1. #1
    Junior Member

    Join Date
    Apr 2002
    Location
    New England
    Posts
    10

    Question Engine cool down (especially turbo)

    We run 5 engines, our newest is a 500 hp Detroit Diesel turbo,the others non-turbo diesels. After run the other day one of our drivers backed the engine into to station and ran up the rpms to build hp air pressure then shut off the engine without any cool down. My understanding of Turbo Diesels (from my experience in marine applications) is that they should be allowed to idle after being run hard to allow the turbo to spool down and engine to cool.

    Do turbo diesels need to idle before shut down? More than non-turbos?

    Does any department have established procedures in this area?

  2. #2
    MembersZone Subscriber
    F52Westside's Avatar
    Join Date
    Jul 2000
    Posts
    268

    Default

    Our Lt. told us that we are to let the Trucks idle for at least 5 minutes. He works part time for a Fire truck repair company and that is what is recommended.
    Stay Safe & Bring 'em Home!
    Eddie C.
    I.A.F.F. Local 3008

    "Doin' it for lives n' property"

    ** "The comments made here are this person's views and not that of the organizations to which I am affiliated" **

  3. #3
    Senior Member
    ENG6511's Avatar
    Join Date
    Mar 2000
    Posts
    174

    Default

    ABSOLUTELY!
    Bob Compton
    IACOJ-Proud
    IACOJ-HALL OF FAME-2003

  4. #4
    John_Ford
    Firehouse.com Guest

    Default Cool Down

    I got my heavy truck training in the military. Cummins Multi-fuel Great Motor. Here's the deal. ANY diesel not just a turbo needs a cool down after running. Our standard was 1000 RPM for three minutes and then shut down. The issue with the turbo is that when you shut the motor down the turbo is still spinning. Guess what, the oil pump ain't. Now, you let your boot driver do that hot shutdown enough, you'll buy a new turbo. I've had three diesel trucks, two with turbo and a turbo car. I let each one idle down for a minute and then shut down. By doing this you allow the turbo rotor to spin down as it is not under load and you protect it from burning out. Tell your numbnuts driver he pulls a stunt like that again he'll never touch that rig til the day he retires. JF

  5. #5
    Sr. Information Officer
    NJFFSA16's Avatar
    Join Date
    Aug 2001
    Location
    25 NW of the GW
    Posts
    8,434

    Default Spend some IDLE time!

    Excerpt from www.dieselpage.com
    ---------------------------------------------------------------
    The most common failure of automotive turbos is due to hot shutdown. This occurs when the vehicle has been running at a constant speed for a period of time and the vehicle is shut off before the turbo has had time to slow down. A turbo can spin at speeds exceeding 100,000 rpm, the faster the vehicle goes or the harder it works, the faster the turbo will spin. If a vehicle is shutoff suddenly the turbo will continue to spin without oil. Each time this occurs, the life of the turbo is shortened because of wear occurring from no lubrication. Eventually there will be enough wear to allow one of the wheels on the turbo to contact its housing. This causes the wheel to be out of balance. This causes even more contact and the turbo is usually destroyed. Allowing the vehicle to idle for a few minutes after its been running hard or allowing the exhaust temperature to cool to below 500 degrees will greatly reduce the risk of premature turbo failure.
    ----------------------------------------------------------------



    Refer to the paperwork and manuals supplied with the vehicle when you got it from the manufacturer.
    Proudly serving as the IACOJ Minister of Information & Propoganda!
    Be Safe! Lookouts-Awareness-Communications-Escape Routes-Safety Zones

    *Gathering Crust Since 1968*
    On the web at www.section2wildfire.com

  6. #6
    Junior Member

    Join Date
    Apr 2002
    Location
    New England
    Posts
    10

    Default

    I'm the second most junior member of our dept. I just wanted to confirm my opinion before shooting my mouth off. Its just that I bother to read manuals and have had experience with turbo charged cars and large turbo diesel boat engines. People don't understand that you need the the ciruculating oil to carry the heat away from the turbo charger. Without it the temp of the turbo can rise as much as 100 degrees F after you shut the engine off.

  7. #7
    Forum Member
    SCOOBY14B's Avatar
    Join Date
    Sep 2001
    Posts
    360

    Default Like crunch said...

    I have VAST experience with diesel motors...turbo and non turbo.

    Turbo motors need the oil circulating to carry the tremendous heat away. After a hard or not so hard run your EGT (exhaust gas temps) down to 300 degrees before shutdown. Of course no one specs their apparatus with EGT gauges.

    After returning to station, allow your apparatus to run at high idle (1000-1200 rpm) for 3-5 minutes, then allow it to idle normally for 30 seconds to 1 minute.

    Also dont forget the importance of high idling a diesel when running for extended time periods. After about 15 minutes you stand a chance of having the fuel not completely burnt, therefore mixing with the oil and causing damage within the motor. This applies to turbo and non-turbo diesels.

  8. #8
    Senior Member

    Join Date
    Jan 2002
    Location
    SF CA
    Posts
    122

    Default

    I find this all very interesting and also appropriate. From what I see in our department (that has no r&r's on cooling an engine before shutdown) is that the turbos tend to hold up very well under our "regular" use.

    That is, we start 'em cold, drive 'em hard, idle them at the scene unless we're pumping, drive 'em back to that station, back 'em in and shut 'em down.

    I would say that most our rigs go out of service for non-turbo related issues... and we have some rigs that have been in service for 20+ years. Of course I don't know the full mechanical history of these beasts, but typically, the rest of the rig starts to fail before the engine or turbo.

  9. #9
    Member
    Baker FF/PM's Avatar
    Join Date
    Feb 2002
    Location
    Keene, Texas
    Posts
    60

    Default

    I had heard this but only in passing by senior guys who never practiced what they preached. I am good about high idling and was under the impression the engine only needed to idle for about 30 sec before being shut down, now I know the rest of the story.

    Thanks guys.
    I would...but no!

  10. #10
    Forum Member

    Join Date
    May 2001
    Location
    Greensboro, NC USA
    Posts
    1,318

    Default

    Here's a pic of a Caterpillar Engine during a dyno test.

    You make the call.
    Attached Images Attached Images  

  11. #11
    Forum Member
    Fire304's Avatar
    Join Date
    Jun 2002
    Location
    At the Helm
    Posts
    1,174

    Default

    Consider this: Even without a turbo, typical combustion chamber temps run aroun 1000F. You shut down the truck as soon as you back into the station, what do you think happens to the water around the piston sleeve? Normally, with the engine running, coolant is constantly flowing past the hottest parts of the engiine, keeping it from boiling off. Within seconds after stopping the engine on a hot combustion chamber the water there is boiling and this can lead to all sorts of problems ranging from pitting on the sleeves to cracked liners.

    Find the manual for the engine of your truck and read it. Pay special attention to the warrenty details. While the fact is most dealers won't ask the question, if there is a problem, almost any problem, they could deny a warrenty claim for your failure to follow proper proceedures.
    ________________________________________________
    If you are new to posting please CLICK HERE for an essential lesson
    ________________________________________________
    A bad day in the boat is better than a good day in the office. And in my case the office is a boat!

    IACOJ Fire Boat 1

  12. #12
    Forum Member
    FIREMECH1's Avatar
    Join Date
    Apr 2008
    Location
    HUSKER LAND
    Posts
    2,425

    Default

    Now my 2 cents....

    If you don't have an exhuast ventilation setup (plymoVent) then stop your rig outside, and let it run for 5 minutes, at IDLE. If you do have exhaust ventilation, then back her in, and let it idle 5 minutes, then shut it down. You need to get turbo rpm's down to almost nothing, and cooling it with cooler oil, if possible. If you run it at high idle, then you still need to do it for 5min at IDLE.

    If you've just come back from a run, back her in, and shut her down, your YELLING for a problem to happen.

    For the turbo only, this is what can happen. You coke up the oil on the bearings. Then you lose boost. You overheat the oil seal, and wonder why it is blowing smoke out the exhuast.

    Those are just 2 examples, if you don't know how to shut your rig down.

    FM1

  13. #13

    Join Date
    May 2008
    Posts
    2

    Default

    I could be wrong but, buy the time you get back to the station, your high rpm-turbo work is done. Pulling onto the ramp and into the station or backing in seems like a nice cool down for the engine and you would not need to idle for another five minutes. Now, after a pump test or after pumping for an extended period of time, absolutely let things cool down to normal temps. Just my thoughts.

  14. #14
    Forum Member
    SCOOBY14B's Avatar
    Join Date
    Sep 2001
    Posts
    360

    Default

    Quote Originally Posted by 2austintashus View Post
    I could be wrong but, buy the time you get back to the station, your high rpm-turbo work is done. Pulling onto the ramp and into the station or backing in seems like a nice cool down for the engine and you would not need to idle for another five minutes. Now, after a pump test or after pumping for an extended period of time, absolutely let things cool down to normal temps. Just my thoughts.
    Yes, you are wrong. Lugging 36k+ lbs is still working the motor and the turbo is hot. If the apparatus was equipped with an EGT (exhaust gas temp) gauge you'd be able to see this. You need to idle any diesel motor and let the turbo cool so you don't "coke" it with oil.

  15. #15
    Forum Member
    Fire304's Avatar
    Join Date
    Jun 2002
    Location
    At the Helm
    Posts
    1,174

    Default

    Quote Originally Posted by 2austintashus View Post
    Pulling onto the ramp and into the station or backing in seems like a nice cool down for the engine
    If you can pull onto the ramp and back into the station w/o touching the throttle than you could count that towards the 5 min cool down period, but most stations I've been too have an incline to the ramp in front of the station requiring you to throttle up a little as you back in. As soon as you touch the throttle combustion chamber temp climbs and the turbo starts spinning up. It needs time to cool off, at least that's the theory.
    ________________________________________________
    If you are new to posting please CLICK HERE for an essential lesson
    ________________________________________________
    A bad day in the boat is better than a good day in the office. And in my case the office is a boat!

    IACOJ Fire Boat 1

  16. #16
    MembersZone Subscriber

    Join Date
    Dec 2002
    Location
    Central NJ
    Posts
    1,214

    Default

    Quote Originally Posted by FIREMECH1 View Post
    Now my 2 cents....

    If you don't have an exhuast ventilation setup (plymoVent) then stop your rig outside, and let it run for 5 minutes, at IDLE. If you do have exhaust ventilation, then back her in, and let it idle 5 minutes, then shut it down. You need to get turbo rpm's down to almost nothing, and cooling it with cooler oil, if possible. If you run it at high idle, then you still need to do it for 5min at IDLE.

    If you've just come back from a run, back her in, and shut her down, your YELLING for a problem to happen.

    For the turbo only, this is what can happen. You coke up the oil on the bearings. Then you lose boost. You overheat the oil seal, and wonder why it is blowing smoke out the exhuast.

    Those are just 2 examples, if you don't know how to shut your rig down.

    FM1
    We need to take into account the high exhaust temperatures being put out by some post 2007 engines. This can seriously damage a Plymovent (read exhaust removal) system if attached and idling too long; as I understand.

  17. #17
    Forum Member
    FIREMECH1's Avatar
    Join Date
    Apr 2008
    Location
    HUSKER LAND
    Posts
    2,425

    Default

    Quote Originally Posted by MG3610 View Post
    We need to take into account the high exhaust temperatures being put out by some post 2007 engines. This can seriously damage a Plymovent (read exhaust removal) system if attached and idling too long; as I understand.
    Your half right, and half wrong.

    At idle, your EGT's, will go down (pre 2007 and post 2007). On the post 2007's with the regenerational exhaust systems, you cannot let it activate, as it will melt the rubber seal. But you can still hook it up to the rig, and let it idle for 5 minutes, without any harm to it.

    I've run rigs up to 1500 rpm's, in pump gear, to do whatever I needed to, to diagnose a problem, and fix it. As well as aerials, that have the high idle activated, to do what I need done. And have yet destroyed or hurt a plymovent system.

    On your side of it, you can play it safe. On my side of it, if I can't do what I need to do, to fix a problem, then your going to change over, to a rig you don't want.

    And if you are really concerned about hurting the plymovent, then disconnect it. We used to do it without it, in station, before someone cried about the fumes. And they were worse, than they are today.

    FM1

  18. #18
    MembersZone Subscriber
    mcaldwell's Avatar
    Join Date
    Apr 2003
    Location
    Panorama, British Columbia, Canada
    Posts
    3,022

    Default

    Remember the need for the plymovent is primarily for the cold start, or extended idling, not a hot shutdown. Just before shutdown the engine is usually burning clean. It is only during the cold starts, and perhaps incomplete combustion of a hard acceleration (where the black smoke is visible) that the engine is producing large amounts of the carcinogenic fumes.

    There should be little to no problem with running your cool down period off of the exhaust capture provided there was some fresh air being provided.
    Never argue with an Idiot. They drag you down to their level, and then beat you with experience!

    IACOJ

  19. #19
    Forum Member
    FIREMECH1's Avatar
    Join Date
    Apr 2008
    Location
    HUSKER LAND
    Posts
    2,425

    Default

    Quote Originally Posted by mcaldwell View Post
    Remember the need for the plymovent is primarily for the cold start, or extended idling, not a hot shutdown. Just before shutdown the engine is usually burning clean. It is only during the cold starts, and perhaps incomplete combustion of a hard acceleration (where the black smoke is visible) that the engine is producing large amounts of the carcinogenic fumes.

    There should be little to no problem with running your cool down period off of the exhaust capture provided there was some fresh air being provided.
    The section in red, is 100% wrong. The rest is 75% wrong.

    The plymovent is there to capture the exhuast gases, nothing else. Even as you put it "Just before shut down the engine is usually burning clean." It is still putting out carbon monoxide. Still deadly.

    And the last part, concerning running your cool downd periond with fresh air, makes no sense.

    Check this out: http://www.plymovent.com/templates/Page____403.aspx

    FM1

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts

Log in

Click here to log in or register