Boost Gauge for Turbo?

[ALeeL]

Except, of course, that you need to let the turbo cool down before shutting off the engine. That "dumby gauge" would take the guesswork out of that.

True, but for 99.9% of Jeep owners, they will never be in the situation to need to idle their engine for a while to let the turbo cool so the oil doesn't coke on the shaft.

The problem mainly comes from big diesel trucks that would tow heavy loads on the highway and immediately pull over to a rest stop or fuel station not giving their turbo enough time to cool after putting a heavy load on it. For most of us who aren't towing heavy and/or giving it the beans for long periods of time, the mild driving we do without any load will not be of any concern.

Heck, even those that do tow heavy with their Jeep or go foot to the floor constantly. Just the short drive going through your subdivision at speeds below 45 mph on your way home from doing these things will cool it off enough to allow you to shut it down as soon as you get home.

But I understand your view. I am also one of those who likes to have more gauge info, however, working on the dealer and manufacturer side for so long, I know what kind of headaches letting some people know this info will bring.

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[SonofaSeabee]

I typically shut down when turbo is in the 390-400* range. At what temp are others shutting down?

 

[JamC12H23]

I typically shut down when turbo is in the 390-400* range. At what temp are others shutting down?

Once it gets under 500 I consider it good.

 

[Ratbert]

True, but for 99.9% of Jeep owners, they will never be in the situation to need to idle their engine for a while to let the turbo cool so the oil doesn't coke on the shaft.

The problem mainly comes from big diesel trucks that would tow heavy loads on the highway and immediately pull over to a rest stop or fuel station not giving their turbo enough time to cool after putting a heavy load on it. For most of us who aren't towing heavy and/or giving it the beans for long periods of time, the mild driving we do without any load will not be of any concern.

Heck, even those that do tow heavy with their Jeep or go foot to the floor constantly. Just the short drive going through your subdivision at speeds below 45 mph on your way home from doing these things will cool it off enough to allow you to shut it down as soon as you get home.

But I understand your view. I am also one of those who likes to have more gauge info, however, working on the dealer and manufacturer side for so long, I know what kind of headaches letting some people know this info will bring.

And when you come off of the interstate how do you know when it's safe to shut down?

 

[ALeeL]

And when you come off of the interstate how do you know when it's safe to shut down?

I never tow anything or put enough a load to warrant a cool down period in my Jeep. My various Cummins trucks over the years have been a different story. I do tow enough to warrant a cool down period, however, I have very rarely been in a situation where I would immediately come off the highway into a shut down. I generally keep it idling while towing even when getting fuel or I've had several minutes of slow driving like going through my subdivision where it is 30 mph to cool it down.

The only time where I had to shut it down was when I was hauling cattle a few towns over to the stock yards. I had to shut it down right after getting off the highway because the lady on the intercom could not hear me over my engine to tell me which gate to pull up to, however, I started back up about a minute later after the conversation was over. Other than my 2014 JK, all my vehicles since 2000 have been turbo(even my work truck which I abused) and I haven't had one fail yet.

 

[Ratbert]

I never tow anything or put enough a load to warrant a cool down period in my Jeep. My various Cummins trucks over the years have been a different story. I do tow enough to warrant a cool down period, however, I have very rarely been in a situation where I would immediately come off the highway into a shut down. I generally keep it idling while towing even when getting fuel or I've had several minutes of slow driving like going through my subdivision where it is 30 mph to cool it down.

The only time where I had to shut it down was when I was hauling cattle a few towns over to the stock yards. I had to shut it down right after getting off the highway because the lady on the intercom could not hear me over my engine to tell me which gate to pull up to, however, I started back up about a minute later after the conversation was over. Other than my 2014 JK, all my vehicles since 2000 have been turbo(even my work truck which I abused) and I haven't had one fail yet.

I've had mine derate a few times after making quick stops. Two times when the temps were in the 70s. Has nothing to do with towing. Wasn't loaded with gear either time.

The last time (this past Monday) I was (and still am) loaded with camping gear. Stopped about five hours out of Moab at a station that only had the fat diesel nozzles. Took off again and only made it about a quarter mile before it derated. In Tahoe now about to do the Rubicon Trail tomorrow. Check engine light is still on.

Yes, I'm fairly confident that a turbo temp gauge would have prevented all of that.

 

[grimmjeeper]

I never tow anything or put enough a load to warrant a cool down period in my Jeep.

Just running 75-80 on the freeway is enough to need a cool down period. I've seen sustained temps around 800° just running down I70. That's enough to need a cool down.

 

[ALeeL]

I've had mine derate a few times after making quick stops. Two times when the temps were in the 70s. Has nothing to do with towing. Wasn't loaded with gear either time.

The last time (this past Monday) I was (and still am) loaded with camping gear. Stopped about five hours out of Moab at a station that only had the fat diesel nozzles. Took off again and only made it about a quarter mile before it derated. In Tahoe now about to do the Rubicon Trail tomorrow. Check engine light is still on.

Yes, I'm fairly confident that a turbo temp gauge would have prevented all of that.

I am not sure what this derate has to do with the cool down period or the turbo temp. Are you referring to turbo temperature gauge as the EGT/pyrometer gauge? Oil coking is caused by oil remaining on the turbo shaft and the turbo gets heat soaked pulling in heat from the engine and rest of the exhaust. This oil on the shaft will essentially cook itself on shaft which can cause catastrophic turbo failure over time if down frequently especially with the old style bearings that would seize.

It is not needed as much with todays turbo bearing and oil technology. For one, most modern turbos have hydrodynamic(journal) bearings which are not only less prone to coking, but also less likely to seize if coking did happen.

Secondly, these cooldown periods were a major issue when using conventional 15w40 which is much heavier than the synthetic we use. Synthetic oil itself is next to impossible to get to coke due to it much higher temp tolerances. Then add in that fact that our recommend oil is much thinner making it harder to remain on the shaft long enough to coke like conventional 15W40 was known to do.

I am just basing my opinion on the many diesels engines I have seen on the dyno when I worked at Cummins putting them through various load conditions. Unless someone is towing moderate to heavy or really racing their engine, a cool down period is not needed when unloaded. It is just not as much as an issue as many think it is these days, and most are concerned due to old turbo and oil technology.

Just running 75-80 on the freeway is enough to need a cool down period. I've seen sustained temps around 800° just running down I70. That's enough to need a cool down.

Are you referring to the pyrometer/EGT temp as well? If so, 800F is not that hot. Although that depends on whether the gauge is pre or post turbo. Post turbo is sometimes 100-300F cooler than pre turbo. If you think 800F is hot, you should see what gasoline turbocharged engines exhaust gas temps run just going down the road.


EDIT: After doing some further reading, it appears that the Gen 3 Ecodiesel has a water cooled turbo which makes it even harder for oil coking to occur and a cool down period less necessary unless it is immediately after a full load situation with no light driving before a shut down.

 

[Ratbert]

I am not sure what this derate has to do with the cool down period or the turbo temp. Are you referring to turbo temperature gauge as the EGT/pyrometer gauge? Oil coking is caused by oil remaining on the turbo shaft and the turbo gets heat soaked pulling in heat from the engine and rest of the exhaust. This oil on the shaft will essentially cook itself on shaft which can cause catastrophic turbo failure over time if down frequently especially with the old style bearings that would seize.

It is not needed as much with todays turbo bearing and oil technology. For one, most modern turbos have hydrodynamic(journal) bearings which are not only less prone to coking, but also less likely to seize if coking did happen.

Secondly, these cooldown periods were a major issue when using conventional 15w40 which is much heavier than the synthetic we use. Synthetic oil itself is next to impossible to get to coke due to it much higher temp tolerances. Then add in that fact that our recommend oil is much thinner making it harder to remain on the shaft long enough to coke like conventional 15W40 was known to do.

I am just basing my opinion on the many diesels engines I have seen on the dyno when I worked at Cummins putting them through various load conditions. Unless someone is towing moderate to heavy or really racing their engine, a cool down period is not needed when unloaded. It is just not as much as an issue as many think it is these days, and most are concerned due to old turbo and oil technology.



Are you referring to the pyrometer/EGT temp as well? If so, 800F is not that hot. Although that depends on whether the gauge is pre or post turbo. Post turbo is sometimes 100-300F cooler than pre turbo. If you think 800F is hot, you should see what gasoline turbocharged engines exhaust gas temps run just going down the road.


EDIT: After doing some further reading, it appears that the Gen 3 Ecodiesel has a water cooled turbo which makes it even harder for oil coking to occur and a cool down period less necessary unless it is immediately after a full load situation with no light driving before a shut down.

Ok, so what causes these EcoDiesels to shut themselves down after being run for long periods, being shut off for a few minutes, then being run again? Two out of three times the ambient temps were in the 70s and in all cases none of the gauge temps were unusual.

 

[ALeeL]

Ok, so what causes these EcoDiesels to shut themselves down after being run for long periods, being shut off for a few minutes, then being run again? Two out of three times the ambient temps were in the 70s and in all cases none of the gauge temps were unusual.

There could be a multitude of reasons, but shutting itself down is counterintuitive to the reason why you would need to do a cool down period. As stated before, an idle or low load cool down period is needed after extended periods at full load because if you immediately shut it down then the heat from the engine and manifold will heat soke the turbo housing causing the stagnant oil on the shaft to coke. If this is done enough times, then it will seize the shaft causing the turbo blades not to spin.

The reason for the idle or low load cool down period is so that the turbo shaft will have a continues stream of oil going over it as it cools down so it does not coke on the shaft. Once you shut the engine down, this stream of oil stops due to zero pressure pumping it through the turbo housing.

So why would Jeep program the engine to shut itself down after an extended period at full load to keep oil from coking if shutting the engine down immediately after full load is what causes coking? It is derating or shutting itself down due to another reason, not because of the shut off cool down period that is generally not needed when unloaded.

 

[Ratbert]

There could be a multitude of reasons, but shutting itself down is counterintuitive to the reason why you would need to do a cool down period. As stated before, an idle or low load cool down period is needed after extended periods at full load because if you immediately shut it down then the heat from the engine and manifold will heat soke the turbo housing causing the stagnant oil on the shaft to coke. If this is done enough times, then it will seize the shaft causing the turbo blades not to spin.

The reason for the idle or low load cool down period is so that the turbo shaft will have a continues stream of oil going over it as it cools down so it does not coke on the shaft. Once you shut the engine down, this stream of oil stops due to zero pressure pumping it through the turbo housing.

So why would Jeep program the engine to shut itself down after an extended period at full load to keep oil from coking if shutting the engine down immediately after full load is what causes coking? It is derating or shutting itself down due to another reason, not because of the shut off cool down period that is generally not needed when unloaded.

Ok, so it's "something else" that only happens after running for long periods (2x at over 80mph, 1x at 65mph) (2x temps in the 70s, 1x temps in the 80s). Always very quickly after a very short stop. Temp gauges gauges always look fine.

Fortunately only 1x was on a crowded interstate. Unfortunately my wife is losing her trust in this thing.

I've started leaving it running when filling up.

 

[SparkleTooth]

The Scan Gauge 3 or something similar is almost a must for these diesels. I monitor the turbo temps, regen status, and oil / coolant temps the most.

I wait until turbo is around 430ish before turning it off.

 

[ALeeL]

Ok, so it's "something else" that only happens after running for long periods (2x at over 80mph, 1x at 65mph) (2x temps in the 70s, 1x temps in the 80s). Always very quickly after a very short stop. Temp gauges gauges always look fine.

Fortunately only 1x was on a crowded interstate. Unfortunately my wife is losing her trust in this thing.

I've started leaving it running when filling up.

I am getting kind of confused here. I thought our discussion was about the need for a idle cool down period before you turn the engine off and you seem to be talking about something else. As stated before, it is counterintuitive for the engine to be programmed to shut itself off immediately after a high load because you didn't idle it after said high load. If anything, jeep would program it NOT to shut down after this. Your issue is something else. it is not shutting down because you didn't perform and idle cool down period.

I want to help you with your problem and think you are stuck on the wrong solution. If these engines were derating or shutting down due to not performing a shut down period, then this issue would be more pronounced on this forum, but it is not. I for one would have this happen to me all the time if this were the case.

I am willing to bet that your issue is emissions system related. Do you have the ability to look at the various pressure and NOx sensors on your Jeep. I would look there to see if they don't look right. I had a similar issue with a customer in one of his class 8 diesel trucks. Basically, the pressure sensor after the DPF was not reading correct pressure drop and thought that the DPF was always full and therefore caused the engine to regen constantly which caused a derate due to heat and other issues. A new sensor fixed the issue, but it took months to solve because the sensor never triggered a code because it was still within it's working range.

Not saying this is your issue, but it is a place to look if you have the ability on your scan gauge.

 

[Ratbert]

I am getting kind of confused here. I thought our discussion was about the need for a idle cool down period before you turn the engine off and you seem to be talking about something else. As stated before, it is counterintuitive for the engine to be programmed to shut itself off immediately after a high load because you didn't idle it after said high load. If anything, jeep would program it NOT to shut down after this. Your issue is something else. it is not shutting down because you didn't perform and idle cool down period.

I want to help you with your problem and think you are stuck on the wrong solution. If these engines were derating or shutting down due to not performing a shut down period, then this issue would be more pronounced on this forum, but it is not. I for one would have this happen to me all the time if this were the case.

I am willing to bet that your issue is emissions system related. Do you have the ability to look at the various pressure and NOx sensors on your Jeep. I would look there to see if they don't look right. I had a similar issue with a customer in one of his class 8 diesel trucks. Basically, the pressure sensor after the DPF was not reading correct pressure drop and thought that the DPF was always full and therefore caused the engine to regen constantly which caused a derate due to heat and other issues. A new sensor fixed the issue, but it took months to solve because the sensor never triggered a code because it was still within it's working range.

Not saying this is your issue, but it is a place to look if you have the ability on your scan gauge.

I'll take it to the dealer and have them do that analysis. Thanks for your insight.

And yes, it derates when I restart it too quickly after running for extended periods.

 

[grimmjeeper]

It's not that the engine shuts itself off.

It's a derate scenario.

Drive on the freeway and pull off for fuel, shutting off the engine. Start it back up within a few minutes and get back on the highway immediately. The engine derates while you're on the on ramp.

Cruising on the freeway you maintain a fair amount of continouos boost. So you have some heat in the turbo and exhaust. If you shut down the engine without a cool down you heat soak a bit. When you fire it back up within a couple of minutes that heat soak triggers the derate. It's temporary. Let it idle for a couple of minutes and you're fine.

The important part is that the temps which trigger the derate are not shown on the dash, nor is any notification shown that you are being derated. You just lose power and the dash shows normal. That tends to be somewhat disconcerting to most people.

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