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Camshaft bearings. Share all,

Will L.

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6.5 eats cam bearings. They wear horrible. Share all you know please. My knowledge is really lacking, so I am asking for help along with hoping everyone’s knowledge grows so we all know the best option for doing this the best way possible.

Back coating that can be burnished (like sanding) to get the best fit.
Face coating the camshaft itself to reduce wear & resistance.
Cleaner oil to stop soot (carbon) from wearing the surface faster.

That’s pretty much all the tricks up my sleeve.

I seen cam bearings fail in 2 ways. Scoring, or the seam coming apart and snagging the cam.

Worn cam bearings are #1 reason for oil pressure loss.

We know roller rockers lower the stress, is there any stats on how much? Is it enough to extend bearing life?
 

DieselAmateur

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Is there a good write-up out there on how to replace cam bearings? Never attempted it myself but would certainly love to know.

Wish I had known about the cam weak link when Chris had my P400 apart. I had pretty much everything in the long block coated EXCEPT the cam and bearings...oh well
 

MrMarty51

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Cam bearing install.
Borrow or purchase a cam bushing driver set. They usually are not terrible expensive for what You get.
I usually start with the rear bearing and work forwards to 1/2 way. Then switch the operation and install the forward bearing and work My way towards the back.
There is a cone that needs to be held in position in the front or rear cam bore to make sure that the bearing is getting drove straight.
I use a felt tip marker and mark the oil galley holes just outside of the cam bearing bores. I also mark a line from the oil holes in the bearings towards the outside edges(s) so that I can align the marks to be sure that the bearings will be installed with the oil holes of the block and the bearings directly in line.
Some engines there will be two or more sets of oil galley holes in the block, and in the bearings. Be sure that all the holes in the bearing align with all the holes in the block.
Some, or most, bearing have an oil groove carved all the way around the center of the inside of the bearings. That is to help spread the oil flow.
After the bearings are installed, before lubing the bearings, be sure to dress out any shavings left from the bearings being forced into the bores. Try dry fitting the cam shaft. If the cam hangs up when entering a bearing, it then will he necessary to lightly dress the forward exge of the bearing. I use a utility knife for that purpose.
The reason I say to dress the bearing before lube is so that the shavings from dressing the bearings can be easily removed without having to wash the bearings with a solvent to get rid of the contaminated, with shavings, lube.
Do not try to spin the cam in the bore until the bearings and cam have been lubed.
Be very careful when sliding the cam into and out of the bores, that the bearings do not get marred, that could possibly create another escape route for the oil.
Thats about all I can think of to add about cam bearing installation.
Usually if the bearings need to be dressed on the leading edges, it will be an ever so slight amount.
A poorly made bushing adaptor can cause the bearing to sort of distort on the driven end of the bushing and that is the reason some bushes needs to be dressed slightly.
 

Twisted Steel Performance

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Wish I had known about the cam weak link when Chris had my P400 apart. I had pretty much everything in the long block coated EXCEPT the cam and bearings...oh well
Peter you don't have nearly as much to worry about as others do, the oil you have used from the start has most of the same ingredients the coating do and it's a fact those work there way into ALL the moving parts... just keep clean oil in it..
 

MrMarty51

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Peter you don't have nearly as much to worry about as others do, the oil you have used from the start has most of the same ingredients the coating do and it's a fact those work there way into ALL the moving parts... just keep clean oil in it..
I am wondering about using the Liqui Moly oil additive.
I’ve been using that stuff. A can to an oil change.
It is suppose to coat components with platelets.
 

MrMarty51

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@Twisted Steel Performance have you had a chance to examine a set of coated cam bearings after they’ve been run for a while (at least 20-30,000 miles) with “regular” oil?
I once tore down an engine that the owner had the car from brand new. 360 Dodge V8. Once the break in was accomplished, the only oil he had run in it was Standard oil, some kind of moly oil recipe put out by Standard.
All the bearings in the engine was dark grey/blackish from the moly lube.
There was not a scratch nor mar on any of the bearings or cam bushings.
If that black would have wore off with the use of regular oil, possibly so, but it was tough. Could not scrape it out with a finger nail.
 

Twisted Steel Performance

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@n8in8or , A 6.x I have not, but gassers and cummins yes, they looked new, both had owners that kept clean oil in them, I have also seen rod bearings from a dmax sled puller that lost a oil pump during hook up, his sponsors required him to make the pull, his rod bearings were not scored at all but he also had TriboDyn for oil...
 

MrMarty51

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I think I know what my next set of cam bearings will have on them.
Thinking I too might have to make the change over.
An oil change probably last Me long time now. I have not fired up the truck for about two weeks, except to move it from in front of the garage to get the motorcycle lift table in. Truck is once again back in its position. Just dont never go anyplace. 🤷‍♂️
 

Will L.

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Yeah, my diesel fuel bill is mighty low with no engine in the truck! Haha.
I wish I could find tri-metal billet cam bearings. There isn’t a lot of places I can or would spend 5 times the cost on a part- but cam bearings fits the bill imo.

I will be shipping my cam to Chris for coating (along with other pieces parts)
The. The outside gets the “filler” costing that will get burnished down for exact fitment.
And the tribodyne is already on my shelf.

Where the oil hole in the bearings changed over the years by different manuals.
iirc, one change was when they went away from the mechanical lift pump.

Does anyone have input as to loose/medium/ tight clearance numbers they shoot for?
Tighter clearance means higher pressure, but much easier damage form any debris or failure like my optimizer had where the seam of the cam bearing caught the cam and spun.

Loose clearance means less friction and you have a higher volume oilmpump pushing a lot more oil through. But that is ok in racing because you don’t try going super high mileage with that set up.

All the fleet 6.5 builds over the years- generic spec was checked but nothing ever dealt with. But we did have more than one we did cam bearings in the truck, just doing the front four bearings.
 

MrMarty51

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I have thought of how a person could detect cam to cam bearing clearance.
Like a rifle chamber. Get the spec from the book then make some round steel gauges to those specs. Have one a thousandths over size and one a thousandths under size. Like a go no go chamber gauge. Could make several more up to about .003 over size and a couple to go to .002 under.
Thats about the only way I could possibly figure to get a real accurate clearance reading of the cam bearings.
Then measure the cam bearing surfaces of the cam shaft and compare those measurements to the go/nogo gauge system.
 
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