Ok, so I gott an '84 f250 6.9 a few months ago. At this point, I have a facet duralift, rebuilt injectors and a reman-ed Standyne. My remaining issue is what I could classify as a clacking noise. It only makes it under load and only with certain RPM/throttle combinations.

Example: starting from a stop, getting on a highway. At idle, runs Perfetly - no tick/clack whatsoever. Hit the gas and clearly audible clack for about 1-2seconds then smooths out a bit but still noticeable tIck. 30mph, ease off a bit and it goes away completely. Hit the throttle and it's back. Ease to a coast and it goes away. Hit the throttle after a short coast and you get a clack like when you first hit the pedal from stop. Using enough throttle to maintain speed on level road (mostly empty truck) at just about any speed and it's only maybe the faintest of ticks.

Before I start tearing things apart, what do you think?

 

a diesel SHOULD have a noise commonly described as "diesel clatter". its quite possible thats all you're hearing, and its foreign to you because you're used to gassers. i would suggest you spend a little time listening to some other diesels to get a feel for how they sound, and judge from there if yours is normal or abnormal

 

added, IDI diesels, they are a whole different animal.

Vintage, you took care of the standard maintenance with a pump and injectors, but who timed it and how was it done? a lot of your issues sound like they could be timing related.

either you are not driving a diesel, or it is not running right! the clack that is often associated with bad or noisy, is the injectors popping when they should as they should. A properly timed stock IDI diesel ALWAYS clacks! No clack is retarded timing!

You say "clack" does it sound top end and high pitched, or bottom and low pitched?

both could be timing related, but we aren't sitting behind her like you are.

My first guess is your timing is off.

 

Thanks for the replies guys. It's true that I'm more familiar with gassers but this is not diesel clack - it makes that noise too. Also, my comment about almost no tick at all was referring specifically to the extra-loud one that I'm worried about, not tick/clacks in general .

In fact - new information - I was playing around with it a bit more on my way home from work last night and I was able to get it to make the noise by revving with the hood open. I think I was able to do it this time and not before because the noise seems to be more pronounced once she warms up and I had not yet tried to listen under the hood with her fully warmed up. That said, it's in the PS valvetrain so I'll pop the valve cover off today and have a look.

I'm actually leaning toward oil pump or restricted oil passage associated with a lifter because the sound goes away when you get on it and has a couple seconds lag in returning when you ease off. It also doesn't seem as pronounced when the engine is cold, oil is thick and oil pressure is slightly higher - but maybe I just don't hear it because of all the other clacks. Are oil pumps known to be problematic on these trucks? i haven't seen anything on that topic yet.

My timing is just set straight on the marks for now (as the one before it was until I advanced it to verify that it was my most likely culprit) which seems to be pretty good - smoke only when it makes sense and started last night at 50F on the first crank with about 3 seconds on the glow plugs (manual GP) after sitting 8 hours. Once I get the other issues worked out, I'll play with that a little and decide where I want it. And no, I didn't remove the timing gear housing while replacing the IP - I do my research...

Questions? Comments? Input?

EDIT/ADDITIONAL INFO: Oil passage issues come to mind first because I Seafoamed the crankcase at my last oil change and you should have seen all the crap that came out of there! Lots in the filter but plenty in the pan too (no metal or anything just lots of carbon-y/oil-gunky stuff).

 

If you can post a video of it it would be much easier to give advice concerning whether it is a normal sound or there are issues and what kind of issues they may be.

Here is a video of my truck starting cold with the timing advance on. its not the easiest to hear the clatter of the diesel but its fairly loud. This was with the timing having just been set at 8degrees not a month before with an actual meter.

7.3l idi cold start - YouTube

 

Also I have never heard of oil pumps having problems in these motors. They are big, heavy gear driven(actual gear not like a distributor in a gas engine) pumps. I don't think the pump would go out but if your strainer got plugged up from seafoam it wouldn't be pumping much....

Do you have an actual oil pressure gauge that you can trust to show you have enough oil pressure?

Alot of guys are weary of seafoaming an old engine because of the large amount of deposits that become dislodged.

 

Maybe a long shot here, but have you checked for an exhaust leak at the manifold? Mine comes and goes as it gets plugged with soot then unplugs and so on. To me on mine i would say it sounds like a pretty good lifter tick.

 

My van has had a "clack" in it also since i've done the pump and injectors. You can't hear it from outside, only from inside, it's coming from the drivers side of the engine, and is consistent to 1 cylinder.


And it's the loudest around 1500-2k RPM. Goes completely away after at least a half hour highway drive though. And it's really loud when the cold idle/timing advance is on.


I figure gotta be timing, all I did was line up the lines, didn't have ti timed yet. No one around here has the equipment to do it...

 

anyone else think the idi rattle of the navistar is far better sounding than any other medium duty diesel equipped pickup?

 

An old 6.2 GM Diesel or an early Cummins in a 89-93 Dodge is good competition if you ask me

 

my pops had a 6/2 n/a suburban back in the day. he loved that car, i miss it too. rust got to her. averaged 11L/100 mostly in town

 

Yep I'd love to find a 6.2

No power what's so ever, but amazing mpg with the right setup!

 

Ok, I'll try to shoot video and post it later on.

No, I don't have a real oil pressure gauge - just the factory one.

As I've been thinking more about it, it might be a combination of something being just a bit sloppier that the rest (lifter? rocker?) and too advanced timing. When I get smoke, it's blue (not white) which, on my understanding, indicates too much advance. Also, when it does quiet down, it may be a little too quiet - further indicating too much advance. Perhaps that, coupled with slight old-engine sloppiness is just enough to make one of my valves unhappy.