School Bus Fleet Magazine Forums
Home | Profile | Register | Active Topics | Members | Search | FAQ
 All Forums
 Professional Garage
 Enter Forum: Professional Garage
 Cat 3126 hard to start after sitting two days
 New Topic  Reply to Topic
 Printer Friendly
Author Previous Topic Topic Next Topic  

waverlybus
Senior Member

94 Posts

Posted - 09/21/2017 :  09:03:04 AM  Show Profile  Reply with Quote
HEUI cat 3126 cranks but will not start after sitting over the weekend unless you crank the hell out of it. When it does start it will fire on all but one cylinder and will run out of it and run fine after about a min of idling. replaced check valve on the back of the head, it was definitely bad but problem is still occurring with same symptoms. fuel filter stays full of fuel and oil is on the full mark. checked flash codes on dash and I get a 61 which I believe is overheat.
(we are a rural school district with 90% gravel roads, terrible place for a rear engine bus we constantly have to wash out the radiator and I replace the engine air filter every 2-3 weeks.)
Does anyone know if I can pressurize the injector oil rail and be able to see if I have a bad injector o-ring on the oil or fuel side? I believe it to be a problem with injector oil pressure but I do not have a scan tool to check pressure nor do I have a 6000psi gauge to manually check it. Once its running it runs just fine.

aaronwilmoth80911
Top Member

538 Posts

Posted - 09/21/2017 :  09:38:11 AM  Show Profile  Visit aaronwilmoth80911's Homepage  Reply with Quote
Your best bet might be to pull the valve cover and start it and look for obvious oil pouring out from around an injector. You can disconnect the valve cover harness to disable injectors and have someone crank it while looking for oil around injectors as well.
Go to Top of Page

RonF
Top Member

867 Posts

Posted - 09/21/2017 :  12:24:14 PM  Show Profile  Reply with Quote
I had this problem a few years ago, had to replace all 6 injectors. Mine big giveaway was oil in the fuel filter.
I don't think on a 3126 you will be able to see oil leaking if you crank it with the harness unplugged. The orings are in the head, not on top of the injectors.

US Army retired CMBT
Go to Top of Page

waverlybus
Senior Member

94 Posts

Posted - 09/21/2017 :  1:06:39 PM  Show Profile  Reply with Quote
I tried looking for oil pooling/leaking by the injectors with the harness unplugged and no leaks seen. I also replaced the fuel filter and it didn't seem like the fuel was darker. I had a dt466 do this and the fuel was black, reringed the injectors and it took care of my problem there but this fuel does not look like the 466's did. It did just start happening though, I will keep an eye on it, thanks.
Go to Top of Page

namao
Senior Member

Canada
89 Posts

Posted - 09/22/2017 :  1:39:20 PM  Show Profile  Visit namao's Homepage  Reply with Quote
Hello just couple thoughts, with out a scanner pretty hard to find out which cylinder or if its a fuel or hp oil issue. Couple things we use to do in the old days to find miss was first use a temp gun and check the exhaust runners to see which one cylinder is cold and not working second way was spray bottle with water , spray runners again and the working ones will evaporate the water right off, cold one will not. Once I figured out which cylinder I would start by pulling injector and checking the orings then change out injector if all else looks good. I had a c7 [3126] leaking oil into fuel recently [was very obvious in the fuel] and it ended up being orings. Bus ran smooth after and cranking to start problem was curried. Good luck.
Go to Top of Page

waverlybus
Senior Member

94 Posts

Posted - 09/25/2017 :  2:07:15 PM  Show Profile  Reply with Quote
Thanks namao, I have done this before to find a miss but I did not think to try it in this situation. I went to try this today after the bus had sat all weekend but of course it fired right up with no issue. Next time I get it to act up I will have my temp gun handy!
Go to Top of Page
  Previous Topic Topic Next Topic  
 New Topic  Reply to Topic
 Printer Friendly
Jump To:
 


School Bus Fleet Magazine Forums © 2022 School Bus Fleet Magazine Go To Top Of Page
This page was generated in 0.05 seconds. Snitz Forums 2000