Possible Cam\Tappet issue

[cerberusiam]

Have a 93 with about 170k on it my son has been driving for the last year. Runs good but has always had more of a rough idle than we thought it should. Advancing the timing seems to smooth it out a lot.



Long story short LP died, and power was down after a new pump. A rebuilt VE and we ended up with a dead cylinder, the clatter, and a miss in the video. Changed HG, all the cylinders looked good, nothing that would point to damage. Valves water tested tight.



Still the same dead cylinder in #3 and now the clatter is getting worse. Pulled injectors and pump to another engine and they run like a top with no problems. Checked pushrods, vlaves springs, etc. NOTHING that stands out as problem.



Sooo, thinking possibly a bad lobe on the cam, a bad tappet, partially sheared crank key, or ??? Sounds like a bad cam lobe and a collapsed lifter on a gasser. Compression tester on the way to rule out valves, springs, rings, etc.



Any more ideas?





Thanks



Alan



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[JHumphries]

Have you tried pulling the injectors and doing a compression check?

That should let you know if the whole valvetrain is working.

 

[cerberusiam]

Have you tried pulling the injectors and doing a compression check?

That should let you know if the whole valvetrain is working.

Thats the next step before we pull any more pieces off. Had to order the adpater and gauge for a diesel. The valves all work when you roll the engine by hand and nothing looks like its hanging, not moving far enough, and the lash is correct and staying set.



#3 cylinder seems to be the issue as the injector comes out wet but works fine in another engine. We went thru 3 sets of injectors and got the same reaction on all of them.



Need to pull the dust cover off the lifter gallery and see what can be seen. Just not sure if it spossible to diagnose wihtout pulling cam.

 

[GHarman]

Just wanted to chime in with my experience with "Old Ugly". That is precisely what was found when the oil pan gasket was replaced. The damage to the cam lobe was caught in its infancy, but it was there, just like a little time bomb! GregH

 

[NIsaacs]

Possibly a bad #3 injector line. Plugged up or kinked shut?



Nick

 

[cerberusiam]

Possibly a bad #3 injector line. Plugged up or kinked shut?



Nick

I will check with my son and make sure he examined the lines closely.

Just wanted to chime in with my experience with "Old Ugly". That is precisely what was found when the oil pan gasket was replaced. The damage to the cam lobe was caught in its infancy, but it was there, just like a little time bomb! GregH

Did you get the tapping noise you could hear in the cab, rough idle, and a miss or did you catch it before it got that bad?

 

[GHarman]

I will check with my son and make sure he examined the lines closely.









Did you get the tapping noise you could hear in the cab, rough idle, and a miss or did you catch it before it got that bad?

Caught it before it got bad. The damaged lobe only had a 1/8" diameter erosion/flaked area. However, it would have deteriorated from there, fairly quick! Replaced the cam and tappets, (Cummins kit by Cummins mechanics). Some cams got through the QA/QC with improper heat treating, as I understand the problem. Dropping the pan for an inspection is just as much a pain as just pulling the cam. However, it is well worth the headache. Another thought is do an oil analisys. If there is a high iron/steel content, you most likely could investigate further into the cam possibility. GregH

 

[cerberusiam]

Caught it before it got bad. The damaged lobe only had a 1/8" diameter erosion/flaked area. However, it would have deteriorated from there, fairly quick! Replaced the cam and tappets, (Cummins kit by Cummins mechanics). Some cams got through the QA/QC with improper heat treating, as I understand the problem. Dropping the pan for an inspection is just as much a pain as just pulling the cam. However, it is well worth the headache. Another thought is do an oil analisys. If there is a high iron/steel content, you most likely could investigate further into the cam possibility. GregH

Thanks, that just reaffirms what I had read somewhere and couldn't remember. Is it possible to see anything by removing the lifter gallery cover?

 

[GHarman]

Thanks, that just reaffirms what I had read somewhere and couldn't remember. Is it possible to see anything by removing the lifter gallery cover?

I am not familar with that cover. There are others, with more experience/knowledge that could weigh in on that one. Hope you get it squared away! GregH

 

[JHumphries]

As you tear it apart, some pictures would be greatly appreciated, just in case we ever have to do it.

 

[cerberusiam]

I am not familar with that cover. There are others, with more experience/knowledge that could weigh in on that one. Hope you get it squared away! GregH

Thanks, we'll find the problem no doubt. Just trying to minimize the pieces strung across the gargae floor to do that. :-laf

As you tear it apart, some pictures would be greatly appreciated, just in case we ever have to do it.

Will do.

 

[JLEONARD]

You could probably measure rocker arm lift under the valve covers and know if the cam lobe is worn. That would be the least invasive approach and should be easy to do. Measure #3 compared to another and you'll be able to confirm or deny cam wear.

 

[cerberusiam]

You could probably measure rocker arm lift under the valve covers and know if the cam lobe is worn. That would be the least invasive approach and should be easy to do. Measure #3 compared to another and you'll be able to confirm or deny cam wear.

Yup, in the process of rounding up a dial indicator also. Right now he's chasing his tail trying to move all the pieces over to the 92 so he has a vehicle to drive.

 

[PToombs]

You won't be able to see the cam from the tappet cover. The block is solid there with only the tops of the lifters sticking thru.

 

[cerberusiam]

You won't be able to see the cam from the tappet cover. The block is solid there with only the tops of the lifters sticking thru.

Thanks Pete, I have never had to dig that deep yet on one of these engines. Was hoping it was open tot he cam. Ah well, time to pull the cam I guess.

 

[GHarman]

cerberusiam, Have you done an oil analysis? Course, with the skills to remove and replace the cam, you would be able to inspect all the critical wear areas. GregH

 

[cerberusiam]

cerberusiam, Have you done an oil analysis? Course, with the skills to remove and replace the cam, you would be able to inspect all the critical wear areas. GregH

Have not. The problem I see with a single sample is there is no way to trend whats happening. It might indicate excessive wear but no way to tell what is wearing.

 

[GHarman]

Very true! GregH

 

[cerberusiam]

Grrrrrr!!!!!



After flow benching the pump, setting pop pressures and balancing injectors, and way lots of hair pulling I believe the problem has been identified.



Number 1 cylinder has TWO injection events activating it. #@$%!



Since we had nothing to loose, a couple mating surfaces got a coating of aircraft selant. Noticeable difference to the better but still rough at an idle and a pop in the exhaust.



Just crack the injector nut and the engine smoothes out, quits smoking, and the pop goes away. I think this ain't right! Back the nut off all the way to make sure and it drops a cylinder. HAH!!!!! The only thing that makes sense at this point is the head has a crack in it that is bleeding pressure from ANOTHER injection cycle into #1. This after sending the pump to a shop to make ABSOLUTELY sure everything was correct.



Need to order a new head and see if that solves the problem.

 

[Greenleaf]

I just got my new cyl head. It was much less than I thought and had it right away. I used Tri State that sells Flo-Tech heads. Bill Gilbert uses one on his 89 old rusty.



I was "told"/suggested/recommended, to buy the entire head gasket kit. That was a waste as it is full of crap that I don't/cannot use. Just get the individual items... ... ... . save a hundred dollars... ... jez