So, as a recap, this truck of mine is a 1993 non turbo IDI. It used to do this loud noise when starting cold that sounded like a real loud "wumph, wumph, wumph though the intake. I always believed it was a sticky valve. When I took the valve cover off I found 3rd valve from the fire wall on the passenger side had a broken bolt that holds down the rocker. I also found the companion (fourth valve from the fire wall) valve had the lifter coming apart. So new rockers, lifter, bolts and back together. When I did the compression test after it was all back together it was back up to 490 or so. Put about a thousand miles on it with the new R&D IDI pump and injectors and she runs like rocket. Only thing is I heard the death shake again a few days ago.
So questions:
1. So I am thinking, maybe the reason that the rocker bolt broke is that the valve is sticky?

2. So I am thinking maybe remove that head and see if the valve is sticky?

3.Is there anyway to check that check valve without removing head?

4. Let's say it is a sticky valve, I remove the head free up/fix the valve. Should I actually do a valve job on the head or maybe the other head too on an engine that has 197,000 miles on it and has really good compression all around. I did a valve job on a 6.9, but it had quite the wear ridge, it started blowing a lot of gases out the oil fill after this. So I am i little apprehensive about a full on valve job with this kind of miles.

Any suggestions will be appreciated.

 

If you go through the trouble taking the heads off....and if it were me i would. ..i would take them to a machine shop have tgem checked,cleaned and valve job done, its work taking them off, do it once and forget it, i would stud the heads going in too, gives you room to grow latet

 

"Sticky"??? That is perhaps a misleading phrase. If you are breaking rocker fasteners I assure you that you are not dealing with carbon deposits, oil varnish or any other form of petroleum based deposits. If the valve is stickING, that would indicate a bent valve stem and/or a badly galled valve stem and valve guide. IF the problem is on the valve side, the only solution is new valves and new guides that are machined to spec at a shop. As mentioned, you might want to have the rest checked and re-ground while the heads are off. IF the broblem is not on the valve side, you would be looking for a bad lifter, bent push rod, or a bad rocker folcrum. If you really want the problem gone and can't find an obvious culprit, replace everything on that cylinder.

 

Well that is good info. Good to know that the only way it could be sticky enough to break hardware is if the valve being bent and/or the valve or guide being gaulled. I had the intake off before this and replaced the one bad lifter and and all the push rods were straight. Could I take a pair of large channel locks and grab the rocker arm and compress the valve to see if it is hindered?

thanks,

V-465

 

I suppose you could manually open the valve, but keep in mind that the valves can rotate as they run. If it is binding up the problem may not be as noticeable at certain orientations. That said, if you can detect any difference from the action of the other valves it would confirm that suspicion. The one other possibility that occurred to me is if you had a broken off glow plug tip in that cylinder... But you would most likely be aware of that...

 

Broken Glow plug tip. OK, let's just say yes to that for a moment, how would that affect the valve action unless it got up into the area between the valve and the guide? Just for the record I pulled and replaced all the glow plugs during the last go round. All the old glow plugs that I took out were intact.

V-465

 

There is very little clearance between the valve and the piston face when it is at the top of its stroke. A broken GP tip could definitely prevent opening of the valve if it were caught between the piston and the valve face. If the fragment lodged in between the valve and the seat in the head the valve would be forced open, not closed, and that would not strain the rocker. It might bend the valve though, which could still be a root cause. It is hard to speculate these things if you don't know the long term history of the engine.

 

Well, history on the engine goes like this:
1. We bought the truck in 2011 and supposedly the engine had 161,000 miles on it from new in crate.

2. From the very beginning when we got it in 2011 it did the death shake (the loud wumpf wumpf from the intake) every now and then on a cold engine.

3. Out of nowhere it made a loud noise on the highway and started shaking. This was the broken rocker hold down bolt and the bad lifter.

4. After I replaced the lifter, rockers and the broken bolt, bolted it all together it didn't make the death shake for about a month.

5. Now, about every 6th cold start it does the death shake.

6. It seems to run great though I would say there is a little "tick, tick, tick" that I can't really seem to harmonize with the rest of the diesel engine sounds. And it is possible that I could be wrong about the "tick, tick".

V-465

 

The ticking is probably play somewhere in the lifter/push rod/rocker/valve tip clearances. Since it had the problem when you bought it, anything is possible. I am guessing it was a lousy rebuild or maybe there was a broken GP or other known problem that motivated the seller to get rid of the truck. Unfortunately I think the only solution is going to be pulling the head. Make sure there is no other signs of damage in that cylinder, and then have new valves and guides installed in that cylinder at a reputable machine shop. Also install a new rocker arm assembly in case that one is damaged.

 

Well, sounds like compression check for info and pull the heads to see whats going on....I think it will be a bit before I do that though. I suppose I should replace the lifters since I will have it that far down. I have noticed they almost give the lifters away. Thanks for all the advise.

V-465