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tropical36's avatar
tropical36
Explorer
Aug 04, 2016

Engine Oil leak Cat C9

OK folks, you just might be my last hope for finding this on our new to us Coach.
Here's the symptoms.....
Clean Engine can idle for an hour or more without seeing any leaks. Then with going down the road, it's running along the oil pan and even getting on the back of the rock guard and a little on the passenger side of the toad, as well. When you stop, it might drip a few drops, but that's about it. Consignment sale Dealer dropped the oil pan and installed a new gasket at no charge. Didn't help much if at all. Then a Cat service center where we're camped for the night, first decided in was the slobber tube and was about to extend it lower. Then changed their mind and now most sure it's at the front of the engine up high and with a plug with an 0 ring under a lot of pressure because of the HUEI pump and at the opposite end of the starter. This theory is for it running down a little ridge on the driver's side and then down over the front to the starter below. The rear main seal has been ruled out and fortunately for that.
Sooooooooooooooo, anyone experienced this and what might have been found, to be the real culprit?
Class A

4 Replies

  • tropical36's avatar
    tropical36
    Explorer
    Aug 04, 2016
    wolfe10 wrote:
    Sorry, but not sure over the internet we can do a better job than a Caterpillar dealer (at least let's hope not).

    At your next oil change, do "Calibrate the engine oil dipstick". It is not a Caterpillar part, and if inaccurate and you overfill the crankcase, it WILL come out. But usually from the crankcase breather hose.

    Actually I'm still hoping and it wouldn't be the first time for that to happen, as we have some pretty good minds on here and especially after years of ownership. Even at that, some dealer might have found a difficult problem that can be passed on.
    Just had an oil change and with what was put in, it should be a little shy of 34 qts actually and at least that's what the book says a rear sump takes with filter.
  • tropical36's avatar
    tropical36
    Explorer
    Aug 04, 2016
    Preacher Man wrote:
    Check where the oil dipstick goes into the engine block. There is a portion of that tube that is replaceable. Mine rusted at that point and needed to be repaired. I used some tubing, leak stopped. My dipstick is on the right side of engine/passenger side of the coach. Something worth looking into.

    Mine is on the other and opposite where the oil is coming from.
    We're going to work on that slobber tube as well and just in case.
  • Preacher_Man's avatar
    Preacher_Man
    Explorer
    Aug 04, 2016
    Check where the oil dipstick goes into the engine block. There is a portion of that tube that is replaceable. Mine rusted at that point and needed to be repaired. I used some tubing, leak stopped. My dipstick is on the right side of engine/passenger side of the coach. Something worth looking into.
  • wolfe10's avatar
    wolfe10
    Explorer
    Aug 04, 2016
    Sorry, but not sure over the internet we can do a better job than a Caterpillar dealer (at least let's hope not).

    At your next oil change, do "Calibrate the engine oil dipstick". It is not a Caterpillar part, and if inaccurate and you overfill the crankcase, it WILL come out. But usually from the crankcase breather hose.

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