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wallynm's avatar
wallynm
Explorer
Oct 08, 2013

CAT HEUI Oil leaks- UPDATE

This is what I posted to RV Service review which updates this topic.

RV SERVICE REVIEW

I understand this was a common problem with school buses that had this engine. The defective part was a rubber hydraulic hose about 9 inches long and it was leaking at the metal crimp joint on the end of the hose. Thanks to all that responded.

Original Post


We are having a severe oil leak problem form the high pressure side our HEUI unit on a 3126 CAT. Any one else having a similar problem. Unit is 2002 with 90,000 miles. Shop foreman states this is a common problem with this vintage CAT. So much so that CAT has a standard improved "UPDATE" package available to fix it. My analysis is that it must really be a common problem because they stock the "UPDATE" improved repair package for over night delivery. Overnight delivery = we sell a lot of them so stock them. More later
  • If I remember correctly leak was usually in HEUI line between pump and head.When you bought line it came in a updated kit that contained line o rings and I think some other small parts.Been a long time since I have done one as last buses have cummins engines.Wasnt a big job in a bus but would suspect a bigger thing in a motorhome due to access.
  • Dakdave,

    Do you have any info on exactly what was replaced and the labor involved? Tech bulletin?

    That would likely help Wally and perhaps others as well.
  • Wally,

    In that thread, the OP's final post give the root cause of his oil leak: "Those covers, (one of which has the oil filler tube attached), have something to do with,(or contain/are push rod guides?, cam followers?. (Since there are three covers, apparently two cylinders are served by each)."

    Doesn't sound like a HEUI pump.

    But, you are correct-- one of the posters (Charlie) did have the leaking HEUI pump you are talking about.
  • Wally,

    At least on RV's it is either uncommon or not expensive to fix, as there is very little discussion on it.

    Did a quick look through the topics of the 108 posts on the Diesel RV Club website-- sub-group lubrication and did not find anything. Might bear a closer look through-- I am being called to dinner.

    http://forum.dieselrvclub.org/index.php/board,13.0.html
  • I would call the CAT hotline and ask question do not tell them your rig is in the shop. Next I would visit this site:
    http://forum.dieselrvclub.org/

    I would also send out a request to Brett Wolfe. He has a 3126B, see what he says.
    But I have not hear what you have describe. It is possible, that the hose/o'ring are just getting old and need replacing.
  • Our school buses had these cat motors.I think that they all had the oil leak and update,some sooner than others.Most of ours were warranty items.
    dave