Hey guys, I have a Peterbilt with a 3306 which has around 180,000 miles. Truck runs strong but it’s burning through a good amount of oil and blowing some smoke. It blows smoke when it’s idleing for a while and when you go to accelerate it blows out but clears up when your cruising. It also smoke on deceleration down steep hills. When I go to get back on it, it blows out a big puff of smoke. It always seems to clear up when I get it up to speed. I’m looking for advice on how to test it and figure out where is the problem. I’ve been told it could be the rings or the valve seals, but I can figure out how to setup and do a leak down test. I would think if it was the pistons it would have a loss of power but it seems strong to me. I’m new to that site but I appreciate any help I can fer
If you have very many miles/hrs on the engine oil you could take a sample and have it sent out to be tested. If the rings are bad you will likely see high levels of soot in the engine oil. As for low power, probably not, I’ve got a Cummins that had all the rings broke on 3 out of 6 cylinders and it started easy and had plenty of power but it pumped a gallon of oil out the blowby tube in 100 miles at highway speed. Which leads to the next point, either rings or valve guides will cause a higher level of blowby than Normal.
Be sure to check the turbo and make sure it’s not leaking past the seals
I just had the turbo rebuilt. Smoked like it is now before the rebuilt. I’m looking for any way on how to test the cylinders to narrow down where the leaks coming from.
This sounds like valve seal leaks.
Thats what I’m leaning towards. Do you know how to perform a test on this engine? I read somewhere you can change out the seals with out pulling the head. Do you know if that’s possible?
I would always remove the valve cover and inspect the valve seals with a flashlight between the springs........look for cracks or a loose fit. That can be done by positioning the piston on each cylinder at TDC, then using a j-type valve spring removal tool to compress the spring (the piston prevents the valve from falling into the cylinder) and remove the valve keepers. This only works for the external type of seals. I have seen internal seals...........for that type the valve has to be removed which requires the cylinder head to be removed.
On a 3306? Bad Bob
Maybe? Hell I don't remember every single engine set-up...I'm old and get confused easily. I've learned that on Cat stuff you are the go to and that you will correct all of us on bad or incomplete information. Good job!.....keep up the excellent work! PS.........I love you Bob
It might have 180,000 miles but how many hours?