83 6.9 Valvetrain Noise?

[mintmoballen]

Hey guys, I recently bought this 1983 6.9 IDI and I've been noticing some annoying ticking that I can hear in the cab. The truck is 2wd with an ATS 085 and T19 with a Gear Vendor. The noise has not gotten better or worse in the few weeks I've been working on it. I ran some seafoam through the oil and changed it but it didn't seem to improve anything. I've owned two other IDI trucks before (a 1990 7.3 and a 1984 6.9) and neither of these trucks made these noises, however I think my friends old 84 had the same-ish noises (but I'm not totally sure). The truck has other weird issues to fix such as some terrible transmission noise but this ticking is the most concerning issue at the moment. It's also my daily driver for the time being (my 6 leaker is torn apart) so I can't really dig into it. Any help would be greatly appreciated. Was just wondering if anyone has experienced the same noise.

Kind of difficult to make out in the videos but in person it's very noticeable.

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(Please excuse me if my formatting is a bit wonky, I haven't posted much)

 

[franklin2]

Sounds like normal diesel noises to me. If it gets louder as you step on the throttle going up a hill, it might be a exhaust leak. Otherwise, everything sounds normal to me in all 3 videos.

 

[mintmoballen]

The weird thing is that it doesn't make the ticking I'm hearing for the first few seconds of running and only starts ticking when the oil pressure comes up. That's what makes me think some sort of lifter issue. I know it has the normal idi clatter but it does also have some ticking. I might just let it go though since the engine seems very healthy.

 

[CDX825]

Pull the valve covers and check the rockers for play. The early style rockers were problematic.

 

[BrianX128]

Not hearing it loudly until oil pressure [from running a few seconds, nothing to do with oil pressure itself] leads me to believe it's an injector not popping at the right pressure. That cylinder probably doesn't fire for a few seconds. When it starts firing every time the combustion is slightly out of time. When I got a new IP and injectors for my one idi few years back one of the injectors had a defect and leaked at the threads. While the seller was shipping me a replacement I went to Unadvanced Auto and bought one of theirs and it simulated a ticking lifter and the truck just didn't idle quite right at any rpm.

I wouldn't condemn anything but it's something to check.

 

[mintmoballen]

I had the passenger side valve cover off when I was repairing the A/C and it all checked out good. No play in the rockers and they were all torqued good. It was also extremely clean with no old oil deposits and yellow paint marks on every valve spring (which would wipe off when I just barely touched it with my finger), very pleasant surprise! I know the 6.9 valvetrain is problematic and I was thinking of swapping to the 7.3 style regardless of it actually needing it or not. I'll pull the drivers side valve cover and get a picture sometime soon. I did also read somewhere that the early lifters were a different design with a bushing instead of needle bearing so maybe these early lifters are inherently not good/quiet?

I would think that maybe it's a fuel system issue but it doesn't really sound like a fuel knock/tick (to me at least) and the engine runs surprisingly smooth and fires with a tap of the key. In the near future I may replace the return o-rings and pop test the injectors while I'm digging into it just to rule that out as an issue. The injectors and pump almost look original but I also have no idea since the history the truck is largely unknown. (Owned by a disabled veteran and his wife before me) Pump has the original calibration despite having an aftermarket turbo.

The noise hasn't gotten worse *yet* so I don't think it's life-threatening.

 

[IDIBRONCO]

The noise hasn't gotten worse *yet* so I don't think it's life-threatening.

That's good news. It means that you can save up the money and buy the new parts slowly instead of all at once because you have to. The lifters with the bushings aren't as good. They can fail because of that bushing. Overall, it sounds like you have a pretty low mile engine to me so I wouldn't be too concerned about parts failure in the near term. Failure can occur, but it wouldn't at the front of my mind. I feel like you've got some time left.

 

[mintmoballen]

That's what I like to hear. I think I might be acquiring a 7.3 IDI core that I could rob valvetrain pieces from and swap everything out. My friends truck has a nasty burnt/cracked valve in his truck and we may be engine swapping it in the coming months. I'll take it easy until then. Thanks guys.