Any tips on changing a broken cam in a Cummins 4bt engine
You gotta hold the lifters up or they'll impede cam removal, and/ or fall into the nether reaches of the motor. I used wooden dowels and rubber bands. For everything but valve adjustment, and possibly timing gear alignment, you can use 6bt instructions. Tons of info on 6bt motors out there. I'm not quite sure how you'll get the back half out.
If you change the cam you need to change the lifters too so you might as well pull the motor as the lifters go in from the bottom. be sure to check your cam bearings
Dave the engine doesn’t have 5 hours on it. The killer dowel pin let go & fell into the cam gear. You really think the engine needs pulled & replace lifters. It’s not nowhere near broken in yet. Just wondering
How well do you think you will sleep knowing you didn't do all that was necessary to make sure the engine is back together proper?
Not saying you cant do it but time wise you could pull the engine and and would be a lot easier in the long run what is it in
It’s in a Dresser dozer. The engine is a new rebuild all new internals. It’s not got no way 5 hours of run time. The killer dowel pin fell into the cam gear causing cam to break.
Who rebuilt the engine? I find it hard to believe the dowel pin falling out in 5hrs, but it should have been taken care of or atleast noticed that it was loose in the block while it was apart. Extremely common issue well documented. All the KDP failures I've seen just crack the front cover below the fan hub mount. Broken cams I've seen were from internal front cover bolts falling out and cam retainer bolts. I've also seen cam gears come apart from improper installation, (heating with a torch instead of hot oil bath) You most likely have some bent valves as well. I'd be pulling it out, stripping her down, thoroughly inspecting and starting over. Take your time and double check everything.
Agree if the cam broke and the engine made even on revolution I would be very surprised if at least one valve was not bent and if a valve is bent I would be worried about damage to the piston.
I’ve got the front cover off & the only thing I see missing is the KDP. I’ve also got a broken cam. So I was just assuming that the kdp fell into the cam gear breaking the cam. I may be wrong. It may have bent valves also I’ve not tore it down that far. Was just seeking some advice.
who rebuilt it ?? what kind of warranty is on it
It was purchased from a Diesel engine builder out of Michigan. Had a 3 month warranty on it. But do to my work schedule then warranty was long gone before ever installed. I don’t know really what to do with it now. Really never even crossed my mind about damage valves or even pistons. I knew all this of course but I was so aggravated & dead set on just a cam change. Guess I’m gonna have to weigh my options on this one now.
Sorry for the bad luck with this engine. Just need to know what a "KDP" is, I can get confused with the abbreviations at times. Just for fun I would contact the engine builder after you get the engine apart and send them some pictures of the damage never know if they will help you with at least some of the parts.
KDP is Killer Dowel Pin, just do a search and it is all over the internet. I agree it is well documented and any rebuilder should have addressed it 20 years after it was identified (?) I would go back to the rebuilder and tell them the story if you haven't already. If they refuse to play ball then tell us who it is so we can avoid them.
When I rebuilt B series engines, I always took a sharp prick punch and staked the aluminum housing in 2-3 places around the dowel hole. Never had one back out of the housing.
Well I missed that one, never had anything to do with the small Cummins engines, other than the 3.9 liter engine that Case used in the 1845C Skid Steer that one is a 1989 that is still working at the quarry. Watch now that I said that it will go bang this week!