6.9 motor problem diagnosis

Leroy

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Thank you for the kind regards gentlemen.

I've settled on removal of the trans and pulling the motor. It will be okay on some firewood rounds or lumber and a tire. I'll leave the cherry picker bolted to something to steady it and make sure it doesn't roll away. Looks like this is going to be quite the job, but i'd rather save my back from crawling sideways under the hood and under the truck. Swinging a screwdriver in there is hard enough, let alone shoehorning heads.

Waiting now, for the hadgasket and upper motor gaskets, they should be here in the next few days, until then, I will see if I have enough random junk laying around to make a homebrew compression tester, to satisfy curiosity, and have some reference on where to begin looking, though my gut feeling is that there will probably be fresh valve prints on one or another piston, or a gasket with a bridge to nowhere in it.

I probably could have saved these gaskets, if that's what it is, by retorqing them at some point, though kind of left whats well enough alone, until now didn't realize that stock were asbestos, that were recommend to be retorqued at least once at 30k, so they probably could have benefited from this, but now they're way beyond just tightening up, I would think, anyway got a new set coming on a big brown truck.
 

IDIBRONCO

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I bet it’s just a rocker failure, I would pull the valve covers off and take a peak, it will be pretty obvious if there is a rocker failure. If you’re replacing one replace all of them with 7.3 rockers, and retorque the head bolts while you have them off.
He already replaced the rockers a few years back with the 7.3 style.
 

Leroy

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Update..


Not much but a few observations,
Today I took off the accessories and drained some coolant,
much of the metallic noise abated with these off.
Notably my alternator bearings have been noisy for quite a while,
I have a new set of bearings for the alt, and will replace them while it’s out.



The chuffing is definitely coming from the crankcase, specifically the CDR,
the pulsating pressure is overcoming the spring..



I pulled the cdr, and my basic push blow test shows that it
is operating as it should, and the diaphragm is good.
it must just be the pulsations that are allowing the
bypass of gasses and oil mist, probably fueling
a cycle that has further injured the headgaskets
with oil bubbling up into the intake.


Using my layman power of deduction, and wishful thinking,
I think this is reinforcing a diagnosis of headgasket
failure. When the air filter assy is off blowby is coming
from the filler neck and dipstick tube, when I cover the intake
screen partially with my hand, the vacuum pulls the smoke
down and it stops. The motor never has had much of any
blowby or oil consumption before, so this is associated with the issue.
Further, there is an acculturation of oily muck at the radiator.



So, my thinking's are it could be that headgasket
blown mostly on the crankcase side. A cracked head,
or a cracked piston.



I am leaning, that with little oil consumption, and the the problem
has gotten steadily worse with time, instead of a sudden change,
no obvious stuck open injector, to burn a hole,
alongside the obvious weeping and coolant contamination, that
the headgasket is the most likely culprit.


Still just a guest a guess at this point though,
I won’t know more until tomorrow when
I dig further into the engine. I left the fuel filter bracket on and
will pull the valve covers again and run it, putting a straight edge
to the rockers to look for any lifter not making or exceeding the gap.
All looked normal a few weeks ago, but a problem would
probably be easier to pinpoint now if there is a valvetrain issue.
I will definitely check the lifters before pulling the heads. Though
I’m hoping all that huffing is coming from the case,
and that the valves and lifters are still good.



I’ll pull the the lifters and visually inspect them and
soak them in laquor thinner if they’re looking alright

The fel pro top end kit has been delivered, so I’m ready to do it.



I have decided to go through the top, rather than pull the motor,
mostly because of the weather, forecasts are showing rain
and snow every other day, and I’ll be doing this outside on
the nicer days in fair weather.

Further, my place floods on occasion, not too often or deep,
but a few days of hard rain could hit and be a spoiler, I think
I’ll keep the motor high and dry, and keep myself under the
hood, and out of the mud. In the summer, with long days
and clear weather, I’d pull it and save my back.

I’ll post what I find tomorrow, hopefully the heads and valvetrain
are alright. And the head bolts are serviceable. I have the exposed
bolts soaking overnight in pb blaster, so hopefully the come up
easy. None look much rusted externally, but will have to carefully
check the shafts and threads.

I’ll drain the oil for reuse, and flush out any coolant with
No2 if any gets down into the block.

I’ve been driving it daily since 2011, so it’s about due for
headgaskets I’d say, betwen the previous owner and myself,
If this is the OE gasket, they’ve probably racked up half a million
miles on em’.



This is the likely the first time it’ll be opened
up in 34 years, other than this issue, never a problem
aside from common burned and deleted GP’s,
fuel delivery, IP, injector, fuel pump, maintenance,
and oil changes.
 

IDIBRONCO

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Something else that I forgot to mention. Be sure to check for broken valve springs while you're in there. They do fatigue and a broken, high mileage spring isn't too uncommon.
 

Leroy

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Kind of.. I admitadly work slow , but you know how it is, they didn't do me any favors how they put this motor together. As I'm sure you know, there's always a 'special trick' to damn everything and always only 1/8 of an inch clearance anywhere, but yep been digging deeper.

I have everything but the, manifold, Valley pan and heads left on top, it looks like by trimming an inch or two of the inner wheel wells I can get the exhaust manifolds off in place and leave the y flanges. I would rather like to leave them on if I can get away with it, every, every single time I take on off, even heated by the oxy acct torch one always inevitably breaks, and also have to hunt down a doughnut, also it looks like I can leave the dipstick if I can get the exh manifolds wired up and held in place.. Is this how it's usually done, looks like they left room almost .. Special.. Lol

Well, so at first notice, the rockers are much covered in surface rust, 3 ish weeks ago when I peeked it was a tiny bit, now it's 4x as much rust on the rockers and pushrods.

Also it's chuffing alot of smoke out of the seals, I think it might be smoke corrosion causing the surface rust by the look of how it's blowing, but could also be coolant contamination in the water.

It wasnt chuffing smoke at all past the valve train last time, now it's like a locomotive.. I'll get on youtube and post a video.

I haven't got the Valley pan off yet, but a sharp straight edge is showing all the rockers are coming up to full motion, with the furthest forward intake lifter on the driver side perhaps a little bit higher than the others inline, but not by much maybe 1/8 of an inch more lift, but repeating on slow cranks and sighting down the row it more or less settled with the rest, I will clean and inspect that closely, but it seems like the top end is pretty much doing what it's supposed to. Hopefully the lifters all pass and it looks like I still got a cam.

I will be changing the oil sooner than later it looks like, shame, just put in fresh juice, but will have to clean up this surface rust and give her fresh dino blood when this is all through, head gaskets in this truck sure ain't a weekend job, or I drink almost as much I wrench, have to on this one!
 

Leroy

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IDIBRONCO

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and also have to hunt down a doughnut
The good news here is that there are no exhaust doughnuts. The pipes seal right to the manifolds. I always left the manifolds on the heads. It was just easier for me to remove and install them with the heads compared to trying to get all of those exhaust manifold bolts loose in the engine compartment. You ma have issues with getting the bolts installed back into the heads if the manifolds are still attached to the rest of the exhaust system. It can hold them toward the back of the truck a little bit, making it hard to impossible to get the bolts started.
 

IDIBRONCO

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It's pretty easy to hear the intake noise in that video. It's not easy to tell where the extra "smoke" is coming from. I couldn't tell whether it was coming past the valve stems or out of the oil drain back holes in the heads.
 

Leroy

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The smoke is pushing past the valve stems and pushrods and probably the drain holes too and everywhere else, the thumping is really not originating from the intake though, with the cdr off it's thumping from the crankcase, just makes it into the intake through the cdr and made it sound like intake thumping.

It's good to hear there aint no doughnut on this n'. I will see if I cant cheat and leave the exhaust logs, if it's not too hard from the wheel wells, if it gives much trouble, or won't reinstall, I'll have to take em off the studs, just kind of a curiosity, it looks like they may be removable with just a little plastic trimming, and I already cut in access, so what the heck, worth a try, hey does this thermostat housing HAVE to come off, or is this optional, looks like it'd pass over that alright and it's on the block not the head. What about this dipstick tube, does it pop out of the block? Is it reusable if so done? That kinda worries me, and the primary reason for attempting to leave the smog logs attached to the exhaust in truck.
 

IDIBRONCO

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The thermostat housing doesn't need to come off, but it does make it easier to lift the head out and install it later. It's also easier if you remove things like the alternator, A/C compressor, vacuum pump, Etc. Assuming that the 6.9 is in the Bull Nose truck in your profile picture, it probably has the 6.9 style dipstick tube with no bracket going over the top of the passenger's side valve cover. It is secured by a bolt that goes into the block underneath the exhaust manifold. The tube will come out after you remove this bolt and is reusable.
 

riphip

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First time I did my head gaskets, I pulled the front clip & could get to every thing much easier. Pulled the Rad, batteries, A/C ( I do A/C work), propped the hood, disconnected wiring & removed mounting bolts. Had 2 of my brothers help lift off the clip and set it to the side. Wallaa
 

Leroy

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Alright, good to hear it's just got a bolt holding that d's tube in there.. Whenever I replaced the thermostat probably 6 years ago, one bolt broke off flush, I was able to grind, drill, and tap it successfully but gunshy, swore not to touch that thing again if I can avoid it. Really hoping all the head bolts are made of tougher stuff.

weather man, calling for t-storms after noon, not going to bust out the cherry picker today.

I do hvac too rip, mostly commercial refrigeration self employed, some residential and mixed in remodeling.
 

riphip

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Yeah, I do the same work. If you have not reworked the A/C to 134a, would be good time for this also. DO NOT Scrap old condenser!! These work better than the replacement parallel flow condenser.
That rust is probably due to condensation from the years of variable hot/cold Tennessee weather. Mine have done the same.
Don't know what kind of $$ you have but check out these mini-inductors for removing old bolts: https://www.tooltopia.com/search.aspx?find=bolt+heater
I think Danielle has one in her shop. Tooltopia runs discounts on all their tools and have some good pricing. Tools usually arrive in 2-3 days from order.
 

Leroy

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Confirmed: broken head gasket .

- - also yea, I did have to evacuate the a/c. But will charge it rather than converting it over. R12 works great, imo. Can't get it anymore though, too bad. I won't be re charging it with blue rhino propane, though it works well as a drop in for r12 and is compatable with the mineral oil already in place, it is not safe because in case of wreck, the propane is released, it is clearly x /plosive.

Okay, so I been digging further. Yesterday I had the Valley pan, rockers, pushrods out, and couldn't identify a clear break in the hg to the crankcase.

All the lifters and cam action look good, and move as they're supposed to. No problems with rockers or pushrods, no clear break in hg to crankcase.

To further pinpoint the offending cylinder, prior to head removal, in the unlikely event that with it off, that I still wouldn't find fault. I put the pushrods and rockers back on with the intake off, reinstalled the IP just hanging out there and cranked.

The chuff was now clear and easy to identify as coming from the second forward most intake runner on the driver side.

Only one of two possibilities at that point, and either would be apparent only with the heads removed. Either damaged intake valve or seat, or broken hg between cylinders.

Upon removal of the head bolts, things began to clarify, as those surrounding that troubled cylinder were lightly coated in exhaust soot and were slightly more difficult to retrieve from their holes.

At this point, I was feeling relieved, as I was more convinced that I would find a broken hg, and not a more serious mechanical failure.

The damaged hg is on the driver side, with no dipstick to concern with, I unbolted the exhaust flange, and pulled the manifold with the head.

The studs and bolts are good quality and didn't give me any problems or break anything, easy to get to as opposed to taking it off separately.

With the head off, the diagnosis was confirmed, there is a break between the forward most two cylinders on the driver's side. It looks likely that it'd been leaking for awhile, and finally blew out an unhealthy chunk.

I don't know how this would have caused the knocking that occurred that one day, I didn't see any valve prints, though it was very unbalanced, and maybe some of the oil that was blowing through the cdr accumulated too much and lightly locked up a cylinder.

I'm not sure, but I'll have that other side off tomorrow and will look for anything out of the ordinary,

Overall, I'm very happy to finally know for sure what the problem is. I have the gasket kit in hand, so it will be put back together and running strong sooner than later.

I'm also pleased that the condition of the engine looks very good. Rockers, pushrods, lifters, valves, pre-cups, piston tops, look good.

Cylinder wear looks good just catches the fingernail. A disturbing amount of grime fell into the cylinders when I pulled the head, I will have to turn the motor by hand back and forth a few times to get all of this debris out of the engine.

I will certainly be changing the oil again at the first opportunity, with as dirty a job digging down into the motor is, completely unavoidable.

No coolant seeped into the case with removing any of the top end, so draining it out is definitely a good idea.

The Valley pan gasket came out beautifully with no bends or breaks in the mating surface, I will certainly reuse it without hesitation and I'm sure it will seal up, with rtv front, back, coolant ports, and form a gasket elsewhere.

The head bolts are in very good condition, and also I will reuse them without hesitation, and I'm sure that they'll be fine.

They were really, really, on there tight, and I broke a serious sweat, backing them out, hoping that none would break, but, they came alright. Will chase the block threads, lube the bolts and washers and torque em down.

One question, specs call for 75 lb. Also I have heard on the forum, 80lb.

What is your recommendation for used good, stock 6.9 / 7/16 head bolt final torque?

Is 75 plenty good enough, is 80 inviting disaster?

I don't push my motor too hard, and it's going to stay non turbo charged, would you stay with 75lb, yes or no and why please.


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