Diesel Mech advice needed

[Robbie Hegwood]

I had an enteresting event Saturday. I have an 04 F-350 powerstroke, cc, lwb, 4x4, srw. I was pulling a hill when something caught my attention. An unusual noise. I lifted a tad only to hear the wastegate bleeding off boost. I looked at my gauge and it was reading 46 psi. exhaust temp 600 degrees and water temp okay and trans temp okay. I tried to lift some but was in heavy traffic and a 18 wheeler close behind. And every time i lifted slightly it was hitting the wastegate alot. After I topped the hill I was able to lift completely and when i got back into the throttle everything was fine. It made for a long hour drive to the job. For info sack i was pulling my tractor, 18k total trailered weight. Any ideas what happened? I have had the EGR tube replaced under warranty and feel it's clogged again but have no idea if they are related. Also had a intercooler tube fail and they replaced that and the plastic piping with metal from the intercooler. Thanks for the help.

 

[KICK]

46 psi of boost?

 

[deereguy]

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[LeadPoison]

46 psi is A LOT of boost.

I would definitely try some other diesel forums.

 

[scesnick]

Never had that problem. I drive a CTD [] just kidding ya. Anyhow, I'm not sure about the Powerstrokes but the CTD's have a code system and the codes can be retreived by the owner with 3 turns of the key. If ford has that ability you couls start there and it should tell you what the problem was.

I would say your EGT's were off the charts and the truck may have been defueling on its own to prevent damage. I have an Edge Juice box with the Attitude monitor and my MAX egt's are set at 500. it will then defuel the truck to prevent damage. Not sure what a high EGT temp is with the Powerstroke though. Have you seen 600 EGT's before??? That is quite high.

 

[Robbie Hegwood]

From what i've gathered fords can go to 1000 degrees for a few minutes at a time without damage. I have read 1100 degrees before danger but that is awful hot. The highest I've been in normal driving while towing is about 750 on a long grade in summer heat. But normal hauling temp 600 degrees max most the time. If it heads higher I'll lift a bit.

The truck didn't seem to be defueling or anything, the only noticable difference was the boost. All other gauges were normal. I think the wastegate or popoff valve(if there different) stuck or hung open or something like that. Because as soon as I lifted completely it was fine.

I was sure I had run into the weak head gasket theory and blown one. What really concerned me was getting my tractor/trailer home and how much it would cost to do so.

 

[bullridin_fool]

i don't know where you guy's are measuring your egt's at but 600* before the turbo is nothing. you can safely run 1250* all day long. **** i've had my 1600* gauge pegged more times than i can count for 10-20 seconds at a time.

 

[jcmseven]

I want to make sure I understand correctly. I am not a diesel mechanic (at all) but I think I have had the same thing happen. Before I went with the Banks System, I was running a boost gauge, 80 hp Superchip, and exhaust with temp gauge. Once, when pulling my tractor up Black Mountain, near Asheville, NC in overdrive, I noticed my EGT going up. I have understood that over 1200 degrees is bad for PSD's, and going up this hill, mine reached about 900 degrees. My boost read 22 psi and the waste gate clicking started and the truck seemed to level a bit in power, if not lose some. My impression of this event was that it was an EGT/defueling event and it resolved soon after cresting the hill. Since I have changed to a full Banks System and away from the chip exhaust combo, I have pulled the same hill with less temp and no problems. My max boost even running what is a max'd out system is 28 psi, so I suspect the 46 was an error. If these events seem similar, I would say I have run the same run many times since without incident and with no engine maladies. I have friends who have said when EGT's change drastically this event has happened to them also. I have not heard anyone mention gauges reading erratically. I am assuming you are running aftermarket gauges, as I do not recall my PSD having a boost gauge stock. Also, I do not know if you are running any power adders, such as a chip, which could have started such a process by increasing the fuel load.

John M

 

[wushaw]

First of all pulling an 18k load is nothing to sneeze at.
46psi of boost is rather high but with only 600deg on your egt temp. That kind of boost means it is pouring the coals to it and as we well know fuel = heat = high egts....something is just not adding up.

 

[Robbie Hegwood]

Let's simplify this. Is there a device ( wastegate, popoff valve, etc.) that could cause the boost to increase 10 psi momentarly but that could reset itself??? My truck does have a banks exhaust which I feel is invaluable. I think I would melt everything without it. I also have a K & N air filter so as to let the motor breath as much as possible. I'm fairly sure the boost gauge was acurate because of the wastegate blowing off boost the instant i lifted. Usaully the wastgate only blows when you close the throttle quickly. I was easing out of the throttle so it shouldn't have hit the wastegate. Does that make since? The highest boost normally is about 36-38 psi max.

Yes I am trying to kill my truck. Death by weight!!! Now you know why i want a medium duty truck. Having to make due in the meantime.

Thanks for the replies. Robbie

 

[jcmseven]

Robbie,

I am a certified diesel gearhead but not a diesel mechanic. I believe Greg H or Donnie could offer some opinions on the "official" end of this topic--you may wish to PM one of them for the official word, but I am unaware of any way the 46 psi would be an accurate reading for boost. As for EGT, it is a little like business overhead calculation--it is all about where you check it. Location of the sensor etc. can have a real impact on your numbers. A few months ago there was a post about pre-or-post turbo numbers and how they differed. The diesel websites are filled with lengthy and heated arguments about where the best place to check is. A 600 degree reading post turbo housing is really not hot at all, as 1000+ is the norm here for a high reading. A 600 degree pre-turbo reading is moderate but not outrageous. Due to packaging under the hood, my sensor is located post-turbo and I drive around at 300-450 and get to 600 climbing a hill--unloaded. The guys at Banks say the EGT of 600 is the sweet spot for a Ford PSD with the sensor mounted post-turbo. This seems to be the temp where the 7.3L is when things are harmonious. With an aggressive programmer and no exhaust, which some do, 800+ could occur unloaded. These guys (or gals) are destined for readings of 1500+ if they are pulling heavy. So, first the numbers you mention about that are not that high so I doubt heat was a primary factor--BUT--the scenario minus the 46 psi could be seen if your EGT was really higher than you were seeing.

John M

 

[JESSE1]

Since you have an '04, you have the 6.0 Powerstroke. It does not have a wastegated turbo. You have a VGT (variable geometry turbo) with movable vanes on the turbo. The vanes probably stuck open temporarily and caused the overboost. It will set a code. You're lucky it didn't blow an intercooler boot off.

 

[KICK]

let me put it this way... if you truly had a condition where you had 46 psi of boost you were probably overspeeding the turbo so bad that it will fail at some point in the future. and then your engine will be full of shrapnel.

I don't know enuf about Ford to say exactly how they do things on the Power Stroke but most Diesle engines that are running EGR have what is called a VNT or a VGT ( both the same thing, variable nozzle/geometry turbo).

they use these turbos as a way of controlling boost and exhaust backpressures for when they need to force exhaust to flow into the intake during EGR mode.

if the turbo isn't being controlled, boost psi can go over the top of its limit.

it is possible that the controls weren't working or the turbo vanes are sticking inside the turbo.

 

[Robbie Hegwood]

Jesse, I think were closing in on what happened. That sure sounds like the most fisable explaination. I knew the instant it did it, weird sound. I pay very close attention to my truck for the weight I pull.

Now, what if the check engine light didn't come on. Does the light always come on with a code?? Mine did not, I lifted a little as soon as I heard the difference.

Also, enteresting enough I did have a intercooler boot fail recently. They repaired under warranty and metal piped the intercooler return. Sure fits into your explaination. That's when the mech told me not to put a programmer on it. Head gasket theory.

Also why I have you here it will surge while idling. I had the EGR tube replaced and it fixed it for a while but it's back. Does this have anything to do with the stuck vain issue???

Just for clarification it is a 6.0, I have the fuel filters replaced every 15k as suggested. It is also the 6.0 without the extra air sensor in the intake tube.

And yes my EGT temp probe is right behind the turbo.

Thanks tremendously for the input. I'm sure it will have to go to the shop for a check up but i like knowing what's going on before i turn them loose. Now I know what to look for to make sure they fixed it. Again, thanks TBN'ers.

 

[JESSE1]

I have an '04 F-350 Dually with the 6.0 and Torqueshift trans. It's been an excellent running truck with more than enough power. I have had the EGR valve replaced once. Truck would become very quiet at idle then start making the normal sound. Replaced under warranty but easy to replace if you had to do it yourself. Using the Motorcraft Premium Fuel Supplement and Cetane increaser will help with the EGR valve. Using the truck hard, putting the engine under load and changing the oil often helps with the EGR problems, too.

I was pulling a large load of hay last summer when one of the intercooler boots partially slipped off. Loud hissing sound when you put your foot in the throttle. Took it to the shop and the computer had set a code of high boost pressure. Mechanic said the turbo vanes probably temporarily stuck open and high boost pressure blew the intercooler boot off. I never got a check engine light. A good site for Ford Diesels is TheDieselStop.Com - www.thedieselstop.com and check out the forums. Lots of good info and knowledgable people there.