6.0 Cylinder Meltdown Trends
#1
10-31-2006, 06:58 PM
6.0 Cylinder Meltdown Trends
Tearing down the engine I discussed in this thread
https://www.ford-trucks.com/forums/5...new-motor.html
Brings the number of catastrophically failed engines (due to cylinder meltdown) I have encountered or inflicted to 5. With this comes an interesting trend I have found as to which cylinders are failing first...and in all 5 engines, it has been the back 3 cylinders of the passenger side (RH) of the engine, cylinders 3, 5, and 7.
The first engine I destroyed from overtemp had catastrophic piston failures on these same 3 cylinders. Cylinders 3 and 7 had holes burned either through the center or on the outside between the skirt and rings, and the cylinder walls. Cylinder 3 melted totally down until the point where the wristpin seperated from the piston on the exhaust stroke and crashed into the cylinder head. Next engine I damaged from this same issue was on cylinder 7 also, where the piston dome started to melt on the bottom outside corner and deposited aluminum plasma onto the cylinder wall and valve seats. Another engine likewise had dome damage to cylinders 5 and 7.
After getting our friend w00t's engine apart, cylinder 3 was melted to the point where some of the piston skirting and outside wall was actually deposited to the top of the cylinder wall at the head, and 5 and 7 had similiar damage to a less severe extent.
Seeing that from a statistical standpoint, 100% of the heat damage failures I have seen in a 6.0 engine are on the same three cylinders on 5 seperate engines, it brings me to take a hard look at what could be causing the issue. There are only a limited number of reasons that particular cylinders in this engine could run hotter than others, and this is what I have thought of thus far.
Fuel Delivery (combustion temperature)
-positive cylinder differential in fuel pressure
-positive cylinder differential in injection pressure
Volumetric Efficiency (combustion temperature)
-negative cylinder differential in intake charge
-negative cylinder differential in exhaust charge
Cooling deficiency
-negative cylinder differential in piston cooling jet flow
-negative cylinder differential in water jacket surface area and/or heat
absorption
Seeing that HEUI-style injectors don't rely directly upon actual fuel pressure to alter fuel delivery, I don't see that as the culprit; especially considering that if you look at the routing of the fuel lines, the passenger side head would be MORE likely to be starved for fuel than the drivers side head due to the longer fuel line. A change in injection pressure at the back of the passenger side oil rail causing higher fuel delivery in those cylinders is possible, because the stand pipe feeds fresh high pressure oil in at the back and the branch tube from the HPOP is somewhat (though minimally) shorter to the passenger side over the driver's side.
As far as airflow is concerned, a lack of fresh incoming air or restricted exhaust flow would both cause a cylinder temperature increase. Less airflow and positive manifold pressure to the back of the heads would make sense given the horseshoe shape of the intake manifold, but I can think of no immediate reason why there would be any difference between the RH or LH cylinder head given the relatively symmetric shape of the manifold. Exhaust restriction would be unlikely since the exhaust runners are symmetric across both heads, and the passenger side exhaust manifold actually has a less restrictive bend into the uppipe than the drivers side.
As far as cylinder cooling is concerned, water jacket flow could be a possible cause, but no cause for flow differential between the RH and LH engine banks is apparent. Cylinder wall overtemp would also result in scored cylinder walls and galling, which doesn't seem to be the case in what I've seen. What DOES seem to be the case is a direct issue of piston temperature, which is controlled by the piston cooling jet spraying oil onto the back side of the piston to remove heat. A negative trend of oil flow and pressure to the back of the RH bank would theoretically result in exactly what is being seen thus far, and leads me to believe it is likely the problem. Now assuming that it IS the problem, I'd like to know exactly why it is happening and a good fix for it.
I can think of a few things that could cause a drop in oil pressure to the cooling jets, but can't really nail down a specific reason. Do any of our resident techs or anyone familiar with the oil plumbing of the 6.0 know of a plausible reason for it?
https://www.ford-trucks.com/forums/5...new-motor.html
Brings the number of catastrophically failed engines (due to cylinder meltdown) I have encountered or inflicted to 5. With this comes an interesting trend I have found as to which cylinders are failing first...and in all 5 engines, it has been the back 3 cylinders of the passenger side (RH) of the engine, cylinders 3, 5, and 7.
The first engine I destroyed from overtemp had catastrophic piston failures on these same 3 cylinders. Cylinders 3 and 7 had holes burned either through the center or on the outside between the skirt and rings, and the cylinder walls. Cylinder 3 melted totally down until the point where the wristpin seperated from the piston on the exhaust stroke and crashed into the cylinder head. Next engine I damaged from this same issue was on cylinder 7 also, where the piston dome started to melt on the bottom outside corner and deposited aluminum plasma onto the cylinder wall and valve seats. Another engine likewise had dome damage to cylinders 5 and 7.
After getting our friend w00t's engine apart, cylinder 3 was melted to the point where some of the piston skirting and outside wall was actually deposited to the top of the cylinder wall at the head, and 5 and 7 had similiar damage to a less severe extent.
Seeing that from a statistical standpoint, 100% of the heat damage failures I have seen in a 6.0 engine are on the same three cylinders on 5 seperate engines, it brings me to take a hard look at what could be causing the issue. There are only a limited number of reasons that particular cylinders in this engine could run hotter than others, and this is what I have thought of thus far.
Fuel Delivery (combustion temperature)
-positive cylinder differential in fuel pressure
-positive cylinder differential in injection pressure
Volumetric Efficiency (combustion temperature)
-negative cylinder differential in intake charge
-negative cylinder differential in exhaust charge
Cooling deficiency
-negative cylinder differential in piston cooling jet flow
-negative cylinder differential in water jacket surface area and/or heat
absorption
Seeing that HEUI-style injectors don't rely directly upon actual fuel pressure to alter fuel delivery, I don't see that as the culprit; especially considering that if you look at the routing of the fuel lines, the passenger side head would be MORE likely to be starved for fuel than the drivers side head due to the longer fuel line. A change in injection pressure at the back of the passenger side oil rail causing higher fuel delivery in those cylinders is possible, because the stand pipe feeds fresh high pressure oil in at the back and the branch tube from the HPOP is somewhat (though minimally) shorter to the passenger side over the driver's side.
As far as airflow is concerned, a lack of fresh incoming air or restricted exhaust flow would both cause a cylinder temperature increase. Less airflow and positive manifold pressure to the back of the heads would make sense given the horseshoe shape of the intake manifold, but I can think of no immediate reason why there would be any difference between the RH or LH cylinder head given the relatively symmetric shape of the manifold. Exhaust restriction would be unlikely since the exhaust runners are symmetric across both heads, and the passenger side exhaust manifold actually has a less restrictive bend into the uppipe than the drivers side.
As far as cylinder cooling is concerned, water jacket flow could be a possible cause, but no cause for flow differential between the RH and LH engine banks is apparent. Cylinder wall overtemp would also result in scored cylinder walls and galling, which doesn't seem to be the case in what I've seen. What DOES seem to be the case is a direct issue of piston temperature, which is controlled by the piston cooling jet spraying oil onto the back side of the piston to remove heat. A negative trend of oil flow and pressure to the back of the RH bank would theoretically result in exactly what is being seen thus far, and leads me to believe it is likely the problem. Now assuming that it IS the problem, I'd like to know exactly why it is happening and a good fix for it.
I can think of a few things that could cause a drop in oil pressure to the cooling jets, but can't really nail down a specific reason. Do any of our resident techs or anyone familiar with the oil plumbing of the 6.0 know of a plausible reason for it?
#2
10-31-2006, 07:54 PM
Interesting theory you have there. Do you remember the conversation we had regarding oil flow and flow restrictors when we were tearing down granny? I wonder if it's possible to get a detailed schematic of the oil flow passages in this motor. I also wonder if there is some kind of "snowball" affect where the oil flow would get exponentially less and less?
Last edited by npccpartsman; 10-31-2006 at 07:59 PM.
#3
10-31-2006, 07:59 PM
Postmaster
if the pistons are melting i would think that the oil being squirted on the bottom would be almost evaporated at these high temps. the way i see it and the way i am thinking, in all the 6.0s the hp system feeds number 7 and then 5 first due to the length of the branch tube. the tubes are shorter going to the right head means the oil pressure gets here first. more oil pressure more injection pressure.
#4
11-05-2006, 08:11 PM
I don't know what model years you're referring to, but the ones I've seen all have had three things in common, 03-04 my, over-boosted and EGR valve jammed open. I had always had problems with the design of the EGR system on the 03-04my engines as it always seemed to favor the passenger side of the engine. That coupled with the direction of air flow entering the intake, it seems like it would be more efficient if it came in from the fornt of the engine, but that's my own junk physics. In 05 however the intake manifold changed drastically with the removal of the EGR throttle plate and the addition of dividers to direct EGR flow evenly to both banks. They also added a scoop to the passenger side up-pipe to improve EGR flow. Being that you folks are more into the competition aspect, I have to wonder whether EGR flow is even applicable to your situation. That leaves me out in left field again playing with my junk physics.
I can tell you that they haven't changed a thing in regards to low pressure oil flow.
I can tell you that they haven't changed a thing in regards to low pressure oil flow.
#5
11-05-2006, 09:17 PM
I had an EGR scoop in my 04 up pipe also. We've already figured out what caused the carnage and it wasn't EGR. I will however add your ideas to the list and see. Sometimes we get too caught up in the complex aspects of this motor and forget to look at the simple things. I'm always interested in redirecting airflow to improve the intake side of the motor, for sure. This was an 03/04 my engine btw, I'm just not sure exactly which one.
#6
11-05-2006, 09:34 PM
Originally Posted by spikebee
I don't know what model years you're referring to, but the ones I've seen all have had three things in common, 03-04 my, over-boosted and EGR valve jammed open. I had always had problems with the design of the EGR system on the 03-04my engines as it always seemed to favor the passenger side of the engine. That coupled with the direction of air flow entering the intake, it seems like it would be more efficient if it came in from the fornt of the engine, but that's my own junk physics. In 05 however the intake manifold changed drastically with the removal of the EGR throttle plate and the addition of dividers to direct EGR flow evenly to both banks. They also added a scoop to the passenger side up-pipe to improve EGR flow. Being that you folks are more into the competition aspect, I have to wonder whether EGR flow is even applicable to your situation. That leaves me out in left field again playing with my junk physics.
I can tell you that they haven't changed a thing in regards to low pressure oil flow.
I can tell you that they haven't changed a thing in regards to low pressure oil flow.
#7
11-05-2006, 09:37 PM
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#8
11-05-2006, 09:59 PM
Well, between the Ford Technical Hotline telling me it was a "lean condition caused by overboost" and the insurance investigator telling me that "an injector stuck wide open, it happens all the time", I'm not ready to accept anything until I read it through myself! Even then I might stick with my own junk physics! LOL 
! I have done a lot of investigation into changes made vs. problems solved just on my own, trying to see how bleak my future really looks doing warranty repairs on these things, and I would be interested in seeing anything you folks come up with.
! I have done a lot of investigation into changes made vs. problems solved just on my own, trying to see how bleak my future really looks doing warranty repairs on these things, and I would be interested in seeing anything you folks come up with.
#9
11-05-2006, 11:58 PM
Postmaster
matt,
After reading your initial post the other day, and then researching the motor design characteristics and thinking about it i have a couple of thoughts to add to your invetigation.
First, lower oil pressure/slower flow in the right side of the motor because the oil galley's on the left and right side are the same size, But, the right side oil galley is responsible for oiling the Cam Bearings, Main Bearings and Connecting Rods, while the left side is not. Thus less flow and more resistance in the right side of the motor thereby increasing the temperature on that side do to inadequate oil flow and increased resistance to oil flow causing increased temperatures in the oil.
Second, the EGR cooler is on the top right hand side of the motor, which should in theory increase the head temperature and top of motor temperature above the left hand side.
Also if the intake air temperature is higher on the right side of the engine, possibly do the the EGT cooler being on this side, that would result in higher cylinder temperatures on this side of the motor.
You may want to install a pyrometer that measures the EGT at each cylinder or head temperature (EGT would be easier) just like the ones installed on all Piston engine aircraft. I know on all the piston engine aircraft i have been around with the pyrometer for each cylinder there is always 2 or 3 cylinders that run hotter than the others and the fuel mix levers are tuned to keep the hottest cylinders within the safe operating temperature range.
Westach makes a quad EGT gauge that i know of and there is also a digital EGT guage available for 4 or 6 cylinders, by Aerospace Logic Inc
www.westach.com
http://www.aircraftspruce.com/catalo...pace_logic.php
http://www.aerospacelogic.com/site/d...sp?pageid=HOME
Hope this helps
After reading your initial post the other day, and then researching the motor design characteristics and thinking about it i have a couple of thoughts to add to your invetigation.
First, lower oil pressure/slower flow in the right side of the motor because the oil galley's on the left and right side are the same size, But, the right side oil galley is responsible for oiling the Cam Bearings, Main Bearings and Connecting Rods, while the left side is not. Thus less flow and more resistance in the right side of the motor thereby increasing the temperature on that side do to inadequate oil flow and increased resistance to oil flow causing increased temperatures in the oil.
Second, the EGR cooler is on the top right hand side of the motor, which should in theory increase the head temperature and top of motor temperature above the left hand side.
Also if the intake air temperature is higher on the right side of the engine, possibly do the the EGT cooler being on this side, that would result in higher cylinder temperatures on this side of the motor.
You may want to install a pyrometer that measures the EGT at each cylinder or head temperature (EGT would be easier) just like the ones installed on all Piston engine aircraft. I know on all the piston engine aircraft i have been around with the pyrometer for each cylinder there is always 2 or 3 cylinders that run hotter than the others and the fuel mix levers are tuned to keep the hottest cylinders within the safe operating temperature range.
Westach makes a quad EGT gauge that i know of and there is also a digital EGT guage available for 4 or 6 cylinders, by Aerospace Logic Inc
www.westach.com
http://www.aircraftspruce.com/catalo...pace_logic.php
http://www.aerospacelogic.com/site/d...sp?pageid=HOME
Hope this helps
Last edited by blackhat620; 11-06-2006 at 12:12 AM.
#10
11-06-2006, 05:58 AM
Postmaster
matt you know if you are serious i would look at the issue with the inequal lenght fuel lines. under high rpms and heavy footage the injectors may be starving on the right side. most of my right side injectors i have had to replace is due to scoring internally due to low fuel pressure and then they start overfuelling. to much fuel means too much heat. and in serious abuse, i would say it would lead to cylinder meltdown due to the increase in egts like blackhat was saying. it might not be a bad idea to make equal lenght fuel lines and maybe get a different pump setup or change the fuel pressure regulator to allow more fuel to the injectors to relinquish this concern.
#11
11-06-2006, 10:14 PM
Originally Posted by blackhat620
First, lower oil pressure/slower flow in the right side of the motor because the oil galley's on the left and right side are the same size, But, the right side oil galley is responsible for oiling the Cam Bearings, Main Bearings and Connecting Rods, while the left side is not. Thus less flow and more resistance in the right side of the motor thereby increasing the temperature on that side do to inadequate oil flow and increased resistance to oil flow causing increased temperatures in the oil.
Was discussing that with Tim yesterday and Ryan Bean at BDP earlier today. If you look up the flow demand for the bearings in this engine and caculate it out, the passenger side bank could have as much as 8 psi of negative pressure differential at full pump capacity...this would reduce the piston jet flow SIGNIFICANTLY and decrease the cooling capacity of that bank far more than enough to cause damage.
Thanks for the ideas everyone, will be working on a fix ASAP.
#12
11-06-2006, 10:25 PM
Postmaster
Cool 
Matt,
I will be looking forward to hearing about your fix. Also i wonder if once the oil flow issues are resolved if the EGR cooler location will still have a small effect on the upper cylinder temperature and/or the intake air temprature to that side of the motor as well? At least in the heavy use category.
I am thinking there maybe more than one piece to this puzzle, but the oil flow is probably the major one.
Matt,
I will be looking forward to hearing about your fix. Also i wonder if once the oil flow issues are resolved if the EGR cooler location will still have a small effect on the upper cylinder temperature and/or the intake air temprature to that side of the motor as well? At least in the heavy use category.
I am thinking there maybe more than one piece to this puzzle, but the oil flow is probably the major one.
#13
11-06-2006, 10:27 PM
Originally Posted by blackhat620
Cool
Matt,
I will be looking forward to hearing about your fix. Also i wonder if once the oil flow issues are resolved if the EGR cooler location will still have a small effect on the upper cylinder temperature and/or the intake air temprature to that side of the motor as well? At least in the heavy use category.
I am thinking there maybe more than one piece to this puzzle, but the oil flow is probably the major one.
Matt,
I will be looking forward to hearing about your fix. Also i wonder if once the oil flow issues are resolved if the EGR cooler location will still have a small effect on the upper cylinder temperature and/or the intake air temprature to that side of the motor as well? At least in the heavy use category.
I am thinking there maybe more than one piece to this puzzle, but the oil flow is probably the major one.
#14
11-06-2006, 10:34 PM
Postmaster
Matt,
That would definitely eliminate the EGR on the Modded motors like yours
As you say it maybe a contributing factor in the stock motors that are working hard.
It will be interesting to see how a stock motor will respond to better oiling but still retaining the EGR cooler. I am starting to lean to your belief that once the oiling problem is fixed, it will solve the problem on the stock engines as well, since i doubt a stock engine sees any higer temperatures than your modded motors.
Good luck with your upgrades
That would definitely eliminate the EGR on the Modded motors like yours
As you say it maybe a contributing factor in the stock motors that are working hard.
It will be interesting to see how a stock motor will respond to better oiling but still retaining the EGR cooler. I am starting to lean to your belief that once the oiling problem is fixed, it will solve the problem on the stock engines as well, since i doubt a stock engine sees any higer temperatures than your modded motors.
Good luck with your upgrades
#15
11-07-2006, 05:52 AM
Postmaster
a stock engine will never see the temps a modded engine does unless some type of issue arises. overfueling and timing of the injector and backpressure all contribute to the heat factor. hot air does enter the system through the egr cooler, but the egr cooler is not a big deal because the cooler does a great job of removing the heat.