Sudden clunking/blue smoke diagnosis

[Car Doc]

On cars we do what is called a cranking compression test as a pre-lim to any driveabillity concern you cant tune any engine with a cyl down.

This diesel can do it too simply crank it with the throttle lever all the way off and compression release inactive and listen for a hitch in its get a long meaning a cyl with an abnormal compression will make the engine turn over different than normal.

Then start it and crack one injector at a time at the injectors and look for the one that either makes the knock change or has the least change in rpm probably both is what you will find. That will identify the cyl in question.

If it HAS a hitch that's when the valve cover comes off to look at springs,rockers push rods etc if all is ok then a compression test would be prescribed.hth

If you take the injectors out and have them pop tested at a diesel pump shop as has been mentioned don't forget to mark the position of each with tape wrapped around them and a number so you can relate back.

CAUTION if you do take the injectors out (pretty good chance you will) do NOT bump or damage the tips in any way that will ruin them!!! You will see once they are out what I am talking about be careful with them!

And also blow out all the dirt around them before pulling them out of their holes or you will get it in the cyls.

 

[evofxdwg]

Diagnostic Report - Good news and Bad news:

Good news: Symptoms were clearly there, but went away after the third start and running it for a few minutes! So its probably not serious lower end or cylinder issues.

Bad news: I dont know what the problem is or if it will come back.
---------------------
Details:

I elected to pull valve cover first:
Compression release linkage worked normally - after looking at how it worked, there is no way it was the cause. No broken springs or loose rockers. All valves actuated normally by hand. Pushrods looked ok. I cranked it over a few rotations with no fuel and all valves appeared to be working. So reinstalled valve cover - now have to order a gasket since it was stretched and flat.

So i decided to "crack" the injector lines with it running:

Cranked it up - started OK - quite a bit of blue-white smoke after a few seconds. After a minute - if i idled it up the clunking got quite loud. I set it to about 800 RPM and I cracked the rear injector line, then the middle. Both times the RPM dropped. I checked the hydro and it was moving the bucket. During this process i started it up twice.

I couldn't get to the front inj fitting with my crescent so i shut it off and went to get a correct size open end that would fit down in there. I started it back up, cracked the front fitting and RPM dropped again. But the noise was not loud or not there at 800 RPM. So i played with the throttle. CLUNK Noise was intermittent, then went away! And i could goose it up to 2500 or so with NO CLUNK, NO SMOKE!

I checked the hydro again, this time lifting the front of the tractor with the bucket rotators - no problem there.

I checked the vent on top of valve cover by putting my finger over the hose nipple - no detectable pressure or pulsing. And nothing visible blowing out. BUT- the valve cover o-ring gasket is sticking out on back and oil is dribbling out so that may not mean anything. I wont be able to seal the valve cover without a new gasket.

When the noise was there, it seems to be on right front side of the engine or near exh manifold. But i did not get around to searching for it with stethoscope - that's just by my ear judgment.

Sooooo.......a piece of trash or goo in the fuel line or an injector????.... That i cleared by playing with the fittings? Intermittent injector about to go permanently bad?

I hate intermittent problems, especially when they make ominu$ sounds.

I did replace the fuel filter a couple of months ago after having power loss and shutoff problems. It had water in the sightglass bowl and I could have disturbed any trash that was stuck there. However, i cleaned the sightglass before putting it all back.

PS: i have been reading recently that the low-sulphur diesel you get now may need some additive. I have never run any additive. Could this be a factor?

What now? Put the valve cov gasket on and use it?

 

[winston1]

The old saying "If there ain't nothing wrong, don't fix it" has some merit. No knock, no blow by, no smoke, runs good, what more could you want. Crank it another time or two before installing your new valve cover gasket. :thumbsup:

 

[clemsonfor]

Im with winston, but i think you have narrowed it down. If at first when u cracked that font line and the noise was there but got quieter that is possibly your proble. An intermitantly bad front injector. Cause some of the fuel was goint out through the line and not into the cyl?

 

[Car Doc]

Sounds good all fuel and mechanical things checked out for you!

It may be a chuck of crap was under a valve now is in the cylinder and will get chewed up and spit out? How is the air cleaner and fitting tight etc?

Carbon from the back of a valve etc sounds like the engine is coming apart specially a diesel where there is no clearance between piston and head but rarely does damage so you may never hear it again. :thumbsup:

 

[MJPetersen]

It sounds to me like a sticky injector problem. Add a bit of atf or "Marvel mystery oil" to your fuel and it should clear up entirely. A bit from time to time will keep it clear. Or you could buy the commercial fuel additives. I would not worry about it any more.
I had the tip actually break off on a diesel injector in a 2.5 liter Ford engine and there was a ton of white smoke horrible sounds and it died when the revs dropped. Another time the that the white smoked poured out was when a turbo seal went out and the engine kept running even with the key off (on engine oil sucked into the intake).

You should be good to go--put it in your bag of experience and get back to work moving that dirt.

Mike

 

[evofxdwg]

I had a near full can of Marvel Mystery Oil sitting around from years ago when i used it for noisy lifters on an old Chevy. Until your post, i didn't know it is recommended for diesel engines. Read the label and put in a few ounces with a fuel fill on my 1610D. Then I used the tractor a couple of hours with no problems and it actually seemed a bit quieter and smoother than normal!

Thanks for the tip MJP.

 

[jonyyuma]

I had a near full can of Marvel Mystery Oil sitting around from years ago when i used it for noisy lifters on an old Chevy. Until your post, i didn't know it is recommended for diesel engines. Read the label and put in a few ounces with a fuel fill on my 1610D. Then I used the tractor a couple of hours with no problems and it actually seemed a bit quieter and smoother than normal!

Thanks for the tip MJP.

Good deal ,,at least two more people now believe in Marvel mystery oil. I have used it for years in all my diesels, with excellant results. I have never replaced a fuel injector pump on any of them.I have stopped mixing it in my cars due to the oxygen sensors...JY.