I have a DJG prefix D6T, just changed an injector... Amongst other bits I replaced a bent pushrod and refitted the valve bridges as one had fallen out. Re checking the valve clearances I need to turn the engine. According to the procedure there is a barring tool hole under a cover on the flywheel housing on the opposite side of the starter... It's not there. The trans oil cooler is in the way of where it would be. There is also no TDC locking hole. How can I turn the motor and be sure it's at TDC on 1? Pull off the starter and use a screwdriver to turn it? Will checking it "on the rock" be accurate enough? Thanks in advance.
According to what I can see for D6T DJG-prefix the Timing Pin installs in a hole on the LH side of the flywheel housing just below the ECM. See below - marked 1. The recommended Turning Tool is either a 178-8615 or a 350-7549. It is referred to as Tooling C and according to the Service Manual - "Note: Tooling (C) uses the bolts on the front of crankshaft."
Probably not what you want to hear but try looking at this link: https://parts.cat.com/wcs-static/pdfs/03-Engine_Tools.pdf Scroll down to about page 257 to 260. The older engines had the egg shaped hole with the 1/4 inch pipe plug next to it that the timing pin went through into the flywheel. Guess that was too convenient! If starter is not too hard to remove that would be one way or something on front of crank. To position for valve settings I would go with the "Valve Over Lap" method. On a six cylinder assuming this is the normal 1-5-3-6-2-4 firing order engine. As the exhaust valve closes on #6 and intake just starts to open you are very close to TDC on #1. Next turn till over lap on #2 and set valves on #5, next overlap on #4 and set on #3. And so on for the other three. Not sure if the overlap positioning would be close enough to do half the valves each time but you may be able to figure out where the timing pin hole is in the flywheel once starter is off. Any good reason why the push rod bent and the bridge fell out. Does not seem to be a normal thing! Good luck
Bent pushrods and valve bridge fallen off... Ya. Not normal. The job was investigate a misfire... Excessively high oil level, (fuel contamination) I figured simple injector... My theory is the injector leaked fuel into the bore sufficiently enough over X amount of time to hydraulic the one pot when cranked, bending one pushrod. Why the bridge jumped off is a mystery. Injector and sleeve replaced and briefly test run. Seemed to run evenly immediately, misfire gone. Still need to set the valves accurately and run her up to temp. Looks good just now tho. Thanks for the advise on turning and locking. Most appreciated.
Yair . . . simonsrplant I'm missing something here mate. Could you explain how "hydraulicing" would bend a pushrod? I just can't get my head around the sequence of events that occurred within the engine . . . to my mind the volume of fluid required to bend a pushrod would have caused a catastrophic failure when it slammed the valve closed on the next revolution. As I have mentioned on this board before . . . to this day I find it disconcerting to start a machine when I have no control of injection. Once it was mandatory to bump an engine over to check for fuel or water on top of a piston before starting. On any large marine or stationary engine it was mandatory to bar them over and on several occasions I have had "lockups". Likewise on smaller engines I have seen several ventilated blocks caused by just turning the key. Not trying to be a smart azz, just curious as I always imagined bent pushrods were just part of the catastrophic failure. Cheers
Scrub, I really don't have the reason as to why I have a bent pushrod and valve bridge jumped off... My theory is that enough fuel to prevent the valve opening was in the bore yet not enough to lock the cylinder up... The valve gear will continue to work... No movement from the valves and something has to give. Now I may be a way off... But it's the only way I can figure three quarters of the symptoms. I'm all for listening to anyone else's ideas?
Yair . . . Gotcha mate, appreciate the reply. It's a curly one and, like you I am having trouble getting my head around it. Your theory sounds like decent logic . . . strange about the bridge though. I am sure there are folks on here that can add to this discussion. Main thing though it appears you have the unit back into production. Cheers.
Well I had to look at the cam and lifter set-up on a C9, never that deep into one. It is basically the same as a 3406C like we had in our 980Gs. Well had one of those that bent a push rod twice. First time not real long after a dealer rebuild. They suggested put in new one and see how it runs. So that's what I did. Sounded good after installing new push rod so put back to work. Then a couple weeks latter same skip. Pulled cover and another bent push rod. This time was not able to just lift out the bent one. Just as I touched it it went clickity click down into the oil pan. Long story shorter after getting rod out found the lobe on cam damaged. Then found the reason, the spring clip (467-4243 in a C-9) had broke letting the lifter turn sideways in bore at times and messing up the cam. In our case it also messed up the lifter bore in the block, Cat bought us a new reman short block! Not saying this is your problem but might be worth taking a good look down into the block near the lifters to see if those clips appear to be in place. Clip is #1 in this picture: Like Scrub, I'm not 100% convinced hydro-static lock in cylinder would cause a bent push rod
If a valve sticks open, then the pressure is released and the pushrod will fall to the side of the rocker, and get caught on the edge of the "cup" and bend the pushrod as the piston comes to the top of the exhaust stroke. Never seen this on a running engine, but I've done it at least twice working on junk engines, not Cat though.
Yair . . . Oh yeh! I'm thinking along the lines of kshansen . It seems to me something may have got in where it shouldn't and gave some extra lift on that pushrod to bend it and flip the bridge . . . I do not know the engine or if that is a realistic possibility. I can imagine the scenario suggested by Delmer but on a well maintained "in service" engine I would have thought it unlikely a valve would stick. Cheers.
I've encountered bent push rods on two different 3126's, both times the cam follower on an exhaust lobe had failed allowing excess valve lash, the operators fail to hear anything wrong and just seem to turn up their music! Anyway the lash became great enough that the pushrod(s) jumped partially out of the rocker(s) and jammed, bending them. Both times the valve bridges for the offending cylinders had fallen off as well, I think once the pushrod bends and falls out from under the rocker the rocker lifts and hydraulic suction pulls the bridge off the valve stems? Both these engine's required new cams.....
Thanks for all the feedback here... So I think it's fair to say the general consensus is a cam issue in the making... It's an odd one for sure. It's running now. If I were to be picky with my work, I'd say it is a little rattlely, thinking the valve set, but I could be being paranoid. I'll keep everyone's points in mind and watch it. Thanks all. Most appreciated.
Just had another thought. I know dangerous thing! Did you take a real good look at the valve springs? Depending on how one broke it might be possible for tension to be good enough most of the time then at some point let the valve hang open just a bit and let the push rod jump out of the follower and get bent. Just something to cause you to loose sleep over! If you have not been back into do a valve set it would be something to look close at while the valve cover is off.
So... Less than two hundred hours later and I'm back inside in valve cover. Dead miss on number 1, same as last time, only no oil/fuel contamination. One pushrod S shaped and the opposing bridge fallen off. From what was discussed it seems like I have a cam issue? Any and all options are greatly appreciated.
Assuming the cam is wearing prematurely, is 150 hours sufficient for oil analysis to detect (or prove) an internal failure?
Absolutely, But I would dehead the oil filter and take a look right off the bat.
From my experience the cam wear is usually of the spalling variety i.e. initially great big lumps of the case-hardened layer falling off, followed by abrasive wear of the core of the camshaft itself which produces a finer metal particle. Incorrect hardening is actually the root cause in most cases. You ought to find traces of metal flakes in the oil filter but if they were really big then maybe they might even be in the suction screen for the oil pump. Either way there ought to be increased iron in SOS readings, but at 150 hours after an oil & filter change whether the iron levels are high enough to trigger comments on the analysis then your guess is as good as mine.
Recently repaired a cam failure on a Mack E7 460...put a dial indicator on the failed cylinder's push tubes (with rockers removed) and barred crank over and measured lift on both int. and exh. lobes...found a lobe about 100 thou (+/-) low at full lift point. Did not detect this lobe failure when on the inner base (valves set point). Also, you might be able to pull up with a magnet on each lifter to check for "H" style retainer or other lifter retaining clip for positioning? Regards, Bob
Thanks gentlemen... I poked my head back inside and the retaining clips are all intact and ok, since the head is still on I cannot remove the offending lifter for inspection. Question for the knowledgeable whilst it is still in near running condition: Can a person do a compression test on the engine or contribution test? Not relating to the fault but to give a further insight into the motor when considering routes of repair.
Are you sure you can't get the lifters out? I replaced a timing case on a C9 a couple of years ago which involved removing the camshaft and I know for a fact that I didn't remove the head to get the lifters out. I don't see why you couldn't do a compression test if you made up a dummy injector but with the automated cylinder cutout tests, I've never found a need to do one. Edit: I've just looked at SIS and it does say to remove the head first, but I stand by my earlier remark. SIS could be wrong??
I did a cam in a C9 recently dew to lift retain failure allowing the lifter to turn side ways the customer complaint was bent pyush tube on intake. What was hapenig was that the exhaust lobe failed. and it would not let exhaust gas out. Build up to much pressure and bent intake push tube.
Sounds somewhat similar... Were the block lifter bores damaged by lifter failure? I found similar information not concisely clear as to requirements to extract the lifters... I stopped in and tried on my way home the other night. The head casting hole for push rods is just too small to allow the lifters through. It seems likely that the failure lies within the cam and or lifters are at fault. Next will be removal of the head and inspection of the lifters, bores and camshaft.
Can the base be dropped and then a visual inspection done of the suspect lobes from under? I know it's not a C9, but in order to pull the cam on the Mack E7, the lifters must be held up regardless of heads on or off (the harbor freight magnets came in several hundred dollars cheaper than the Mack special tool). Regards, Bob
Not in the block that I did. How ever I had to pull the head in order to remove damaged lifter. The rest of the lifters I could remove with head it place.
Great idea magnet will work in other applications also. The C9 I was working on was in a windrow turner so to get the pan of I had to pull the Engine.
Bob; Yes I could drop the pan and look up at the lobes but I would not see the rollers on the lifters clearly. I've been inside an E7 not so long ago... IMO I think the build is a little backward, having to hold the lifters up to slide in the cam... I had that particular motor out and recall supporting it upside down to fit the cam...
simonsrplant, have you measured your cam lift yet on the bent tube lobes? If you measure one lobe lower as compared to an adjacent cylinder (inner base), then I would say your lifter has dropped or "flattened"...if your measured lift (outer circle) on suspect lobe is low but, but correct on the inner base then it's safe to say the cam is shot (and lifter) and looking up the base (even if you have to use a mirror) would give you a visual verification before teardown. Regards, Bob
on edit, also makes me wonder if you could (if needed) replace the cam like the E7 by holding up the lifters, drop the damaged lifters out the base (like the E7) and complete the repair without head removal if normally required? Regards, Bob
TBH in a D6T installation it's probably easier to pull the head off than it would be to get at the front end of the engine in order to pull the cam out without removing the head. The cam is driven from the front gear train so to get it out would probably need either the hardnose with the radiator/aftercooler/cooler completely removed, or at the very least the rear pins pulled and tipped forward to give enough space. I recall doing the cam on a C-15 in an 834H for exactly the same fault as you have here and it needed more than a bit of creative ingenuity to get the radiator/hardnose moved far enough to make enough space to get the cam out. The dealer personnel were hell-bent on pulling the engine because that's "what the book says" until I stopped them. If moving the hardnose would work in a D6T I have no idea. Simon, if the cam is bad (ETER's idea of measuring the lift on the lobe where the bent pushrod is located and comparing it to the others will work) you might be just as well pulling the engine first up unless you can somehow create enough space to get the cam out some other way. If you don't you might end up expending loads of effort trying and at the end of it all end up pulling the engine anyhow.
Good point Nige on expending "extra" effort for a short cut when the correct method of repair will save time in the long run...I haven't been into a C9 or this machine, so there are nuances that I am not aware of. It's just nice before the "rip and strip" process starts to have actually put "eyes on" the failure. That C15 has a very loooong cam, but at least you can inspect it easily! Regards, Bob
I miss spoke this morning and would like to correct what I said The C9 that I worked on I did have to pull the head to remove follower. I had to remove the cam for the damaged follower. It had turned side ways and mushroomed above the roller. The rolled pin and roller were also damaged.
the cost of a new cylinder head gasket is probably around 100 dollars, not more than a couple hours to remove too. least for the c11 its 120 usd here, so it'd definitely not be that much to pull the head, when it'll likely give you a much better view of what's going on hey. the radiator group will have to come out to get the cam out i believe. there was a cam failure on the d6t at another project, just befor i qualified. i got moved there just after it broke down, it was also because the valve bridge kept jumping off. the push rods were ok, and when we set valve lash it would be in spec, it fell off twice more before the cam follower revealed itself to be the culprit. it would turn onto its low spot (i assume) and jump off, then settle on its good face and leave us confused and without an explanation. so it was sent to our workshop n fixed there. there was no SOS sampling to be heard of and only at the end did the metal reveal itself in the oil.
So my plan is to pull the head and cooler group. I can inspect everything properly with it off. With the cooler group off and a majority proportion of the individual rad cores, but nose cone on, I believe I will be able to extract the cam. Dependant on the findings the cam may be left in place and remaining block removed for replacement. What effect would scoring on the lifter bores have? They are just splash lubricated roller followers, surely a "dressed" scored bore wouldn't be detrimental to longevity?
the lifter bores are pressurised with lube oil, don't forget this oil is also low pressure feed for HEUI system
The C9 that I did I also changed the HUIE pump and injectors. I have a componet shop in the area that dinos alot of engines. they told me that after a follower failure thet can not get the horse power with out changing due to the fine metal in system.
Thanks gentlemen... That I was not aware of! The head is coming off tomorrow... I fear the worst for the motor.
jjimbo, how do you think that "fine metal" would find it's way into the lube system after such a failure? Good luck on the teardown simon and update us on your findings. Regards, Bob
In the case of the engine I was on the follower turned side ways and damaged the lobe on the cam. The mechanic before me had removed the head and replace the follower. So when the follower failed again it worn more of the lobe away. So as the lobe was worn away that is where you get the fine metal.
Without changing what...? Any fine particles generated by the lifter roller griding away at the cam lobe ought to be caught in the engine oil filter IMHO. I've seen a number of cam/lifter roller failures on C-series engines and can't recall a single one where the engine wasn't restored to full heatlh simply by replacing the cam and the affected lifter. As I used to monitor the oil analysis on all our engines I'd have though that if anything untoward had gone on after the lifter failure I'd have noticed it.
So as expected the lifter was ruined. There was also visible wear to the cam. Only minor scoring is visible in the lifter bore. My question for the hallowed collective is: Is the minor scoring acceptable and the motor repairable by replacing the cam and lifters or does the high pressure oil system lubribate the lifters to extremes and any damage to the notes have significant effect on motor reliability. Pics to follow.
simon, I would think that if the bore could scuffs could be cleaned up with some 400 or lightly honed so that one of the neighboring healthy lifters can "glide" nicely in the bore, then I would go for it (mostly 'cause I don't have a nickle in it):drinkup. It would be good if you could post a pic of the bore "for the thousand word analogy"? Regards, Bob
Service mag SEPD1810 is for An Improved Guide Spring and Valve Lifter Assembly Are Used in Certain Machines Equipped with C-9, C9 ACERT Engines, and C9.3 ACERT Engines . It mentions two special instructions, SEBF9008 and SEBF8069 which refer to 3400 series block and lifter bore salvage. I can't access these two special instructions from the SIS account I'm on at the moment. Anyone else got access to them?
Thanks Cmark, I'll try to access that this evening. Headed home now. Passed on all the findings to the customer and he has already said that he wants the motor pulling and a long block installing, the machine will be sold with the new motor to recap as much cost as possible. I will post images of the damage when I get in. Thanks for everyone's input.
Mark250 might be the man for that .....
Yep, possibly he might. I believe he's on a generic mining customer license. If they have access to the PI and PS documentation then I think he should be able to get to these two documents.
With the SEBF prefix they will be Reusability & Salvage Guides. I have some saved but mostly relating to bigger stuff and unfortunately neither of the two that you mention.
Sorry for no images as yet, been hellish busy! Had a hell of a job on the rear nose one pins, but the motor is being lifted today. Can anyone read Cat service bulletins? I have heard of this issue and subsequently a bulletin but I don't have access to read it. The reference is PS52705. Thanks in advance.
PS52705 is an After Failure only program published in July 2014 titled "Reworking Valve Lifters and Guide Springs" on a range of models that includes the D6T. I can't access the fine detail though. Get the customer to call his dealer and ask them straight up if his S/N of tractor is included in the Affected Product of PS52705.