Here is what that CHUFF noise in the exhaust means

[Jaybee]

When you start to hear that "CHUFF" noise in the exhaust it usually means that you had an exhaust valve guide go south. Mine went from barely noticable to very pronounced in about 2000 miles while I was on a trip. I finally yanked the head and here is what I found:

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See the valve with #2 on it? That is the exhaust valve for the front cylinder on the driver's side. See ho it looks like it's sagging downward?

Here is another picture with the valve pushed all the way into the seat:

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Notice the shiny area the little arrows are pointing to? That's where the valve was hitting the casting of the head before sliding back in line with the valve seat on it's way down.

Now - if you need a better idea of what's going on I've got a short video of it here: Loose valve video

That makes it real clear, doesn't it? Also explains why you shouldn't run one of these long once it starts making that noise. That valve is only going to stay together so long wobbling side to side as it goes up and down. Eventually it's going to give up, snap off, encounter a piston, most definitely ruin a head, possibly crack the cylinder, and generally just ruin your day!

This engine only has about 120,000 miles on it since the truck was new in 1991. This is the only valve in the whole engine that decided to do this. Doesn;t make a lot of sense to me, but oh well!

Jason

 

[towcat]

jaybee-
you've done it again
I had the same happen on the intake side on a "factory rebuilt" motor with 50k on the ODO.
I drove from TX to kali with the same thing happening. only difference the head was cracked and I was going through 6gal of water every 400mi. After the first night and the horrible sound the motor made the next morning, I knew I couldn't let the motor thermal cycle again before I got to my destination. It made for a very long "day" from El Paso,TX to San Jose, kali.
Oddly enough, even after sitting for 6months, the motor fired up again when I returned from overseas. But it was completely junk though. At least you were able to tear down yours to see the damage before it all looks bad. I did have valve marks on the piston. How about you?

 

[icanfixall]

Talk about being a lucky guy. I think you pulled the head at just the right time. Did you do the other head also? Its a good idea because if something goes wrong with that head later on you will be doing all this labor and gaskets just to do it again... Nice pics too.

 

[typ4]

The next thing that happens is the exh heat goes up to the spring and it fails then the carnage begins.

 

[Diesel JD]

That's a lot of play my friend. Glad you caught it in time. Now you'll be able to get what that cool truck is truly worth with this issue fixed. An instructive video would be one of how a healthy exhaust valve behaves for comparison. I still want to know why these trucks do this. This chuffing sounds like the bark in the intake or a popping back through the intake right?

 

[Diesel JD]

Calvin from what I hear its pretty unusual for the intake side to let go and the failure pattern usually is the exhaust side. I wish I had done the valves when I had my heads off at 153,000 but I was COMPLETELY out of money and a little afraid that the updated positive valve seals were a contributing factor to the problem and explained why more 7.3s had this problem than 6.9s. Is that information incorrect as well?

 

[hesutton]

That's a little scary. Glad you found it before that vavle dropped and killed the motor. What would that "Chuff" sound like....anybody have a sound bite of it? You say it's heard from the exhaust? Just want to go out and listen to my truck idle now!

Heath

 

[towcat]

Calvin from what I hear its pretty unusual for the intake side to let go and the failure pattern usually is the exhaust side.

I've heard just as many make the same sounds through the intake over the years.

 

[Jaybee]

It sounds like the sound file Billy Goat posted here from his truck: http://www.oilburners.net/forums/showthread.php?t=20843 Mine got to be much more pronounced, though.

The funny thing I found was in the valve seals. The intakes looked like I expected - positive seals with springs to keep them in place and a tight seal on the valve stem. The exhaust were simply the old umbrella style. I thought Ford used the spring type on all the valves. I got the truck with only 34,000 miles on it and highly doubt it had valve work done already...

Jason

 

[HammerDown]

With 180,000 on my clock, luckily mine sill purrrrrs like a kitten,
I think frequent oil changes from day one play a big part.

 

[Diesel JD]

Anyone know if this issue is indeed more common with the 7.3s or if that is just something us 6.9 guys like to tell ourselves?

 

[f-two-fiddy]

Any pix of that valve stem?

 

[6 Nebraska IDIs]

Damn, my red truck (6.9) has a sort of loud thunking that you can hear from 20 yards away. Im not sure what it is, but I did have that one pair of rockers fail because of lack of oil. I wonder if it screwed the valve.

 

[Banks7.3IDI]

So, so far I have the Banks Airbox off, the cai, the passenger valve cover, after the drivers will be taken off too and both repainted, the injection pump and steel lines (all at once...a *****! AND without removing the gear housing so it's still timed), but I have two of the glow but connectors that are made out of...Idk...ceramic? or plastic? they're broken but were before because I never went near them on this dissassembly....which sucks but replacement needed? Mine is turbo'd aftermarket so will I need to remove the damn turbo to get the Intake Manifold off or should I take the glow plug connectors out? It's one or the other...it either will slide and tip up or come straight up...turbo's in the way BAD. Let me know!! I'm going for lifters right now because some needed it anyway, and if that doesn't solve it then I'll go from there. Any words of wisdom? I already broke the little intake screen taking it out, and broke a t on the return lines...which will be a ***** to find...unless someone has ideas??

Let me know with this all! I worked for hours after school but didn't have more left in me...screw working on turbo'd IDI's hah

 

[hesutton]

You will likely have to pull the turbo to have the room you need to get the manifold and valley pan off and out of the way so you can access the lifters. Plus, if you need to pull the head or heads, that turbo has got to be out of the way. I'd unplug the glow plug harness and remove it from the top the engine. It's not bad, and again, more room to work without it being in the way. It will be more likely to get damaged if it stays there anyway as you'll have to work around it, move bits of it from time to time. Just pull it and the turbo......... that's my two cents.


Heath