Tappet cracks

[Axekicker]

When we tore down the 5.9 in my 2004.5 last year, I noticed that all the tappets were cracked. I can't find any of them now to show a photo, but what I saw was was a small circular-crack on the 'contact-face' of the tappet directly under the 'stem'... and there were straight-line cracks running at 90-degree angles to the stem-crack around the circumference of the face of the tappet.... just like the face of a clock. The shop tech doing the tear down is their in-house Cummins specialist and said what we were seeing was 'unusual'...as did the shop forman. The ISB had 220,000 miles on it...mostly city miles and had regular 10k oil changes (Rotella synthetic & Stratapore filters). I'm the only truck owner/operator. I first knew I had a problem when I pulled the oil cap off one day, and it did the 'jitterbug' dance-of-death, so I drove it straight to my favorite diesel shop and had them pull the engine. After pulling the head & oil pan we found a broken ring in #1 cylinder so we tore the engine down and found.... the crank & bearings all looked good...no (seriously) scuffed cylinders (amazingly) and the cam journals & lobes were not damaged. That's the part that threw the tech. He said when they saw damaged tappets it was usually in conjunction with a failed cam and damaged lobes. The cam looked fine. Anyway...it looks like a failed & dribbling #1 injector was the likely cause of the broken ring so I decided to do a complete rebuild since it was out-and-apart. Question: Has anyone seen this type of scenario where the tappet faces are cracked-out yet the cam is still in good shape? Possible causes?

 

[2004HPCR]

Is there any chance the engine was "rebuild" or touched by someone who used knock off parts?

How about valve lash adjustments? Were they done regularly? With excessive lash I can imagine the cam lobe might start smacking in the tappet and could possibly cause the issues that you describe. But, also when valve lash becomes excessive the valve bridges usually fall off.

When I ordered my Colt cam with new Colt tappets the owner told me that he was less than impressed with the factory cummins tappets. Quality seemed to be all over the place and instead of being convex, lots of them were actually concave!

Thats all I got.

 

[RVTRKN]

Axekicker, I see your in Vegas, what shop are you going to here in Vegas? Even though I have a new 2019 and under warranty, I'm relatively new in Vegas and looking for a quality shop. I may have them perform the required service, if close to me. Thanks in advance. BTW, good call on the teardown inspection.

 

[Axekicker]

Is there any chance the engine was "rebuild" or touched by someone who used knock off parts?

How about valve lash adjustments? Were they done regularly? With excessive lash I can imagine the cam lobe might start smacking in the tappet and could possibly cause the issues that you describe. But, also when valve lash becomes excessive the valve bridges usually fall off.

When I ordered my Colt cam with new Colt tappets the owner told me that he was less than impressed with the factory cummins tappets. Quality seemed to be all over the place and instead of being convex, lots of them were actually concave!

Thats all I got.

I've owned the truck since new (purchased Sept. 30, 2004) so the engine parts are all factory originals.
Yes, valve lash adjustments were done at 100k and 200k.
I heard the same thing from colt....one of the reasons I decided to run with their cam & tappets.

 

[Axekicker]

Axekicker, I see your in Vegas, what shop are you going to here in Vegas? Even though I have a new 2019 and under warranty, I'm relatively new in Vegas and looking for a quality shop. I may have them perform the required service, if close to me. Thanks in advance. BTW, good call on the teardown inspection.

'Superduty' (Mike or Chase) did the R&R and Universal did the machine work. I also use Diesel Specialists (Daryl) if Mikes shop gets too busy. They're both in the north end of the valley (off N. Cheyenne & the I-15) Email me at -- email address removed -- and I'll send you my phone# if you want 'specifics'.

 

[2004HPCR]

Hmm, well then its an anomaly.

Do you have pictures of the tappets? It would be great to see exactly what your talking about.

 

[Axekicker]

Hmm, well then its an anomaly.

Do you have pictures of the tappets? It would be great to see exactly what your talking about.

Wish I did. I got a lot of parts back in a box when I picked up the truck, but the tappets & cam weren't in there. By the time I realized it and called the shop....nobody else remembered what happened to them. I'll stop by there this week and see if they have some laying around that look like mine did. Like Yogi Berra might have said... 'A good diesel business is half repair shop, half parts bin and half junk-yard.'

 

[sag2]

Diesel Specialists hosts our dyno day for May Madness every year. Great guys and I would urge you to support them if you need service.