Machines with turbos- do you let them idle before shutting down

[243ackley]

I have a 7060 which has a turbo. I have always been told to let machines with turbo's idle for a while so the turbo can slow down and still get oil.

Is this still a big deal?

I have a guy that helps me and he just turns the machine off because that is what he has been doing for 60 years.

 

[Kennyd4110]

I think it’s a good idea personally and try to idle for 20-30 seconds. Does it always happen? Heck no but I do try.

 

[majorwager]

Not sure what Kubota recommends but my MX has a turbo and if I have been working the engine hard, I ALWAYS idle for at least 5+ minutes before shutdown. I find that opening the hood allows the temp gauge to lower more quickly.


Your engine temp operates higher as you have a DPF engine.

Without regard for the advise you receive, if the turbo wears quicker due to overheating @ shutdown, no one on this site will be contributing to the replacement costs.


I have 2 other diesel tractors I use quite regularly, Kubota is the only turbo.



Lull has JD turbo, not used regularly.

 

[SDT]

I have a 7060 which has a turbo. I have always been told to let machines with turbo's idle for a while so the turbo can slow down and still get oil.

Is this still a big deal?

I have a guy that helps me and he just turns the machine off because that is what he has been doing for 60 years.

I do not believe it's the issue that it once was. especially if one uses synthetic oil, but I always let all engines, gasoline, diesel, turbocharged or otherwise, idle a bit before shutdown.

 

[groomerbuck]

Imo it really depends on how your using the machine at the time. If you really loading the machine(turbos working hard) then yes, a couple minutes of idle is a MUST! Now if your just cruising around a 20-30 second idle down is all thats required. These are my typical practices i utilize on all the heavy equipment i operate.
Now according to the engine manufacturers, they want a cool down as long as the warm up.(2-5minutes)

 

[TripleR]

pretty much what groomer buck says on both our turbos.

 

[gcmiller]

I also agree with Groomerbuck. I have an RV with a turbo diesel and my mechanic explained that the turbo spins incredibly fast, which makes it get incredibly hot. By letting it idle you're letting the oil cool down the moving parts. If you just cut the engine off the oil flow stops and the turbo remains hot.

 

[Jimz Toyz]

I usually let my 7040 idle for a few minutes, better safe than sorry! Since we're on the subject if turbo health, I've also capped off the exhaust pipe when I pull it on the interstate to keep backflow of air from spinning it. Not sure if I'm being ocd,! Any opinions there?

 

[BAP]

I usually let my 7040 idle for a few minutes, better safe than sorry! Since we're on the subject if turbo health, I've also capped off the exhaust pipe when I pull it on the interstate to keep backflow of air from spinning it. Not sure if I'm being ocd,! Any opinions there?

It's always a good idea to cover the exhaust pipe when hauling a turbo engine machine that is not running. That's because the air blowing past the exhaust pipe will cause the turbo to spin and without the engine running there is no oil lubrication to the turbo to keep the bearings from seizing.

 

[Redbusdriver]

My work vehicle has two CFM 56 gas turbine engines, 25,000 pounds of thrust each. On first start of the day we idle for 5 minutes before advancing the throttles above a slow forward speed, and before every shutdown we idle for 3 minutes to stabilize the temperatures in the engines and allow the oil to cool the hot section.

Not the same as a turbo on a small diesel engine, but doing an idle cooldown on any engine certainly doesn't hurt. My little BX gets about a minute at idle to stabilize after a play session.

 

[elburro]

I let it idle while I blow the dust off the tractor. Can't hurt

 

[Blondie70]

I idle for cool down on all my engines I always heard the valve temps need to stabilize. I have never had a turbo.

 

[SRG]

What's oil pressure at idle? At full throttle?
Sufficient oil pressure is needed to get the volume of oil across the bearings. Lower oil pressure like at idle, might not be enough pressure, to sufficiently cool the bearing, especially if it was just run under a heavy load.
No load operation/driving with above idle rpm is probably a better way to cool the turbo, than an idle is. Simply due to the pressure increase.

Anything with a turbo should also have the oil changed more frequently than a naturally aspirated motor, because of the super heating caused by the turbo. Oil coking is bad juju for turbos.

 

[spacemanspiff]

I used to have a GMC typhoon. After parking it, I would watch for the EGT gauge to stop dropping, level out and the stop the engine.

For me, the drive to to shed is enough to cool the turbo.

 

[Bulldog]

I got a new Cat 980 G in 97. I always warmed it up summer or winter before use. I always left it cool at least 5 minutes before shutting off. I used it 11 years, racking up 28,000 hrs on completely stock engine including the turbo. Had a few minor repairs but nothing internal and burned no oil between changes.

My point, warm up and cool down will play a huge factor in the life of any machine.

 

[adventure bob]

I think you first have to understand what idling prior to shutdown is doing and why there's perceived benefit from it. The idea behind idling prior to shutdown is to let the turbo cool to a point where the oil wont "coke" in the turbo. Coke is the solid residue created when oil undergoes severe oxidative and thermal breakdown at extreme engine temperatures. The higher the temperature, the harder, blacker and more brittle the coke/deposit residue. According to Exxon/Mobil this is at about 315deg. So the way to accurately make a decision or to decide how long to let it idle is by hitting the turbo with an infrared heat gun. If its below 300, shut it off, its it's above let it idle. That means that rules of thumb, like idle for 1 min, or idle for 5 are completely arbitrary and the timing is actually more related to turbo temp when you decide to start your idle prior to shutdown.

 

[groomerbuck]

I think you first have to understand what idling prior to shutdown is doing and why there's perceived benefit from it. The idea behind idling prior to shutdown is to let the turbo cool to a point where the oil wont "coke" in the turbo. Coke is the solid residue created when oil undergoes severe oxidative and thermal breakdown at extreme engine temperatures. The higher the temperature, the harder, blacker and more brittle the coke/deposit residue. According to Exxon/Mobil this is at about 315deg. So the way to accurately make a decision or to decide how long to let it idle is by hitting the turbo with an infrared heat gun. If its below 300, shut it off, its it's above let it idle. That means that rules of thumb, like idle for 1 min, or idle for 5 are completely arbitrary and the timing is actually more related to turbo temp when you decide to start your idle prior to shutdown.

Well said! Your spot on!

 

[243ackley]

Thanks guys. In my previous life I sold heavy construction equipment and we always told customers to let the machines idle. I did not know if that had changed since I have been out of the business for 15 years.

 

[baronetm]

My diesel engine practice follows the guidelines in the manual for my MH with a Cummins ISC 330. It says to let the turbo cool after hard running. It also states that letting off the throttle during Interstate exits, rest areas etc. is enough to cool the turbo by the time you park. I use this same practice in by 2004 Dodge Cummins and my Kubota, I idle them to the garage. I also do not let any of my diesel just idle, I turn them off and restart. On initial start up I go to a high idle as soon as oil pressure is attained to warm them up to the point the temp gauge starts to rise, then I move them. In real cold (minus 0) weather this could be 15-30 minutes if they were not plugged in.

 

[tempforce]

it depends on how long you want the turbo to spin without oil pressure.... letting it idle down reduces the amount of time the turbo spins without oil pressure. letting it idle for a while before shutting down, lets the oil cool, helping to slow down the deposits of overheated oil... using synthetic oil reduces the concerns of cooling prior to shutdown...