John3406 Posted February 10, 2021 Share Posted February 10, 2021 Any big cam 4 experts here? I have a bc4 stc engine. For about a year now the jake on the front head didnt work. So today i decide to look into it. Got barely enough oil for the rockers and certainly not enough for the jakes. Only thing i can think of is spun cam bearing but cant think it would run a year like that. Only other thing maybe the injectors on number 1 and 2 are leaking to much oil and not enough left to supply the jake. Any ideas? Quote Link to comment https://www.bigmacktrucks.com/topic/65856-cummins-big-cam/ Share on other sites More sharing options...
theakerstwo Posted February 10, 2021 Share Posted February 10, 2021 If the injectors was fed oil from the cam brg then that could be the problem but the injectors are getting their oil from a line that goes in the top of the rocker box. and if that was losing that much pressure them at idle the stc would not be advancing the timing because it depends on that supply from the out side line.Could be a bad cam brg but if its spun the brg most of the time the paint will be burnt on the outside of the block next to the cam brg.I am no expert but did put in 39 years working trucks. 2 Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/65856-cummins-big-cam/#findComment-468746 Share on other sites More sharing options...
John3406 Posted February 11, 2021 Author Share Posted February 11, 2021 Yeah you're right i didn't even think about the injectors getting oil from that line. I think about the only thing it can be is a cam brg turned enough to almost block the hole off. Probably a matter of time before it turns more and completely blocks it Quote Link to comment https://www.bigmacktrucks.com/topic/65856-cummins-big-cam/#findComment-468777 Share on other sites More sharing options...
fjh Posted February 11, 2021 Share Posted February 11, 2021 These had a an issue with the piston coolers breaking off as well !They are plastic! Another easy place to look ! Just sayin! Quote Link to comment https://www.bigmacktrucks.com/topic/65856-cummins-big-cam/#findComment-468782 Share on other sites More sharing options...
John3406 Posted February 11, 2021 Author Share Posted February 11, 2021 2 hours ago, fjh said: These had a an issue with the piston coolers breaking off as well !They are plastic! Another easy place to look ! Just sayin! I have had that people before on big cams an n14s but when that happened i dropped oil pressure. This engine still has good oil pressure but i will definitely pull the coolers and check. Thanks Quote Link to comment https://www.bigmacktrucks.com/topic/65856-cummins-big-cam/#findComment-468788 Share on other sites More sharing options...
14cxu613 Posted June 26, 2021 Share Posted June 26, 2021 O-ring on the line into #1 head Quote Link to comment https://www.bigmacktrucks.com/topic/65856-cummins-big-cam/#findComment-475837 Share on other sites More sharing options...
Bliue dm Posted June 26, 2021 Share Posted June 26, 2021 Is the jack brake heads themselves leaking? Quote Link to comment https://www.bigmacktrucks.com/topic/65856-cummins-big-cam/#findComment-475869 Share on other sites More sharing options...
John3406 Posted June 29, 2021 Author Share Posted June 29, 2021 On Fri Jun 25 2021 at 7:39 PM, 14cxu613 said: O-ring on the line into #1 head What oring are you speaking of Quote Link to comment https://www.bigmacktrucks.com/topic/65856-cummins-big-cam/#findComment-476040 Share on other sites More sharing options...
John3406 Posted June 29, 2021 Author Share Posted June 29, 2021 On Sat Jun 26 2021 at 12:05 PM, Bliue dm said: Is the jack brake heads themselves leaking? No but you can pull the solenoid out on the jake and start it. Barely any oil comes out. Hardly enough for the rockers Quote Link to comment https://www.bigmacktrucks.com/topic/65856-cummins-big-cam/#findComment-476041 Share on other sites More sharing options...
14cxu613 Posted June 30, 2021 Share Posted June 30, 2021 O-ring under the oil lines coming into the head Quote Link to comment https://www.bigmacktrucks.com/topic/65856-cummins-big-cam/#findComment-476091 Share on other sites More sharing options...
14cxu613 Posted June 30, 2021 Share Posted June 30, 2021 I’m trying to think what I did to fix my big cam iv when it happened. Did you check the springs In the jake housing? Quote Link to comment https://www.bigmacktrucks.com/topic/65856-cummins-big-cam/#findComment-476092 Share on other sites More sharing options...
John3406 Posted July 3, 2021 Author Share Posted July 3, 2021 On Tue Jun 29 2021 at 8:47 PM, 14cxu613 said: I’m trying to think what I did to fix my big cam iv when it happened. Did you check the springs In the jake housing? I took the whole jake housing off. Started it up and barely any oil comes out the jake oil feed hole on top of rocker box Quote Link to comment https://www.bigmacktrucks.com/topic/65856-cummins-big-cam/#findComment-476289 Share on other sites More sharing options...
Big R Posted July 3, 2021 Share Posted July 3, 2021 How much oil pressure is needed for jakes to function properly? Quote Link to comment https://www.bigmacktrucks.com/topic/65856-cummins-big-cam/#findComment-476290 Share on other sites More sharing options...
theakerstwo Posted July 3, 2021 Share Posted July 3, 2021 You should be getting alot of oil out of the rocker box with jakes off.It should spray about 6 feet up so look down on the block and see if the paint is discolored at that cam brg.It may have a cam brg bad. Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/65856-cummins-big-cam/#findComment-476305 Share on other sites More sharing options...
John3406 Posted July 9, 2021 Author Share Posted July 9, 2021 On Sat Jul 03 2021 at 8:16 AM, theakerstwo said: You should be getting alot of oil out of the rocker box with jakes off.It should spray about 6 feet up so look down on the block and see if the paint is discolored at that cam brg.It may have a cam brg bad. Yes thats what i was thinking but the paint is not discolored. Quote Link to comment https://www.bigmacktrucks.com/topic/65856-cummins-big-cam/#findComment-476567 Share on other sites More sharing options...
John3406 Posted July 9, 2021 Author Share Posted July 9, 2021 On Fri Jul 02 2021 at 8:26 PM, Big R said: How much oil pressure is needed for jakes to function properly? Im guessing alot more than i have on that head. The other 2 heads are fine Quote Link to comment https://www.bigmacktrucks.com/topic/65856-cummins-big-cam/#findComment-476568 Share on other sites More sharing options...
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