High Pyrometer Reading

[JerryB]

Gentlemen my 04 Vision CX613 w/460 ASET and has 450,000 miles is running high exhaust temp, up to 1200 degree. I carried it to Mack in Houston and had air to air, turbo, egr gate and waste gates checked, no problem found and no codes present. Checked pyro and put in new pyro sensor.

symtoms:

1. when bringing up to operating temp it smokes black smoke like freight train

2. engine coughs like gas burner when accelerated and sometimes white smokes from exhaust only when accelerated

3. fuel mileage has dropped about 1.25 mpg

Thanks in advance for any help. Jerry

[fjh]

Gentlemen my 04 Vision CX613 w/460 ASET and has 450,000 miles is running high exhaust temp, up to 1200 degree. I carried it to Mack in Houston and had air to air, turbo, egr gate and waste gates checked, no problem found and no codes present. Checked pyro and put in new pyro sensor.

symtoms:

1. when bringing up to operating temp it smokes black smoke like freight train

2. engine coughs like gas burner when accelerated and sometimes white smokes from exhaust only when accelerated

3. fuel mileage has dropped about 1.25 mpg

Thanks in advance for any help. Jerry

First guess egr valve is sticking Second guess did they check the boost bypass valve gone haywire? 3 EGR cooler plugged.

[m5040]

If it has the air to air cooler, check for a broken hose clamp or ruptrued hose (on the hoses from the trubo to the cooler and cooler to intake manifold. A damaged hose might just look like a small slit in the hose that will leak out the boost psi. Won't hear a leak at idle. I have seen trucks come out of the local garage and miss this,,,, I can't beleive it either. If the diagnostic equipment doesn't show a problem, it must be in your head.

[Bollweevil]

Two essential elements are required to build a fire. Fuel and oxygen. Normally, until a cold diesel engine reaches operating temp, it will emit a blueish smoke. Then the closer it It gets to 200 degrees, the smoke becomes neutral. Depending on the time of manufacture, you will see either more , or less black smoke, as you add fuel to a warm engine. Black smoke is a result, not a cause. Black smoke is caused by too much fuel, or not enough oxygen. A restricted air supply is worse than too much fuel. In extreme situations the fuel will put the fire out. At highway speed if you see white smoke under acceleration, the engine is adding oil to the fuel, or an excessive amount of fuel is cooling the combustion process. Again in an extreme situation you might be seeing raw unburned fuel. A high EGT is also a result not a cause. Again, it takes fuel and oxygen to build a fire. To build a 1200 degree fire you need a lot of fuel and a lot of oxygen, or too much oxygen, thereby leaning the combustion process. The new generation electronic diesel engines are more effecient, to a point, but a lot harder to diagnose. Engine basics are still the same regardless of what controls when and where. It still is just a big heat pump. It takes BTU's to make horsepower.

[Rob]

Exhaust restriction can also be a factor. Don't know much about newer engines but has the engine been checked for an overboost at load? It would sure seem that if the exhaust path is not as free flowing as it should be the exhaust temp would elevate in short order.

Rob

[fjh]

Exhaust restriction can also be a factor. Don't know much about newer engines but has the engine been checked for an overboost at load? It would sure seem that if the exhaust path is not as free flowing as it should be the exhaust temp would elevate in short order.

Rob

Guys ya can pretty much go with the simple stuff to a point on these engines but then you get thrown a curve ball EGR.Adds a new dimension to the fuel air theroy.Heat, boost preasure exhast preasure inlet air temp humity exhast leaks,yada yada,Not a simple engine anymore, sensors have targets to meet if they don't meet the targets they don't run right. there anit nothing simple about this problem, to many added features to monitor.Its not just as simple as air vs fuel these days.

[Bollweevil]

Guys ya can pretty much go with the simple stuff to a point on these engines but then you get thrown a curve ball EGR.Adds a new dimension to the fuel air theroy.Heat, boost preasure exhast preasure inlet air temp humity exhast leaks,yada yada,Not a simple engine anymore, sensors have targets to meet if they don't meet the targets they don't run right. there anit nothing simple about this problem, to many added features to monitor.Its not just as simple as air vs fuel these days.

I could not agree with you more, due to the complexity of the controls an internal combustion engine is no longer simple. Gas or diesel. That makes your job in the shop a lot harder. The basic engine however remains the same. But, you now have a lot longer list of possibility's that affect the same results. Separating the cause's from the results is a greater problem. Being able to separate them separates a good tech like yourself from a not so good tech. You have got a good attitude, you can handle it. I always figured that if someone designed something and someone else assembled it, then I could fix it. I'm not so sure now. I liked it a whole lot better when I could overhaul one on the side of the road.

[fjh]

[quote I\'m not so sure now. I liked it a whole lot better when I could overhaul one on the side of the road.

ME TOO! You just do the best with what is put on your plate like it or not!I have noticed with theses engines after the inital programing issues were delt with the most comon failures are physical and mechcanical some, Very illusive in nature.

Only experiance will tell ya the answer quickly what is wrong ,and sum times that don\'t even work.

Below is the tool we use to check THE WHOLE engine for boost / exhast leaks and other wierd and wonderfull failers ,turbos passing exhast gas into the base

boost bypass valve failers egr coolers leaking into coolant all can be tested in one operation with this tool on ANYONES engine for the most part,

we built this as I said before ,doing the best with what we had avilable. we use it almost daily.

[JerryB]

Gentlemen thanks to you each and every one. the Houston Mack dealer shop had supposedly done the checks but today I idled the engine up to about 1100 RPM and started spraying all the air intake system and air to air condenser with soapy water and the turbo outlet hose going from turbo to condenser was bubbling like a bubble bath at the far end of metal tube. I put on a new hose clamp and upon testing the engine is back to it's old self. Thanks again I wouldn't have thought after paying over $500 I would have had to check it. my shop receipt says they had checked it already so I didn't suspect it.

[Lmackattack]

never fails.. do it your self and it gets fixed right i would talk to the manager about your bill!

regardless..glad you found the issue and its fixed!

[theakerstwo]

Gentlemen thanks to you each and every one. the Houston Mack dealer shop had supposedly done the checks but today I idled the engine up to about 1100 RPM and started spraying all the air intake system and air to air condenser with soapy water and the turbo outlet hose going from turbo to condenser was bubbling like a bubble bath at the far end of metal tube. I put on a new hose clamp and upon testing the engine is back to it's old self. Thanks again I wouldn't have thought after paying over $500 I would have had to check it. my shop receipt says they had checked it already so I didn't suspect it.

I have worked for the dealer for many years and some times the man that is doing the work spends more time writting a good story than he does working on the truck. It makes the job easy for the clerk closing the ticket. I was never good at writting a good story because i would work as long as i could on the engine and then write a short sotry only me could understand.

[Rob]

I have worked for the dealer for many years and some times the man that is doing the work spends more time writting a good story than he does working on the truck. It makes the job easy for the clerk closing the ticket. I was never good at writting a good story because i would work as long as i could on the engine and then write a short sotry only me could understand.

Almost a daily thing for my boss and I to express differences of opinion on how my reports are written concerning a repair, or the logging of such. I figger if someone wants to know what I've done, they'll ask me, and I'll explain. If they don't ask, I don't worry about it.

For some reason, the entities above my boss that always seem to ask the questions don't want to speak with me direct, but would rather talk to him. Wonder why that is......

Rob

[fjh]

Yup I agree totally with you Glen and Rob , another thing can happen too is a guy can create a leak by tring to do a repair those hoses tend to get stuck to the tubes and leave remnance on the tube which can cause leakes after reasembly. ,another question always asked Why did the job take so long is a comon question!The answer is I DID SOMTHING I REPAIRED the problem didnt write a novel on how too!

Not to toot our own horn but that is why we built the boost plates in the picture I tests the Whole engine charge air system. that leak would have showed it self in an instant and probably more of them!another fairly comon leak on these engines is the inlet and exshast gaskets.

Anyway , Glad it was an easy fix for ya! Anyway talk to the service people if they don't credit you back somthing get eaven!