How Can I Tell If My Turbo Is Working?

[wildebill308]

7 hours ago, wolfe10 said:

Caterpillar does not give a spec for electronic C-7.  Reason for this answer with electronics sensors, regulators , switches,  the value of electronic components have a preset value that the ECM monitors.

I am wondering how it monitors EGT without a pyrometer? 

wingman5th, With your pyrometer in that location I would expect it to run in the 900*-1000* range at normal cruise. When you take it out for a run monitor what it shows under different loads. I would not want to see much over 1250* on a hard pull. I would be downshifting. You will find that lifting on the throttle will drop temps pretty fast, the same with downshifting which will also reduce the load. Let us know what you find out.

Bill

 

[wolfe10]

Bill,

Again, I am quoting a retired (i.e. real hands on tech) Caterpillar tech, not myself.

But, I would speculate that the computer could monitor RPM,  fuel,  air/boost as well as engine operating temperature and get VERY close to what EGT's would be and could easily reduce either boost and/or fueling to keep the engine in correct operating perimeters.

Agree, with a mechanical fuel system, particularly one that has been modified, monitoring EGT is important.

[manholt]

Brett.  If I understand that correctly, it's a redundant add on that has no chance of giving feed back, because, system failure has already happened?  Or to say, excessive heat feed back happens when your on side of the road !

[wildebill308]

Carl, What the Caterpillar tech was talking about was the turbo failure.

"One thing to note as in this case turbo failure ( bearing failure ) the loss of oil into CAC in most cases rod bearing failure from lack of oil before heat build up."

In this case I agree that a EGT gage would not have given any warning about impending bearing failure. However a EGT gage will tell you when temperatures have dropped to where it is safe to shutdown the engine with minimal chance of damage to the turbo oil system.(coking of the oil passages)

Brett, There is no way to extrapolate EGT temps from watching coolant temperature. Your EGT temps can reach dangerously high temperatures and the coolant temp will not move. The reason is you have to heat all the coolant before you get a raise in temp on the gage. The best way would be to have a pyrometer sending signals to the computer. 

Bill

 

[wolfe10]

12 minutes ago, WILDEBILL308 said:

Brett, There is no way to extrapolate EGT temps from watching coolant temperature. Your EGT temps can reach dangerously high temperatures and the coolant temp will not move. The reason is you have to heat all the coolant before you get a raise in temp on the gage. The best way would be to have a pyrometer sending signals to the computer. 

Bill

 

Bill,

Agree completely.  One fact (coolant temperature) alone would never signal of excessive EGT in time, as coolant temperature rises much, much more slowly than EGT.

Again, I am not an expert on how Caterpillar programmed their computer, but knowing engine RPM,  boost and fuel consumption as well, repeat as well as coolant temperature, I suspect that they can predict EGT's pretty closely.

I really wish a Caterpillar programmer could give us an overview of this, but seriously doubt they would allow us a look into their secret book. 

Suffice it to say, THEY are confident that unless the engine is modified, their programming will not allow it to "harm itself", but instead will de-rate to reduce HP/heat if it senses it is approaching a dangerous operating condition.

Would be great for someone with one of these advanced engines to also monitor EGT's and let us know if, indeed, the engine is "self-protecting".

wingman5th-- would look forward to your report.  Thanks.

[jleamont]

I have replaced many many turbos over the years. I will say that the 90% were replaced due to operator error, the rest were part of an in chassis overhaul. The dealership I worked at was on a hill, not a big hill but a hill none the less. Daily we would watch people throttle up into the parking lot towing and go from wide open to shutting off the key (while still moving) and coast into a pull through parking spot. 

I agree an electronically controlled diesel shouldn't be a problem if NOT modified until it crosses over to an abused diesel, then it's a problem. In those situations the gauge wouldn't have helped anyway. 

I will say I was very surprised how long it takes our ISL to cool down to a safe zone to shut it off. None of my modified Powerstrokes ever took that long to cool.

[wildebill308]

I wish I could find real time data on a newer diesel. I have a  2003 computer controlled Cummins 5.9. The computer will run the engine harder than I can with the foot throttle. When using the foot throttle I seldom see 30# of boost. When on cruise the computer will often go to 36-38+# of boost. Also when on long rolling hills the computer will not downshift especially if in (Econ mode) until EGT temps are warmer than I want to see.

I agree with Joe that probbabley more turbos are damaged by improper shutdown then we hear about because it is a cumulative thing. I remember years ago seeing a turbo installation that had an accumulator in the oil line to provide oil to the turbo after the engine was shut off. I think it would be a good thing to have now. Probably some bean counter said "we can save $20.00 if we eliminate that"

Bill 

[obedb]

Maybe Joe can support this, but I noticed as electronically controlled diesel engines made their way into the trucking industry, pyrometers were a rare option. Big fleets did away with them. I preferred to have one over the years. With electronic engines and a downstream probe, it would still be a help when waiting for the point to shut down the engine and extend the life of the turbo.

[wingman5th]

Wow, had no idea my question would generate so much discussion. Again, thank you to all for your input. This is my first DP and have only 28,000 miles of experience in the few years I have owned it. I was warned almost from the day I bought it to allow the turbo to cool before shutting down but never knew how long that was or what to look for so a minute or two of idle time was the norm. 

I'm sorry I have no data to provide but the gauge Freightliner provided was too big for my dash real estate and they only provided 14 feet of cable. I am picking up a smaller digital indicator and a 50 foot harness later today and will install as soon as travel schedule permits.

The FL tech's did say there did not appear to be signs of overheating but not knowing the right questions as well as being rather stressed at my situation, I really didn't get into a good discussion about the possible cause of failure.

As I mentioned early on in this thread, I had no warning or indication prior to failure. No Check Engine, no Engine Protect, no Engine Shutdown. It ran great all day until I pulled off the highway and stopped. My only indication was no power when I tried to go and saw 0 psi on turbo boost readout of driver info center. Coolant temp, oil pressure were normal and engine had good rpm and no smoke from exhaust. Tech's did pull one code from computer, 102-1, Low Boost Pressure. Their inspection report stayed "found turbo locked up and pushing oil."

[wingman5th]

Okay sports fans, we have some initial results. Finally got the harness and gauge installed and took the coach out today for a short run.

With cruise set at 65 over rolling hills here in northern Mississippi, EGT normally ranged in the high 700s to low 800s. Climbing a grade with about 23 psi of boost, EGT was stable at about 840. Some occasional peaks just over 900 but they were momentary and I didn't have a chance to gather any other parameters before temp settled lower.

Varying the set level of the installed MP-8 module from off to 50% had no apparent affect on EGT.

This was just a short 30 minute run so I will monitor over longer range and varying grades/loads to get a better idea of my EGT ranges.

[wildebill308]

Glad you got a chance to try it out. Keep in mind that with your pyrometer after the turbo you will get considerable lower temps than with it mounted in front of the turbo. Most sources I have seen say it could be as much as 450*+ hotter. Especially under heavy load/climbing. My experience is if you can't accelerate in a gear to down shift till you can. Now you have a tool to help you.

I don't think you will see any difference in the MP-8 settings affecting temperature till you are climbing under load.

Bill

[wingman5th]

Thanks Bill.

So that being said, (450+ hotter), what is a safe turbo input temp red line so that i can set my output temp red line?

[wildebill308]

1 hour ago, wingman5th said:

Thanks Bill.

So that being said, (450+ hotter), what is a safe turbo input temp red line so that i can set my output temp red line?

 I don't have a lot of data on Cat. Most of my experience /research is related to Cummins. Here is a good read about EGT

http://bankspower.com/techarticles/show/25-Why-EGT-is-Important

I have a warning buzzer set for 1400 I have seen 1350 when under load. When I see 1350+ I lift on the throttle or downshift.

Bill