Opinions Requested

[TNhobbyfarmer]

I recently purchased a TN75-A. The manual suggested that the engine should be allowed to idle at 1000 RPM's for 3 minutes before shut-down after usage. The reasoning had something to do with the turbo charger. I asked my dealer about this and his opinion was that this wasn't necessary. What do you guys think?

 

[jimg]

I had a truck w/ a TCed engine and the manual gave the same advice. I believe this has to do w/ cooling the TC bearings so that the oil doesnt burn off (in a hot unit) and form what amts to an abrasive. I think though its not strictly necessary unless you're running the TC constantly (which was how my truck worked) or it was running immediately prior to shutdown (in the case of on-demand boost). In any case I followed the instructions for a few months and quit b/c it was very inconvenient to sit around for 2-3 mins everytime I stopped. In the end the body wore out before I experienced any engines problems. In fact the engine/TC were the most troublefree part of the vehicle.

 

[AndyMA]

I'm not a fanatic, but I do pull the load off my TN75D and let it idle for a couple before shutting down. It has to do with cooling down and getting lubrication in the turbo on restart. On restart I always wait about a minute for the turbo to be lubricated. Unlike some of the trucks I've driven, I usually can't tell when I'm gettign turbo boost and I'm not sure it matters much anyway as far as turbo temp. Based on the price of turbos I'd rather be safe than sorry. On my excavator, I can definately hear the turbo kick in.
Also allow it to cool. I think your dealer is wrong about it not being important.
Andy

 

[LarryD]

Although I personally don't know anyone who's ever destroyed a TC, I've always been told to let them idle if the've been working pretty hard.

I use the minute or two to walk around the tractor and look to see if I managed to snag any brush or find a stick where it shouldn't be /forums/images/graemlins/shocked.gif

 

[bgott]

Good advice here, also make sure to idle the engine for at least 20 to 30 seconds even if you haven't been working it hard. You don't want to slam the throttle shut from higher RPMs and then just cut it off because even if it's not hot you don't want to cut the oil flow with the turbo spooled up.

 

[boomer4snow]

It is very important. The turbo is cooled and lubricated by the oil pumped to it by the running engine. On all turbos they are spinning/working whenver the motor is on due to exhaust spinning the vanes in the impeller section of the turbo. Without a shutdown period two things happen, first the turbo is spinning much faster it takes some time to spin down to a slower rpm (they can spin well over 10,000 RPM) second they are not being fed a constant stream of oil to cool the bearings down. Turbos will COKE with burnt oil deposits Over time this will lead to turbo failure which will result in Major $$$$ especially if the turbo seizes and sends little turbo pieces into the Engine.

I am not saying it will happen, In fact I have seen lots of folks with 200,000 mile plus on turbo diesel motors just treat em like a gas engine, but it certainly cannot hurt, and whats a couple minutes compared to the cost of a turbo that a warranty may not cover

BTW the manual for my Cummins says to allow 1 minute cooldown after running the motor for any amount of time, 3-5 minutes after heavy use.

 

[jimg]

So, which is most important...letting the TC spin down and cool off or keeping the oil changed at the recommended internal?

 

[thcri]

I would let it cool down. Even new oil can burn off. Just my opinion.


murph

 

[Soundguy]

Bqack in 84 I had a pontiac sunbird.. I was younger.. and didn't read manuals in those days. It wasn't long before I had to replace my siezed up turbo charger due to lubrication issues...

I DO let my tractor cool down at idle before shutoff.

Cheap insurance...

Soundguy

 

[JerryG]

Turbos can spin at 100,000 rpm. They are going very fast even if they are not producing boost. The Coke problem is a very real problem. The oil will cook on the bearings making them rough, which will cause the turbo to go out. Letting it idle for a short time at shut down is cheap insurance. Keep the oil changed in a timely manner, because the turbo will break down the oil faster.