LDT 465 Multifuel. Andy3's Broken Camshaft

[JasonS]

Wouldn't we be seeing evidence of rod bearing failure first? A cam is not loaded nearly as much as a rod. The Cummins 5.9 only has one replaceable cam bearing; the rest ride directly in the block.

 

[o1951]

Wouldn't we be seeing evidence of rod bearing failure first? A cam is not loaded nearly as much as a rod. The Cummins 5.9 only has one replaceable cam bearing; the rest ride directly in the block.

I agree, on the surface, it would seem so. 30 years and more ago, often the cam bearings were not changed when rebuilding automotive and light truck engines. I do not know about today, as my engine rebuilding ended in mid 1980's.

The differences here are special Diesel engine. (multifuel)
Gear driven cam, which as I previously posted adds to the forces on the bearings caused by the cam lobes pushing the tappets. Chain drive forces are in the opposite direction.
Other concerns that may compound the problem are some of the oil to the bearing feeds both the IP and the compressor.

Some owners say it takes 10 seconds after starting for oil pressure to develop.

This may be fine under ideal conditions, but when circumstances necessitate "extended service intervals" beyond manufacturers recommendation, possibly with other than recommended lubricants, then weak spots show up.

Under those conditions, the oil probably had insufficient film strength, and there were brief periods of metal to metal contact. We know that properly maintained, these engines are capable of long life. One member recently posted he drives his 25,000 miles/ year, and others have posted thousands of miles of trouble free operation.

But this is civilian use, where maintenance schedules can be adhered to, and proper lubricants and filters always used.

If you have a vehicle that saw a lot of service overseas, problems with engine, transmission, transfer case, differentials should be considered. Proper lubricants and proper service will slow the progression, but once some types of damage start, even with the best servicing, they will continue, albeit at a slower rate.

 

[oddshot]

I've pulled the camshaft and lifters.

For the indicated time on this engine, I and very surprised to find so little wear on the cam and followers. Indeed, the cylinder bores and pistons show very little wear especially when compared to the amount of wear I found on the front camshaft bearing.

 

[oddshot]

Attached are pictures of the cam followers. I see that 3 of them have some light pitting or flaking and one shows signs that it has stopped rotating and the nose of the cam shaft is beginning to wear into its surface. The pitting could be attributed to anything including lack of assembly lube.

Not to bad with an "indicated" 54,000 miles. To be honest, were I to rebuild this engine with a used, but good camshaft, I wouldn't hesitate to re-use these followers.
I've taken a harder look at the drive gears on the front of this engine and have drawn the same conclusion.

Of course, I wouldn't be building what I would describe as a 200,000 mile engine.

All this being said, apart from the camshaft bearings, this engine just is not worn all that badly.

 

[Jeepsinker]

I don't like the pitting. It seems that once they get like that they have a tendency to just start coming apart like crazy with no warning. Granted, I've not seen it in a multifuel, but plenty of other engines. And a lifter is a lifter. Same for followers. I'd at least replace the pitted ones with good used, preferably new.

 

[JasonS]

Continental's literature says minor pitting is OK. You can resurface lifters.

 

[oddshot]

Attached is a copy of the oil analysis I had performed. I have to admit that I am a bit disappointed in the report.

I had expected that the lab would have SOME data on these engines to give a baseline or average of what to expect. I guess these engines are not as numerous as 350 cid Chevies.

Unfortunately, l all I got was an analysis of the oil I sent as if this sample was from the first oil change of a new motor.

I have sent off a sample of the oil from my own truck and will compare the two when it comes back to see what can be seen, but I'm not expecting much.

If anybody else has any oil analysis data, please post what you have. Thanks

 

[rustystud]

I don't like the pitting. It seems that once they get like that they have a tendency to just start coming apart like crazy with no warning. Granted, I've not seen it in a multifuel, but plenty of other engines. And a lifter is a lifter. Same for followers. I'd at least replace the pitted ones with good used, preferably new.

I don't like the pitting either. That tells me that the thin layer of hardening has gone and that wear well start accelerating. Still the cam itself looks really good. I will stick with my original theory of bad manufacturing ie: incorrect forging. The metal could have cooled off to much before the forging began. This could have left a stress fracture which finally gave way.

 

[oddshot]

Continental's literature says minor pitting is OK. You can resurface lifters.

For those following along at home, could you please cite your source more fully including the name of the manual and where it can be found or downloaded.

Somebody down the road might find it useful.

Thanks.

 

[oddshot]

I cut both of the oil filters open, spread out the paper elements and ran a large magnet over the paper. I found NO ferrous material at all in the filter elements. For the record, I found NO material of any type in the filters. This comes as a bit of a surprise. When I first examined this engine at the SS Rally, I DID find some bits of material. Unfortunately, I did not test nor properly secure these bits and now they are gone.

Suffice to say, I will be removing the oil pan to give things a look.



BTW, I learned a long time ago that cutting open oil filters, and fuel filters for the matter, is a very good diagnostic tool.

This, along with dropping the pan and checking what lies in the bottom, is an important test. It could help a person who has had a failure of this type decide if he is going to 1) replace the cam, bearing and etc in the chassis, 2) remove and rebuild his engine entirely or 3) swing in a new or used engine.

 

[mobileauto2000]

As far as pitting I have no comment. But if you do a Google search for lifter resurfacing you will find that it is normal machining service performed by many.

 

[oddshot]

Using a wrench, I spun the engine to make sure that the engine was free and the gears meshed and turned correctly and found no problem.

I did find that I could rock the cam gear quite a bit. I removed the retaining bolts from the front of the cam and removed the gear and front portion (i.e., the broken piece) of the camshaft.

The cam shaft had broken immediately behind the first bearing. I found no evidence galling, excessive heat, or oil starvation on the bearing journal of the camshaft, and none on the camshaft bearing. Both are worn smoothly and the broken bit of the cam shat spins freely in its bearing.

Also see post #24 of this thread.

I have gotten the feeling that some readers have either misunderstood what I meant by "rock the cam gear" or do not fully appreaciate the impact that .009” clearance between the cam journal and the cam bearing had.


Since I made that post I have tried to come up with a way that would illustrate what I was trying to describe and also show just how badly the front cam bearing in this engine is worn. So I reinstalled the broke bit of cam and the cam gear back into the block. I was careful to set the thrust and torqued the plate down carefully to spec. Then I made a movie.

I have never made a movie before, therefore, using this descriptive tool did not occur to me until recently. I wasn't quite sure just what was going to come out of the camera; I also have NO idea how to edit these things, so I will appreciate your indulgence and patience when viewing this vid.

https://www.youtube.com/watch?v=R3yVg-ecY4g&feature=youtu.be

Some have speculated that we might not find the direct cause of what broke this cam shaft. Others seem to feel that a manufacturer's defect or design flaw was responsible for the failure. They are certainly welcome to their opinions, but I think this video clearly shows the stresses that the camshaft had to withstand.

I feel fairly comfortable stating that this camshaft broke due to worn camshaft bearings. I don't think I'm overstating my case when I say, "the cam broke where it was going to break", i.e., its weakest spot.

Further, I feel that I have seen enough of this engine to SPECULATE that the lack of oil pressure on start up especially due to the design of the cam drive caused the bearings to wear long before they should have. To this point, the camshaft bearings are the only component in this engine I have found worn beyond the wear limit spec.

Have all of the camshaft failures in the LDT465 occured due to worn cam bears caused by dry start up? I don't know. I have only examined THIS engine. But I DO know that ALL LDT465 engines take 8 +/- seconds to build up oil pressure.

This being said, it might be wise to start looking into developing a pre-luber for your multi-fuel engine. Based on what I have seen in this engine, I know building one has moved to the top of my list of projects for my own truck. A person with the money and other resources might think about producing a kit ... Just please don't have the thing gold-plated.

Going forward I do intend removing the rest of the cam bearings. I do intend dropping the oil pan and pulling a couple main and rod caps to see what might be seen.

More pictures will follow.


Finally, at this point, l am of the opinion that this engine could have had its camshaft, bearings, the bent push rods and bent valves replaced and put back into service. Of course, I am reserving the right to change my mind based on what I find when I drop the pan and etc.

 

[bchauvette]

I second the motion. along with this thread there are other active threads that are showing a preluber could be cost effective.

 

[RAYZER]

Wow, that's a lot of play!

 

[oddshot]

Wow, that's a lot of play!

And if the gear were 6 feet across it would appear to be even more.

The word "rock" just wasn't giving the best picture. A measurement (.009") is sometimes a static and lifeless thing.

 

[oddshot]

... But that being said, at this point, l am of the opinion that this engine could have had its camshaft, bearings, the bent push rods and bent valves replaced and put back into service. Of course, I am reserving the right to change my mind based on what I find when I drop the pan and etc...

From today forward, I am shifting my focus slightly. I am going to be looking to see if ALL of the cam bearings can be replaced without removing the engine from the chassis, or the trans/clutch/flywheel from the rear of the engine.

With the cam out, I can see all the way through to the core plug at the end of the cam but I cannot see if there is enough space between the end of the rearmost bearing and the core plug to allow a tool of some sort the room needed to grab onto the bearing and pull it out.

 

[JasonS]

For those following along at home, could you please cite your source more fully including the name of the manual and where it can be found or downloaded.

Somebody down the road might find it useful.

Thanks.

It is in the "Operation and Maintenance Instructions" for the Continental Red Seal six cylinder diesels. This includes the 427, 572, and 802 cubic inch engines. The multifuel was derived from these engines and is an amalgam of the 427 and the larger engines; not a simple adaptation of the 427. Page 95 states "Tappets must be inspected visually for scores or damage to the contact face. Two or three small pits in the latter is acceptable, more than that calls for replacement of the tappet." The tappets shown above are clearly outside that guideline.

I also found it interesting that Continental stated it normal for the main bearings to exhibit minor cratering after a few hours of operation.

Paper copy purchased from eBay. I have an extra copy if someone wanted to purchase one.

 

[crusader]

Oddshot,

Thank you taking the time to do RCFA on this engine.

 

[rustystud]

OK , after viewing your video I see what you mean Oddshot . There is extreme lateral movement of the cam. I also agree a "Pre-Luber" should be installed in our engines. I was working on one a few years ago, but lost interest after going to the spin-on oil filters. For those who want to regrind there tappets, you need to surface harden the bottoms again. Any shop that offers tappet grinding usually offers surface hardening too.

 

[oddshot]

OK , after viewing your video I see what you mean Oddshot . There is extreme lateral movement of the cam.

Words just didn't describe the amount of movement I was seeing ... I knew if I could show folks they could see it right off. Because there are so many different ways a cam shaft can move, its difficult to come up with how to explain. What is clear to one guy just might confuse the crap out of another.

Next time I'll make a movie right off.

I also agree a "Pre-Luber" should be installed in our engines. I was working on one a few years ago, but lost interest after going to the spin-on oil filters.

The way that this cam drive works puts different stresses on a camshaft. I have read to the different oil filter set ups HELP cut down the time to pressure ... but with this geared setup, to a dry bearing, I think that 3 seconds is too long a period of time to be with out lube.

Hopefully this thread will inspire some bright young lad to look over those pre-luber threads and come up with an in-expensive fix.