georgecl Report post Posted May 6, 2021 (edited) I have a 97 beaver with a 3126 cat. It blows massive smoke out the case breather tube. RV will die after an hour from low oil due to heiu pump not having enough oil to create fuel pressure. I just figured that out. Motor runs great. Starts great. Uses maybe a quart every ten miles and thats conservative estimate. its got 30k on it. at first before i associated the oil loss with the smoke i was hopping for water in gas which wouldnt combust and cause the smoke. now that im aware its eating oil and keeping in mine the 30k miles (good rings?) im praying for a solution with the huei pump dumping oil in the fuel or a bad turbo maybe like the oil induction or return line dumping oil into the intake during forced induction. i cant see a cat motor with 30k miles having rings bad enough to dispurse oil at a rate that is quite frankly unheard of. im a youtube mechanic but i aint skered and ill tear this motor apart by myself. i know dave is the best of the best and always leans towards cat certified repairs but ladies and gentleman this is covid season and i can not afford it. does anyone (including dave) have some input on this? this thing is beautiful and runs amazing it just smokes like a siv and eats oil faster than gas literally. Edited May 6, 2021 by georgecl Share this post Link to post Share on other sites
huffypuff Report post Posted May 6, 2021 (edited) Fuel injector o-rings? Check to see if fuel is getting black from motor oil. Edited May 6, 2021 by huffypuff Share this post Link to post Share on other sites
jleamont Report post Posted May 6, 2021 If you have that much blow-by that's a sign of a piston ring problem. Due to the extremely low miles id bet one is stuck or stuck and broke on start up. Share this post Link to post Share on other sites
dickandlois Report post Posted May 6, 2021 (edited) Georgec,Welcome to the FMCA Forum ! Think it is time to run a compression test on all of the cylinders! This test requires removing the fuel injectors and they can be checked as Huff mentioned and Compression test will cover Joe's thought of a defective Ring in one or more of the cylinders. Rich. Edited May 6, 2021 by dickandlois Share this post Link to post Share on other sites
wildebill308 Report post Posted May 6, 2021 (edited) Welcome to the forum. One outher thing that they can do is when they have the injectors out look at the cylinders with a bore scope. I certainly hope not but it does sound like the symptoms described by others of a "dusted" engine. There is definitely something major when you can say "Uses maybe a quart every ten miles and that's conservative estimate." Bill Edited May 6, 2021 by wildebill308 Share this post Link to post Share on other sites
dons2346 Report post Posted May 6, 2021 I sent your post to a friend that is a Cat guy. His reply is not encouraging. His reply. "Well it could be injectors, broken oil rings, kind of a throw away motor because it doesn't have piston liners. Could be oil pump idle gear bad. Could be the HEUI pump system. Turbo could be bad dumping oil into the exhaust, just hard to say". Share this post Link to post Share on other sites
rayin Report post Posted May 7, 2021 FYI, on a different discussion forum a man had his CAT 3126 runaway and destroy itself from what sounds like a similar problem (one of the above mentioned). He had to leave their MH in TX truck stop until he figures out what to do next. Share this post Link to post Share on other sites
georgecl Report post Posted May 8, 2021 ok guys thanks! Share this post Link to post Share on other sites
manholt Report post Posted May 8, 2021 george, sorry for the "not so good news!" Time to break out the tools and good luck! Please advise us on what you find....feed back is important to other posters! Share this post Link to post Share on other sites
bm02tj Report post Posted May 9, 2021 When you find an answer be sure to post it With crankcase pressure sound like rings or a piston Share this post Link to post Share on other sites
