Cylinder head wear...

[dhirocz]

...just trying to do my I's and cross my t's here.

Short background, my 871 suffered a cam failure at 685k miles. Engine still ran great up to that point. Waited for 4 (!*#$) months waiting for the company to keep their promise and assist me in an inframe. After getting the run-around, I'm not only told that they basically lied to me, but I was loosing my loaner truck.

Upon a second inspection, I found not only #5 intake pitted and chewing the cam, but #1 intake roller LOCKED UP and was skidding on the cam. I just found it...made a nice flat spot on the roller and just started eating the ramps on the #1 intake lobe as well. At this point, I'm committed to repair seeing as it won't last long.

Upon disassembly I find the cam bearings are shot, all injectors pass a cut off and leakdown test, bottom end in good shape minus the little bit of metal I flushed out of the pan. Liners are decent, I suppose typical of an engine of that age (boroscope/bottom of liner inspection) All other rockers were ok, crossheads in great shape. Engine has had regular oil changes since 605k (since I got it) and a bypass filter. All rockers were flushed with brake cleaner and did not appear to be plugged. Oil pressure was typical. Intake and exhaust port inspection shows slightly oily valve stems.

Keeping in mind I'm now on a very limited budget thanks to the loaner spending most of it's time in the shop, then getting taken away, I'm still wondering if the cam failure was a result of wear leading up to when I got it, cylinder head worn out, etc...

Up to this point, the plan was to swap cam bearings, injector o rings and valve stem seals, flush the engine, replace the oil cooler, valve cam and bad rockers, and reassemble to buy enough time to pay off the last $15k I owe and to save for an inframe out of pocket, since the company only cares to sell me a new $145k Pete with paccar power (no!).

Are there any other inspections I can do to the head, short of pulling the springs and inspecting the valves with my boroscope to gauge the condition of the head? At what mileage do worn isx heads typically break valves?

While I'd hate to pull the head, since I should really consider a piston and liner kit at that point, I also am kind of anal and don't want to only get a week of use before I get stranded somewhere. I need to consider that the locked up roller...which still rolled when it came off, by the way...might be a sign the head junk. I figure I really need to make sure this head is still serviceable before I go replacing cam bearings, etc...

It's a hard balancing act, seeing as I can't afford the head, piston and liner kit and the counterbore cutter.

Also, is there installed height and open/closed pressure specs available for the springs on isx heads? I do have a valve spring pressure checker. Also, if I knew the correct open height and acceptable range of wear for the seats I could judge the head that way by comparing those specs to my current open height.

[dhirocz]

   

Rocker that started sliding on the #1 intake. It just started seeing as it didn't cause massive damage to that lobe yet. You can see all the pitting is to the one side of the flat spot.

[Rawze]

If your in that much of a pinch, it sounds like maybe you could put a new cam and rocker in it and run it for a few months, saving money then replace the head later on. Just be really careful installing the cam and keep an eye on the cam bearings after to ensure one does not spin on you. The injector cam is more prone to spinning a bearing when they get really worn out more-so than the valve cam.


Inspect all the other components and definitely take the time to clean out all the cross-channels of the rockers so they get good oil. I would also shim the pump so that you get good oil flow. if you have not done so and run a gallon of gear lube in it too.

Mr. Hag has made some pretty good observations towards oil flow and intake rockers. He showed me a about a month ago the difference between setting the intake rockers to 0.014" vs 0.015". the oil flow is quite a bit better on the intake rockers when they are set to 0.015" and it does not seem to effect fuel mileage in any measurable way on them. I am still up in the air on it, but the oil flow is significantly better when they are set this way. I am going to set my own intake valves at 0.015" next time I do my overhead and see if the fuel mileage is effected on mine.

[dhirocz]

.015 it is.

I already cleaned all of the other rockers and verified they were flowing with brake cleaner. The Jake's will be getting new springs too before I reinstall the assemblies.

My main concern is putting this thing back together and it not making it that far, like dropping a valve. I have no indication that the head gasket leaks or the head is cracked. I'm just concerned that #1 stopped rolling perhaps because there was no more clearance due to sunken valve seats. It may be that, or metal flaked on the cam and wedged the between the lobe and the roller. That lobe did have streaks in it.

The last thing I want is to get a couple weeks out of it and drop a valve.

I already have some 85-140 GL to put in it, and have new Cummins cam bearings and the appropriate driver. It'll be my first time putting them in an isx to be honest, but certainly not my first time ever.

I did notice that the center injector cam bearings have no lube passage. I'm assuming they use the puddled oil between the rocker stands and rely on the bottom of the cam bearings to be submerged? Found it kind of odd Cummins didn't see fit to put a lube passage under the center injector cam bearings like there is for the valve cam.

Tomorrow I'll be setting the cam timing, shimming the oil pump with 8 dimes and swapping out o rings and valve stem seals. Trying to get this done before my wonderful weekend on ft Stewart.

I want to do the head around thanksgiving this year, as well as a piston and liner kit so I can call it done and know what is in my engine. I found a company in PA that's supposed to have a superior casting dohc head( jury isn't in on that yet), new for $3500. I just need to get myself out of this hole my company isn't helping me out of like I was assured they would.

Then I'd like to meet up with you to sort out this ECM, rawze.

[Hammerhead]

(07-06-2017 )Rawze Wrote:  Mr. Hag has made some pretty good observations towards oil flow and intake rockers. He showed me a about a month ago the difference between setting the intake rockers to 0.014" and to 0.015". the oil flow is quite a bit better on the intake rockers when they are set to 0.015" and it does not seem to effect fuel mileage in any measurable way on them. I am still up in the air on it, but the oil flow is significantly better when they are set this way. I am going to set my own intake valves at 0.015" next time I do my overhead and see if the fuel mileage is effected on mine.

I would be shocked if even you will be able to see an actual fuel gain/loss with an extra thou Rawze. Back in racing days I played with valve timing a lot, and the real gains were only noticeable in the extremes; perfect atmospheric conditions to below sea level DA, and high altitude in the mountains.
During dyno testing there was no discernible difference with as much as 0.005" difference, and in high altitudes we actually made gains running an extra 0.015" (intake), but this was NOT forced induction. Our theory on the altitude gain was the delayed opening created extra vacuum force upon opening and the thinner air responded more to the velocity since the flow capabilities exceeded the density.
I'm quite confident that the turbos forced induction would wipe out any perceptible difference.

Hard to imagine that 0.001" would make that much of a difference on the oil flow, but then again I've never looked into the metallurgical composition of the valves and the amount of thermal expansion that takes place. If the expansion is enough that a 0.001" difference quantifiably increases oil flow, one can only surmise that Cummins tolerance spec is too close. I wonder if the exhaust valves are too close as well?
This also really highlights the lunacy of C stating overhead adjustments not required for 500k miles doesn't it?
I would think due the torque loads demands of my job, I would certainly benefit from the extra clearance if this is the case. I doubt the fuel economy difference for me would even be calculable, but longevity certainly is. I will also be trying this.

[Hammerhead]

(07-06-2017 )dhirocz Wrote:  ...I'm just concerned that #1 stopped rolling perhaps because there was no more clearance due to sunken valve seats. It may be that, or metal flaked on the cam and wedged the between the lobe and the roller. That lobe did have streaks in it.

If you had that much cam bearing wear, consider this to help put your mind somewhat at ease; #1 intake is the highest point in the oil galley. Oil is pushed from the bottom up, therefore #1 intake is actually the lowest/last flow and pressure oil delivery. Breathe in, breathe out, don't overthink it. #6 is at the back of the engine and sees the least amount of cooling air flow and that's why it has the most heat issues, right? Think logically and methodically.

(07-06-2017 )dhirocz Wrote:  I already have some 85-140 GL to put in it, and have new Cummins cam bearings and the appropriate driver. It'll be my first time putting them in an isx to be honest, but certainly not my first time ever.

The gear oil will help with your high mileage engine, good. As far as bearings go, they're just bearings and you say you know what you're doing, so...

(07-06-2017 )dhirocz Wrote:  Tomorrow I'll be setting the cam timing, shimming the oil pump with 8 dimes and swapping out o rings and valve stem seals. Trying to get this done before my wonderful weekend on ft Stewart.

With a higher mileage engine, and since you're not doing rods & mains at this time, I suggest 9 dimes. Valve guide seals, good call since you're already in this far. Enjoy your wonderful weekend.

(07-06-2017 )dhirocz Wrote:  I want to do the head around thanksgiving this year, as well as a piston and liner kit so I can call it done and know what is in my engine. I found a company in PA that's supposed to have a superior casting dohc head( jury isn't in on that yet), new for $3500. I just need to get myself out of this hole my company isn't helping me out of like I was assured they would.

Then I'd like to meet up with you to sort out this ECM, rawze.

I don't know anything about this "superior casting" head. Is this their claim, or actual first hand knowledge from someone who has/is using one?
Good luck with your financial extrication. Asking questions, and picking up a wrench and getting dirty instead of bending over at a stealership is certainly several steps in the right direction.

As far as the lesson, my accountant always reminds me that "A kick in the ass always results in a step forward." So look at your companies kick in this way instead of a negative. They are helping arm you with knowledge and experience that can't be learned in a classroom!

[dhirocz]

I experimented with running zero lash with hydraulic roller cams in small block Chevy's vs preload vs running with extra clearance. I did notice that it always ran best with a little extra clearance, but too much made it extra noisy, hammered the valvetrain and set off the knock sensors so I desensitized them after getting it set where it was reliable and efficient.

I began to notice if I set my lash cold (prior to initial startup) then checked it hot, the clearances changed, understandably so. I started noticing the changes correlate to valve stem length and material (oem vs stainless vs inconel) vs temperature. So I try to use that experience as a guide for setting them to run as close to my desired spec as possible. On an engine like that I would check valves at least twice a year, depending on usage. Even OEM, at most 200k before you are into it for an overhaul or repair that requires you touch the valvetrain. Keep in mind this is a sbc, not an isx.

...which brings me to my point. Which is...why the hell 500k is a good overhead interval is beyond me! An engine is still an engine. Way too much going on and too many possibilities for those dimensions to change. Must be 'corporate and financial engineering' at play.

[dhirocz]

Hammerhead, that sounds just like what I told my wife. While it pisses me off, it's experience. Experience is knowledge. I'm being sort of forced to do this to stay profitable per my business model. As a diy kind of guy, I welcome the opportunity to learn how to rely on myself more and profiteers less, again, per my business model. That's why I'm here. Otherwise I'd be driving that new Pete right now.

That superior casting is just that, a claim. I'm tempted to ask if they have a cross section of that head and photos comparing it to an OEM head. If you want I can pm you the info. Either way I have a hard time listening to anyone who is trying to sell me stuff.

Good point on the #1 rocker. I did notice it was higher up there. Didn't connect the dots on that one.

[Hammerhead]

(07-06-2017 )dhirocz Wrote:  Hammerhead, that sounds just like what I told my wife. While it pisses me off, it's experience. Experience is knowledge. I'm being sort of forced to do this to stay profitable per my business model. As a diy kind of guy, I welcome the opportunity to learn how to rely on myself more and profiteers less, again, per my business model. That's why I'm here. Otherwise I'd be driving that new Pete right now.

That superior casting is just that, a claim. I'm tempted to ask if they have a cross section of that head and photos comparing it to an OEM head. If you want I can pm you the info. Either way I have a hard time listening to anyone who is trying to sell me stuff.

Good point on the #1 rocker. I did notice it was higher up there. Didn't connect the dots on that one.

Share the "superior casting" information, others may have some insight neither of us have. I have zero knowledge of it so sharing it with just me is sharing it with someone who has to learn it from scratch. I welcome multiple viewpoints that can show me what I may miss.

No Problem, sometimes a different set of eyes can point out the obvious that we've overlooked because we see it too often.