cat twin turbo question

May be so but you can not say this truck he is looking at has a broken ring just because of the blow by or from your experience. I know guys with over 800,000 on these twin turbo cats with no issues. The blow by is normal for these motors and just because it has some does not mean theres a problem. Like i said the only way to know for sure is to do a dyno. To many guys think just because they had issues with there Cats that every other Cat is going to have issues to.

 

3 out 0f 3 pretty good odds. I would not by one without figuring an overhaul, unless it's already had one with the upgrade rings. Not going to start a fight but we really don't know whats causeing the blow by till we tear it down.

 

Acerts normally have around double the blowby of older C15s but if you are concerned have them take it to a reputable shop with a dyno and have the blowby check, you will have to pay for the dyno yourself but unless the dealership has something to hide they should have no problem with you wanting it dyno check before you buy it.
Haney is right, all Cat truck engines have to be blowby checked under load, the keystone top ring design relies on combustion pressure behind the ring to push it against the bore to seal properly, thats why cat doesn't give specs for cranking cylinder pressure tests.

 

I recently looked at a 01 w900 with a 475 acert with 760k on it. The blowby was one of the the things i checked out and i could not see any so i got down and put my hand under the tube and i could feel a little but not much. At first i thought it was strange to see nothing coming out the tube and it might have been plugged until i felt it.

In my opinion if you are buying a used truck you should figure in the cost of a rebuild no matter what the miles are unless you personaly know it was just done. Just like this truck i am looking at it might go to 1 mil with no problems or it might only make it to 761k you never know.

 

A 2001 with an Acert ? must have hit the wrong key...

 

The dealer said the previous owner changed it out. It is a BXS 475 and its in a 2001 kw.

Not sure why he changed it but it runs good.

If i go back to look at it again i will ask them to do a print out on the ECM. I am taking my time when it comes to buying a truck.

 

Another option might be to buy the Caterpillar Advantage Plus warranty if the engine is eligible. I did that on my present truck, and while it didn't cover everything on my overhaul, it did cover a lot. I don't disagree with the idea of putting away enough funding to cover an overhaul on a used truck, it's a good idea, this is just an additional option. Stay away from the aftermarket warranties, it's wasted money. Don't ask me how I know!!!

 

Caterpillar no longer is concerned with blowby volume regarding warrantable failures. CAT now uses engine oil consumption to verify a problem relating to excessive blowby. If you have broken rings in a BXS/MXS/NXS you will see a "locomotive" puff out of the oil fill tube, you will also develop a check engine light under load, if you back out of the load and right back into the accelerator the code will go away. The code is caused by the oil filter becoming plugged with carbon that has bypassed the piston rings and when you snap the throttle it sends a pulse through the filter relief and re-seate the relief.

These have been proven repeat offenders. One such MXS would run on all 6 cylinders seperatly untill it wouldn't run on #2...low and behold #2 had broken rings. It also ate alot of engine oil as well.

These engines commonly have more visable blowby but unless you consume engine oil don't worry about it.

 

Worst engine cat ever built

 

The BXS was the first design and the pistons had problems, they were the first truck engine to use one piece steel pistons and had alot of broken and or scuffed rings. Half way through the 05 model year they changed piston designs and some other things when the MXS came out.