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Thread: My boat needs to quit smoking.

  1. #1
    GREENLEAF13
    I'll try and keep this brief. I'm running a BBC with banks twin turbo deal on it, the thing smokes like hell out of the left bank ONLY under 1500 rpm. The engine was fresh last fall, everything was rebuilt except the turbo's, I'm been suspecting a leak on the compressor side of the turbo but that would cause it to smoke out of both sides.? I pulled the left head and found oil in #7. I had new guides installed, tossed the umbrella seals, and put positive valve seals on all 16 valves,.. still smokes. My machinist says if it were rings i woudnt have had oil on top of the piston, must be valve seals.? I've probably got 15 hrs of tuning on this motor and it smoked when i first started it last fall and still smokes now. The only thing that i've noticed is it will smoke much less with less timing (Ignition) and more with more advance. WTF is going on here? engine runs great but the oil burning is just plain embarrising. Any thoughts?

  2. #2
    obnoxious001
    I would have the turbos checked and/or rebuilt. I have been around quite a few turbo engines, if a seal starts leaking, it can be quite dramatic, however I have seen some that smoke on idle and clean up at speed. You might also try leaking down the engine to explore for problems. What kind of breathers do you have?

  3. #3
    GREENLEAF13
    I'm running one tall stye breather on each valve cover, not sure what thier called. Could crankcase ventilation be the problem? Doesnt smoke at all when you get on it or while cruising.

  4. #4
    058
    Check your turbo drain lines for any blockage or restrictions. Sounds like the oil might be backing up into the housing. If this is a new or re-done set up check for the placement of the drains, they need to be above the oil level in the pan. Also make sure your drain lines are big enough, seen a couple setups that the drains were too small causing the smoke screen.

  5. #5
    ghittner
    Nicotine patch

  6. #6
    GREENLEAF13
    Check your turbo drain lines for any blockage or restrictions. Sounds like the oil might be backing up into the housing. If this is a new or re-done set up check for the placement of the drains, they need to be above the oil level in the pan. Also make sure your drain lines are big enough, seen a couple setups that the drains were too small causing the smoke screen.
    I'll double check my drain lines tonight, when i installed them I made sure they were straight shot down hill to the pan. The lines themselves are 1/2"or 5/8" i believe, fit over the stock elbows on the Rajay turbo's.

  7. #7
    DUCKY
    Check your turbo drain lines for any blockage or restrictions. Sounds like the oil might be backing up into the housing. If this is a new or re-done set up check for the placement of the drains, they need to be above the oil level in the pan. Also make sure your drain lines are big enough, seen a couple setups that the drains were too small causing the smoke screen.
    I second that...Also make sure that your drain fitting is at least 1 " above the oil level in the pan, and that it's not right in front of a crank counterweight that is trying to throw oil into the fitting..... You may also take a look at the inlet side, and be sure that you are not trying to overload the turbo(s) with oil. They don't need much. I have a -3 line with a welded up fitting and a 3/32" hole drilled in it feeding the turbo on my sand rail. 3/32" doesn't seem like much, but at 50-80 psi, it's a lot more than you think.....

  8. #8
    obnoxious001
    I second that...Also make sure that your drain fitting is at least 1 " above the oil level in the pan, and that it's not right in front of a crank counterweight that is trying to throw oil into the fitting..... You may also take a look at the inlet side, and be sure that you are not trying to overload the turbo(s) with oil. They don't need much. I have a -3 line with a welded up fitting and a 3/32" hole drilled in it feeding the turbo on my sand rail. 3/32" doesn't seem like much, but at 50-80 psi, it's a lot more than you think.....
    The Banks systems came with -6 (3/8) feeds to the turbos. Running -4 is probably fine, but all of those old systems worked fine with the standard plumbing, and Banks sold a bunch of them back then, as did PFM and Race Aero.
    I still vote for pulling the turbos and having them checked, as I said earlier. Blowing oil until 1500 probably means it pulls oil past the seal until it starts to come into zero vacuum. It probably won't fix itself.

  9. #9
    DUCKY
    I had one of the PFM systems, and it did have -6 AN fittings, but it also had restrictors in the fittings at the turbo with 1/8" holes in them..... Doubt it was factory but it worked.
    The Garrett on my buggy and the RayJay 301-E-10's on my last boat don't/didn't even really have seals on the shafts so to speak. They have a series of small ceramic discs and stainless steel separators and are easily overcome by an excessive volume of oil and unless they break, they never wear out. In fact, I could be wrong, but I have never seen a "positive seal" in any turbo I've ever taken apart (maybe 50 total)
    Just curious, is there oil residue in the compressor housing or your intake piping, or is the oil just dumping into the exhaust and being burned?

  10. #10
    Boostedballs
    Instead of pulling the turbos-
    Disconnect the drain line for the smoking turbo at the turbo and plumb the turbo directly into a container. Do the same thing for the return line except have the line come up above the intake manifold and then down into a container. This will keep it from siphoning if oil level is too high.
    Have someone put the engine under load and watch what happens. (The oil coming out of the turbo may look like milk shake because of the whipping action of the turbine shaft.)
    This test will tell you:
    A: is turbo making smoke with no back pressure on the drain? If yes, bad seal in turbo. Make sure you have a carbon seal if it's a drawthrough setup.
    B: Is drain line from crankcase blowing oil? If yes, move drain line to new location or increase the venting capacity of the engine. You can use a breather filter on both valve covers and plumb it to the compressor inlets. This will give a slight vacuum on it. Turbo engines under load can make some serious pressure in the crankcase.
    I would like to see some photos of your setup. Sometimes a new pair of eyes can shed light on something that is overlooked.

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