It has the 4-390 engine.... was in a light push to fill the bucket with debris and "tink". literally tink, not loud, just enough to hear and it shut down. Thought it ran out of fuel so I went that whole route filling the tank and bleeding everything to no avail. OK I said.. lets try a little either, nothing happened. So I pull the valve covers and nothing is moving, an occasional quiver but that's it. Sooooo my questions are: Is this an interference engine or am I gonna get lucky there? Next, has anyone had the keyway on the cam gear sheer off since none of the valves are moving and the injection pump is still trying to inject? Lastly (maybe) do you think I can get that gear off the cam (if that's the problem) easily without taking all the gears off? Thanks
I'm so sorry man. The experts will be along soon, but I thought most/all diesels were interference engines due to the high compression ratio. Interested to hear the real answer. On the bright side, you shouldn't have any problem finding any parts you need for that Case/Cummins.
OK.....Had to get my buddy to pull me 1/2 a mile to get it close to my garage.... So I got it all apart..........It snapped the camshaft right behind the first bearing and the cam gear must have wobbled just enough to knock half a tooth off which fell onto the crank gear and took 2 teeth off that before they fell out of harms way. The injection pump gear and the oil pump gears are fine. The hardiest part I think was draining the hyd oil from the frame so I could get the hyd pump off...... got two baths on that deal, I'm gonna drill that 2" plug out in the center for a 3/4" pipe plug to make any future draining a little simpler... The rest came apart fairly easy. I guess I'll have to cut the crank gear and split it to get it off, I don't see anyway to get any puller on that gear. Not sure if it hurt any valves in the process yet. Anyone know of a reasonable priced aftermarket supplier for those parts?
Those cams don't normally do that, there may be something more involved that either caused the cam to seize or went through the gears, or maybe a valve got whacked by a piston.... Or not.
Does the Killer Dowel Pin apply to the 4BT?
The dowel pin is fine......... yea, thinks that make you go hummmmmm. We all like pictures.
I put my swami hat on and I am receiving a mental image of some hard object going between those two gears, thus causing the cam failure... may be in the bottom of the pan....
I hear what your saying... I do.... but we did a lot of fishing with the magnet and all we came up with was the teeth that you see missing. So who knows, but I don't see something between the teeth breaking the cam on the other side of that bearing. I can see however the cam breaking and the cam gear angling enough to break that half tooth off and that busting the crank gear. Further investigations will continue for sure and in the back of my mind I will always be wondering what the exact cause was. Hopefully I'll know more when I pull the cam out.
Looks like a whole lot of wear in that front cam bearing.
Yes..... Definitely is. That's why I think once the Cam broke, the gear was able to **** a little bit and break a tooth. At least that's my take on it. I haven't put a mic on it yet... but I will for sure. I'm gonna do a leak down test on it to see if any of the valves were hurt in the next day or so then make up a plan of attack...lol
Before you do a leakdown, the pushrods on several cylinders are most likely bent as those are an interference engine and when the cam stops and the crank keeps moving things get bent.
Look carefully for a case bolt missing. What you have is not uncommon in a Dodge truck engine. It may be worth the trouble to remove the oil pan and look for a loose bolt.
pushrods are out and all are fine.... possibly I got lucky. Tink..... not sure what you mean by a case bolt? I'm thinking I'm gonna have to pull the pan to look at the lifters. I don't want to put a new flat tappet cam in without first making sure the lifters look like new. So if you can tell me what to look for I'll make sure I do it.
Case bolts hold the front case onto the block. I never have worked on a 4bt. How do you replace the camshaft without removing the lifters ? Those lifters need to be thoroughly inspected for damage and excessive cupping where the cam lobe contacts them. I have never replaced a camshaft without installing new lifters and camshaft bearings. You may find reading this thread on 4BTSWAPS.COM interesting. Putting 4bts in Dodge trucks is quite popular. http://www.4btswaps.com/forum/showthread.php?1403-4bt-s-amp-broken-camshafts-is-it-common
it's a 4B... not the turbo model 4BT. I also have never replace a cam without the lifters but the owner seems to think it's not a problem as long as they aren't cupped. I have always been under the impression that on a flat tappet cam you replace them as a set and that's what I will do so it all breaks in properly. I have replaced cams without replacing the bearings, however if the others look like the front one they all need to be replaced. The front case bolts are all there and tight. I'll check that read out, thanks.
Found the culprit when I pulled the oil pan....... never noticed the missing cover bolt. From this spot right above the oil pump
That sucks.... err... might want to get the crank magnafluxed and checked for straightness?
Well I think I got pretty lucky that the cam snapped and killed the engine instantly, only took those teeth off that the pictures show. I put a dial indicator on the front of the crank and it's perfect. I spins with no tight spots also. No loctight on the cover bolts, another one was loose also. They will have loctight on them when it goes back together..
Your crank might be ok. But checking the small area where the gear sits is not enough while it's in the block. Getting it magnafluxed would be the best way to know for sure because a cast iron crank is going to crack/break before it bends to far. And while some of the shock went to the cam it also went to the crank. Yes it's more time and money but your half way there now. But that's up to the owner.