start having problems.

Thanks.

 

[davekc]

I will attempt to answer most of your questions. I personally like the cat for a smaller engine. A kw we have has one with 450,000 and no problems, and we have a freightliner with 900 plus before it was rebuilt. Rebuild has 75,000 on it now and no problems.

Your questions;
Would you replace the rest of the injectors?
A; depends on the result of a dyno test

New head, pistons, rings?
A: are you using oil, and if so, how much?

New main bearings and rod bearings?
A: oil test and consumption rate will answer this one.

What else would you do to the engine, if anything (don't say replace it with a Cummins)?
A: depends on what you have replaced, and what the hours are.
Idler pulley, roller bearing assembly on Vbelt, have water pump tested.

Would you look for a new engine if you could get one for under $10k?
A: Depends if it is new, remanufactred, or rebuilt

How much would you invest in a rebuild?
A: Somewhere between $6,000 and 7,000

Assuming you can't you do an in-frame rebuild on it, why can't you?
A: depends on whether they can get to the back cylinders. Most require a out of frame

Other than the parts mentioned above, what is there in the engine to break in a high mileage engine that might make sense to replace now rather than waiting for it to break? I just hate the idea of something like an injector tip breaking off and causing a chain reaction that messes up the whole motor.

Would you switch to sythetic oil?
A: with your stated milage..........no

Is there any fuel additive that could realistically give me more service from the engine?
A: yes........lucas oil additive

Would you lower any of the maintenance intervals (I am changing oil at 10k right now)?
A: No

When people talk about rebuilding this engine, they talk about a long block rebuild, but why wouldn't I use the block from this engine if it's running fine and I can take the downtime?
A: I would use what is in the truck already. The only reason they wouldn't use your block is if there is damge to the cylinder wall

I don't want to get rid of the truck, it's too clean and I simply would not get what it's worth (to me) anyway. Even if I put $15,000 into replacing the engine, I would still be happy with the truck and my investment in it. I would just rather spend a little money now that more money later since I know that this engine is nearing a mileage level where lots of people start having problems.
A: without knowing anything else about your truck, I would have it rebuilt when the time comes. New is ok too, just depends if the age of the truck warrants a $15,000 investment. Shop around, new engine and labor can be had much cheaper than $15,000

There is my take based on my experience with them
Hope that helps
Davekc
owner
20 years

 

[guest]

Thanks for the quick reply. One thing in your post that got my attention was the recommendation to use Lucas oil additive. I know everyone has an opinion on this topic, but I thought that the latest thinking on this issue is that oil additives can do more harm than good because the chemistry in the multi-grade oils is already carefully balanced for the best performance. I thought that oil additives like Lucas can cause oil foaming. It's a pretty compelling argument when you hear that if there was something in Lucas that could improve upon the balance that is already in Rotella or Delvac then Shell or Mobil would have already engineered that into the oil. In other words, what does Lucas know that Shell and Mobil don't know? Like I said, I know everyone has a different take on the oil additive issue, I've just never read of an engine manufacturer recommending oil additives, and you would think that if there were a product that would truly make an engine run better, the engine manufacturer would suggest you use it.

As for the rest of the information in your post, that is very helpful and thank you.

It sounds like I should have a dyno run on the engine and just keep an eye on the oil analysis.

As for an engine under $10k, I occasionally see new engines that were purchased in bulk in some kind of surplus deal that can be had for under $10k, with no core charge. My thought there is to take as many spare parts from my current engine as I can, so that when something on the new engine breaks I will have a cache of parts that I can use.

 

[davekc]

With regards to Lucas, it is recommended by Cat and Cummins for the reduction of dry starts ect. You will also notice a 4 to 5 lb increase in oil pressure. In addition, it doesn't void warranties ect. Most oil change places carry it, including your dealer.
Davekc

 

[rolling force]

I agree with Davekc about Lucas. I have an old 3126 and when the oil gets down a gallon I refill it with Lucas and you can feel and hear the difference in the motor. It really quiets down and becomes smooth.

I wouldn't use more than a 5 or 10% mixture in extreme cold weather though.

 

[RichM]

I use Lucas in a Cummins C 8.3 and I have actually see the idle rpm increase slightly. I believe this is due to less friction on the bearings and rods.