CarterKraft
Thread ****ter Upper
Popping in the exhaust would have to be a valvetrain issue.
Do you feel a miss? "thud" during power stroke?
Do you feel a miss? "thud" during power stroke?
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vetteboy79
It's bent. #ttb
Valve lash adjustment? Pretty common thing on 4/6BTs...
CarterKraft
Thread ****ter Upper
I would think too much lash would make for low power and altered valve timing but not necessarily a open exhaust valve during the wrong stroke.
Really with valve train anything is possible.
I guess it could be fuel related as well, stuck injector, broken tip etc. but id think you would see visual signs in the exhaust.
WaterH
Well-known member
- Thread starter
- #1,145
Right now I’m leaning towards bad injector. I saw a couple videos and the sound is right. I’ve been getting some light smoke on startup. That is apparently a symptom of hector problem. I plan on checking the valve lash too. I may have to cut an access panel in the cab. Great timing for this ****. Family coming for Xmas.
WaterH
Well-known member
- Thread starter
- #1,146
So whether it’s injectors or valve lash, I need an access hole in the back. I could remove the entire bed in the back of the cab, but that is a major job that would probably be reserved for an engine change. So access panel it is.
First map it out and drill 4 corner holes.
To the untrained eye, that might look like 6 holes. The first problem is there is sound deadening “Kilmat” on the back side of this aluminum. When I drilled through, shavings had sticky tar in them. There wasn’t much in 4-6 holes, but I was worried about tar flinging all over when I cut through the panel with a saw.
So I stuck a small piece of kilmat on a strip of aluminum and cut it to see what happens.
Not too bad. In any case, I have a saying “I trust everybody, but I cut the cards”. In this case, that means I covered the dash and console.
It cut cleanly. Would you believe I cut to the wrong holes on the first cut? Good thing the outer holes were the correct ones.
The next issue was I planned to have the access cover screw on from underneath. That ment that I needed to strip about an inch of the Kilmat away around the hole. I wasn’t sure how hard that stuff sticks, so I did a little test on the cut out plate.
You can see, as long as I have a good line cut with a razor, it’s not too hard to strip away. At least working from the top on the bench. The problem is getting a razor under that panel with the engine in close proximity. Also, I don’t know about working with a mirror. After some thinking, I came up with an idea worthy of “tips and tricks”.
I started with a 1” square tube.
I cut a small piece and slit the side.
I got rough with it with a couple pairs of pliers.
Then I sharpen the little 1/4” over hang.
To be continued,
First map it out and drill 4 corner holes.
To the untrained eye, that might look like 6 holes. The first problem is there is sound deadening “Kilmat” on the back side of this aluminum. When I drilled through, shavings had sticky tar in them. There wasn’t much in 4-6 holes, but I was worried about tar flinging all over when I cut through the panel with a saw.
So I stuck a small piece of kilmat on a strip of aluminum and cut it to see what happens.
Not too bad. In any case, I have a saying “I trust everybody, but I cut the cards”. In this case, that means I covered the dash and console.
It cut cleanly. Would you believe I cut to the wrong holes on the first cut? Good thing the outer holes were the correct ones.
The next issue was I planned to have the access cover screw on from underneath. That ment that I needed to strip about an inch of the Kilmat away around the hole. I wasn’t sure how hard that stuff sticks, so I did a little test on the cut out plate.
You can see, as long as I have a good line cut with a razor, it’s not too hard to strip away. At least working from the top on the bench. The problem is getting a razor under that panel with the engine in close proximity. Also, I don’t know about working with a mirror. After some thinking, I came up with an idea worthy of “tips and tricks”.
I started with a 1” square tube.
I cut a small piece and slit the side.
I got rough with it with a couple pairs of pliers.
Then I sharpen the little 1/4” over hang.
To be continued,
WaterH
Well-known member
- Thread starter
- #1,147
Now I had a razor I can pull upwards and slide along the edge of the hole. It cuts almost exactly 1” from the panel hole. I was amazed how good it did. This part of the job did take longer than you think. But you can see the results in the mirror.
So when I got to this point, I figured I would adjust the valves before finishing the cover panel just in case I needed a bigger hole. As it turns out, I had good access to all the valves . Most of the valves were with in a thou of spec. One exhaust valve was about 3 thou out. When I got done, I started the truck and I do believe it ran better. But it seemed to have white smoke on start up. That was a symptom of a bad injector, so I’m going order a set tomorrow. I can finish the panel cover while I wait for them to come in.
So when I got to this point, I figured I would adjust the valves before finishing the cover panel just in case I needed a bigger hole. As it turns out, I had good access to all the valves . Most of the valves were with in a thou of spec. One exhaust valve was about 3 thou out. When I got done, I started the truck and I do believe it ran better. But it seemed to have white smoke on start up. That was a symptom of a bad injector, so I’m going order a set tomorrow. I can finish the panel cover while I wait for them to come in.
CarterKraft
Thread ****ter Upper
Now's the time for the "marine" or whatever the latest hotness is injectors.Now I had a razor I can pull upwards and slide along the edge of the hole. It cuts almost exactly 1” from the panel hole. I was amazed how good it did. This part of the job did take longer than you think. But you can see the results in the mirror.
So when I got to this point, I figured I would adjust the valves before finishing the cover panel just in case I needed a bigger hole. As it turns out, I had good access to all the valves . Most of the valves were with in a thou of spec. One exhaust valve was about 3 thou out. When I got done, I started the truck and I do believe it ran better. But it seemed to have white smoke on start up. That was a symptom of a bad injector, so I’m going order a set tomorrow. I can finish the panel cover while I wait for them to come in.
gt1guy
Apparently a racist
Well ****. That certainly sucks.
WaterH
Well-known member
- Thread starter
- #1,151
Yea, well it’s not getting better.
Compression test complete. #1,2,3 appear to be good. Approximately 400 psi. The #1 was lower initially, but came up in a later test. Maybe it gained pressure due to oil moving around while testing the other cylinders.
That brings us to #4. I only got 100 psi on two separate attempts. Also, I noticed that the engine cranked easier than on the other cylinders. I’m guessing the compression tester makes drag on a good cylinder.
So what would be my next move. I guess remove the head unless someone has another thing to test? Is there a way to test if the valve spring was too weak to hold pressure? I guess I could change them before removing the head. Does anybody do that? I guess I would change springs if I took the head off anyways, so I could get them in first.
ThePanzerFuhrer
The Rock Breaker God
Best case You probably lost a head gasket. What was the water temp at? A diesel like this it should never go above 180 even under full power. Run it with the cap off and fill of water to the top look for bubbles. Worst case cracked a head, or burnt a valve.
AgitatedPancake
Frobot
Do you have a stethescope? If you have the right adapters with the compression tester, you can hook an air compressor up to the cylinder and constantly pump air into it (make sure it's on the compression stroke so valves are closed). Then listen with the stethescope, if you hear the air in the oil pan it's rings, if you hear/see it in the coolant it's head gasket or a crack, then if you hear it in the intake or exhaust it's a valve. I dunno how effectively you could actually do this, but seems reasonable enough.
But all of those lead to head removal anyways so meh
But all of those lead to head removal anyways so meh
Dethmachinefab
Well-known member
- Joined
- May 19, 2020
- Messages
- 1,757
I may have missed it but what's the valve adjustment look like? Tight or loose? Stuff move normally when it cranks over?
ThePanzerFuhrer
The Rock Breaker God
As long as they were close you can kinda rule out bent pushrod/wrecked cam lobe. Hopefully it’s just a head gasket not a cracked head or broken ring groove in a piston.
WaterH
Well-known member
- Thread starter
- #1,158
So I hooked compressed air to the compression injector. I put 60 psi to it and the shop was dead quiet. I put 120 psi to it and the only hiss I could detect was right at the quick connect for the compressed air. Nothing (by ear) at the tail pipe, nothing at the intake, nothing at the engine vent. I removed the rad cap and there were no bubbles. I used a stethoscope and couldn’t hear ****. Actually, I could hear the slightest tap on that rod, but can’t hear air hissing at all.
I was so baffled that I removed the compression plug and cleaned the threads and mating surface. I did clean a little grime off and reinstalled it. Put the pressure to it, same thing. For good measure, checked it again with the guage. 100 psi again.
I know all this is wishful thinking, but I would still like to know why I can’t tell where it’s leaking. I’ve done this on many aircraft engines and it was easy to hear where it was coming from.
At this point, I think I will remove the turbo next. It has to come off to remove the head, so it can’t hurt. I know the turbo is not in great shape. So I can check it better and repeat the compressed air test. I’m told the exhaust valve is the most likly problem if not the head gasket.
Last edited:
WaterH
Well-known member
- Thread starter
- #1,159
So I took the head off today.
I used those two rods to roll it back. I was surprised how easy it came off. Didn’t really seem stuck to the gasket. Anyways, a look at the valves showed the problem.
Maybe not that pic. Have a close look at #4.
The bottom valve is not centered and has a tilt to it. I assume the piston hit it.
If you look at the piston, I would say the valve is not the only thing that the piston hit.
This creates a question. Did the turbo vanes disintegrate and go through the motor?
A look at the turbo would indicate no. The intake side.
Exhaust side.
After a bit of thinking, the turbo couldn’t send shrapnel to my intake because the intercooler would catch that ****. So that piston must have been like that from a previous incident. (There was no intercooler on this motor stock) I guess after the previous owner had a turbo explode, he deturnined that piston was ok and he just cleaned it out and put a new turbo on it. (This was a fleet truck motor)
I’m going to be ordering a bunch of new parts. Would I be stupid to keep running that piston since it was not the culprit here and it worked good all this time?
I used those two rods to roll it back. I was surprised how easy it came off. Didn’t really seem stuck to the gasket. Anyways, a look at the valves showed the problem.
Maybe not that pic. Have a close look at #4.
The bottom valve is not centered and has a tilt to it. I assume the piston hit it.
If you look at the piston, I would say the valve is not the only thing that the piston hit.
This creates a question. Did the turbo vanes disintegrate and go through the motor?
A look at the turbo would indicate no. The intake side.
Exhaust side.
After a bit of thinking, the turbo couldn’t send shrapnel to my intake because the intercooler would catch that ****. So that piston must have been like that from a previous incident. (There was no intercooler on this motor stock) I guess after the previous owner had a turbo explode, he deturnined that piston was ok and he just cleaned it out and put a new turbo on it. (This was a fleet truck motor)
I’m going to be ordering a bunch of new parts. Would I be stupid to keep running that piston since it was not the culprit here and it worked good all this time?
CarterKraft
Thread ****ter Upper
It ate something for sure.So I took the head off today.
I used those two rods to roll it back. I was surprised how easy it came off. Didn’t really seem stuck to the gasket. Anyways, a look at the valves showed the problem.
Maybe not that pic. Have a close look at #4.
The bottom valve is not centered and has a tilt to it. I assume the piston hit it.
If you look at the piston, I would say the valve is not the only thing that the piston hit.
This creates a question. Did the turbo vanes disintegrate and go through the motor?
A look at the turbo would indicate no. The intake side.
Exhaust side.
After a bit of thinking, the turbo couldn’t send shrapnel to my intake because the intercooler would catch that ****. So that piston must have been like that from a previous incident. (There was no intercooler on this motor stock) I guess after the previous owner had a turbo explode, he deturnined that piston was ok and he just cleaned it out and put a new turbo on it. (This was a fleet truck motor)
I’m going to be ordering a bunch of new parts. Would I be stupid to keep running that piston since it was not the culprit here and it worked good all this time?
Look real close at the piston and try to figure out what is?
Left over hardware in the intake piping or intercooler? It happens. Grid heater parts?
WaterH
Well-known member
- Thread starter
- #1,161
Now that you mention it, I noticed some rattling in the grid heater when I took it off. I looked it briefly and it appeared the some things were loose. I need to look at it better. Is that a known problem with them? I’ve never even had that heater hooked up. I just thought I would install it for the possible need later. If that is the problem, I will gut it.
gt1guy
Apparently a racist
Can you remove the oil pan in the vehicle?
If you have to remove the block from the rig, no way I'm just swapping a single piston on any engine.
If you have to remove the block from the rig, no way I'm just swapping a single piston on any engine.
AKnate
Icehole
- Joined
- Mar 5, 2022
- Messages
- 1,860
0.003" isn't going to make any noticeable difference.Now I had a razor I can pull upwards and slide along the edge of the hole. It cuts almost exactly 1” from the panel hole. I was amazed how good it did. This part of the job did take longer than you think. But you can see the results in the mirror.
So when I got to this point, I figured I would adjust the valves before finishing the cover panel just in case I needed a bigger hole. As it turns out, I had good access to all the valves . Most of the valves were with in a thou of spec. One exhaust valve was about 3 thou out. When I got done, I started the truck and I do believe it ran better. But it seemed to have white smoke on start up. That was a symptom of a bad injector, so I’m going order a set tomorrow. I can finish the panel cover while I wait for them to come in.
I did the 6.7 in my Dodge shipping crate last year, a few were around 0.040" too loose. (Yes, not 0.004")
It quieted it down, but that's it.
No idea why they were so loose. Engine was replaced by dealer in 2012 and can only guess on what they did or the previous owner did.
CarterKraft
Thread ****ter Upper
Not sure on specifics but there are grid heater issues...
Bad vibrations might accelerate those issues.
Leadfoot21
Well-known member
- Joined
- Mar 27, 2021
- Messages
- 577
Have a better picture of the damaged ? Zooming in I see a couple tiny chunks of the edge of the piston missing which makes me think the damage could have came from below ( ring or piston material ) . It’s the one straight line that’s throwing me off .
Bebop
Well-known member
- Joined
- May 26, 2020
- Messages
- 6,335
I'd start by getting the head fixed and removing the piston to see what you're dealing with.
Check if the cylinder walls are fine (which I suspect they are).
Check if the piston is ok (no cracks).
Check if the rod is straight (should be).
I would only replace what is broken.
If nothing is broken, I would have no problem using a dremel to smooth out the piston some, throw new rings and slapping it back in after a dingle ball hone.
If the cylinder wall is scored then I would get new pistons and do a full bore/rebuild at this point.
Check if the cylinder walls are fine (which I suspect they are).
Check if the piston is ok (no cracks).
Check if the rod is straight (should be).
I would only replace what is broken.
If nothing is broken, I would have no problem using a dremel to smooth out the piston some, throw new rings and slapping it back in after a dingle ball hone.
If the cylinder wall is scored then I would get new pistons and do a full bore/rebuild at this point.
WaterH
Well-known member
- Thread starter
- #1,170
Yes, the oil pan can come off.
The piston is all the way down and the walls look good. I’m leaning towards replacing the piston. Do they sell single pistons/rings?
I’m thinking of replacing those two valves and lapping them myself. Would that be crazy?
I figure one of two things happened.
1. There was previous damage to the piston that was not fixed. The valve spring was weak (because of age) and the valve got hit because the spring didn’t pull it up fast enough or it got slightly stuck in the guide.
2. The grid heater lost some parts that went through.
I’m going to check that grid heater out real good. When I heard something loose in it, I did a Quick Look at the bottom. It had a whole row of slats that looked fine. I didn’t separate the top plate/tube that goes to the intercooler. I will do that today.
In any case, if I think #1, I will replace all the valve springs. If I think #2, I don’t really see the springs being bad. I will gut the grid heater. It’s going to piss me off if that heater is the cause since I never even needed it.
